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Mesh/Geometry quality
tried searching but couldn't find anything.
I do not have a 3d printer so can't really experiment on my own, which means that when I am going to order a 3d print I want to get it as good as possible. So, my question:
Do quality of geometry matters when 3d printing? Will 3d printer only print quads, or ngons are fine? Are there shapes to avoid?
Cheers :)
M.

There are design issues based on the printing method. Do you know what kind of printer they're using at the print shop you're considering?

As commented on my answer, you should specify the technology which you are asking about. SLA or FDM are quite different in terms of the quality which you can achieve for example.

It is going to be Ultimaker 2 most probably.

Welcome to the site!
In regards to quads, vs polygon. People will often reduce the overall detail to make it easier to print. But so long as after you export it to a STL and verify that your Manifold edges were done correctly and what you though was solid is solid, you should be good to go. As near as I can tell so long as you can export it to STL then it doesn't matter what meshing you use. That said I see Polygons more than anything.
Worst case you can run it through a STL repair program and it will make the required changes for you. Usually I used these tools to fix poorly rendered files.
My favorite is Nettfab. which is now part of microsoft.
You can verify if it will print by downloading slic3r, then "slicing" the file. After that you should be able to view a layer by later output.
Article talking about quads vs triangles from design
Shapeways article on preparing blender files for 3d printing

Thanks for the comprehensive guide, this is true what you posted - I will going to fight with a lot of those issues but still your answer is not what I need, I will try to detail my question more:
I wonder if 3d printer (PLA one) will have issues with triangles and ngons - like pentagon and higher (one face made from more than 4 verticles).
Will it be able to print such polygons, or I have to make sure my geometry is clear, made from quads only?

Updated. In short if you can export it you should be good. I cannot find anything saying you have to use a poly mesh vs something else. However you will likely want to reduce the quality to something more simple to printing.

If you're talking about the shape of the end result, rather than the constituent elements of the model - the answer is no, there is no simple geometric restriction. Have a look at 3D benchy for an example of how print quality can be affected by different aspects.
One obvious issue is overhangs, so the orientation of the part is important for printing. A flat circle will (on a cartesian printer) come out smooth as X any Y move in sync, and have good support. A vertical circle will have steps introduced by the slicing which quantises X and Y from layer to latyer.
Sharp, un-supported corners may be the weakest aspect to resolve in the print - extruded filament tends to shrink as it cools, but as far as I know the errors like this can be reduced by printing more slowly (and reducing the dynamic flexing of the frame too).
Talking about a top surface of an extruded n-gon, if you look at the slicing output, you'll see infill in the bulk, with a layer filling only the top 3 or 4 layers. There are several infill patern options, but yes, there is scope for a scenario where the top layer needs to bridge a long way. However, since the alternate layers fill in orthogonal directions this should be a minimal effect. Tweaking the infill percentage, or chamfering the corners can fix these small defects.

The overhangs are only a problem with FDM printers. The poster didn't mention which type of printer he is considering


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Thick wall or solid part of an otherwise medium-fill part
I'm trying to design a camera handle, which will be around 8" long and will have a brass camera thread insert in the end, where the camera will be mounted.  (That way, I don't have to screw the camera thread into plastic which will wear out faster.)
If I print the handle normally, the end of the handle won't be solid so I can't solidly put that brass fitting in.  If I set the fill in Cura to 100%, the print will take a very long time and will be unnecessarily solid.  I only need a centimeter or two at the end to be solid.
Is there a way to get one particular wall in Cura to be very thick (1-2cm) without affecting the other walls?  Is there some other way to get a solid chunk in the end of the part?

I think you are approaching this wrong. Sounds like you need to design it to have a hollow wall. That said to answer your question no you cannot have your slicer modify prints like that. But it bears mentioning you can set all shells to what ever you want have have a very sparse infill. To you can set vertical shells to 3 or so. Top to 3 bottom to 2 and infill to 7-15% so it will be 93% hollow not counting the 3 layers of solid skin.
Post pics of your design. Or let me know what else I can add. Check out my answer to this other stack overflow question

Now that you mention it, I think what I'm going to do is hollow out the handle in the design, and print at 100% infill.  Easy fix, and then allows for a USB cable or something down the middle.  Thank you for your input!

I'd suggest creating a hollow tube with ~1 to 1.5 mm walls. Then to increase the strength design your own internal structure rather than relying on the slicer to fill the part. This takes longer to model but you can design the strength of your part much better.
Something like this
If you were to then print this with 60 % infill you'll have the strength and also use less material. If you happen to know specifically how your part would be loaded, you could then change the dimensions on that internal cross structure to take the loads better.

There is a way to do this in Cura 2:

Load in a cube.
Place it over the location where you need 100% infill.
In the per-object settings (tool on the left of the screen):

enable Infill Mesh, and;
set Infill density to 100 %, and;
Wall Thickness to 0 mm.

I believe the solution is to use more walls in Cura.
Here is a 50mm cylinder with a 20mm hole.  I specified 10 walls in Cura.
This should give extra plastic for the screw to bit into, but not take all day to print!

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photogrammetry with partially translucent objects
I've captured a stationary spinning object in a computer game. It's semi translucent and there are stationary objects behind it.
As I expected it did not convert using Autodesk's remake. It gives no explanation other than 'Error'. I obviously can't paint the object. Are there any techniques in Photoshop that will let me manually fix the images to reduce the translucency?
Any other program that might produce a mesh from images? The game objects can't be extracted via any other program I've tried.

Did you mean to post this in 3d printing?

The intent is to 3d print the result. I'm not sure anyone without 3d scanning/printing experience would understand what I need to do.

Hi, @Jay! You question does fall somewhere in between several sites here on Stack Exchange. Do you think Photography or Robotics perhaps could give more feedback?

Regarding your actual question: is it so that you have several individual photos captured from a spinning game object? If so, could something like photomodeler perhaps do the trick?

I captured a video stream of a floating spinning crystal. I was then able to extract and crop individual frames. The autodesk online site is unable to work with translucent or shiny objects. Unfortunately this is both so it failed. I suspect photomodeller will have the same limitations but thanks for the link. I'll try it

I downloaded the photoshop cs5 and work in it.

I found at least 2 online pages that'll create a 3D stl from an image, basically using intensity (brightness) to determine depth.
selva3d.com  and   embossify.com
I used it with success on a binary (black or white) image, at least.

Nice links, but this object is fully 3d. It's a crystal that floats in the air. The blue thingy in this picture: http://vignette3.wikia.nocookie.net/asheron/images/4/42/Lifestone_Live.jpg/revision/latest?cb=20141117092544

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Printer changing temperature after selecting file
I have just got a Monoprice Maker Select 3d printer (which is really just a Wanhao Duplicator i3).
I want to print a model that came on the included SD card (1.gcode) with ABS filament. I first press "Preheat ABS" and wait for the display to show the correct temperatures, 245°C for the extruder and 90°C for the print bed. Then, I mount the SD card and select the file to print.
However, once I do that, the "goal" temperatures change to 195°C for the extruder and 50°C for the print bed, and the temperatures reported by the printer gradually go down as the printer waits for it to match the "goal" temperature. This results in a failed print, with the filament sticking to the extruder in a clump.
What is going on here? I am trying PLA with the same file, and it seems to work fine, although the temperature change still occurs.

The demo files are gcode files generated for use with the sample PLA that comes with the printer. If you want to print it with ABS select the file and set the temperature manually afterwards.

If you want to use the demo files, you can probably pause the print as soon as it starts, and manually set the extruder temperatures before resuming the print. Easier to generate new g-code though.

If you want to print the demo files with ABS rather than PLA, as the files are designed to do, I recommend loading the file into CURA and saving out a new gcode file with the adjusted temperatures. You can load the file from gcode, which will give you the basic settings that are included in the PLA file. I would also recommend slowing down the first layer a bit as adhesion of the initial layer is much more important for ABS than PLA, as ABS tends to warp more. Also you should reduce, if not turn off your cooling fans. Then once all the settings are where you need them to be for ABS, just export out a new file and probably change the name to include _ABS so you know the difference when you're mounting the card.


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Arduino Mega voltage regulator overheats with RAMPS board
This is my problem:
I'm assembling a 3D printer with the RAMPS 1.4 board and Arduino Mega. I have assembled the structure and the electronics (set drivers, placed the jumpers, connected stepper motors...) and have uploaded Marlin firmware (configuring: thermistor, endstops...) on the Arduino Mega.
I've tried to connect, via USB, to the computer and using the Repetier software I have commanded the printer which did do some movement. The printer worked perfectly. After a few tests, however, I've noticed that the Arduino was restarting several times and at one point I saw a component on the Arduino board burning. Searching the internet I saw that the burned component was the voltage regulator.
I heard also about unplugging the screen because it consumes a lot of current, that passes through the voltage regulator, thereby heating it up. I then proceeded to buy another Arduino Mega. I also checked the voltage of my 12V 360W power supply and it is correct. I always powered the Arduino with USB and RAMPS 1.4 was connected to the power supply from the two terminals.

When the new Arduino arrived, I connected the whole (without connecting the screen) and tried. The printer worked very well until it started giving the same problem as the first Arduino board. Someone can tell me if I have done something wrong, or is it the RAMPS board that does not work properly?
EDIT:
I read that the endstops can cause this problem. I have these endstops: 1 PZ di Alta Qualità Finecorsa Meccanico Per rampe Reprap 1.4 stampante 3D Con imballaggio indipendente kit fai da te and I connected the black wire to GND, red wire to 5V and the green wire to SIGNAL.

It seem unlikely that the endstops particularly cause this problem. Yes, unplugging the screen will help (but not fix the problem). This seems like a hard problem to diagnose without some experience. With the screen disconnected, your electronics really shouldn't be taking too much power. Maybe it is the stepper motors, these are able to take a lot of power, particularly if there is a mechanical problem.

@SeanHoulihane Your last suggestion makes no sense, as the stepper motors are not powered using the 5V regulator.

I wouldn't be so quick to rule out the endstops. Perhaps the connector is backwards, or the black and green wires exchanged, who knows? Maybe try measuring the resistance between 5V and GND (on the RAMPS shield) with the endstops inserted (and triggered/not triggered).

@TomvanderZanden, I wasn't sure, thats why I didn't try to post an answer.

Thanks for the replies! I measured the endstops resistance between 5V and GND and when the endstop is not triggered there is no resistance but when i press the button there is resistance. I tested also the boards without endstops but the voltage regulator heat up the same (but now i think that arduino doesn't work very good because the computer doesn't recognize the board). @SeanHoulihane

@Francesco The resistance between 5V and GND being zero is a very bad sign. You hooked up the endstops wrong.

@Francesco - Did you manage to solve your problem? If so, would you like to post an answer, as it may prove to be very useful for someone else who is experiencing the same problem. Was the issue, as Tom suggests, related to the endstops? Indeed, if there is zero resistance (0 Ohms) between 5 V and GND, when the endstops are closed (not triggered), then that would indicate that there is a short circuit, and that is, most probably, what is damaging your Arduino board(s).

@Greenonline Yes i've solved. The problem was that the voltage  regulator on the Arduino wasn't the original, so it wasn't able to absord too much current. To resolve the problem i unsoldered the diode(D1) on RAMPS board so the Arduino is only powered by the USB and everything works good.

@Francesco - that's great that you managed to fix the issue. It sounds as if other people would find this very useful information too. Could you expand upon your comment, maybe with a photo or two, and post it as an answer (not as a comment) and then mark it as the accepted answer, using the tick icon? That way, it will remove your question from the "Unanswered question" list. Thanks. :-)

I've solved unsoldering the diode(D1) on RAMPS. This diode provides to power the arduino board with 12V. If you have a chinese arduino this will probably cause some problems.

I hope this will help someone.

I ordered an authentic Arduino Mega today after the voltage regulator on my Chinese clone Mega went up in smoke. But I couldn't wait two whole days so I dug around and found an old 7805 (less than US$1 new btw) and soldered it in. It worked! Just one more possible solution. Actually that's two if you count buying a real Arduino.


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How does a 3D printer print itself given the huge size?
How can this be done given that the object to be printed is the same size as itself? In the CubePro printers that I have used before, the object to be printed is inside some kind of glass panel. Only objects that are smaller can be printed.

This question is based on an assumption, namely that 3D printers can print themselves in one piece. Maybe you could edit this question to add some basis for this assumption?

This question doesn't show much sign of any research. I'm struggling to see how it can be improved to be honest.

3D printers obviously do not print themselves. 3D printers are sometimes used to make parts for other 3D printers, and this is what is meant by "self-replicating" 3D printers (which is a bit of a misnomer, considering that all designs require a substantial amount of non-printed "vitamin" parts).
A printer that is able to produce many of its own parts is the RepRap snappy, which (as the name suggests) consists of plastic parts that - while they each fit within the build volume - snap together to make up the larger parts for the printer.

So, replicating printers mean they print components of a 3D printer but assembly of these components is still a separate process?


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Are self intersecting meshes dirty from a 3D printing perspective?
I have never much cared about self intersecting meshes when slicing with Cura. Geometry like the one below are often practical. I for instance add lots of rivets that self intersect with the base geometry:

Now I have switched printer, and am using Simplify3D instead. All of a sudden, I get lots of problems with these models. The intersection of the objects become hollow. Simplify3D has a setting to join the outer solid shell but it also fills holes (such as the center hole of a gear).
I make models to sell so this is a big deal for me.
EDIT: Also, they printed perfectly fine in formlabs "slicer".

Self intersecting meshes are considered dirty, yes. The reason you haven't had trouble before is probably that the software you were using was cleaning your mesh for you, behind the scenes.
Generally speaking, these meshes can be cleaned without too much trouble by software like netfabb (https://www.netfabb.com/) which has a nice free version that I use for basic cleaning of some of my meshes. A quick google on "netfabb free fix mesh" should turn up a tutorial or two.
If you're interested in learning more about an operation you can use to make this a single unified mesh, it's called a Boolean Union, and the blender project has a nice (open source, I think?) implementation of such: (https://www.blender.org/manual/modeling/modifiers/generate/booleans.html)

Except for the netfabb free version there's a free online STL repair service (based on netfabb) at https://tools3d.azurewebsites.net/ also, every copy of Windows 10 includes an app called "3D Builder" that does not actually build 3D models but as a pretty good auto-repair feature

hmmm, so joining the separate closed but intersecting meshes like the cubes in the OP's image is one thing, but do you know if netfabb and blender can also fix self-intersection on a single connected mesh?

@Andy Netfabb has the ability to fix some self intersections, yes. However it is case-by-case; generally if the self-intersections "aren't bad" Netfabb can handle it -- but it can be tricky to perform complex self-intersection resolution, because it eventually converges into something quite similar to mesh booleans as described above.

You definitely need to get rid of the self-intersecting meshes in order to be able to 3D print your object. I would personally recommend you try MakePrintable:  automatically clean these type of meshes.
Makeprintable is a cloud service (your model is uploaded to their servers and processed there) currently in beta. You need to sign up but it is free (and they state that they will keep it free).

Definitely is a strong word. :-)

You can download MeshLab from https://sourceforge.net/projects/meshlab/ and use it to head stls.
This video has healing instructions: https://www.youtube.com/watch?v=eLGIRAgLz4w

The video only shows how to get rid of duplicate geometry and merging close vertices. It doesn't show how to get rid of self intersections. Perhaps it is the wrong link?


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Reprap prusa i3 Y and Z axis swapped when printing GCODE files
I'm having an issue with my new Prusa i3. (This one: https://www.amazon.co.uk/gp/product/B01DLIRDFW/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1)
For some reason the Y and Z axis are swapped when I print Gcode files, even though all the axis move correctly when I manually move them with the interface on the LCD. Also, if I try to print an STL file, the Z axis moves in one direction more than it is actually limited to, and then does the same again in the opposite direction when the print starts.
Anyone know the solutions?

Sounds like your slicing program is not set up right.. Or more likely your printer isn't.
I would use Pronterface
I use simplify 3d, but the best free software is Slic3r.
Try those then report back. Honestly I think you might not have it wired correctly. With pronterface tell it to move X. Then try moving it and manually holding the endstop. Then if it does not stop try going tho incorrect way with that endstop still pressed. If you find that your reversed you will need to correct this with your firmware. If I knew this was a ramps board you could reverse the wires, but lets do it in firmware as I am not buying you a new board.
After that you should work. Software wise we just made sure your interface and your slic3r work and talk the same language. Those two I know will not be doing anything funny. After that report back if it is still not working.

UPDATE I've managed to get it to connect. I'll do a test print now

Okay, I've managed to get my printer to connect to Pronterface, but the Y and Z axis do not move the correct distance in accordance to what distance I control them to move. For example, if I command the Z axis to move forward by 10mm it moves way further and tries to go over the limit. The Y axis moved too little of a distance. What is causing this?

@solluu The Z axis generally moves up and down, not forward (or backward). Are you sure you're using the right names for the axes?

That's solved the issue :) Thank you so much for your help! All I need to fix now is a blocked endcap lol.

Hmm yes I should have included documentation of which direction is which. Glad it is working.


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Prusa i3 Z axis not moving up
I just got a Hictop Prusa i3 printer and I have it fully assembled. When I tested out the motors to check them the Z-axis motors were not moving and it was making a grinding sound. I have lifted the screw rods out of the coupling to see if the motor would move the coupling would move and it did. I can move the screw rods manually and it works. How can I make the Z-axis work?
Thank you in Advance!
Edit
Here is the vidoe of the problem https://www.dropbox.com/s/93g0pg0qfhq965d/IMG_0369.MOV?dl=0

Are you sure the extruder & drive assembly are mounted at the same height on both Z-screws?  If they're cocked, that'll cause a lot of binding.

@CarlWitthoft I second that. Bubble level Everything.

If you wouldn't mind uploading the video to youtube so that the question will be of use for future people. Dropbox is not known for its long term use.

At this point we can take it into Chat http://chat.stackexchange.com/?tab=site&host=3dprinting.stackexchange.com Or I might suggest a few groups that can add more interactive answering. As there is a need of a bit of back N forth.

Welcome to the group! A video would help. Or at least some photos.
Are both the motors connected? If you remove them from the coupling do they move? Likely it is binding (too much friction, not level etc) or you need to adjust your voltage controller. I am going to say 80% confident you need to play with the voltage.
Chances are it's just the voltage. I do not know what electronics you have but if they are RAMPS 1.4 then you are looking for these

Also here is the wiki on the 1.4. Just turn the screw gently. One direction will give it more power. The other less. When it has too much power your motors will start making a thud noise.
EDIT post adding the video
Oh yeah that is binding. If you wouldn't mind putting the video on youtube to that the video can help people for years to come? Dropbox is a bit volitle.
I would also in addition to my advice in your other question take a bubble leveler to all the rods. It could be a distortion on your camera but it looks like the rod is a bit bent. Also in my Prusa (original) I used to have to make the motor mounts lose, as it did not fit all that well and had binding issues. Try making the screws loose enough so that they float and can move around a lot. The lead screws are less important to the overall stability.

I found out the issue. Thank you for your answer. I have posted another question (http://3dprinting.stackexchange.com/questions/3294/is-there-a-problem-with-removing-a-polished-rod-from-the-z-axis) seeing if what I did is okay.

The rod is very slightly bent. I have put the rod back into the printer and it is not aligned with the hole. I was thinking of cutting the acrylic piece so the rod would fit into the hole, since I have tried running the z-axis when the rod was out of the hole and there was not problems, is this a bad idea? I have updated my question with a picture of this.

I would replace the rod. Should only be a couple bucks from mcm or other online sites. You can cut it to length with a saw or Demel. Changing the mount won't fix the issue which is the rod is bent.


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3D print Configuration Cura - Anet A8
I'm new with my 3D printer, I just print two different pawn pieces from thingverse. I just used Cura to convert the files to be readable for the printer. Is my problem with the pieces has to do with the configuration from the Cura software? or with my printer itself?

Update:
I just printed a baymax that came with the SD printer. And it looks awesome. I think the problem is with the configuration from Cura.

Could you edit the title of your question to be slightly more descriptive of the problem? "Problems" is too generic.

You should include a bit more information in your question, like what settings you are printing at, what material, etc...

I update the title and add an Image. The default piece (Baymax) looks awesome. Dont know yet the configuration it has.

What printer profile do you use in cura?

Don't use the GCode on the memory card. Setup your Cura correctly and try with new filament.

Underextrusion (as this looks like) could be a extruder problem. The extruders main part is the small gear that pushes the filament through the hotend. There could be lots of reasons for it to fail:

The motor driving it isn't strong enough. Poorly designed printer (yeah, ultimaker, I'm looking at you). Not very likely. But a geared extruder or motor can improve extrusion.
You print at to low hotend temp. If you increase the temperature the filament will become more fluid and easier to push out. Increasing the temperature will unfortunately increase risk for clogging and stringing.
The filament has absorbed moisture. Try drying it.
You print to fast. Lowering the speed may do the trick. You also have to wait longer (dhu).
The acutal gear in the extruder is full of filament bits, clean it.
You don't put enough force on the filament against the gear. Can you tighten it?
The gear is not hobbed. A hobbed gear will grip the filament better. You might not be able to switch it.
The filament has become tangled on the spool. Be careful when you handle it to not unroll it. This usually results in that the filament becomes entirely stuck though.
The nozzle is clogged. See answer from @Tom van der Zanden.

If you don't have a geared extruder you can print one. There are plenty of them on thingiverse. Increase the temp and lower the speed to get this vital part in good quality.
Or you can buy a geared extruder. (I use the titan extruder from e3d)
Or you can buy a geared motor.
How to detect an extrusion problem:
It is quite easy to hear if you have extrusion problems (at least some of them). The Extruder will make a sound like "drrrr" with regular intervalls as it tries to push through the filament. Almost like a clock ticking but slower. This is the gear slipping against the filament.
If you don't have an extrusion problem:
Experiment with upping the Material flow rate in your slicer (in your case Cura). Try something like 300%. Stand watch and see what happens.

If this almost fixes the problem, you must calibrate the printers extrusion. It is possible that the already generated Gcode (found on the sd-card) compensates for this.

I just print a baymax that came with the SD from the printer. and it print great. I think the problem is with the configuration from Cura

@Pulse9 edited my answer

Yeah, the problem was the configuration from cura, Im not sure what was my last configuration but when I update everything it looks awesome. Thanks

this is more than a year and half later: but always check the line above flow to be the right diameter! I had one time CURA resetting from 1.75 to 2.85mm after an update.

That looks like horrible underextrusion. Either the extruder steps/mm are way off, but more likely is that your nozzle is clogged (because I wouldn't expect the steps/mm to be this far off). It's also possible that the temperature you're printing at is inappropriate for the filament you're using. Also, make sure that the fan that is cooling the heatsink of the extruder is always on. If not, filament may soften in places it's not supposed to and jam.
Try heating the extruder up and pushing the filament through by hand. You'll probably feel a lot of resistance and the filament won't come out smoothly. You could try doing a couple of cold pulls, that is, put a piece of filament in while the hotend is hot, then let it cool down and attempt to extract the filament at the lowest possible temperature. This may pull debris or particles blocking the nozzle out.
If this doesn't help, there are various other ways of clearing a clog from the nozzle. One popular technique is disassembling the entire hotend and burning out all the debris from the nozzle with a blowtorch. Another is using a special drill bit to clear out the nozzle but this has a high risk of damaging it.

I use a strand from a wire to clear the nozzle if I need it. But the cold pull is preferred.

Hi, I printed a baymax that came with the SD card from the printer (I update the post), and it printed really well. I think the problem is the cura configuration. Is there any how to get the configuration from the baymax file?

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How to prevent bend (or warping) with M3D printer?
Hello is there a way to prevent bend on print with M3D printer?

You need to provide more information...  What material are you printing, is the bed heated, if so what is the bed temperature, do you have anything on the bed?

You can to print a brim, a thin layer on the bottom connected to the model. This will help hold it in place. Since it is thin (one or two layers) it will not warp itself.
The brim is not the same thing as a raft. A raft is under the model. The brim is on the same layer as the models bottom layer but outside the model. It looks something like this:

I assume that you use a heated bed if you have one?
Also, it is imperative that you get a good first layer. Calibrate your machine carefully.

Do you mean like a raft? I already did that and still it warps on top of the raft

@xybrek I edited my answer

Going to also say you need to provide us with a ton more information. What settings, what temps, what plastic.
That said the best thing I can recommend is doing a Raft for your print. Adding a Fan to your printer. Making sure your heated bed is on. I also like to use gluesticks for PLA, hairspray or Kapton for ABS.
Here is Ultimakers guide to Gluesticks
Here is a guide on rafts and Brims from simplify 3d
Comment on my answer once you provide more information and I will improve my answer.

Try using an adhesive before you print. This could be http://airwolf3d.com/shop/wolfbite-prevents-3d-printed-parts-from-warping ... What is the temperature of the room you are printing in like?


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Is there a problem with removing a polished rod from the Z-axis?
I recently had a problem with the z-axis of my printer. To resolve the issue with the Z axis not moving I remove the left polished rod. Am I able to use the printer with just one smooth rod?

Please define "problem."    Arbitrarily redesigning a system without knowledge or analysis is a bad idea (TM)

First a resounding no. Not a good idea. Are you saying it works now that you have removed the smooth rod?
That tells me for sure your issue was Binding. Which is a tricky problem to solve. Binding usually happens when your carriage is not level. Take a bubble leveler and verify.
Another time it happens is when your Acceleration / Jerk settings are too high. Try reducing the Acceleration for Z in the firmware.
Another possibility is your rod is Bent. Take the rod on a flat surface. Inspect it as you roll it around. Do the same with the other rod. If it bows and is not completely flat, then you will need to replace it.
Last is make sure your printers frame is put together. If it is causing the rod to bend as it is not aligned right then you should try to see if you can fix it and contact the seller.
Technically you can run without the second rod. Maybe. I do not advise. It is sort of like cutting off a leg because you have a cramp. It will hurt your overall quality and it is better to just resolve the issue.

quick note that a bubble level is only going to work properly if the surface the printer is on is level too.  it doesn't  need to be level to gravity, just relative to the printer.    laser leveler works if you got one, though you can just level the surface the printer is on first then bubble level it.

No, this is not a good idea. Your X axis is now free to rotate by a few degrees around the remaining Z rod. Parts may appear to print OK, but depending on the dynamics of a print, you will see offsets between layers. You need to resolve the issues with your Z-axis.
 These questions, z-axis hard to move in some areas - what could be faults, how to improve? and Z-axis steppers and bed alignment problems have some answers that are probably relevant.
Obviously, you can use this limited setup to print new parts if you need them, but you'll be lucky to make anything accurate enough.

It may help someone I am just noting that all your comments are valid.  I was reading through forums to find a solution to the binding problem.  After calibrating, levelling, and adjusting, what I found out was rather simple.  The two motors came out of phase (not sure how).
Here are the steps I took.

I unplugged the motor on the left and the other motor was driving the Z axis just fine.
I unplugged the motor on the right and the other motor was driving the Z axis just fine.

I started thinking in terms of my power supply providing enough current to drive both motors and then I rebooted the controller.  When the system came back both motors were driving in synch.


text:
Retainer for PTFE in throat
I've tried using a throat with a PTFE tube, but encountered the problem described in this question. It seems only a small amount of excess pressure in the extruder is enough to force out the inner tube. This makes me worry that with this particular part, I won't achieve a reliable configuration (and I'm experiencing some binding with the original plain steel throat, so a PTFE liner seems worth exploring).
I was wondering about the advisability of using a retainer to apply some pressure at the cold end - a nut with a washer soldered on maybe.
My goal is to prevent the teflon tube from rising up, so I can use this part and retain some resilience against excess extrusion pressure. I was assuming I had a slightly sub-standard throat part (in a pack of 6).
However, I now wonder if the problem was caused by too high a temperature (this is ABS filament) and maybe the teflon will be too soft to function as designed, so if I go back to PLA filament, maybe it is more likely to work without modification.

Why do you think you need this modification? I am not sure what you are trying to accomplish. That said so long as it's outside of the melt zone... else use metal.

@SeanHoulihane I have temporarily closed this question as it is currently unclear what you are asking. I believe you're trying to prevent the teflon tube from being forced out, but I'm not sure. Seeing as how this question has been active for a little while now, I would recommend trying to make your question a little clearer. I will keep tabs for a few days and re-open if it becomes better. If I forget, don't be afraid to PM/ping myself or another moderator. Thank you.

@Sean Thank you for updating your question. Hopefully our answers help.

In this case I would like to first recommend replacing your PTFE tube with a better quality product. Unfortunately, the quality:price ratio is as to be expected here. My reasoning:
PTFE has great thermal properties for a polymer, just like ABS. In fact, the glass-transition state begins at relatively the same temperature between the two materials. ABS starts transitioning at about 105°C and about 127°C for PTFE.
However PTFE, traditionally, has a much higher melting point at about 327°C as opposed to the usual 125° we use in 3D printing.
My Point: I think the hardware you currently have has low-quality PTFE.
PTFE can be recycled for re-use in other PTFE products. In recycled PTFE, you can lose a lot of the desired properties in the material (true for any material). This includes both the ideal "friction-less" and thermal resistance we need in 3D Printing.
What I think happened: The higher print temperatures of ABS transitioned the PTFE into its glass-state. As the throat expands, the path of least resistance in the assembly is towards the extruder motor since the nozzle holds more pressure.
I would not recommend "fixing" this problem with a retainer! By forcing the PTFE throat to stay in position, you could potentially force the PTFE to expand in other ways. Most likely resulting in constricting the filament, leading to grinding of filament on the drive gear and clogging of the nozzle. Worst case, you end up with gooey PTFE in your nozzle and/or around your retainer.

I see, you want to Block the tefflon tube from going Up and Out of the extruder. Yes I see no reason why you would not fid a nut cap. Drill a hole and have it work. There is likely a special nut cap with a pre existing hole in it already but I decided the keywords was asking for bad results on a work computer.
The only thing I can see happening is you will 1) possibly not have the clearance. 2) have a larger thermal mass.


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Tool to measure in STL files
I want to create parts for a 3D printer using OpenSCAD. Having some STL files from the vendor, but nothing else (no technical drawing, no CAD files).
Does anybody knows a free tool, that allows me to

measure distances between 2 selected vertices,
measure distances between a selected vertex and a plane defined by 3 vertices,
measure the radio of a circle defined by 3 selected vertices?

I very much like the way Blender allows to work with meshes, especially select vertices or planes, but unfortunately haven't found a way to measure with Blender.

As far as I know, there is no real size information saved in .stl files, only relative positions of points in a generic unit measure. When opening an STL-file, you will have to specify how long one "unit" is. Most editors probably use millimeters or inches by default, but mixing them up will yield results such as this. Just thought you should know. :)

At thingiverse, for example, you often find only STL files that print in the right size, so the values in the files seem to be mm.

There is also a Blender community here on the Stack Exchange network if you have more general questions about Blender.

I suggest Blender. It's not the simplest of tools but it is free and learning it will improve your 3D printing skills. :-) (I write this answer also for future viewers of this question so I start basic).
Another answer can be found here, How do I measure a distance between two points?

Import your STL file.
Press the Home key to view everything.
Select the model by clicking on it with your left mouse button. (Blender changed to left-click-select as of version 2.80)
Hit tab to enter edit-mode.
Press N (or use View | Properties) until the Properties panel shows up.
Select the "Length" checkbox in the "Edge Info" section of the Properties panel (see image below).
Select "Edge Select" mode (see image below)
Select the edge to measure by clicking on it with your right mouse button.

If you need to measure the distance between to vertices with no edge. Create the edge by selecting them and pressing F.
If you need to measure the distance between a vertex and any other point, select it and press E to extrude.

Blender also has a tool to measure: Ruler and Protractor independent of edges.

As @Gunslinger suggested, I would also recommend Blender for these tasks.
Blender comes with the Add-on "MeasureIt", which has to be activated manually in Edit ► Preferences ► Add-ons ► Official/Community ► search for MeasureIt, check the checkbox:

Import your STL file via File ► Import ► STL ► ...
Select your object and hit TAB to enter Edit Mode and then follow the tips in this screenshot:

Use Meshy "...a WebGL-based tool that does measurements and simple transformations on STL and OBJ files.": https://0x00019913.github.io/meshy/

If you're running Windows, MS 3D Builder has a measuring tool and may already be installed on your machine.

I'm having pretty good measurement success with 3D Builder

Meshmixer has various measuring tools for STLs as well

That is great. You can also do the 3D model measurements using SelfCAD software.
I can confidently recommend to all users because it is suitable for both 3D artists and beginners.
The software has a built-in Measurement Tool that allows users to accurately measure the size of 3D models. The tool can be used to measure the length, width, height, and angle of a 3D model. To use the Measurement Tool, users simply select the part of the model that they want to measure and then move the pointer to the desired measurement point. The Measurement Tool will then display the measurements in the software’s measurement panel.
Check this video on how to do the measurements of 3D models using SelfCAD

I recommend Ultimaker Cura 4.3 for dimensioning.
You can access it here.

As can be seen, detailed measurements can be made over the specified coordinates.

However, you can make an accurate dimensioning by using the Render program. I recommend doing this before working on the STL file.
I wish you good work.

As it’s currently written, your answer is unclear. Please [edit] to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers in the help center.

Why referring to an old version, 5.3 is now the current version! Please explain this, e.g. because the feature isn't available in the new version or something like that...

I worked a lot with this version.  Although the version difference is not much, I wanted to recommend it because I am satisfied with the version I use.
Upgrades may consume more memory on your computer. This version, which works efficiently, will be sufficient for the work to be done.

Why reference an version at all then?


text:
What causes these round corners
Nozzle diameter = .4
Extrusion multiplier = 1
Extrusion Width = .45    <-- I feel like this could be reduced to fix it?

Layer Height = .3

I'm using Simplify3D.

What looks interesting is that the right hand side bevel seems to have excess material, but the left hand side does not. I assume this is the part which you're asking about? Extrusion width should match the nozzle size.

Left side does as well.  Look at each corner, you see how it looks like there is a circle on each of them?  Also, I'm using the extrusion width profile from the manufacturer...presumably it's supposed to be good?

Is that photo from the top or bottom of the print?

The effect can be seen on every layer.

To me, it appears that the short segment is offset about 1mm in the NE direction. Left side seems slightly open, right side seems compressed.  So on the left side, the curve is due to the sides peeling back from open ends, at the right, there is over-extrusion. This would make it a mechanical problem of some sort - possibly due to drag from the filament feed making the travel asymetric.

Are any of the answers posted here solutions to your question? If so, you may want to mark them as such, if not what else is still outstanding?

If it's on each corner, and not the layer change corner, it's a combination of overshoot and the short "pause" of the printer when it changes direction.
You can minimize it, but it won't go away 100% (due to overshoot from direction changes), usually models with a slight rounded corners work great.  If you, say, increase the jerk as an experiment and they get sharper (but you obviously have to deal with potential ringing artifacts) then it's due to that pause and acceleration after a direction change.
I would try lowering the temperature a bit to slow the flow/oozing of the nozzle and calibrate extrusion - just to keep the settings tight as possible to keep dimensional accuracy, but not under extrude obviously.
If it's where a layer change occurs, tweak and play with retraction settings - such as coasting and extra distance on restart (you can put negative values here). Once those are set, as an advanced tweak, try to max the z speed... Obviously this involves motor current, testing for skipped steps etc... but this would make the layer change a bit quicker, to further reduce oozing, due to the delay in layer changes if retraction settings don't fix it.
Usually, you can fix the corners with retraction settings but then it can mess up other parts of a model, since those settings are global... I wish slicers were more intelligent.

I don't think it's whiplash. It it was it would be less uniform and not on every axis. Also while there is no photo they did not complain about the walls having deformities caused by the random offset.

true, other case would be if the belts were loose on both.  forgot about that.

One of the belts was loose, I also played with the retraction settings and speeds.  Problem has definitely minimized.

Oh thats simple. First you will see the "elephants foot" on first layers if you have the extruder over-extruding or do not have enough distance between the bed and nozzle.

It's very common that the first couple of layers of a print is wider than you expected them to be. This is because you will generally want to make sure the first layer is nicely squished into the build platform so that it sticks properly. By doing this the plastic gets squished out into a thicker line than normal and thus the bottom of the print will bulge out a bit like an elephant's foot. You can decrease this effect by leveling your bed so that the nozzle is slightly further away from the bed and lowering the bed temperature a bit. It's hard to get rid of this effect entirely without sacrificing bottom layer quality and bed adhesion. It will be easier on small prints as they are less likely to warp and detach from the platform and you can therefore get away with not squishing the first layer as hard.

See this visual guide on more information
If you are seeing this on all layers. That means you have oozing. When your printer hits the end of the line. It has to slow down, stop and start the next vector. During this time if your printing very hot, you will ooze material at this intersection. Also the extra time over that spot mayhaps also warm the corner, causing more disruption. Best thing in this situation is to verify you cannot lower temps more. Add a fan. Also double check that you are extruding the exact amount you think you are. (distance of material and the material size average)
Here is another visual trouble shooting guide
I will note, I don't think thats too bad. If it needs to fit into something, just clip it.

Hmmm, I guess it could be oozing due to the temp.  I'll try some cooling settings.

If you want to post your firmware settings and temps as well.

Three factors that will impact the 'sharpness' of corners, first is your extruder speed, second is retraction rate and third is nozzle diameter.
By slowing down your extruder will be able to track the features of your model better. I generally try to print with extruder speeds of ~10mm/s which gives fairly good results. The nozzle diameter will be the most extreme limiting condition on how sharp you can get your corners. This I think is likely your issue.
Retraction rate could have an effect on the corner sharpness. I don't think that's the problem you're experiencing but worth mentioning. Depending on the specific geometry if your nozzle stops at a corner while it raises in Z if your retraction is too low additional filament can ooze out making the corners appear more rounded.
Typically a nozzle diameters are about 0.4mm which is pretty sharp, however if you have something larger that could effect it as well. Again, not your specific issue but something to keep in mind for future builds.

Enable "classic jerk" in the firmware and put it to 12 on both X and Y.
That helped me get perfect prints.

Your printer is over extruding.
It looks like PLA on the photo, the preset multiplier in S3D is 0.90 (not 1.0!)
The nozzle diameter should be the same as the extrusion width (both 0.40).
When you set the width to auto you get a bigger width. I don't really know why, but it was told me so.
If you print 1.75 mm you have to measure it and (the actual diameter is often around 1.78 mm, maybe less too). The multiplier of 0.9 is because PLA is softer then ABS for example. Maybe you should try other multipliers as well, maybe down to 0.85 in 0.01 steps.
I hope you can figure this problem out. I am experimenting by myself for days now to get it as sharp as possible. The goal is to get an edge with the diameter of the nozzle - not a bit more.

This answer is almost completely wrong. The preset multiplier depends on the tension of the spring in the extruder, it cannot be blindly predicted but it must be measured. The extrusion width can be the same of the nozzle diameter, but it is recommended that it is around 10-15% LARGER, so 0.45 mm for 0.4 mm nozzle. Filaments are usually smaller than 1.75 mm or equal, not common to be larger (for obvious reasons: larger diameters may not fit in some low quality printers). Also, PLA is far harder than ABS.


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Makerbot Replicator 2 Halts during print
I am running a MakerBot Replicator 2. During the print, the printer just stops executing and I am running out of ways to troubleshoot.
After restarting, I can load and extrude filament.
I have replaced the SD card, and even borrowed one from another working replicator, and the freeze still occurs.
Likewise, I've regenerated the x3g file, and that did not work.
The panel does not freeze, I can cancel the print during the freeze.
I've made sure Z pause is off. It tends freezes randomly on the first layer.
In general, it looks as though the print is "in progress" but not making progress (Timer ticks up, % completed does not)
Does anyone have any idea as to what could be causing the problem?

Ouch. If I had to guess something is overheating on your controller board. Probably need new electronics. But that is a complete guess.. The rep 2.. I think you can take that guy apart. Verify all the connections. Put back together.

You got it, I'm not sure which connection it was, but after hunting down all the connectors and giving them a firm press, the issue was corrected.

Are you running the most current firmware version?

There are a few options. First your board could be overheating etc. That is harder to verify without some overpriced replacements. So to start lets take everything apart (photo and labeling is Strongly recommended). Then simply put it back together. Hopefully it is just a loose connection.

By "stops executing" do you mean that the extruder stops extruding but continues to run through the motions? or does the entire machine lock up?
If your extruder stops depositing plastic, then I would suggest checking your settings. Specifically retraction distance, filament diameter (compered with your actual filament diameter)  and temperatures. Sometimes bumping up the extruder temp 5 degrees can fix this issue.
If all that's ok, then I'd suggest possibly swapping your extruder nozzle, if it has a bur inside from manufacturing then this could be causing too much pressure and the nozzle gets clogged.
IF however the extruder gantry freezes up and the z-axis keeps pulling away, I'd suggest calling maker bot directly as this would be more of a serious hardware issue, likely covered under warranty.
Good luck!

After removing the front panel and the bottom protector plate (the one that protects the controller board) and firmly pressing every connector, the issue corrected itself. It seems that something was loose, and that causes the freeze behavior.

Seems like others have had similar issues: https://www.thingiverse.com/groups/engineering/topic:3849. Their issue was a bit more mechanical than firmware, though. I hope this helps!
You might also want to check the software you're using to slice the file. Sometimes the software doesn't slice the file properly, which causes problems mid-print.


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Orientation of long thin rod on P3Steel v4
I have a derivative of the P3Steel v4, which is not the Irobri design but another version (I'm not entirely sure which), from Poland: Frame Prusa I3 P3Steel v4.0 +RODS.
I have assembled the frame, following this guide, manual_p3steel_xl, only to be left with one part, which is the long thin rod, which has a small hole, only in one end (the hole is marked by the big arrow in the image below):

This part obviously goes into the slots at the bottom of the Z axis arms, as shown by the curved arrows.
However:

Which way around does the part go?
Should the small hole be on the left or the right hand side, when looking at the printer from the front?
Also, what exactly is the hole for? Is it just for a zip tie, and to be used to keep the cables (maybe from the heated bed (power and thermistor)) tidy?

I have looked at a number of other photos and videos for the P3Steel frame, and none of them clarify which way around, or how, the rod should be fitted. The bar is either omitted completely, or the image is not clear enough to show the correct orientation.
The guide does not show this part being used, although it clearly shows the slots for it in the Z axis arms, in a number of the pictures, such as here:

I think you are overthinking it... Unless there is a reason for the small hole, then it is likely just the result of the Manufacturing process. Then there is the tried and true method of plugging it in and seeing if it works!

@StarWind - I know what you mean, but it is not an artefact from manufacturing, it is in the part specification (I'll try to dig them out). Also, I could just put it in and hope for the best (which is actually what I have ended up doing, to be fair). However, to change it would then require some major dismantling - in order to just reorient it. That's the only reason why I want to get it right the first time around :-)

If these frames are ever sold powder coated or plated then that hole could be present to hang the part for said processes as most other parts appear to have a hole or easy way to hang.  Otherwise maybe it's a hole to route your motor wires through to prevent them getting in the way of the carriage or to run a cable tie through to hold wires?

You can see the placement of it on the ebay pictures, small hole is on the right side when looking from the front.

@tjb1 - Well spotted on the eBay pictures. Thanks. I hadn't noticed it before.

This is half of an answer. I have finally received an answer from my supplier, which says:

Long thin rod is mounted as in the photo. I do not know what is a
  small hole.

So the small hole is still a mystery.
Here is the photo that was included with the message (which confirms my placement, just not the orientation):

Update
As tjb1 points out in his comment, the hole can be clearly seen on the right hand side of the bar, in the eBay photo:

If the hole isn't used by anything and everything else works, I'd say just ignore it. It may have been added during prototyping phase and never removed from their drawings, or could have been added as a datum feature for their manufacturer (though this seems a bit extreme for a part like this). It may also be a mounting hole for a set of features or upgrades that aren't yet available or were ever followed through on.

@Diesel - "datum"... For confirming that the printer is set geometrically square, flat etc.?

It's possible. I was thinking more for the the manufacturing of that specific part though rather than for the full assembly. I've sometimes added simple features to parts specifically for making measurements at final inspection easier. Generally they're ridiculously complex organically shaped parts that are hard to measure, which is why I don't think that's the case here. My guess is that this hole is either an artifact of a previous design that was never removed, or a mounting point for a future upgrade if it isn't required elsewhere in the assembly.


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Skipping Y-steps, only when using Ultimaker Cura
In order to find out why my printer sometimes skips Y-steps (always in the same direction) only in Ultimaker Cura, I am digging into the G-code to understand the problem better. However, thousands of lines of G-code are hard to analyze.
I am using a Mk2 heatbed with a glass sheet, and a NEMA17 motor in a P3Steel Toolson Edition printer. The axis feels reasonably easygoing in both directions.
Reducing the acceleration to 4000 did not get rid of the problem completely - it might have relieved the issue, though. I didn't do quantifiable tests, sorry.
Are there any other obvious things I might have missed? I know the acceleration might still be rather high, but since it works with Slic3r easily I would like to take advantage of some features in Ultimaker Cura with this printing speed.

Just to clarify, you never get Y-axis skips when using Slic3r? So, it is definitely a software issue? Otherwise it might be that the stepper motor driver for the Y-axis is providing too much (or too little) current...

Yes, of course, increasing the maximum supplied current to the motor gets rid of the issue. Still, I'd rather go with lower current to limit heating up the motors. I was just wondering if there is something in the two slicing engines that makes cura provoke much harsher movements that cause the printer to lose steps...

Skipping steps means the current to the motor is insufficient for the required motor torque.  Principle driver of torque in a 3D printer is acceleration.  You could compare the GCode to see what is being set in the M201-M204 commands.

Assuming you set the same acceleration in both Cura and Slic3r, are you sure they are applied correctly in the gcode file? In the case that the software does not output the correct gcode to set the acceleration, then the default values already set in firmware are applied.

Is the same infill pattern being used?  Some infill patterns stress the acceleration much more than others.

@markshancock yes, and jerk too!

@Valmond, for an interesting discussion on jerk in 3D printing see Jerk and Acceleration in Marlin.  While the "jerk" settings in the 3D aren't exactly "jerk", they are close enough to be the same (except for the units).
In my experience (outside 3D printing), too high "jerk" typically causes mechanical distress.  Sort of like on a Roller Coaster, acceleration stops your heart rattles jerk rattles your bones.

For 3D printing limiting jerk too much on the print axes can cause globing in the corners.  Limiting it too much in the extruder could cause problems with retractions.

@markshancock Interesting read for real world jerk-examples, but there is a lot of bad comprehensions there IMO (the math part of jerk etc.).

Without more information this issue will never be able to be solved

You answered your own question in a comment.

Yes, of course, increasing the maximum supplied current to the motor gets rid of the issue. Still, I'd rather go with lower current to limit heating up the motors. I was just wondering if there is something in the two slicing engines that makes cura provoke much harsher movements that cause the printer to lose steps... – kamuro May 21 '17 at 21:22

Motors are tough
Motors are meant to be warm, some are made to be hot.  Not all motors have the same specs, but I pulled one on Amazon (link) which shows a rated temperature rise of 60°C above a rated ambient temperature of 50°C.  If these specifications stack, and they should because the insulation of the motor is rated to 130°C, you can boil water on the stepper motors.
But ... other factors
But, what are the real limits, and how much current should you run through the motors?
First, many 3D printers have plastic mounts for the stepper motors.  You don't want that plastic to soften.  It can if the motors get too hot.  I've seen it in a commercial 2D printer, and gnashing of teeth across the Pacific ensued.  Even for PLA, that temperature is uncomfortable to human flesh.  I soften PLA at 75°C when fitting tight parts, but PETG and ABS are good for higher temperatures.
Low current hurts accuracy
Motors are remarkably linear converters of current to torque, but they still have non-linearities at the limits.  This matters most when micro-stepping, which (AFAIK) all 3D printers use for higher resolution.
Two factors hurt accuracy at lower currents when micro-stepping.
Non-linearities in the drivers result in magnetic fields that do not linearly align with the commanded drive strength.  The torque is not exactly what is needed to position the motor between the poles at the correct angle.
Static friction, sometimes called stiction, requires additional torque to overcome.  In a slow micro-stepping move, this will result in the motion hanging back, then jumping ahead.  Motion can be ragged rather than smooth.  Extrusion can be pulsating rather than smooth.
Both are improved by applying enough current to the motor to generate enough torque.  More current gives more heat, but also better behavior and performance.
Power up the motors!
They can take it.  Check their mounts to be sure the mounts aren't underdesigned.
Why Cura and not Slic3r?
A deeply detailed review of the g-code would be needed.  It could be as simple as the direction of infill, or the preferred direction of your model compared with the direction chosen by the two slicers.
It could be some limits coded into the "custom g-code" portion of the two slicers.  I am not familiar with Cura, but Slic3r allows you to insert additional g-code under many situations.  Something brought in with a printer profile may be limiting acceleration of jerk.
Could be differences in fan setting, or almost anything.
When you are dealing with a marginal situation, and it sounds like this is right on the edge, very small differences can cause dramatic changes in how the whole system responds.  3D printers are complex systems, with resonances, many vibration modes, non-linear friction.  Knowing for sure may be beyond the scope of your and our engineering tools.
Don't operate on the Margins
Set the motors to the proper current levels.  Set the bed to the proper height.  Set the hot end to the right temperature.  Try to always stay in the sweet spot.  Your prints will reward you.


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Why does Cura insert G0 commands between G1 commands while Slic3r doesn't?
While looking into G-code I was wondering why Cura inserts G0 commands in between G1 commands every other line like this:
G1 F2400 X144.612 Y130.187 E1652.56358
G0 F6000 X144.612 Y129.621
G1 F2400 X72.905 Y57.914 E1654.16570
G0 F6000 X73.471 Y57.914
G1 F2400 X144.612 Y129.056 E1655.75518
G0 F6000 X144.612 Y128.490
G1 F2400 X74.036 Y57.914 E1657.33203
G0 F6000 X74.602 Y57.914
G1 F2400 X144.612 Y127.924 E1658.89623
G0 F6000 X144.612 Y127.359

It seems like it wants to move to a slightly offset starting position for the next extrusion. I dont understand why, though. It wants to have touching lines as a result, doesn't it?
I do see this making sense in a fill situation, - this section is called 'type: skin'. How does slic3r get away doing infill without this?
Am I correct to read slic3r gcode correctly to use G1 instead of G0 commands for this?

It might be a smoothing-type option set in your slicing engine. Smoothing essentially performs an action similar to this.

Formally, G0 is a rapid move and G1 is a coordinated move. A G1 will cause the printhead to move in a straight line from the begin to the end position, whereas a G0 allows the printhead to move in any curve, so long as it ends up in the target position. Because of acceleration and deceleration constraints, it can sometimes be faster to move in a curve rather than a straight line.
However, I don't think any actually firmware implements this, and a G0 behaves in the exact same way as a G1.
What the piece of G-code you posted is doing is creating a solid infill, which consists of a bunch of parallel lines, each slightly offset from the next:

It makes sense that no material is extruded when it moves from one line to the other, as otherwise too much material would get deposited at the edge.

If you set the pattern to Zig Zag then Cura will shorten the long infill lines a bit and connect them with a printed line in such a way that you don't deposit too much material.


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Display crashed/corrupted on AnyCubic Prusa I3 clone
I've recently completed assembly of an AnyCubic Prusa clone.  It's working, but having some issues.  My prime concern at this point is the LCD display.  It occasionally becomes "corrupted" for want of a better term (see image) and no longer responds to the control.  It's done this unattended in the middle of a print attempt, which means I can't pause it to remove the imminently dripping filament from the leaking extruder (another issue I'm dealing with).

So three questions I guess...
Is this a typical problem?
What's the likely culprit (main board, display, firmware)?
How to fix it?
I'm working with AnyCubic's tech support, such as it is, and wondering if I need to push them for replacement hardware.
Thanks!

Issues like this are often caused by the length of the ribbon cable connecting to display to the board, or by its vicinity to other wires. Try routing the ribbon cable away from other wires, and use a shorter one if possible.

Thanks - I'll see what I ca do.  There are two ribbon cables - no problem with them being close to each other, right?


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Out of order operations on AnyCubic Prusa-I3 clone
Another thing I'm seeing with my new build.
Late in a small print, the unit appears to perform operations "out of order" occasionally.  Here's a picture where it's running a layer across the model.

These "skips" can start in the middle of a line.  It always comes back and fills them in before starting the next layer - more or less accurately.  But from my very limited understanding of gcode, it doesn't seem like this should happen.
When watching the print closely, I'll occasionally see small glitches, where the head jogs very slightly as it runs a line across.
This was sliced with Cura - I'm going to try a different slicer and see if I get anything similar.
Thanks!

This is just your slicer doing this. If you inspect the G-code file, you will see that the printer is faithfully doing what the slicer told it to. Most slicers use a fairly simple heuristic for determining the order in which lines are processed, which sometimes comes up with sub-optimal solutions like these.

It's funny to wonder what the "logic" is reading or playing when it skips peculiar shapes in a fill operation. Change one little parameter and the skipped parts are in a new location or vanish entirely, sometimes.

I have seen this in Cura 2.5 when selecting different printers, then altering the specifications to suit. Changing the printer seems to change the slicing behavior. As yet there is no specific printer set up in Cura for the MEGA so you will probably have to find something that fits your needs, unless someone has the full settings. For example, is the Machine Center at Zero? Maybe try the Prusa Mk2?


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Can't get print to stick, no matter what I try
I'm new to 3d printing, so I might be missing something obvious. If so, please let me know.
I printed my model successfully yesterday, but today I'm trying to print the same model and the first layer refuses to adhere, which means at best several layers after that are messed up if it manages to recover, but usually it just means I have to cancel and start again.
It will print one horizontal line (across the x axis), then when it tries to vertical line (across the y axis) the horizontal line doesn't adhere and gets dragged along with the print head and everything is screwed up.
I've tried leveling the bed over and over again. (I use a sheet of paper and try to slip it between the bed and printhead. I adjust the bed so that I feel a bit of resistance as I push and pull the paper under the printhead.)
I've tried increasing the preheat on the printhead and on the bed. I'm using black PLA 1.75mm that says it has a print temp of 205-225. I've tried printing at 205, 210, 215, 220, and 225. I've tried a bed temp of 50, 55, 60, 65, and 70.
I've tried setting the print speed multiplier to 0.5 to give it time to adhere, but no changes.
I'm trying to print something a wireframe cube that is at the extent of my printable size, so I don't know of a way to use a raft or a brim to help adhesion.
This is what my model looks like:

When I printed a good one yesterday, here is what the first two lines looked like:

When I print today, even after multiple attempts to level the bed, this is what the first layer tends to look like:

I'm using a Monoprice 15365. I created my model in SketchUp, then exported as STL, which I imported into Cura 2.3.1. Then I used Cura to export a gcode file to an SD card. I put the SD card into my 3d printer and printed from there.
Any advice is welcome. I don't know if the problems I'm having are because the bed is too low or too high or too hot or too cold or if the printhead is too hot or too cold... nothing I've tried seems to change the results.

What are you printing on - white painter's tape / masking tape?

Print a large skirt or brim around your object. Now you have time to adjust the bed level to the correct height.

@vwegert It's whatever came with my 3d printer (as I said, I'm brand new). It appears to be one giant sheet of a material like masking tape.

@Gunslinger The screws to adjust the height are on top of the bed, so I'd be really worried about the allen wrench getting in the way of the machine. :/ The model I'm trying to print is as big as my max print size, so I don't think I have any extra space for a brim or raft.

I stopped using paper as a feeler gage to set the gap between the nozzle and bed and just bought a set of metal feeler gages for a few dollars. A small but noticeable improvement.

I threw away the white cheap-o masking tape that came with my printer right at the start and bought a roll of blue tape. That helped a lot, but in my case, it clearly was some cut-off crap stuck into the packaging to make it look complete.

I've been trying all of the suggestions below and not getting any improvements. I've been watching a bunch of YouTube videos and I've been inspecting the machine while it prints, etc.. and I'm starting to think my nozzle is clogged. I don't think enough material is coming out and THAT is why it is sticking. I'm getting these tiny, almost hairline, plastic lines, but when I watch videos of the same printer I see nice, thick lines being laid down.

Eureka! All of the other answers and suggestions on this post were all very helpful, and would likely be the right answers 90+% of the time, but they didn't give me any relief. I spent a bunch of time watching YouTube videos about 3D printing and I started to notice a difference in size of the lines of plastic being laid down on the build plate.
In the videos, the lines of plastic looked bigger. Mine were very fine lines. That lead me down a series of different search terms until I found some other videos that talked about nozzle cleaning.
I noticed that one of the symptoms they mentioned was that when the plastic would come out of the nozzle that it would curve around. That's a sign that it's partially blocked and causing it to bend and curve. After the people in the YouTube videos cleaned their nozzle, the plastic would then extrude and drop straight down.
If my nozzle was partially blocked and only about half the right amount of plastic was coming out that would make sense since there wouldn't be enough surface area of the plastic to make a good connection to the build surface.
I acquired some 0.4mm drill bits from Amazon and followed the instructions on this YouTube video.
Sure enough, when using the 0.4mm drill bits, I could tell the nozzle was clogged. After clearing it out, the plastic started extruding in a straight line down, just like the video. I was stoked!
I tried another print and it was NIGHT AND DAY. I was finally getting nice plump lines that stuck to the build plate. I still had an issue or two on certain parts of my build plate, but I think that's because in all of my tries I had damaged the masking tape. I put down new blue tape and started up my print and it's BEAUTIFUL.
Thank you all very much for your help. Hopefully, this will be helpful to someone else as well.

Your nozzle is clearly too far from the bed. The plastic should be squashed down slightly. Some firmwares have an option where you can adjust the height of the nozzle "live" during the first layer, in Marlin this is called "babystepping". This can be very useful because you can get the height correct without having to mess with the physical leveling of the bed.

Your photo has shadows which seem to suggest that your tape layer has some wrinkles.  That won't help.  Try removing that tape and laying down the fabulous blue painter's tape.
If you read any dedicated forum  for plastic extruder printers, you'll find plenty of claims that X or Y is the best way to guarantee adhesion.  Some folks swear by glass+gluestick, others by PEI sheet, and so on.  The only general consensus is that use of a brim or a raft is highly recommended so as to increase the total contact area.

I've been struggling to work out what is wrong with the process where you claim to be leveling the bed OK (and the print is starting in mid air). Now I remember I had exactly the same problem with my first prints.
I think you are leveling OK, but getting some binding in the Z-axis. As the head jumps to start printing, it goes up, then down (but not as far due to some mechanical problem). So although your Z-endstop is aligned with the bed, after finding the zero, the head is not reliably able to move and return to zero.
Check these questions for more detailed ideas about how to fix this:
Z-axis steppers and bed alignment problems
z-axis hard to move in some areas - what could be faults, how to improve?
You can try and confirm my diagnosis by zeroing, them moving Z-position up 2/3 of the full travel, and back down. See if it is still at the position where you leveled it to.
If it is not this, I suspect your Z-endstop may be giving unreliable results. Check the microswitch is securely mounted. I ended up replacing mine with an optical sensor, and have seen huge improvements in repetability (<0.1mm rather than around rms 0.3mm from zero to zero)

I find 60-65 for bed. You are COOKING your pla. 175-200 unless you are a fast / expert. That said get rid of the tap. Use a Elmer's glue stick. Also set first layer speed to 30% and do like 130% material for layer 1. Let us know what happens!
Agree with Tom. Likely your too high up. I take a piece of paper and try to get the distance just so when moving the paper between the nozzles and the bed it has some resistance but not too much.

Some folks swear by gluestick; others by blue tape.  I've found, as Tom's    answer suggests, that getting the first layer squished is ideal.   I agree his temps are high, but I've had great success at 205, and up to 230 when using wood-filled PLA.

I used to do blues but its a lot better with glue sticks. Mine is the same but more subtle, hence the 130% flow on the first layer. Wood PLA would be different. Wood has less thermal conductivity thus higher temps

@StarWind The reason I'm using the high temps is because the spool of PLA says that temp range on it. It's definitely higher than what I've seen for other PLAs when I search online, but it explicitly says on the spool that it has a 205-225 print temp.

Re: 130% material flow on layer 1, is that a setting that I would need to configure on software like Cura and then do I have to print FROM Cura or is that 130% material setting something that can be represented inside the gcode file so I'm still able to print from an SD card inserted directly into the printer?

I use simplify 3d. Its under settings, layer, first layer height % for S3d. So yes it is a setting in your slic3r. You do not need to do more then generate the GCODE with this setting.

Thanks, I'll look for that type of setting in Cura, or I'll find another app to generate my gcode.

You can use the masking tape as base, however the height of nozzle is higher than required. Check that your fist layer height is 70% lower than your nozzle size. In my opinion this can be the step layer minus 0.05, for example layer height is 0.2, then my first layer is 0.15, this makes that the material squizes a little more.
If this is not possible you might change the offset of printing level until you reach the height required.
Manually you can add some layers of masking tape to minimize the overgap within the nozzle and bed. (some times I do this, due mi home 3D printer gets out of calibration on changing nozzles)
For PLA i´m using 210°C because using 190 and 200 makes some balls like your photo. also try to use a lower speed like 90 or 80 % to allow a good melting inside the heater.


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Is the 8mm x 20mm bearing axle for the X-axis idler (of a P3Steel) a custom part?
Here is the X-axis of the P3Steel:

The X-axis idler end of a P3Steel printer, employs an 8 mm diameter rod for the axle on which a 608zz bearing is mounted for the GT2 belt. This 8 mm rod is approximately 20 - 24 mm in length, with grooves at either end, for circlips.
A photo of the assembled idler, with the rod and circlips highlighted:

My question is: Does this part need to be custom made?
The short rod didn't come with the frame kit that I purchased (nor was it listed in the parts list, or shown in the photo of the parts - so it not as if it was omitted with my order). I have searched on eBay for it, using various search terms, and I am unable to find one. As I was not trained in mechanical engineering, I am not sure if this part has a special name, or is it just called a "smooth rod, with grooved ends"? I have also done a fair amount of googling, and although I have found some people who have constructed this particular frame, no one makes mention of this axle, nor any difficulties in sourcing it.
I have contacted the supplier of the frame, Frame Prusa I3 P3Steel v4.0 +RODS, and I am awaiting a reply.
This missing part is holding up my build progress - I already have the 608zz bearing and circlips.

Additional images
This image shows the "exploded view" and the 8mm rod can be clearly seen:

Here are images of the assembled idler, showing the bearing inside -
Front view:

Side view:

This images are a little blurry, as they are screen shots taken from the video, I3 Steel CORDOBESA con extrusor/with extruder.

It almost looks like a rivit..

@StarWind - I can see what you mean, but it's not a rivet, there are circlips on the front and (I assume) the rear also. I'll try to find a better photo - that picture was a screenshot from a YouTube assembly video.

You could look up a Clevis pin with one groove.
You could look up a Clevis pin with a hole for a split pin.
Perhaps a Shoulder screw with a ground shank and a low profile head.
Use a plain rod with Dome caps if you will not need to remove often.
If available an internal threaded Standoff would work.
A Slotted spring pin may work if the hole dimensions are suitable.
EDIT:
You could also cut the grooves yourself pretty easily.  Cut a section of 8mm rod to length and mount it into a drill chuck so it stick out 2-3mm 1/8". Hold a hacksaw at the edge of the chuck and run the drill for a minute with gentle pressure, try hacksaw on other side or reverse direction if nothing is happening.
A hardened rod will cut better with a Dremel type cut-off disk

I have finally received a reply from my supplier, which backs up StarWind's answer:

I did not use a rod with grooves for retaining rings.
I used bolts and nuts with a thin head.

Doesn't really answer my question though, as I really rather hanker after the 8 mm smooth rod with the circlip grooves.

Oh fascinating. It took me a while to figure out what exactly that is. It is a smooth rod used as the idler for the X belt.
What I would do is get a bearing / wheel. Take a thicker screw, nut and washer. Put the idler / bearing / wheel into the slot, then fit the screw / nut. Should work without any issue!
That said they likely had some sort of special fitting etc. Doesn't matter so long as the belt can move without wearing.
This Thingiverse does exactly what I am thinking.

As you have a low profile need due to the interesting design I came across this. a TNF8 - Nut Sert - Flanged/Ribbed.

Or you may just need a standard low profile nut. Not like you need it to do more than hold it in..

Thanks for the reply. The smooth rod is not the idler, per se, yet it is the axle for a 608zz bearing. I have updated my question, with additional images and a link to an assembly video, that I found on YouTube. I had considered using an M8 Bolt, however, space is rather tight, and the head of the bolt could interfere with both the Z-axis 5 mm smooth rod and the M5 threaded rod (or M8 lead screw). Hence the requirement for the grooved rod, and the circlips, as this requires less clearance.

Yeah that's exactly what I thought it was

Yeah that is a tight design. Contacting the MFG for the part / the seller is best.. Else you will be Epoxying that thing together...

You know they do sell thin nuts. Edited answer for something that may help

-The nut sert looks promising. :)

I do hanker after that special short rod though. I have contacted my Polish supplier, but as I mentioned, they aren't very communicative. I may need to try to contact the Spanish chaps who designed the idler, if/when I manage to locate them.


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First layer lines don't stick at all
My Ultimaker 1 with a heated bed doesn't print good first layer lines at all. The single lines keep detaching from the printbed, no matter what nozzle or bed temperature or the height of printhead from printbed. I cleaned the printbed thouroughly, too. It worked a while ago, I don't know what I am doing wrong.
Data:
Ultimaker 1 with Heated Printbed (Glass)
PLA @ 200°/60°
This is how it looks like after removing a print (one and a half layers) from the printbed.
It is quite thick though.

Besides this question possibly being a duplicate (there have been quite a few questions on adhesion already) there isn't really enough detail in your question either. What material are you printing with, what temperatures are you printing at, what material do you have on the bed to promote adhesion, what does your first layer look like (picture)?

Is that better?

recommend closing as duplicate.

This looks a bit like your build plate isn't level. I'd suggest re-leveling using feeler gauges.

Problem is, the print bed can be really tight or loose and everything inbetween. It does not matter at all.


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Calibrating steps/order
Does anybody have an overview of what things should be calibrated (and in what order) for a certain 3d printer or after changing the printing material?
I only know about:

calibrating the extruder steps per mm, e.g. Tom's youtube tutorial
determining the print temperature, e.g. RepRap Neo's youtube tutorial
calibrating the extrusion multiplier (for each different filament), e.g. RepRap 101's youtube tutorial

How to calibrate/determine the maximum speeds or accelerations?

How to Calibrate. Oh man that is a good 2-3 page long blog post.. So I will try to give you the bullet point section.
High level

Mechanical
Firmware
Software
repeat

Mechanical
Level everything. Bed. The X axis. Make sure there is no binding, etc. Also make sure the surface you are on is flat before leveling the printer by it.
Firmware
Get that printer moving. This is where you do you Steps per MM. I like Triffids guide.
Now is when you go into the software and start setting your slicer settings. This includes your filament measurements etc. You should go back 2-3 times between this step and the previous to make sure your extruding EXACTLY what you think you are. As mentioned by others filament calculation is hard. You need to measure across a lot of material. Take the averages. You will never get it perfect as the plastic is never perfect. Picking a solid supplier is a factor here too.
Once you think you have that all working. Repeat. Start at step one.
After your done looping though you will start with the slicer calibrations. Which is the meat of your question. You will take collections like this one or this one and tweak settings until you can pass each test. Do your tests in this order

single wall test
hollow cube
solid cube Here is a Bonus solid cube
bridging test (honestly I rarely do this one..)
part fitting test

Now for testing when switching material. Honestly its best to start with their settings, and tweak them. I like to have a spread sheet of xy speed, Z lift, temps. Massage it till you are happy. The firmware settings like jerk and acceleration will be less of a factor between materials. Get it perfect once and don't touch it (till you decide it is not perfect).
You will be testing the new material with the same STLs as I mentioned in the precious section. You also might want to look into Simplify 3d (no affiliation) if you get really into it. Also SAVE THE SETTINGS. Nothing sucks more then losing all this work and having to recreate these profiles for materials. Do not trust slic3r to back them up, or to not randomly delete them. Hard lesson there.
Far as max speeds and accelleration..
Max speed will really be a function of how fast can you hear up plastic. If you have a e3d with Volcano mod you can really crank the speed up. So you go to the point where your extruder just cannot hit target temps AND you are unable to print solid infill. Far as acceleration and jerk. When you knock your extruder causing your print to shift, then you know it is accelerating / jerking too hard.
Best of luck! Let me know if I can clear up a section for you.

Recalibrating your machine for the new filament diameter is a good idea. Filament diameters vary slightly between manufacturers.

Calibrating your machine for the new filament diameter, after changing to a new filament; doesn't answer "what calibration steps should be taken after changing to a new material?"

I see what you meant, and edited to clarify

Hi Diesel. Welcome to the group. Might I recommend taking a look at the answers the top 10 users provide? I have noticed your solutions are a bit short and do not include enough information.

Message received, I'll try and be better in the future :)


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Dimensions off on final part
I'm experiencing an issue with my Makerbot Replicator 2X (2000+ hours printing). The dimensions of my final part are smaller than what is initially modeled. My parts have been coming out roughly 0.3mm smaller than what is initially modeled. Is this a common issue or does this sound more like I may have a hardware issue?
I've confirmed that all my belts are tensioned properly and lubricated correctly. I haven't seen a calibration step that would correct for this issue short of manually scaling my parts to correct for the offset. The offset appears to only occur in the XY axis, never seems to happen in Z though
Example:
In the part modeled I had the width designed to be 35 mm (face to face, parallel walls). It doesn't seem to matter what size of part I have the final dimensions always seem to be off by about the same amount.

Hi Diesel. Can you please include a photo?

Is this a consistent 0.3mm, or does it increase with part size?

It seems to be fairly consistent offset. (I'll be able to add an image on Monday)

Are you using a filament which shrinks more upon cooling than the software is configured to compensate for?

I think so? Only because the z-axis dimensions are usually pretty spot on (variance largely due to roughness), and the amount of shrinkage stays constant regardless of the size of part. If it were a thermal contraction issue I would expect it to shrink more the larger the part is? (That's half statement half question)

Yup that is what happens. It is simply the plastic cooling and shrinking. It will happen on just about any printer. 0.3mm on a what 40mm part. That is 99.3% on target.
There are some great blog links about it,
and here is a Stack overflow where I talk about it more in detail.
The only mitigations I can think of is
1) use a hear chamber.
2) use a SLA 3d printer.
I wouldn't worry about it. Just make sure your designs have good tolerances.

Great info! I hadn't thought about the internal dimensions shrinking due to expansion. But, it seems that I'm experiencing the opposite effect. My outer dimensions are smaller than what is modeled. 35mm becomes 34.7. Would this still be a result of the same thermal expansion do you think?

Yup. Things will Shrink when cooled. You will see Expansion only at the first level  (IE elephant foot) but that has to do with over extrusion. Circles will always shrink as well.


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Black goo from only one linear bearing - serious issue?
I have a cheap cartesian printer with the usual arrangement - X axis with three linear bearings, build plate moving as Y axis on three linear bearings as well, Z axis with lead screws. After about 2 kg of filament printed, I can see that one of the linear bearings (the single bearing on one side of the Y axis) is leaving an almost black residue at the front of the axis. I have thoroughly oiled all of the bearings before mounting them and repeated that after about 1 kg of filament printed. No other bearing is showing this issue, and the black goo appears only on the front side of the rod, not the back side. What might cause this goo - is the bearing breaking up or is it just some residue from the manufacturing process that is slowly being pushed out of the bearing?

Hi vwegert, please remember to include photos in these sort of questions :-) You don't want us to have to use our imaginations.

After completion of the print job, I was able to perform a closer inspection. The black goo contains metallic particles, and the rail the bearings are riding on has a visible groove - which means replacing both the bearings and the rail.

Your new oil butted out the old graphite lubricant.
Don't know about the metal particles though, might be dust, or your new oil caused damage to the bearings and/or rails.


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I am using a stereo 3D pen. What surface should I use?
Using a 3D pen I printed a small box. However, I was doing it on plain paper and of course the paper didn't come off the plastic very well. It didn't matter for that specific case, but if I want to print something else, which non-sticky surface would you recommend? Is there any way to use transparent surface (so that I can put a paper with picture as a guide under it)?

I assume you want to draw with PLA?

You could use a piece of glass, that's what most people using 3D printers have as a build surface.  An easy source of glass for pen use would be a picture frame but the edges are likely sharp so be careful.  Acrylic would also work and is easily obtained in small pieces from places like Lowes/Home Depot, I used Acrylic for some time on my Kossel.  The plastic can stick to Acrylic very well but I had no issues using it with my printer, just test it out and see what process works if you go that route.

Note that you can improve the adhesion to glass by applying a layers of gluestick, hairspray or similar as well (there are many options and opinions about this).

I'm curious what brand of pen you are using. I haven't found a STL one yet, and might be interested.

Someone trying to get a surface to not stick. This is a first. I would try glass first. If you still have issues, I would look into coated surface, like an old tefflon pan (do not cook with PLA residue). I would suggest oil but you might start a fire..

You might want to experiment using Kapton tape. Although it's yellow-coloured, it is transparent and provides a good surface for hit-bed adhesion. You should be able to remove it from your print by flexing it.
Attaching it to your paper sheet is a one-way process, but you can use guide marks on the paper below.

I use parchment paper, the kind that you buy on sheets for baking.
It come off nicely but there are adhesion problems if you want to do sharp corners.
I prefer using ordinary printer paper for that. You can simply soak any scraps of paper off in a sink.


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Issues with OctoPi connecting to FlashForge Creator Pro via Serial Communication
I've recently initialized OctoPi onto my Raspberry Pi, proceeded to connect it to my local internet, and then connected it to my FlashForge Creator Pro (2014 edition)
Everything seemed to be going smoothly until I tried to connect to the printer; the Pi didn't seem to be able to pick up a usable Baudrate (after being trying out all of the usable ones).
For example, when trying out 9600, I would get:

Trying baudrate: 9600
Send: N0 M110 N0*125
Recv: ��r>#    ���& �

What should I do to fix the problem?

Note that I got the same types of messages back (with garbled 'special' characters) when trying using the "auto connect" feature.

I got the same problem.
Auto-detect baud rate was not working too.
So I manually tried every baud-rate and finally found one working, for me it was 115200.
Good luck!

Install GPX via command line. To do this, type
/home/pi/oprint/bin/pip install "https://markwal.github.io/octoprint-download/OctoPrint-GPX.tgz"
then go ahead and restart octoprint and try connecting again.


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Printer homes to Z stop-switch, but presses on heat bed during printing
I have a Prusa i3 that homes properly when you use the menu. After adjusting the bed and homing several times, it keeps the head at a reliable distance. However, when I try to print from an SD card, the printer buries the hot end in the heat bed.
What needs to be adjusted to fix this issue?
G-code from one of the 2 files
M190 S50.000000
M109 S200.000000
;Sliced at: Mon 13-06-2016 15:39:25
;Basic settings: Layer height: 0.2 Walls: 1.2 Fill: 20
;Print time: 3 hours 47 minutes
;Filament used: 11.435m 34.0g
;Filament cost: None
;M190 S50 ;Uncomment to add your own bed temperature line
;M109 S200 ;Uncomment to add your own temperature line
G21        ;metric values
G90        ;absolute positioning
M82        ;set extruder to absolute mode
M107       ;start with the fan off
G28 X0 Y0  ;move X/Y to min endstops
G28 Z0     ;move Z to min endstops
G1 Z15.0 F3000 ;move the platform down 15mm
G92 E0                  ;zero the extruded length
G1 F200 E3              ;extrude 3mm of feed stock
G92 E0                  ;zero the extruded length again
G1 F3000
;Put printing message on LCD screen
M117 Printing...

;Layer count: 446
;LAYER:0
M107
;LAYER:1
M106 S127
G1 F2400 E-4.50000
G0 F3000 X81.474 Y58.603 Z0.300
;TYPE:WALL-INNER
G1 F2400 E0.00000
G1 F2220 X83.063 Y56.456 E0.06663
G1 X84.277 Y55.080 E0.11240
G1 X84.836 Y54.444 E0.13353
G1 X85.799 Y53.476 E0.16759
G1 X86.755 Y52.587 E0.20015
G1 X87.179 Y52.244 E0.21376
G1 X88.836 Y50.911 E0.26680
G1 X89.285 Y50.610 E0.28029

Can you share the beginning of your g-code (from the beginning until it starts getting into printing moves)?

The correlation between the endstop switch  -- or sensor -- and the surface of the bed is not known a priori .  In your case, there are two possibilities.  I'd say the more likely is that your g-code generator is not setting the Z-height offset from the bed correctly.   The other is that your bed is tilted, so proper Z-home at one corner does not match the entire bed.
Try this:  first manually move the extruder head to all four corners and adjust the bed screws until the separation is identical at all times.   Then let your gcode start up -- and don't worry if the extruder depresses the bed during homing, as that doesn't matter.  See where the extruder is once the print starts.  Adjust the endstop switch up or down to compensate until the print head when printing is just off the surface and the first layer adheres well.
If all that doesn't work, then you may have the wrong printer profile settings in your slicing softwqre.

I did a leveling and prior to printing it properly stays at height.  the gcode came with the printer as a test file from the manufacturer.  I tried 2 of their files and with the same result. when it starts printing it mashes down on the switch untill it cant bend it any further. If i manually raise the nozel to the proper height and resume printing it seems to print normally.   The other thing i noticed was in my instruction manual there is a z offset option in the marlin firmware but on my machine it does not have that option.  the display shows z height as 0 from the beginning and raises.

Bad Gcode  "G1 Z15.0 F3000 ;move the platform down 15mm"  for some reason the manufacutrer put that in the startup of the profile for the machine in the slicing software as well as all there test prints.

You didn't share much details, which is problem with any question. But let me give some recommendations - I have Prusa i3 MK2 1.75mm.
The fact that it homes correctly does not at all mean that your Y axis is OK.

Verify that PINDA probe's bottom end is maximum 1 millimeter above the extruder head.
Double check that PINDA probe is correctly screwed and does not wiggle.
Manually check that the printer does not allow you to toutch heatbed with extruder, follow these steps:

Wait for both heatbed and hot end to cool down.
Put paper sheet on heatbed
Go to Menu - Settings - Move Axis - Z Axis
Move the axis down. If hot end toutches and presses on the paper, the calibration is not OK at all.

Updating your firmware can't hurt if you didn't do it already.

If this advice does not help you, please update the question to address the following questions:

How does your G-code beginning work? Ideally, share some short G-code, I could easily check whether it is correct with my printer.
Does XYZ calibration pass correctly in your printer?
Take a picture of your extruder so that both PINDA and extruder are visible

Z-axis is usually vertical.  Typo on your part?

BTW, Prusa i3 stock uses a limit switch, not a probe.

I had the same issue: Z-axis correctly homing manually but not when printing.
What worked for me is disabling the following line in the Marlin configuration file:
#define Z_MIN_PROBE_USES_Z_MIN_ENDSTOP_PIN