Attach handle on a loose screw The handle of a micro wave oven broke.

I can't just order a replacement part because I can't even attach the new one.

The problem is that the screw heads are somewhere on the interior side of the door, which cannot be disassembled (non destructively at least). I wouldn't even do it because of safety reasons.

I have access to the threads of two loose and captive screws to work with (indicated by the two red lines on picture one). The screws are not machine screws, but screws for plastic like in the attached picture.

The plan is to 3d print the plastic part of the handle and reuse the front aluminum cover.

I don't want the handle to be loose, so I'm looking for suggestions to attach the new handle. I have a lot of ideas, maybe I will share them later if they are not mentioned at some point. The main problem is: how to attach something when all I have to work with is a loose, non machine screw ?

You are facing 2 problems in this case:

Material choice
Design

Material choice
As far as I can see, this is an oven that can heat its interior to roundabout 250 °C, which means that the door will radiate a lot of heat. This needs special high-temperature plastics to withstand - PLA and ABS are not an option for this!
I would suggest looking for PEEK (stable at ~260°C) or a high-temperature resin print in this case, as there are some resins which can withstand much higher temperatures after curing. Note that PEEK is traded usually for above 100 €/kg and needs a specialty printer. Even the less stable PEI filament (works under 170 °C) needs a specialty printer: All metal hotend and 350-380 °C extruder are needed!
Design
The plastic screws you show are self-cutting plastic screws. if their head is accessible, they get screwed into holes that have a bore large enough for the center.
If the screw head isn't accessible, for turning but can be pressed down, then one could opt to use high-temperature resin to cure inside oversized holes over the screw. This is not an option if the screw can't be pressed into the part though, as then the handle always will rattle.
Repair?!
Note that you might be able to access the screws with a little work, if you have the right tools and manual.


Filament isn't going into the Bowden tube, instead it goes "into the room" The pictures explain my problem. I have already tried to reduce the retraction but that showed no effect. Thank you for your help.

The effect is a total stop of the print (no material is extruded).

Creality CR 10
Cura 3.4.1

I recently added this new feeder aluminium block because the 3D printed stock version was bad quality.

This is typically caused by resistance in the tube or hotend but in your case it appears to be mostly caused by a very poorly designed extruder.  The filament needs to be constrained closer to the drive gear.  You may be able to drill out the PTC connector to allow the PTFE tube to reach closer to the gears or print a spacer to fit in between but you need to support the filament in that gap.

You can try raising the hotend temperature as a band-aid until you can fix the problem, do not exceed 240 C if you have a PTFE lined hotend. Long retractions can also pull molten filament into the cold zone where it solidifies and make extrusion harder.

As an example, here is a picture of a Bondtech BMG extruder.  Note how the extruder constrains the filament path all the way from the drive gear to the hotend entrance.  While this example is extreme for normal PLA/PETG/ABS, it is required for flexible filament.  A 4mm gap (or closer) should be fine for PLA/PETG/ABS or other hard filaments.


What can cause a sudden and dramatic loss in the inter-layer registration of my prints? Suddenly, my printer has started producing prints that have a very pronounced layering. Normally, the alignment between layers is very good, and the prints look very smooth. Suddenly, the prints have become much worse and the layers are misaligned with respect to each other.

The part on the left is my "normal" quality, while the part on the right show the deterioration. Here is another picture (in which the good part is on the right):

The parts are both printed with 0.1mm layer height, and identical slicer settings/filament. I am printing on a custom-built FDM printer; the mechanism is roughly similar to that of an Ultimaker.

There are many factors, here are a few things to check:

I'd first suspect filament feeding.  This type of ridging can be caused by a filament coil that is binding occasionally, or a filament that doesn't have an even diameter or volume per length.  Binding within the filament feeder and feeder tubes can also be a cause. Bubbles in the filament, or sometimes a mismatch between the filament ideal temperature and the head temperature could create results like this, but it probably wouldn't vary so much between the layers.

Next I'd look at the print head.  If it has blockages, or poor temperature control this could result.

Lastly, I'd check the mechanisms - disconnect the motors and see if all the carriages slide smoothly without any binding, particularly the Z axis.  It doesn't look like you're missing steps, but binding here may result in greater backlash, which could result in similar ridges. Make sure any belts and gears are tight.


Top-Down SLA Printer Bulging Issue I have designed and built a top-down SLA 3D printer that uses a 405 nm 500 mW laser along with some galvanometers. I filled the vat with glycerin and then topped it off with about 2.5 cm of resin. I designed a wiper system for creating an even layer of resin quickly even on layers with large surface area. In my tests I have been dunking the build plate into the resin and then raising it to wipe the excess off to get a quick even layer (I raise it slightly above the level of the resin to be safe).
The problem I am having is that after the wiper wipes and the laser cures the layer, after a couple of layers the wiper will begin physically hitting the top of the part. The part continues to get higher and higher than the wiper level, which doesn't make sense because the wiper wipes all the excess off, and I am printing above the level of the resin so no extra resin is flowing onto the layer from the sides. This eventually stalls the wiper motor and the print fails.
I have a theory that the resin's surface tension might be pulling the layer of resin to the edges of the layer, causing the layer of resin to "bulge" up a little which would explain why the layer is curing higher than the wiper level. If this is the case does anyone know of any remedies to this? Do I have to heat the resin to lower its surface tension maybe?
Have any of you guys ever had this issue? Does anyone have any other theories? I am really stumped here and can't wait to start printing some cool models but I cannot continue experimentation until this is solved.
Thanks so much in advance for any help!
(I should mention I am using Anycubic Plant-Based Eco UV Resin in translucent green)

Let's look at the problem mathematically:

The bed has a 0 that puts the surface some distance $d_0$ above the surface of the resin, the wiper does put the first layer on that height.
after curing, the printer moves down distance $d_d$ to coat the top surface.
afterwards, the bed lowers back up to $d_0+d_l$ - a thickness of 1 layer lower, or in other terms, it moves $-(d_d-d_l)$

Now, how is it implemented in your G-code? check that!


Taking a new hotend into operation (cleaning, forming, etc) When installing and using a new hotend for the first time, which steps of action should be taken before. This will probably be more applicable to chinese clones than to authentic products (is the statement true?): Should a certain cleaning procedure be carried out (removing swarf/shavings for example)? Should mechanical precision be controlled and if necessary improved (de-edging and nozzle size are two things I could think of)?

I know the topic How should I clean my extruder when changing materials?, which is a nice addon read, but I am concerned about brand-new extruders.

I haven't done anything special to set up mine. But it's probably worth doing a general cleaning. I'd swab it off with alcohol, including running a q-tip or similar inside the fiber feed path. Then blow out the nozzle with compressed air to make sure it's clear.

You could measure the nozzle diameter by fitting fine drill bits in to see which is the largest one the passes through freely. Be sure to measure how much fiber your extruder really takes in when you ask it to extrude a certain length -- but that's about the extruder, not the hotend per se.

Finally, I'd check the insulation, if any. I got a couple hot ends that had big gaps in/around the insulation. I've found that "high-temperature gasket maker" is great for improving insulation (depends, of course, on the shape and design of the specific hot end.


What are the pros and cons of using a BLTouch in place of a limit switch? This is about practicality. I'm hearing that people are using their BLTouch not to adjust the Z offset, but as the limit switch for the machine! Why is this so? What are the pros and cons of using a BLTouch (or any touch sensor for that matter) in lieu of a physical limit switch?
(NB: I'm looking for objective reasons, where no other solution will do as opposed to personal preference reasons where people just like to use it).

Touch sensors (or inductive or capacitive sensors) are generally used to probe the bed to determine the bed shape. For metallic beds that are not perfectly straight this works excellent. But, if your bed is straight and level (e.g. when you are using a straight slate of glass), you do not need to probe the surface as it is level. Instead you can use the probe to determine the Z level.

Pros for a limit lever switch are:

simple and cheap mechanical switch
no firmware changes necessary
no or few soldering
already present on most bought printers

Cons for a limit lever switch are:

needs fine adjustments counter part to work optimally
something can get in between the lever and counter part
it doesn't look cool

Pros for a more sophisticated sensor:

it looks cool
everybody is using it so it must be good

Cons for a more sophisticated sensor:

expensive and complicated sensor
requires firmware changes (e.g. sensor offset value)
requires soldering, or connecting more cables
inductive and capacitive sensor work usually better at a higher voltage
higher chance of malfunctioning (more parts and electronics)


Why is pressure advance usually implemented in firmware rather than in slicer Recently I started looking on pressure advance and how it works and I'm a bit confused about where it is usually implemented.
My Idea of 3D printer was that its firmware is fairly dumb and only replays GCode, not knowing anything about the object being printed, material used, or even the printer itself.
But with pressure advance this whole thing changes and now the firmware needs to know the linear advance factor which combines information about the filament and filament path used. In addition the E axis is no longer controlled directly by the GCode, but it's motion is almost independently determined by the firmware.
Why is this? Is there a reason that slicer (or a post-processor) can't compute all this and directly store the needed extruder axis  movements in the GCode?
Does the printer have some additional information that the slicer is missing?

In addition the E axis is no longer controlled directly by the GCode, but it's motion is almost independently determined by the firmware.

This is the case even without linear advance. G-code does not directly control the movement of any of the axes. G-code only specifies the path the axes should travel, but not the acceleration and deceleration associated with following that path. If you are printing a cube, then the G-code might specify that the extruder has to extrude a square. It will specify that the 4 sides of the square should be printed, but it does not specify how the transition from one side to the next should be handled.
The printer cannot instantly transition from extruding one side of the square to extruding the next side, because the direction of the extruder cannot change instantaneously. It needs to smoothly decelerate and accelerate. This is handled by the firmware, which translates the straight line commands from G-code to smooth acceleration and deceleration of the extruder.
This is exactly where linear advance comes in. It is coupled to the acceleration and deceleration. There is no way to "implement" linear advance in G-code, because G-code does not even have any notion of acceleration and deceleration. The G-code (and slicer) has no idea how the firmware is handling the acceleration and deceleration, so therefore it is impossible for the slicer to know what linear advance is required to match.
Then you might ask: "why is acceleration and deceleration not implemented in G-code (rather than in firmware)?" This is simply a design choice. G-code is meant to be a very simple file format, and it simply allows you to specify straight line move commands. Representing smooth acceleration curves would either require breaking them down into many discrete, small steps, but this would greatly increase the file size. You could suggest a more complex G-code specification that would allow a more "compact" representation of acceleration and deceleration curves but then you're just shifting the computation back to the firmware (albeit with a more explicit specification in the G-code).


Why does jerk have units of mm/s rather than mm/s³? In 3D printing firmware and slicers, jerk settings are expressed in units if mm/s. This is contrary the physical definition of jerk, which is in units of mm/s³, being the second derivative of speed with respect to time (or the third derivative of position). What is the reason for this discrepancy and how does one interpret jerk in this contect?

The jerk setting in 3D printing G-code and firmware represents a concept similar to, but distinct from, the physical definition of jerk. Rather, it's a [limit on] instantaneous change of speed.
Mathematically, one way to make sense of this is to think that, rather than being the second derivative of speed with respect to time, this "jerk" is the entire remainder of the first-order expansion of speed with respect to time - it corresponds to the second-order term and all higher order terms. Such terms cannot be combined just as coefficients, since they all have different units corresponding to different powers of time; rather, they can be combined only with their corresponding powers of time, in which case the resulting unit is mm/s.


PETG nozzle clearance and extrusion multiplier I've started printing PETG recently and I'm happy with results so far, awesome strength and good looking (except for stringing). But I've noticed that PETG prints better with more distance nozzle-plate than usual, and under-extrusion make parts looking better than both normal/over-extrusion.

What distance nozzle-plate is optimal for PETG? (i.e. the distance between nozzle and build plate during calibration)
What extrusion percentage is optimal for PETG?

Here is the mental framework that I use to reason about PETG: In a nutshell you want to avoid nozzle contact.

Unlike most other plastics, PETG sticks to hot brass really well and every time the nozzle moves through material it will pick up some of it. Material around the the nozzle then sticks to a random place creating a blob. It can also cook, turn transparent brown and drop into the print. Investing in a plated nozzle or silicone socks helps but doesn't eliminate the problem completely.

Now to the questions.

1) Nozzle Distance

Distance to the plate has to be such that the plastic is laid down precisely without the nozzle dragging through the material (remember, avoid nozzle contact). Precise lines require the build plate to be level and the flow perfectly calibrated. If nozzle is too low and/or the layer is over-extruded then PETG will stick to the nozzle and rip the lines off the plate again. Inspecting the first layer is required for best results. I like to print a layer test pattern after the flow has been calibrated and tweak Z offset in 0.02mm increments until it's perfect.

With many other plastics it's ok to have a large amount of "squish" in the first layer as it helps to work around minor leveling issues. This is where the cookie-cutter recommendation to raise the nozzle when printing with PETG is coming from.

2) Extrusion percentage

Flow has to be near perfect. Down to one percent perfect. Even a slightest over extrusion and some of the excess material will end up on the nozzle when it makes the next pass. Under extrusion isn't great either as this can lead to holes and affect overhangs where thinner strands of a previous pass may not be enough for the next line to stick to.

There are two critical parameters: diameter of the filament and extrusion multiplier. This is how to determine the settings:

Measure filament diameter. I use an average of ten measurements over about a meter (yard) of filament taken in multiple orientations.
Calibrate the extrusion multiplier using a method described in Prusa
manual:
I print a 40x40x40 cube in vase mode with extrusion multiplier set
to 1 and fixed extrusion width (e.g. 0.45mm), measure the wall
thickness in three spots on every side, average the results and
compute the correction factor.

I perform flow calibration for every new roll of filament.


Flat heated bed replacement for uneven bed So the heated bed I got with my anet a8 is not entirely even. The middle of the bed is lower than the outer edges of the bed, which always causes issues with the first layer, especially with a larger print.

I know I could do mesh bed leveling but I don't want to have to do that every time before I print.

So my question is, where do I find a heated bed that I can be sure of will be even and not have dents anywhere?

Several things to consider:

Nothing is perfectly flat.  It is flat within a tolerance.  The bed you have now is flat to within a tolerance.  If you want a flatter bed, you are going to have to specify how flat.
As @mac mentioned, aluminum is bendable; so, what once was flat can be made un-flat and the other way around.  Note: Your problem may not be your bed, it may be that the bed mounting frame has introduced stress that is bending the bed.
Because the heating element is applied to one side of the bed, the differential heating (between the top and the bottom) can cause the bed to bend at temperature; so, flatness could vary with temperature.

What to purchase:

The Anet A8 has a 220x220 bed.  A very popular size.  You can get replacements heated beds for as little as $20 from a lot of sources.
Because of the considerations above, rather than replacing the bed, you may want to consider attaching a 220mm x 220mm Borosilicate Glass Plate to the top of the bed.  These are also readily available (even from Amazon) for less than $20.  That is what I did.  The glass makes for a very flat surface and a great printing surface.  I attach mine with small binder clips.  That makes it easy to remove to take the print off or to clean when needed.


New Ender 3 power supply turns on but the controller board does not I just got an Ender 3 a day or two ago and was really excited being that it was my first 3D printer.
I got to work putting it together with little issue. I go to turn it on and the power supply starts up just fine (the fan on, the internal light on) but the mainboard fan isn't running and the screen isn't turning on. I wait a few minutes thinking that it needed to boot up but nothing. I tried reconnecting the red and black power cables and still nothing.
I'm not set up for tearing the thing apart and checking every socket with a voltmeter or something. I've checked the voltage switch and have it set for 115 V for North America. I remember now that when I was moving the bed and it lurched (because the wheels were too tight) the screen might have lit up.
I'm worried that the board might be fried. I don't feel like taking this thing apart and sending it back.

I prefer to check basic power connections with multimeter. But indeed if you are not in an emergency, it would be better to send it back. The wires may come loose, I mean on the main board.


Question about the MK8 Extruder I am trying to make a 3D printer (Prusa i3 model). I was testing all steppers and all steppers are working, however the Mk8 extruder (direct drive) is not working and I don’t know why. Can someone help me?

It’s either because you haven’t connected it properly or you have not  mounted it the correct way. This could lead to the damaging of the part and failure to work again.

Check your connections with the stepper motors and hotend power wires. Make sure the connectors are in fine condition and cords are not frayed. Ensure all power is completely off and mains cable is unplugged.


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.

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.


Spiky hotend and bed temps I recently rebuilt my A8 printer to have a metal frame and replaced the board with a GT2560 reva+. I'm having problems with the temp readings from both my hotend and hotbed. Using marlin 1.1x and Its possible I have something configured incorrectly. I can get successful prints with good quality but sometimes I get thermal runaway during a print.

Both cold and at temp (200c) have fairly large temp spikes. I didn't have this problem with my old board. I had much smoother temp curves. I'm using the default PID values for Ultimaker Kp 22.2, Ki 1.08, Kd 144.

I have tried to use PID autotune but get drastically different values every time I run it and using the results gave worse results (sometimes giving a heating error during the autotune). I checked all the wiring and nothing looks frayed or damaged.

First pic is cold temps. Second is trying to do a PID tune. Third and fourth are during a print.

I had a similar problem and there could be three reasons(if the connections are ok):

thin wires to the hotend
one of the MOSFETs was fried
the termal sensor wasn't good enough insert into the hotend

Try to measure the hotend heating element voltage while printing.


Adjusting Z-axis (Monoprice Maker Select) Have a Monoprice Maker Select v2 and have recently changed to an Anycubic Ultrabase glass plate. In Cura, the model I am printing is in the middle, as shown here:

but the printer puts it around 2/3 of the way up in the Y dimension:

Further investigation: I now believe the platform screws were too far down at one point, so that the platform could not move all the way forward, somehow making the printer think the platform is further back than it actually is. The original and the new platforms are the same size, 22x22 cm.

(When I run the Cura "bed leveling wizard", the stops are a bit from the edge at the front, and off the platform at the back, consistent with the theory in the previous paragraph.)

Even more further investigation: I have now dis-attached the Y-axis belt and moved it back and forth with no improvement. Also, the platform screws hit a couple of bolts at the back, which prevent it from moving all the way back (i.e. the extruder head forward), which seems to be the reason it is not getting to the front of the platform. I think I will have to increase the Z position first.

In the above picture, the platform is much higher than the origin position. This is the `back left' corner. If I lower the platform to the nozzle origin, it cannot move all the way back (i.e. nozzle cannot reach front). The screws came with the plate (and are different from the ones I had before). With the platform at the height shown in the picture, it moves freely all the way.

So the question now is: how do I change the Z-axis "origin" position? Have tried to manually adjust and then select "set origin" on the printer menu, but it did not have any noticeable effect. When selecting "home" it goes back to the old position.

I sawed off about 2 mm from the (bed) screw in the photo so it wouldn't catch on the screws of the Y endstop. It now works as before.

If somebody has a more cerebral solution I will gladly `accept' it.


Convert G-code to SVG This question is a bit of an edge case for what 3D Printing SE covers, but it has to do with topics most closely related to 3D printing.

I've found a plethora of ways to convert SVG (vector graphics) into G-code, but I can't seem to find any way to take a series of G-code movements and convert them into lines as a vector graphic.

Why would I want to do this, you ask?

I have a Silhouette, which can cut paper, or draw on paper, depending on if you insert a knife tool or a pen tool.

I have a polar draw bot (Makelangelo) which doesn't want to behave... the motors keep losing steps when the number of steps/second is low, and thus positioning gets off.

I want to use the drawing algorithms in the Makelangelo software to create drawings using my Silhouette, but the Silhouette wants vector graphics, not G-code.

The simplest way in my mind to do this is to convert G-code generated in the Makelangelo software, convert it to a standard vector format (SVG), and import it into Silhouette's software suite.

Alternately, if there's a way to send G-code directly to my Silhouette and have it work, that'd be a much better solution.

There are a number of programs available which will convert g-code to DXF, a common drawing format. If your device does not support DXF directly, there are a number of programs to convert DXF to SVG. I would paste links but a quick search with your favorite search engine should give you useful results. The better conversion programs will allow you to eliminate movement g-code entries, which prevents connections between lines. I did not paste links, as my research shows such variety as to be overwhelming.


How to 3D Print 5-pointed star object that doesn't have flat bottom and hole in the middle? I'm new to 3D Printing. I've created this star from Blender3d. As far as I know, most printers require a flat bottom.

As you can see (blue line is Z-axis, red line is X-axis, green line Y-axis), the star doesn't have any flat sides or points.

There's a hole in the middle of the star.

Is there a printer (brand/model) that can print this object that doesn't have any flat bottom or sides having a hole that goes through in the middle? Any workarounds to print this object?

Typical FDM desktop 3D printers might struggle with this model as it requires you to either print large overhangs and use support structure (when printed laying down), or lacks a natural flat bottom surface to get good print adhesion (when printed upright). A couple of suggestions:

Some FDM printers are great at printing support, and some even allow you to print dissolvable support structure. If you find one of these, you are home safe.
You could split the model in two, print those parts separately, and then glue them together afterwards. This is quite common for complex models, and allows you to print your model on even basic FDM printers. Tom's answer illustrates this well.

There are naturally other 3D printer technologies too (SLA, resin etc.), but I have no practical experience with these myself, and leave it up to others to give you a good answer regarding these.


RAMPS 1.4 losing power with more than 3 drivers mounted I am rebuilding the electronics for an old Reprap with a RAMPS 1.4 setup.

If I plug in just the Arduino/RAMPS board into either 12 V or USB then it starts up fine, I can see this when I have the screen plugged in. However, when I start to add driver boards, the screen begins to dim. After I have three boards plugged in the power starts to drop to the point that the Arduino powers off and restarts, even when the screen is not plugged in. I have had this problem with two sets of RAMPS boards and Arduinos and with a combination of 7 different driver boards plugged into different combinations of location.

Has anyone else had any similar issues or have an idea of what might be going on? Any ideas are welcome, I am just about at my wits end with this.

Your power supply may not be able to provide enough current. Check it's output voltage, the input at the RAMPS and the supply voltage (both VMOT and VDD) on each driver.

If the supply is good, you can suspect the polyfuses on the RAMPS board. These are yellow rectangles, designed to protect against over-current. They age with stress, and typically fail to pass their full rated current (but you need to understand if there is a fault which damaged them). The link describes how to remove them.


Problem with BLTouch on Ender 3 Pro I'm having some problems with my BLTouch.

Yesterday I got the 4.2.7 silent board delivered as well as the BLTouch and a glass bed. I was able to install the silent board without a problem and according to the many, many diagrams I've looked at, I also have my BLTouch installed correctly. I've installed several different firmware versions as well as manually compiling some.
I used the following diagram which was provided in a link by the seller. I also tried the firmware for Ender 3 pro 4.2.7 board on the Creality website as well as a few other firmware versions from various YouTube videos.

When I start up my printer the BLTouch does its normal startup thing and my printer says it's ready. But when I try to auto home, bed level, or even manually control the BLTouch it doesn't extend at all. I've spent about 4 hours trying to figure it out on my own and I'm throwing in the towel.

For anyone who has this problem in the future my solution was to loosen the screw on top of the touch just a little bit


Ender 3 first print some area is smooth but some is rough? Please check following image, Dog looks smooth from left side but its rough from right side , similar on back too.

What could have caused this ?

Can it be due to moisture due to Air Conditioner in my room ?

It is most likely caused by inadequate part-cooling due to poor air-flow. Fit a [better] part cooling fan. There are plenty of designs on Thingiverse.

You may also be able to resolve the issue by adjusting the printing temperature, but the easiest solution is to install a good part-cooling fan.


Reprap variants with servo motors rather than stepper motors? In a discussion about motors with a friend who used to work in the robotics industry, he told me that he despised stepper motor systems, as every stepper based system he had worked on required a bunch of hacky software fixes to make the system perform to the required level.

He said that servo motor based systems had their own foibles, but at least they could generally be tuned out and you always knew that if the encoder said you were in a given place then you would be (to within the constraints of the backlash compensation).

Because of this, I was wondering if there were any options for using brushless DC motors + encoders + drive electronics instead of steppers + drive electronics.

You can get "stepper replacement" servo drives that supposedly put all the needed control in the drive, and accept ordinary stepper inputs. Those should make the servo-drive a "drop-in" option on anything that uses stepper drives.

That said, I've seen an affordable CNC router system based on steppers turned into a much more expensive system based on servos, and I still have the "obsolete" stepper version, as the servo based system is MUCH more expensive and I could not keep up with the "upgrades" and never would have bought it at the price it now goes for. I'm in fact considering changing that to a reprap control system (still as a router, not as a printer, as I currently think.)

Given some practical limits to printhead speed in additive 3D printing based on the material solidifying, there may not be a lot of benefit in the considerable added expense of servos. They can move faster, but how much of that will translate to actually printing faster? How fast can you melt and pump plastic and have it stay where you put it?


Anet A8 - hot end temperature still same I've recently purchased Anet A8. First print went well, but now, the hot end temperature stays at ~230 °C. When I touch it, it is still cold. I tried the thermistor, and it correctly changes resistance when I blow on it (from 100 kΩ to ~70 kΩ). The voltage in connector is about 300 mV.

Does anybody know what could be wrong?

In my case, I had a bad resistor on my board. R41 had only 2.2 kΩ instead of 4.7. I replaced it and everything works now.


Stuttering extrusion after layer change I am currently encountering a problem where under certain circumstances, the extruder stutters when it starts a new layer. I am printing on an Anycubic i3 Mega and am slicing with Cura 3.6.0. The problem seems to occur in the main part of prints, as well as in supports. However it seems to only occur after a retraction has taken place. I have taken a video of the stuttering which can be found here: https://photos.app.goo.gl/G3TLKveMsLNRQmgv7
When a print is done the stuttering results in walls looking like this:

Can anyone help me figure out what is causing the stuttering?
Thank you very much!

You retraction settings may be too high. Direct drive extruders require less retraction than Bowden style extruders. Typical retraction settings for direct drive are 1.5mm at 50mm/s and for Bowden, 4mm at 50mm/s. The speed usually makes more of a difference than distance beyond a certain point.

You can get away with smaller retraction settings if you increase travel speed because there will be less time to ooze. You could also try using Coasting as well.

Anyway, try reducing your retraction settings if they're higher than what I stated above. Another alternative is to set an extra prime distance so that extra filament is extruded after the retraction.


What are the appropriate ranges of gear ratios for 1.75 mm and 3 mm filament extruders? Most 3 mm (mostly are actually 2.85 mm) filament extruders have some kind of gear reduction. Many 1.75 mm extruders are direct-drive / ungeared but some do use gears. What kind of reduction ratios are suitable or optimal?

$ \frac{(2.85\ mm)^2}{(1.75\ mm)^2}=2.65$ which is the reduction you would want assuming a 1.75 is direct drive.

In this answer I am comparing the amount of filament flowing though the extruder by using $ \pi \times r^2$.  Dividing the 2 values gives the ratio of the 2 speeds.  A gear ratio is them used to change the speed.


Problem With large prints on Lulzbot Taz6 I have got a Lulzbot TAZ6 3 days ago. Last night I started a print which is 21 hours long and when I returned check on it this afternoon it was a complete mess.
These are the objects that I wanted to print:

I used Cura LUlzbot edition for printing this, the settings I have opted are:

I need to print them with 100% infill for my project. I printed it over USB, and the cura was still running when I checked now, so i guess its not because of the computer shutdown. This used to happen when I tried printing these on Lulzbot KITTAZ i have, but its not working so I got TAZ6. Please let me know where i'm going wrong.

This was the state of the print(some of it was sticking to the printbed, this picture was taken after i removed it from the printbed)

Edit:

Thanks for the suggestion. I have calibrated the extruder and tried to print only the vertical cylinder. I have changed only one setting, changed the extrusion multiplier to .99. I kept the infill density to 100%(my project needs a cylinder to be completely filled without any air gaps) to see which of those two has greater influence on the print quality.   All the other settings were the same
here is the result(After I saw this I cancelled the print):

Like you suggested the infill is overflowing. What should I do next, i'm concerned if it is printed with reduced infill percentage its density will decrease. Shall I try to print it with 97% and see what happens?

Unluckily - for as much information on your settings you share - it is very difficult to diagnose the problem without knowing how the print failed.  Did a piece become dislodged? Did the nozzle caught onto a printed piece? Did the head began extrude in mid air? ...?

However this are my guesses:

From your temp settings it looks like you are printing ABS.  If this is the case, have you placed your printer in an enclosure?  With ABS, It is very very difficult (if not impossible) to print anything above "small", without an enclosure.
Printing 100% infill is normally a bad idea.  If you are doing it for strength, then you should know that the strength gains are progressively smaller on anything above 60%.  100% infill also means that unless your extrusion is perfectly calibrated (which I suspect it may not be the case, given that your setting is the default 100%) any amount of overextrusion will likely let the nozzle "catch".  Finally, 100% extrusion also increases the warping forces on the piece considerably.
Printing a cylinder "laying down" is hard: you basically have zero adhesion to the printing bed and must rely on the support material to stabilise your part.  But the support material is designed not to bond securely to the main piece and it will be unable to counterbalance any "curling up" that your part may experience due to thermal contraction.

So, my suggestions:

Use an enclosure (even a simple cardboard box on top of the printer will do for a starter).  Definitively use an enclosure if you are printing with ABS
Calibrate your extruder.  Here is a handy guide. :)
Reduce your infill density to something between 60% and 97%.
Print your parts one at a time, start from the vertical cylinder and - when you have got that right - try the horizontal one.
If you must print one of the two horizontal...

Increase the support density considerably, and diminish the Z-distance between support and print to the bare minimum.  If your edition of cura has that setting, use support interfaces at full density.
Alternatively eliminate the headache completely and print two semi-cylinders instead (cut the cylinder in half along its length, printing them with the "cut" as their base) and glue them together afterwards.  If you are using ABS you can "weld" them with acetone instead.


Bowden-direct hybrid I've got a direct drive extruder printer, that I have equipped with a Bowden-tube to give it a nice and defined filament path from my spool and to protect it from moisture when it exits my drybox. I've noticed that this 1 m Bowden tube adds quite a bit of friction to the system. I am keenly aware of it as feeding filament form the drybox into the tube by hand is quite a chore already, especially with high friction materials like PETG. Also I notice that I can sustain only lower volumetric flow without skipping or underextrusion after adding the tube.
So I figured, why not have a motor on both sides of the bowden tube? A big and heavy one at the entrance, providing a baseline pressure on the filament. And a comparatively light one on the other end, adding that fine control you want for your retraction, rather than trying to implement that via a 1 m wet noodle full of static friction.
Seems like it would give you the best of both worlds. Not quite as light as a full Bowden system, but you could have all the control of a direct drive system, with much less of the weight/flow rate tradeoff.
Anyone aware of this being done before? Or any good arguments as to why it is a stupid idea? Seems like a fairly straightforward mod; in the simplest implementation, just add an additional extruder of the same spec on the other side of your Bowden tube, and split the control signal to be the same amongst both motors.

A Bowden tube is by design fairly small diameter to match the filament within, constraining the forces applied by the remote extruder mechanism. As you've noted, friction is a consideration.
For your application, you would not have to have such a tightly constrained diameter. You could use a Bowden tube for 2.85 mm filament, if your direct drive extruder is made for 1.75 mm filament.
You'd have the environmental control of the smaller tube, the path control and all of the other benefits, but none (or little) of the friction.
Additionally, you would not have the complexity of managing retraction or synchronizing feed that a dual motor system presents.


How is the extrusion rate matched to the movement speed? A typical line of (depositing) G-code seems to set a maximum speed (F), a new position to move to (X, Y, Z) and a new extrusion distance (giving a filament distance for the move). The F is common for the line of code, and I understand gives a maximum for the XYZE combined speed.
My question is: "How is the extrusion rate synchronised to the movement distance and speed?"
The G-code doesn't seem to have enough information to deal with this, but I've tried looking at a Marlin configuration file and don't see anything obvious there.
To take a really basic example: A 30 mm long single filament, layer height 0.2 mm and width 0.4 mm. A basic slicer will assume 0.2x0.4x30 mm³ total volume, but for each mm of travel you want 0.2x0.4x1 mm³ to be extruded. How is it ensured that this happens regardless of travel speed, without say more being extruded in the first half of travel than the second or vice versa?
It feels like this is dealt with somewhere in the firmware but I don't know where to look. A 'worked' example for a desktop printer or as much detail as you dare would be absolutely perfect. If it helps, I am generally using either an ANet A8 or Ultimaker 3 with the CURA slicer using Marlin-based firmware.

I'm not sure what you mean by "XYZE combined speed", but I wonder if it's the same misconception as in Details of Marlin's feedrate calculation. The feedrate is a regular 3-dimensional velocity in XYZ space which is the maximum rate the printer will attempt to achieve, subject to individual axis feedrate limits (including E) and acceleration profiles.
In any case, the simple answer your question of how the E-axis motion is synchronized with motion in space is no different from how motion along the X-axis is synchronized with motion along the Y-axis. If X and Y motion were just allowed to take place independently up to the desired speed, with no constraint that they happen in step with one another, then the path the print head traveled would not be a straight line but (ideally) the junction of one horizontal or vertical line with one diagonal one or (with acceleration profiles applied) some approximation of that by curves. But of course the X and Y motions do take place in sync with one another. Each spatial coordinate during the move is a function of time computed by the "planner" logic in the printer firmware based (essentially) on the ratio of the magnitude of individual components of the move to the overall length of the move and speed.
In traditional firmware prior to Linear Advance, the E axis is synchronized exactly the same, according to the ratio of the move completed to the whole and the total amount to be extruded. With Linear Advance, that's adjusted by an offset proportional to the current baseline (before applying LA) extrusion speed, to compensate for the filament being compressible and/or its travel path (e.g. a bowden tube) being elastic.


Best gear STL to print with ABS I spent the last days trying to make the best gears I could but they are not "smooth" nor good. I searched at thingverse with "gear" but I see no set of gears. I would like someone to point me a good set of gears (with 5, 10, 15... teeth for example) so I can use this STL file with Google Sketchup.

Do you guys know any good matching gears that I could print?

I will be using this gear in a fast spinning matching so it would be nice these gears to be well designed to support some fast moving.

Also, I think in my case I would like to use gears with this shape (the white gear). Any idea why is this gear design better than the usual?

This type of gear is known as a "herringbone" gear. A traditional straight-cut gear is strong, but can cause more vibration as each tooth engages and disengages. A helical gear (slanted tooth) reduces that vibration as the tooth engagement is more uniform. However the angle of the teeth causes a sideways force that may be undesired. A herringbone tooth design effectively cancels the sideways forces but gets the uniform tooth engagement.

A search for "herringbone" on Thingiverse comes up with many gears of this type.

Regarding the quality, if you are not happy with the results of your own design, that's OK - gears are shockingly complex, and people make careers of gear design! However, if you have a good CAD model that just isn't printing well, it's not likely a bad STL.

An STL from a different source is likely to have similar quality with the same slicer/printer setup. You might be able to improve print quality of your design by changing settings on your slicer or adjusting your printer. I'd suggest asking a question with your current setup and specific print quality issues.


Ender 3 Y-Axis Stretched (I don't believe it's layer shifting) I've got a peculiar issue today, and was looking for some help with it.

Of the six Ender 3s I manage at my college, one of them seems to be stretching the Y axis of all the prints I make with it.

Some points about the issue:

It's variable, but is much more pronounced in larger prints:

A raspberry pi frame-mounted case I printed came out too long along the Y-Axis by over 2 mm.
To troubleshoot, I printed a calibration cube but the Y-axis was only 0.5 mm longer.
It seems to affect only part of some prints; a bit over half of the pi case was stretched, but a section at the top appeared normal (screw holes were perfect circles, but towards the other end they were ellipse-shaped).

I tried tensioning the Y-belt, and while I noticed it was loose before tightening it, this didn't make a noticeable improvement.
It doesn't occur in any of the other five Ender 3s, all of which are equal in modifications.
A re-flash of the Marlin firmware didn't fix the issue. It's a preconfigured Marlin version that I pulled off github based on a recommendation. I flashed this version to try and solve the problem, the previous version was installed by the printers' previous caretaker but the new version didn't help (makes me think we might have both grabbed the same version).
It means that I can no longer print any components that require high tolerances, as they simply won't fit together.

The most recent print was a 40 mm fan shroud for a "hero me" setup (which I'm working on installing on all six printers).

I ran two of them, one on the printer with the issue and one on a perfectly functional printer.
They were run this morning, in identical conditions and started at the same time.
There are no other structural defects aside from the stretching, it simply looks like a normal, print but as if someone used the photoshop transform tool and pulled it.

Here is a side by side of the two finished prints, comparing them along both the X and Y axes. As you can see, the X axis is perfect on the problem print, but the Y is consistently stretched (visible in the shape of the round cone and the screwholes).

This issue has been consistent and I'm honestly stumped, any help is appreciated! If anyone needs me to obtain more documentation or test something, I'll be back in with the printers in the morning (roughly when this post is 10 hours old) and I'm happy to get any documentation needed.

If an axis doesn't print the sizes you command it there are basically 2 options causing this.

The printer is incorrectly configured,
The printer has an hardware issue.

To find out which of the 2 is applicable, you need to look into your setup and into the firmware settings. E.g. from the printers display you can read the amount of steps the stepper needs to make to move the axis 1 mm. Alternatively, send M92 through a terminal and look at the steps per mm. If X and Y are the same, the firmware is correctly configured and you are facing a hardware issue. Note that for the stock Ender 3 the value for X and Y needs to be 80 steps/mm. Do not alter these values!!! These values are based on the mechanical layout and the micro-stepping used by the stepper drivers.

Since you have flashed a stock hex firmware file it is highly improbable that the firmware contains the incorrect steps per mm value for the Y axis (unless you accidentally changed this through the interface/display). This leaves you with a hardware issue. Common reasons that could identify the source of the problem are:

Loose grub screw of the pulley on the stepper,
Missing steps, e.g. due to too much friction (if dimensions are smaller, in your case this is not the problem, it is added for completeness),
Loose, under tensioned belts,
Stretched belts as a result of over tensioning the belts.

Considering the stretched Y dimensions, the most logical explanation would be that your belts are stretched, you cannot fix this by changing the steps/mm value, it requires mechanical attention; i.e. replacing for new belts.


Graphite self-lubricating bushings performance? I'm about to start building a CoreXY style printer and can't decide which bearings/bushings to buy. My first printer was a Delta with belts and opendbuilds wheels, so I'm lost regarding this matter.

Anyone tried these self-lubricating graphite bushings?
How do they perform compared to the standard LMUU bearings?

Robotdigg link

Aliexpress link

Do they run smoother, more silent?
Do they have play?
Do they stall after a while? Need maintenance?
Any feedback is much appreciated.

Bushings will be quieter than linear ball bearings.  Some online discussions complain of the linear bearings becoming noisy, and (in what I think is a failure of the balls to circulate properly) for the balls to develop flat spots.  If the balls aren't moving properly, you will end up with a bushing.  You might start with a bushing in the first place.

Bushings spread the load over the surface of the rods, so there should be minimal wear.  Bearings and bushings are limited by the load and the speed.  In 3D printers, neither the speeds or the loads are particularly high.  Bushings should work well.

Bushings may have slightly higher sliding friction, which could result in slower maximum printing speed for motors with the same torque.  The characteristics should be more stable as they age.

Others may have different experience, but I would consider either the self-lubricated brass bushings, or perhaps the self-lubricated graphite bushings.

As an example, inkjet and laser printers do not use ball bearings for the carrier.  15 years ago, it was bronze bushing on stainless steel shafts.  Over time, it has evolved to PTFE pads sliding on stamped sheet metal.


Lack of isolation between axes Sometimes I notice that if I manually command a single axis movement (typically Z, when I want better access to the extruder), I observe that several channels move together (and they maybe move slower than I expect). After one 'coupled' movement, subsequent commands have the result I'm expecting.

What happens is as well as the Z-axis moving up, the bed moves forward, and the extruder moves to the right. I have no auto-leveling or anything else non-standard on this printer (dual Z steppers, X, Y, extruder, bed, extruder heat).

It even happens if I simply extrude some of the time (e.g. changing filament after warming up, retract gave me some X movement)

Printer is an ANET-A8, I'm using mainly OctoPrint, but I think I've also observed this with other PC software manual controls.

It doesn't happen often enough for me to have identified any pattern - maybe it only happens if I've not homed first after turning the printer on, but I suspect not.

It's not so much of a problem, as just a question for interest. Also not sure how to tag.

This is easily explained - it's the stepper motors getting powered up. Stepper motors even if not moving are constantly powered up and actively hold the position they are in exactly at the stepping point where they are.

If you power down the machine or if the board disables the stepper drivers to save energy or because the power is offline then the stepper motors can get in between steps. When powering on then the movement is  quite noticeable on some cheaper motors where the inrushing current can kick the motor over multiple steps before it locks down into position.

You can test this, try to move one of the axis manually by hand (not too fast to not damage the board by providing it too much current) if the printer is powered of it does move pretty easily. Then power the printer on, it should still move pretty easily by hand. Now execute one move command on the axis via the printer board. Afterwards you should not be able to move the axis by hand anymore (or at least not without unnecessarily excessive force).


Problems with X axis movement I have been printing with no problems. I have finished the spool of filament and removed the remaining filament from the Bowden tube and hotend. Before loading the new spool of filament, I decided to level the bed using the installed BLTouch.
Probe grid 3 x 3. Centre point of the build plate, X:135, Y:130.
Homed the bed (G28). Leveled the bed (G29). The first four probe points worked as expected. When the printhead moved to the fifth probe point, the screen read that the printhead was in the expected position (X:130, Y:130). The printhead had only moved about 20 mm, meaning the true position was X:240, Y:130, I had checked this with a ruler. The sixth probe point also moved about 20 mm on the X-axis. The seventh point moved along the Y-axis correctly. The printhead tried to move correctly to the eighth point and promptly crashed into the side of the printer as it was trying to move 130 mm to the right. The screen had X:0 when in reality it was X:230.
I tried the ABL again. This time I aborted the ABL on the fifth probe point as the previous event had been repeated. Reported position, X:130, Y:130. The true position, X:240, Y:130. I then tried to home the bed (G28). The printhead moved a short distance to the left (<20 mm) on the X-axis, reported on the screen X:0, and started along the Y-axis. When it had reached Y:0 (true position) it then moved diagonally to where it thought would be the center of the bed, but would have crashed into the side of the printer frame if I had not cut the power.
After re-setting the board, I could home the board either by using G28 or via the screen. I could move the printhead along the X-axis freely, both through Pronterface and the printer screen. If I tried to home the printhead when X>140, it would only move a short distance to the left, set X:0 on the screen, and head down the Y-axis.
I have checked for loose connections and everything seems tight. The only difference from when I was last able to print is there is no filament loaded.
Anybody any ideas what is wrong?
Printer: Hypercube Evolution (CoreXY)
Board:   KFB2.0

After many hours tinkering, pulling things apart, testing them and re-assembling them, it turned out that the problem was a broken wire for the X_Min endstop. This has now been replaced and the problem is resolved.


Sealant to increase Water-Resistance of SLS print We are attempting to print some single-use prototypes using an SLS printer. The parts must be somewhat water-resistant for short-term usage, but do not have to been waterproof entirely.

According to this page, Post processing for SLS printed parts - Water tightness, any silicone type or vinyl-acrylate sealant should work well, but I was hoping that the Stack users here might have some specific suggestions.

Does anybody have specific recommendations for sealing SLS prints?

SLS prints from nylon are somewhat porous. This means, that they will let a stabilizer soak into the outer surface to some degree.

What kind of stabilizer is needed is depending somewhat on the properties you want, but generally I believe these might be useable depending on the viscosity:

2-component resins could be used, but they are usually very viscous. Their viscosity, however, is dependent on the exact type and mixture and could be altered by temperature.
1-component (air-hardening) resins or resin lacquers can be thinned to achieve a solution into which the item is then dunked and dripped off. How much thinner is adviseable depends on the exact material
Nitrocellulose lacquer, like it is used in guitar building, is extremely fluid and could be used for treatment via dunking.
PU lacquer could be used too.


How do I wire the z-axis motors in parallel on the Prusa i3? There is a little circuit board, or breadboard or something in the diagram of the wiring for the i3.

And it's mentioned that the z-axis motors need to be wired in parallel but beyond that they don't give you much detail about parts or how the wires go in.

Can someone provide me with some more detail on this?

In the diagram, they do show the wires connecting together, which is right. You can accomplish that just about any way you like, so long as you pair up the wires correctly from one motor to the other.

I'm assuming both "Z" motors are the same type and have the same color-coding for their wires. If not, you'll need to figure out the correspondences first (you may want to post another question if you need a hand with that, since it's pretty specific and generally useful).

Many control boards have "headers" sticking up, with 4 bare pins for each motor. Connectors that plug right onto those are readily available, such as at https://www.sparkfun.com/products/10364.

Some ways you can wire the motors in parallel:

Some control boards, like my RAMPS 1.4, provide 2 sets of header pins next to the Z stepper driver board. In that case, just put a connector on each motor (if they're not there already), and plug them in next to each other.
If there's just one set of header pins (or one Z-motor socket of some other kind) on your controller, make a "Y-cord" by soldering the wires from one connector (that plugs to the controller) to 2 4 pin connectors, one to mate with each motor.
Or you can skip the 2 extra connectors entirely, and just solder the motor wires to the wires from the connector: 2 reds to red, 2 blacks to black, or whatever.
If your controller just has empty holes, either solder in header pins and do as above (preferred, IMHO), or wire directly into the holes, splicing the 2 sets of motor wires if there's only one set of holes.

Motor and connector wires are wildly inconsistent, so make sure you get them sorted out right if they aren't already. The first thing is to check continuity: find 2 pairs of wires, which are the ends of two separate coils. If your motors have more than 4 wires it's trickier.

With RAMPS (see handy diagram RAMPS 1.4 RepRap Arduino Mega Pololu shield),

the 4 pins are commonly labelled (starting from the one nearest the power-supply end of the RAMPS board):

2B 2A 1A 1B

It means coil 1 and coil 2, each of which has ends A and B. I find this unclear because it could just as well have been numbers for the coils, and letters for the ends (if you wire it that way it won't work). So be sure you have continuity (maybe 15 ohms or so) between the wires you connect to 2B and 2A, and between the wires you connect to 1A and 1B.

The really good thing about this pin order is that if a motor is running backwards all you have to do is power off and then turn the plug around. That's one reason I think it's important to keep connectors in there, rather than soldering directly.


Can the filament tube be outside of the nozzle? I bought a few new nozzles expecting them to come with that little tube that comes out of the nozzle. They didn't come with them after all, so I tried to reuse the tube I originally had in the printer. Turns out my old tube is 4mm OD and 2mm ID, but the new nozzles have 2mm holes for the tube to go in. I use 1.75mm filament, so it seems like to be able to fit the filament through the tube would be impossible barring a tube with an 0.125mm wall.

My question is, can I put the tube outside of the nozzle? That is, not stuck in the hole for the nozzle. In theory, the tube would still direct the filament into the right place. It looks like that might be the point of these new nozzles, since it seems so unlikely that someone would be able to stick a filament tube in the nozzle.

If not, where can I find the tubes I need? I've looked in a few different places and I can't find it. Or are the nozzles useless, and should I return them? Thanks for the help.

Let me clean up a little nomenclature
The PTFE tube is either a Bowden Style Setup delivering the filament from the extruder down through the cool-end and to the heatbreak or just a liner in the cool-end and heatbreak for direct drive. In both cases they are to prevent clogs. In most setups it is not pushed into the nozzle which is in the heater block (they exist, see below).
The liner/Bowden tube guides the filament through the heatsink and into the proper Hotend/Meltzone. In the better designs intended for higher temperature like ABS (see left half), it ends in the heatbreak. This also has the added benefit of having less chance to leak if the tube slips a little bit.
Simple setups (see right half) butt it against the nozzle and thus limit the temperature range. This kind of butted setup can lead to leakage if the tube slips up. In either case, it is no problem to reuse the PTFE tube when changing nozzles, it is even advisable in the case of a Bowden setup as it might change the length of the path.
The nozzle is usually screwed into the heater block from below, and for best use, one screws it against the heatbreak in a heated state - this is called hot-tightening.

If you somehow end up destroying your PTFE Tube, you can get them under the keyword PTFE tube, Bowden tube or Pneumatic PTFE tube on the internet.
PTFE inside the nozzle?
Yes, these exist, OP has them, they look like this, and are not what has become the industry standard.
I can think of no good reason to put an PTFE Sleeve into the nozzle, but someone did it, and it sis a valid approach. However, I see several problems with it:

the PTFE tube degrades if pushed deep into the melt zone and can lead to clogs.
the added PTFE is not a very good at transmitting heat, thus reducing the effectiveness of the melt zone. This can lead to needing either much lower printing speeds or a much higher printing temperature to achieve good prints

It should be of no issue to convert from this style into the butted-style (right) just by using a short length of PTFE in the heatbreak. I would prefer though to combine it with a heatbreak where the PTFE ends and making this what is commonly referred to as an "all metal hotend" (left).


How to use a multimeter to test how many amps RAMPS is pulling? This is in with my other question about components and the other question about electricity; how can I check to see how many amps are being pulled?  Can I check a component at a time to make sure I'm not going over the limit, and then just add them all in together once I've summed the amps to make sure it's safe to hook everything up.  The amps shouldn't change right?

What settings should my multimeter be set to?  And to check how much it's pulling, do I just put the multimeter's leads on the green terminals on RAMPS 1.4?

To measure amps (current), the meter has to be wired in series with the item to be measured (for this reason, ammeters are designed to have very low resistance).

This has the down-side that you have to disconnect the component to put the meter in line with it. That makes it hard to do the "check a component at a time" method you mentioned.

An ammeter measures actual current flow, so you really can't test a component for it in isolation. Components can have wildly different "current draw" depending on the situation. For example, motor current varies with torque and speed; current through a resistor varies with the voltage across it; and so on.

There are special "clamp-on" current meters that just clamp around a conductor and report the current by using induction. Very nice if you have one.

If you just want the total current the entire RAMPS board is pulling, put the ammeter between the power supply and the RAMPS power input connection(s). Be very sure not to have the meter set to read volts or ohms when you do this (it might or might not survive).


Spindle DC motor and drill bit specifications for Circuit etching CNC machine I'm making a Circuit etching machine (CNC) and I need a good DC motor and drill bit for the spindle.

My machine should be able to etch, drill, and cut:

Etching: take copper off the surface like chemicals or a laser would
Drilling: drill holes for THT (through-hole) components and possibly 2-sided boards
Cutting: cut out a piece of the board (cutting a big piece in half or cut a circle out of a big piece)

I'd like to have 1 drill bit work with all 3 functions if possible. Having to switch out different bits is OK but a single bit is prefered.

What sort of specifications should my spindle DC motor (rpm, voltage/amperage rating, ...) and drill bit (material, size, angle, ...) have?

There are several sources of PCB "etching" bits.  They tend to be single straight flutes and high angle, very pointy bits.

For the motor, high speed is good.  Look for 30k+ RPM.  The main thing to be concerned about is the amount of runout, or wobble in the tip.  With a tiny tip, you can't afford much runout at all.  It will broaden the gap you are cutting and put stress on the bit, probably snapping it.

The key to low runout is very careful alignment of the chuck that holds the tip with the shaft of the motor, and a collet chuck to hold the tool.

The power needs aren't high since the speed is high and the cuts are light.  I would think that a 250 watt motor should be way more than sufficient.

The question now asks for drilling and routing, which should work better with the high-speed spindle.  30k is better for the tiny drills than a much slower spindle.  These are hurt by run out.

Usually the drill bits are made of carbide.  For cutting, carbide router or file bits are used.  All drill-bits and router bits and copper cutting bits I have seen for sale have 1/8" or 3mm shank.


Good methods to clean extruder gear (hobbed) from filament pieces? I'm using a CraftBot original to print PLA, but some of the filament has become stuck in the teeth of the extruder gear on its way into the hot end.  I'm having issues with the gear becoming stuck and "clicking" instead of turning, and I suspect it is because of the clogged teeth.  I haven't changed materials in a long time.  I've cleared several print head clogs, but each time the gear gets back around to the one spot, it seems to get stuck again.

Are there any good ways to clean this gear?  I was thinking of putting it in a toaster oven and trying to melt the PLA off it, ideally without setting my house on fire in the process.  Anyone have better ideas?

If your gear skips at the same place each time I have found on my machine that the gear does not fit the motor shaft properly and has a larger gap between the gear and the idler roller.

Check to see if there is a thicker buildup on one side of the gear than the other.

On my machine what I had to do was to use a spare motor cable and watch the gear as it turned, and at one point on the gear it would slip and shave off a small amount of filament.

If that turns out to be your problem use a good caliper to measure your motor shaft, and the inner diameter of the gear.

Sometimes the minimum shaft diameter and the maximum bore diameter of the gear are just enough to allow that small variance in the outer rotation diameter of the gear.

Sometimes just replacing the gear will solve the problem, and sometimes it will require a new motor and/or gear.

As an alternative you can clean the gear using Acetone and a toothbrush, but that will be required often and you will have buildup in the chamber below the gear which can also cause feed problems, and you must make sure that all Acetone has dried before using the extruder again.

I suggest starting with changing gears since they are the cheapest and using the Caliper to find the closet fit possible.

You can get gears on e-bay at very reasonable prices. and I bought several to get the best fit possible.

Good luck and consider if you want to make a more permanent repair or temporary repair when making your choice. I chose the more permanent one because the slippage was affecting some of my prints.


3D printers for ceramic clay? Are there any extruders and printers that do a good job with ceramic clay?

I assume the clay has to be fine grained and with enough water added to be able to be pushed out through the extruder's nozzle. I also assume the print speed would have to be arther low for the already printed layers to gain stability before printing the next layer. Perhaps some extra equipment on the printer to spped up this drying process?

At the same time, the print speed can't be too low: if the bottom starts to dry enough to start shrinking, the object will crack.

Also, some solutions I've seen tend to result in rather low resolution/thick layers, which is negative.

So, what equipment is "out there"?

What you are looking for is the Frostruder style extruders.
Here is a link to a thingiverse file for it.
You honestly cannot expect fantastic results but it will get the job done! There are many other types. Quality will depend on the size of the point. However with something as high viscosity as clay I would not expect you to be able to push the quality very high.


How to print a 6" wheel in ABS? I'm using a Flashforge Pro and attempting to print a wheel about 6mm thick to serve as a platform.  In other words, the wheel doesn't have to be solid, but spokes won't do the job.  I've experimented with different temperatures, but, because of ABS' thermal expansion, I don't think that will solve the problem.  Also tried putting lots of 2mm holes in the wheel.  I've considered other designs for the interior, but doubt that would be a solution.  Has anyone tried using different print paths, i.e. actually altering the path that the slicer suggests?  (grasping at straws)
Thanks for your suggestions.

If you can, set your slicer to do honeycomb fill.  Depending on the weight requirement choose maybe 10% - 20% fill.   That ought to do the trick.  It won't be solid, but it should be strong enough.

What are you going to put on the platform?


Why does hairspray work as an adhesive for ABS? Since I have a 3D printer, I worked primarily with printing ABS. I tried multiple methods for adhesion (various soluble glues, ABS juice) but always had the most success with hairspray on clean borosilicate glass, as long as I print with a bed temperature above 75 °C and inside an enclosure.

So I wonder, if it is known, why and based on which chemicals the hairspray method works so well?

First of all, not all hairsprays work. The chemicals in hairspray that causes the bonding is "VA/Crotonates Copolymer", it is also called "vinyl acetate/crotonic acid copolymer". Most commonly known as PVA, which is also a filament used as water soluble support material. This is a synthetic polymer created from monomers.
When heated to a certain temperature this ingredient becomes sticky, this makes the filament stick to the plate. It is the double bonded Oxygen molecule that makes this happen. This is not only present in chemicals you put onto the bed, but also the chemistry of certain bed materials. Quoting our own Ryan Carlyle from this thread, A replacement for Aquanet Hair Spray?? Wolfbite by Airwolf:

Most of the popular build surfaces have very similar underlying chemistry. That's because they all rely on diffusion welding for adhesion. The molecular chains at the interface slightly dissolve into each other.
Gluestick active ingredient - http://en.wikipedia.org/wiki/Polyvinylpyrrolidone

Aquanet and liquid PVA glue active ingredient - http://en.wikipedia.org/wiki/Polyvinyl_acetate

If you're familiar with organic chemistry, what you see here is an identical polyvinyl backbone chain, and functional groups that both have a ketone/ester double-bonded oxygen adjacent to a space-filling component. (The space-filling component probably decreases adhesion so the print can be released.) And guess what? Permanent build plate surfaces rely on the same underlying chemistry:
Lexan also has exposed double-bonded oxygen on a polymer backbone: http://en.wikipedia.org/wiki/Polycarbonate

Kapton also has exposed double-bonded oxygen on a polymer backbone: http://en.wikipedia.org/wiki/Kapton

Acrylic also has exposed double-bonded oxygen on a polymer backbone: http://en.wikipedia.org/wiki/Poly(methyl_methacrylate)

PET also has exposed double-bonded oxygen on a polymer backbone: http://en.wikipedia.org/wiki/Polyethylene_terephthalate

Now, if you look at some common solvents for filaments, what do you often see? Double-bonded oxygen on small molecules. Here's ethyl acetate (dissolves PLA) and acetone (dissolves ABS):

These molecules are still diffusing into the filament polymer, but they're so small and mobile that they are able to completely liquefy and dissolve the plastic.
Isn't chemistry great?


High temperature flexible filament I need to cool some liquid (250 °C) while it’s flowing through a tube which has to be able to bend and flex.
My idea is to make a flexible tube with a second tube spiraling around it through which coolant will flow.

I’d like to 3D print this tube if possible so I wonder if there is some printable filament that:

doesn’t melt at 250 °C
is flexible enough that it can print some tube that can bend (bending radius of 30 cm)
optimally also has good heat conductivity

Is there any 3D printer filament available that has these properties?

Ok, so to answer the primary question: What flexible filament will operate consistently at 250°C?
Man... this is a tough one. Some filaments, like PEEK and ULTEM 1010 can operate up in the 200c range.... but they're not flexible at all.
Silicon might be able to work, but you're still pushing boundaries.
Now.... I'm lucky to be in a 3D Printing company.... and we're testing a super-high-temp flexible material, very similar in temperatures to ULTEM. I'll definitely check back and let you know how it goes, but....
Honestly, that's so hot, readily available thermoplastics may not be an option unless you're in Aerospace with an unlimited budget..... which, based on the requirements, would make sense, lol!
I'd say the most readily available way to get this done would be 3D Printing a mold, in which to put your silicone, and bam -- you've got the part.


Printrun doesn't connect when 12 V is on I'm able to connect to Arduino+RAMPS through USB. I can even check end stops with M119. However, if I plug it to the power supply, my MacBook goes crazy and restart itself! Things I have tried:

Uninstalled OSX, installed Ubuntu, I get readiness error when PSU is connected.
Bought a new pair of RAMPS + Arduino.
Run RAMPS all naked without anything on it.
Measured PSU output, 12.2 V is stable.

I'm at a point I started to think my MacBook's USB ports are messed up. It is a 2008 model, do you think that would be right to blame?

Update

Tried a new and a very short USB cable: It worked for the first time and I'm able to home all axes, but laptop's trackpad gets very hard to control for some reason. I can only use an external mouse.

It sounds a bit like you are having (additional) grounding issues1. Are your MacBook and the RAMPS using the same ground, i.e. are they using the same mains circuit?
If you are using the same power strip, then the next thing to check would be that the PSU on the printer correctly grounded (at the bottom of the unit).
From David Crocker's superlative blog, see Upgrading the large delta printer - Power supply output grounding:

Power supply output grounding
While taking some measurements on my machine, I discovered that the
negative side of the output of the 12V LED power supply I am using was
not connected to ground inside the power supply as I expected. This
presents a safety hazard. So I added an additional wire from ground to
the spare negative output terminal of the power supply.

1 Why do I think this? Three reasons:

Because grounding issues is one of the most common, and over-looked, problems, in circuit design;
I have often had peripheral devices, that use a separate additional power supply, cause a PC laptop to go "haywire" (or worse, die) once connected via RS232/USB (especially charge sensitive devices on the laptop, such as the track pad), due to different, or floating, grounds, and;
I had recently read the blog and made special note to check all of my power supplies as they are all terrible, cheap, Chinese knockoffs, and grounding circuits in Thailand are usually non-existant, or, at best, poorly wired up.


LCD for SLA 3D printer resin curing I'm doing some research on what types of LCD displays can be used to filter and pass UV light for resin curing - specifically in the context of building a DIY 3D SLA printer.

The community commonly uses the Sharp LS055R1SX03 module. Looking through the datasheet, there doesn't seem to be any information pertaining to the characteristics of the device when passing UV wavelengths. Is there something special about this module that allows it to filter/pass UV wavelengths compared to other common LCD displays?

Hmm I seen videos off people pealing filters off of lcd screens to let uv pass through.

I believe the sharp unit maybe popular because not all lcds have square pixels and have poor pixel alignment towards the edges, (the focus of the eye can only take in so much information why waste materials producing inperceptable rises in quality, much like having a 8k small screen unless the picture is static your hard pushed to notice difference).

There is also diffraction to think about, crystal size in the resin, oxygen membrane or delamination layer to stop cured resin sticking to lcd, I think there are projects of floating resin on another liquid (fluorinated oils work).

Even with better resolution(4k,) the voxel size does not increase in a linear manner, unless the uv light source is focused an colimated like in a lazer.

I don't know much its just info I've gleaned whilst browsing, I'm sure someone will correct any inaccuracies.


Which is more durable to sunlight/weather - PLA, ABS or PETG The backstory: I'm installing a pigeon net in my home. Because of the shape of the opening I'm installing the net in and the material on the sides it's difficult to anchor the net using the normal means but I can print clips that will hold the net in place.

The clips will be outside and will be exposed to the weather and direct sunlight, the weather here is relatively hot (up to 30C) with a lot of sun most of the year and rain in the winter.

I only have PLA, ABS and PETG available, anything else will take too long to arrive.

I don't care about the parts changing color and mostly I don't care about them deforming a little bit - only about breaking.

If the parts have to be replaced after a year I'm ok with it, less then that will be annoying, longer will be better.

So, under those conditions, which of the 3 materials is more durable?

Ok, I tried all 3 materials.

PLA failed after less then one day, I believe it deformed from the constant pressure and fell out (I didn't find the part but I didn't really search for it, there's some tall grass below the window)

ABS lasted about a year, it fell strait down and I found the part, it looks ok if probably deformed by just a few mm so it doesn't pressure fit anymore.

PETG still going strong as I write this


Filament material for chemical application I am doing laboratory experiments and need to print some components.

I am working with different aqueous (water) solutions containing sulphuric acid (H2SO4), hydrochloric acid (HCl), and hydrogen peroxide (H2O2), separately and in combination. The pH of the solutions are in the range 0 to 7. Temperatures don't exceed 40° Celsius.

In another application we have aqueous solutions containing high concentrations of FeCl3, HCl and in some cases H2O2 at temperatures of up to 180° Celsius.

Which 3D printing filament materials can you recommend for these applications?

There are two issues you have here, one is temperature stability and the other is chemical reactivity of plastics. I can't help you with the chemistry side, but I can help with the temperature.
Application 1 (Temp < 40 °C)
Any FDM plastic will perform reasonably well under these temperatures. I would suggest trying a Nylon, PETG or a PolyCarbonate filament as I know these are more resistant to acids than PLA or ABS. As far as strength of the parts, all FDM plastics will work well
Application 2 (Temp > 180 °C)
This temperature range is above the glass transition temperature of the PLA, ABS, PETG and Nylon are all well below 180 °C and therefore aren't worth considering. Your best option is PolyCarbonate, or PolyCarbonate-ABS which are both fairly high (roughly 140-150 °C). However, are both below your minimum temperature threshold.
My conclusion is to try a polycarbonate sample and see how it reacts to the chemicals you're working with, though it doesn't look hopeful.
For Chemical reactivity, I did some Google-fu and found a few links that look helpful for PolyCarbonate:

Chemical resistance polycarbonate

Polycarbonate Chemical Compatibility Chart


Gaps in top layer of prints I have a Monoprice Maker Select Plus (Wanhao Duplicator i3 clone) and I'm having issued with the top layer of my prints. The bottom surface and the sides always come out perfect but my top layer is left with gaps in it. I have tried adjusting the print temperature, flow rate, print speed and layer height all with no success. I use Cura for my slicing software. If anyone knows how to help it'd be much appreciated

This is probably caused by too few top layers in combination with a too low infill percentage. Increase skin layers and increase infill percentage.
If you have multiple layers already (at least about 4 for 0.2 mm layer height, for smaller layer heights even more), you might be printing at a too high temperature and or too few part cooling percentage and a too low infill percentage.


12v 25A 300x300 Heater bed Mosfet I'm building a 3D printer from scratch (My first one, so yeah, tall order), so I'm buying all the parts separately, now one of the things I bought was a 300x300 12v 25A Silicon heaterbed (Yeah, I know, should have gone for a higher voltage, but that's the only one I could get at the time)

I have a RAMPS 1.4 board in all it's crappy MOSFET glory, so I tried giving my math skills a shot in trying to find a decent MOSFET that won't explode, though I'm still having issues deciding. And due to where I live, getting anything very specific is not the easiest thing to do.

So can anyone recommend a MOSFET that I can use to switch 25A and mention if it will need a heatsink?

I live in South Africa, So one place that I can get them from is from RABTRON Electronincs

There are a couple other places, but I'd prefer to get them here if I can.

I have looked over the 20 or so most expensive MOSFETs in that shop, and none are suitable.

It might be easier to go with a DC Solid State Relay rather than a bare MOSFET.

If you do want to go with a bare MOSFET instead, a TO-220 package MOSFET can dissipate around 1W without a heatsink, and around 3-4W with one. For 25A of current, that means the resistance of the MOSFET can be at most 1.6mΩ (without heatsink) or 5.6mΩ (with heatsink).

The IRLB3034 might be suitable. It is readily available on ebay (for under $1 shipped). 195A, 40V and an Rds(on) of only 1.4mΩ. A caveat is that this resistance is specified at a gate voltage of 10V, whereas it is slightly higher at lower gate voltages (1.6mΩ-2.0mΩ at 4.5V). This is on the upper edge of what is acceptable without a heatsink, but should still work (junction to ambient resistance is 62C/W, so in the worst case of 2.0mΩ the temperature would get to 77C above ambient - the MOSFET is rated for operation up to 175C). With a heatsink it will definitely work well.

Note that the gate charge is much higher (10x) than that of the MOSFET used on RAMPs so you should use a low switching frequency.


Tips for making parts that push/snap together I would like to make some parts that will fit together. Specifically, I'm making an array of holders for small glass vials, which will stack together vertically to make a kind of extensible spice rack, for a scientific application.

Of course, I could just give each module a flat top and bottom surface and glue them together. However, it would be more convenient (and more fun) to make some kind of connector, so that I can just push the parts together and pull them apart when needed. The connection will need to be relatively sturdy, and they'll need to sit flush against each other with no flexing where they join. I am a novice at 3D printing, so I'm looking for tips on how to design interlocking components, both in general and for this particular case.

These parts will be printed in ABS using the Zortrax M200, and I'm designing them using OpenSCAD. They will almost certainly be printed lying on their side.

One option is that there are several parametric Lego brick clones available, which I could easily incorporate into my OpenSCAD project. My only worries are that this might be overcomplicating the problem, and that printing Lego type parts on their side will result in having to scrape a lot of support material out of the hollow parts. (Though on the plus side, the lego compatibility might actually be useful, in terms of not having to manufacture additional supporting material.)

Any tips would be welcome on how to design and print parts that can be pushed together. I am sure I can work it out myself in time, but any knowledge that will save me a design iteration or two would be very greatly appreciated.

There are many different ways too approach this and the question may be too broad, but here's a stab at it...

Here are a few different ways that I've made parts that connect in the past:

Example 1: Utilize the elasticity of the plastic by creating a semi circle to fit around another object. When fitting the part to the other object, the "wings" will flex out and relax around the back end of the object.

Example 2: T-Slot style designs are a nice choice for semi-permanent or interchangeable parts. The key here is just using trapezoids and make sure the "female" end is slightly larger and/or tapered to make it easier to insert the slides.

Example 3: Create snaps. This can be a bit more difficult, but can provide a more professional look to your design. It's best to start off by designing on L-Shaped slot on the parent part and a smaller L-Shaped extrusion on the child part. Then you can add a taper to the bottom area of the "L" to make it easier to insert into the slot.

Example 4: Creating plugs are similar to snaps, they're just circular. Try starting off with a cylinder and joining either a sphere or a slightly larger diameter and tapered cylinder on top. Then you should be able to snap the assembly into a hole that is slightly smaller than the "top" of the plug.

It's important to weigh the usefulness of some design choices against the purpose of your part. For me, if I'm designing something for the shop or something that I think I'm going to be swapping out often, I'll use the T-Slot idea. Other things that "looking pretty" is more important, I'll try to hide the connections by designing a type of snap that can go into the walls of the part.

The T-Slot designs seem to print quite easily with no need for supports (depending on how gradual the angles of your trapezoid are) and provides a lot of structural strength.

Printing snaps has been difficult for me in the past and its best not to try to unsnap the part too much as you run the risk of shearing the snap upon removal. Printing such a small feature means that it is usually not marginally strong. However, including multiple snaps in an area and designing them with tight clearances can provide a very neat/clean connection that is appealing for consumer products (for example, phone cases).


Ultimaker original X-axis not moving - possible electronics problem I'm writing this question here hoping someone will be able to help me with the fixing process that I'm currently involved in!

Last week during a printing session my Ultimaker original unexpectedly stop working. The problem was on the extruder step motor which push the filament from the back and literally is not moving anymore! The first thing I have done was to check if the motor was burn or something similar. So I swap the extruder motor with the X-axis one and it then worked fine.

Then later the X-axis motor into the extruder connector and is not moving! so I decided to check the step driver and they seems to work all well. So the problem must be on the Arduino or on the motherboard! I bought new step driver a new step motor and new Arduino + motherboard, connected all up and nothing, still not working for the same reason! It is just the extruder motor that won't work anymore!

Do you guys have some idea or tips to find out what the problem can be or how can be fixed in alternative ways? Your help will be much appreciated and looking forward for some answers.

I'm not sure I know exactly what is wrong or what steps you've taken so far, but it seems like your extruder motor is broken and you've narrowed the problem down to electronics.

If so, replacing the Arduino, motor, and driver leaves only the Ultimaker PCB as the source of the problem. I would suggest ordering another - but not until you've contacted Ultimaker with the problem you're outlining here.


Connect to 3D printer via internet without router My problem:
I need to connect to my 3D printer via the internet from an Android app (using IP address and API key).
My 3D printer is based on Marlin firmware latest and connected to a Raspberry Pi running OctoPi. I don't want to use a router and port forward it, because the Raspberry will be connected to internet via a Wi-Fi hotspot.
My question:
Is it possible to control the printer using a cloud platform or a server (another Raspberry Pi) if my OctoPi Raspberry Pi can access the internet? If it is possible, how can one do it?
Any suggestions or solutions are welcome.

There are a few solutions, but each one needs to match same criteria: an open network socket visible outside the local network.

So from TCP/IP protocol theory, we don't even need to have an IP address to send a packet to another computer as we can use layer One which is just the MAC address to identify the receiver. But things become more complicated when we have to provide a link to two separate endpoints.

Basic requirements:

We need to know public accessible IP address and port that server is exposed (listening) on
We can have a DNS entry that will be translated to public IP, but that assume that public IP is same all the time (or we have a dynDNS service)

Solutions:

Have the RPi exposed with public IP address and routed properly;
Create a VPN bridge from RPi to your home/cloud network and connect Android to the same VPN;
Do a port forwarding to RPi from public IP and expose that in the firewall.

So at this point, if you don't have admin access to network devices then only solution '2' is viable, IMHO.


Why is 2 / -2 / 2 equal to -2 in OpenSCAD? (Mathematical Order of Operations) Recently I have been doing more complicated math in OpenSCAD and I have run into something that I find strange. Take a simple math expression: 2 / 2 / 2. By any programming language this will equal 0.5 (1/2), and OpenSCAD agrees. Something like this: 2 / -2 / 2 should also be -0.5 for the same reason. However, OpenSCAD thinks this is -2. That is echo(2 / -2 / 2); gives ECHO: -2. My calculator, other programming languages (and myself) all say its -0.5.

Is this a quirk of OpenSCAD, or am I missing something obvious?

I suspect the behavior you are seeing is an undocumented feature (aka, bug) of OpenSCAD. I've found in the latest stable release that if the - is placed on either end, the result is -0.5, but in the middle, my results are the same as yours. Surrounding the -2 with parentheses results in a correct answer, however.

It appears that the parentheses turns a mathematical operation into a signed integer. It follows that the operations without the parentheses is right to left:

2/2 = 1, negative 1 with the minus, 2/-1 = -2


Z-axis steppers and bed alignment problems I've actually solved this, but I think its still a useful question which I don't think is easy to answer with existing questions.

As soon as I'd built my ANET-A8 (Prusa i3 DIY kit), I found I was having problems with the extruder crashing into the bed. Although I thought I'd adjusted the bed leveling OK, the calibration seemed to keep getting messed up.

I tracked this down to two factors. First, I was winding the extruder head up some distance before loading the filament and starting a print. Second, at roughly half-way up the axis, the right-hand thread seemed to be getting stuck (more often when moving up than down).

What wasn't clear (and not mentioned in the building instructions) was what might cause this problem.

I assume you did everything according to the instructions but here is a checklist of what could be possibly wrong:

Friction - check if you can rotate/move parts without lot of resistance
Screws - check if screws on couplings are tight and they don't slide over a shaft or thread
Stepsticks - check if they are cooled properly and similar (as there are two of them)
Carriage nuts on threads - check if they do not slide out of their nests while [the x-axis] carriage goes up
Filament - check if filament unrolls without resistance which can eventually cause [the x-axis] carriage to hang.

IMO #2 and #3 are the most possible cause


parts for autoleveling Prusa i3 I am following this video series to add auto-leveling to my Prusa i3.  https://youtu.be/awsI9bMndJA

I have printed the parts I need and have the servo and ss-5 endstop in my cart at Amazon.  What I need to know is what wiring I need to connect the endstop to the RAMPs board?  I bought this printer as a kit and all parts were included so I am learning slowly.

The switch
http://www.amazon.com/gp/product/B00HPLBAYW?psc=1&redirect=true&ref_=ox_sc_act_title_3&smid=AZHZ102UTKBMA

Thanks!

You just need some wires, nothing special about them. You can use any wire that's flexible enough. For the endstop you'll need 2 wires, for the servo (if you need to extend the cable) 3. The connectors on the end are known as dupont connectors.