text:
3D printer test troubles (M999 error, motors do not move)
I've been recently building a 3D printer and I'm having issues testing it.
This is my hardware:

RAMPS 1.4
Arduino Mega 2560
4x Pololu Motor shields A4988
1x Nema 17 extruder
2x floppy stepper motor
1x DVD stepper motor
Generic hotend with 0,4 mm nozzle

Then I assembled everything and I started testing... I tried the RAMPS test code and it didn't work (motors did not move, but I'm sure they are OK), then I tried using Marlin and Pronterface; it showed hotend temperature stuck at 150°C, but the hotend was not hot. Moreover the motors would not move.
I also tried Repetier host and it returned an M999 error without any further explanation.
I had no problem installing firmware on the Arduino and the fan of the hotend is working. I also tried changing baud rate but it seemed not to work.

I don't think we can resolve this here; the troubleshooting required is too complicated and open-ended to fit in a stackexchange answer. Can you formulate a more specific question? Perhaps it is better to ask this on a site with a more "chatty" format.

Try disassembling your electronics, and testing the components individually: first the bare AtMega (can you upload firmware to it?), then add the empty ramps board (does it still work?), then install the thermistors and troubleshoot them, add the motor (drivers) one at a time, etc... By the way, what power supply are you using?

If you have had no problem in uploading the firmware to the Arduino (via the Arduino IDE?) and Pronterface connects to the Arduino Mega, then changing the baud rate will not help you at all, as it is clearly working well at its original setting. Changing it, may (as you have found out) stop it from communicating. It sounds as if some, or all, of the electronics is not wired up correctly (in particular the steppers and thermistor). Do as Tom says and connect it in steps and test each part as, and when, you connect it.  What printer design are you building? Do you have any links?

What was the exact error that you received? Was it: Printer stopped due to errors. Fix the error and use M999 to restart? No additional information whatsoever? Please provide as much information as you can, in your original post. The more information that you provide, the more likely it is that someone will be able to provide yo with a solution. However, if you have managed to solve your problems, maybe you could post an answer, as it would probably help other people, who are experiencing similar or related issues.

Two immediate issues I can think of are:

Do the floppy drive and DVD drive stepper motors have sufficient torque to turn whatever you have connected them to? You don't say what sort of printer you have built, but a holding toque of 44 N·cm (62oz·in, 4.5kg·cm) or more, is desirable. Maybe you should consider upgrading your floppy ad DVD drive motors to Nema 17 motors... See RepRapWiki - Nema 17 for more details.
Do you have the correct thermistor selected in the firmware? Check your firmware configuration file.

To further check the thermistor, disconnect it from the RAMPS board, and using a multimeter, check its resistance at room temperature. Then compare it with the temperature characteristic graph of your thermistor type. A general 10K thermistor has the following response curve (source):

Does the reading that your multimeter gives, seem reasonable?
Also check the RAMPS thermistor input, by shorting the thermistor pins on the RAMPS board (using a jumper). What is the temperature reading now? It should be whatever MAX_TEMP is defined as, typically around 400°C. Again, check your firmware configuration file.

In addition, M999 is not an error, but a command used to reset the firmware/printer, after an error has occurred.


text:
Should you use hairspray on a metal bed 3D printer?
I've heard that using hairspray is useful for keeping the 3D objects from peeling off of the bed, but every example I have seen where someone uses hairspray, they use it on a glass bed.
Is it okay to use it on a metal bed as well?

In any case, only use it on a removeble bed, when the bed is not in the printer. You probably don't want hairspray in your printer's bearings and other mechanical parts.

I have been using a sort of a very strong hairspray called 3DLAC for about 2 years directly onto the aluminium heat bed of the Anet A8 printer I have.
Basically, all those sprays contain copolymer constituents, PVA (PolyVinyl Alcohol), Vinyl or Acetate.  These are also found in  certain glue sticks or wood glues. For me this spray works perfectly! On day one I assembled the printer, the paper tape tore and I was too anxious to wait for new tape to arrive. This worked so well that I have not changed it for that printer.
Cleaning is very easy as PVA or any of those constituents are solvable in water, so a moist cloth or paper towel over the plate is all to clean it. Furthermore, you do not require to spray before every print.
To answer your question if you should use a PVA based spray like hairspray directly onto the metal build plate is a matter of preference, but you definitely could use it as I have been doing it for about 2 years.

To address the comments:
I spray the heat bed platform whilst it is attached to the printer. I do pull it forward and gently spray the bed or just the location where the print is going to be build. Note that you do not need to do that for every print. I recently did notice very little spray on the X guide rods (maybe I have been careless once or twice), but that has not been a problem for my Chinesium iGus ripoff plastic bearings. It is very easy to clean with a damp cloth. It also works great on the glass bed of my Ultimaker 3E, but I usually (unless when I'm lazy ;) ) remove the slate of glass before printing. You could consider shielding the rods with a piece of paper, but it has not been necessary for 2 years.

I have a home-brew printer with a 9.5 mm (3/8"( thick solid aluminum heated bed. The bed is bare, with no additional tape, plastic film, or glass. For PLA I use purple Elmers glue stick or Aqua Net hairspray directly on the aluminum.  For ABS I use acetone/ABS solution.
Yes, it is OK to use hairspray on an aluminum metal bed.

The adhesive that you use is determined by the type of filament that you are printing. For most types, PVA (White glue) will allow for adhesion to the build plate. Filaments like PETG will tear off the glue when it comes off the bed. PLA however does not. ABS requires ABS slurry, and Nylon sticks to PET film.

Do you mean bare metal or metal with some film on top? You can apply hair spray to bare metal, but you will have troubles cleaning it off. Solvents do not evaporate hair spray, they only turn it into thick sticky goo you will need to clean off. I recommend that you try glue stick or even beer (seriously) before hair spray.
You should also know that any adhesive is required only when your printer has bed leveling issues. After I finally dealt with bed leveling, I print ABS, and even ABS/PC mix (nasty) without any adhesive, on a bare kapton film over a metal bed. I rub it with alcohol before printing.

The Kapton tape works as an adhesion element for certain types of filament.  PVA, be it from Elmer's Glue Stick, hairspray, or printing a layer of PVA support material, acts as another bed adhesion element which sticks to a bare metal bed.

Bed leveling issues compound adhesion problems because it causes the pressure between the bed and the filamant to vary over the area of the print.  Bed adhesion is necessary even for a perfectly leveled bed the intended distance from the head, and the surface treatment and condition of the bed is critical to achieve bed adhesion.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/

authors: евгений иванов

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

sort: votes


text:
Increasing hotend temperature to compensate for increased filament throughput
It seems that when filament throughput is increased (by increasing movement speed or extrusion width/height), printing temperature also has to be increased to compensate, because the filament will have less time to spend in the melting zone. That much seems clear from practical experience. But I have two questions (or to be more precise, one question on two levels):

Is there a good rule of thumb for this, to help people calibrate their settings?
How much do we know about the formula governing this behavior? Can we calculate the required hotend temperature precisely based on the increased throughput?

For anyone who has studied physics / thermodynamics, this is probably simple stuff. But has the work been done for 3D printing specifically, in a way that is practically applicable?
I share the following train of thought to start off with. Let me know if I make any errors in reasoning.

Presumably, every material has an optimal printing temperature just above its melting point.
But the thermistor doesn't read filament temperature. It reads the heat block temperature.
Below a certain throughput, the temperature of the filament will have time to equalize with the temperature of the heat block before it leaves the nozzle.

For those slow speeds, heat block temperature should be set exactly to the material's optimal printing temperature.

For greater speeds, however, heat block temperature will always have to be higher than the mark, because the filament doesn't have time to equalize.

At that point, it becomes a balancing act. Find the best heat block temperature (°C) given a rate of throughput (mm³/s), the optimal printing temperature for a given material (°C), the volume of the melting zone (mm³) and < some other property of the material >, which determines how fast it heats up. I don't know what that last property is, nor can I come up with the proper unit. The material probably approaches the temperature of the environment asymptotically. This is where thermodynamics comes in, I guess.

Theoretically, running filament also cools down the heat block, but we can ignore this. If this effect is significant at all (is it?), this is already compensated for by the PID controller.

I'm almost certainly missing some key insights. I'm curious to know what work has been done.

Did you ever find the answer to this? I have the exact same question.

My first thiught on this it that we need a PID tunning correlated with extruder speed. E.g. PID auto-tunning procedure involving extrusion of an actual filament on different speeds. Also, thermal capacitance of a specific filament is an another variable.

I think I see what you're asking, but I think you may be thinking about it incorrectly.  It's really all about heat being added to the system at the same rate that it's leaving.  The heat block is there as a heat reservoir from which the filament draws heat for the glass transition.  The heat in that reservoir is maintained by cycling the heating coil to add energy (more heat) to the systems as it's lost.
In the very local vicinity of the nozzle, the temperature will decrease slightly as it's being transferred to the filament, but because the heat block is massive in comparison to that drain, and because the heat block is a good thermal conductor that temperature reduction is very small.
I do not know what tolerance and hysteresis are built into the temp controller, but think the variation is likely small.  The difference in additional heat required (more energy into the system) for any practical difference in feed rates (40 instead of 60) is thus likely to be very small compared to the filament cooling experienced immediately after it leaves the nozzle.
Bottom line: the adjustment you would want to make is not to increase the temp, but increase the duty cycle of the heating element to maintain the desired temperature.

It's a bit more complicated than that. The problem is that it takes a certain amount of time Δt₁ for plastic to reach the temperature of its environment (the melting zone). That heat transfer is not instantaneous. Furthermore, there is a certain amount of time Δt₂ that the plastic can spend in the melting zone before it is extruded. As you increase throughput, you decrease Δt₂, to the point where Δt₂ < Δt₁. In those cases you have to either increase temperature or use a larger melting zone. That's why E3D has its volcano upgrade.

Increasing temperature would help because the plastic would heat up faster, reducing Δt₁. The problem there is that it also becomes possible to overshoot your target temperature, causing the plastic to come out too hot, resulting in droopy, saggy prints. --- Using a larger melting zone does not have this problem. But if you set your temperature higher than the ideal, it becomes a delicate balancing act. That's why I'd like to see the formula that describes this dynamic.

I think an equation would be very difficult, but doing an FE simulation might be tractable with the parameters you have.  Much depends on the thermal conductivity of the heater block, flow rates and actual melting point configuration.  Because it is hard to move temperature at singular point quickly, most systems naturally rely on heat reservoirs, which is usually an "overdamped system" in control parlance.  What I think you're considering is an "underdamped system" of temp control which is faster acting, although usually less stable.  Interesting problem, though.

Yes, you set the temperature of the heater block higher than you want the plastic to be with the hope that the plastic exits the nozzle at just the right time. Faster acting and less stable. But I'm not considering this, so much as observing that this is what everyone does if they want to 3D print faster and/or with larger diameter nozzles. It's simply the only way to do it short of buying better components. I'm just trying to understand the dynamics better so that I can calculate the optimal set temperature for a given throughput.

No there is no rule of thumb as far as I know and no, it's not obvious for someone with skills in thermodynamics.
I know that if you want extreme speeds you need extreme overtemperatures, for example Annex Engineering uses ABS at 290 °C (about 50-60 °C overtemperature) with a Mosquito Magnum (rated at about 40 mm^3/s) to reach 60 mm^3/s:

Still, you need to find the optimal value based on your hotend, your extruder, your nozzle size and target flow rate. You may do static tests as explained here:

There cannot be a rule for such a complex behaviour.
Also, be aware that Annex Engineering uses 23 000 mm/s^2 (not a typo, really 23 thousand) as acceleration, therefore their printing head moves at basically constant speed. Also, they set the slicer with the same speed for inner/outer perimeters, infill, and so on. If you have more common accelerations like 1500-2000 mm/s^2 and different printing speeds for different features, somewhere the filament will be pushed super fast through the nozzle and everything is good, somewhere else it will slow down and it will overcook.

I see an answer not a question. It's a balancing act and there is no predefined formula. Trial and error. Keep a spread sheet. I'll dwell on this a bit.. but as someone who did speed sprinting there's really nothing else to be said other than buy an e3d and the volcano upgrade.
You will calibrate one at a time. Thin wall. Then find solid infill is the true thermal barrier. Then sparse. You will tweak with layerheights. Get thicker nozzles 0.8+. It's a game of spinning plates. Each change will wack out another.
Last you will get to where I did. You move so fast 5 layers down your print is still molten and moving. Especially on small parts.

It feels like you're answering a question I did not ask. The situation is: I have decided on a material, an extrusion width/height and a print speed. The hardware is also fixed for the purpose of this question, and not available for tweaking. Question: How to find the optimal temperature setting (given that I've already found it for a lower speed)? A rule of thumb would be useful, but I'm especially curious about a formula to help us understand the dynamics involved. If such a formula hasn't yet been written down, then surely it could be written down.

Hi mhelvens I am sorry the answer did not work for you. I see now what you are asking. Might I politely suggest considering rewriting your question with the simplified and direct question you posted as a comment? Good questions get good answers. That said I am afraid there is no universal formula. Every printer is considerably different. My answer actually still works with some rewording. Examples like my melting 4 layers down is an example of the issues that appear the faster you go and cannot formulate. Same with jerk acceleration whiplash.

It really comes down to too many unique factors with your printer. You can create a formula but it would have to be for one printer. Well I shouldn't say that. I know for a fact these formulas exist but only as IP of major companies and so buried not even their employees can easily find them. Or in the major 3d printing companies and they aren't going to share.

This is all based on relatively simple physics, though. Sure, such a formula might have some additional variables in there that depend on the printer, but not that many. Mostly it'll be about the hotend and the material used, and such values could be found experimentally (and gathered in a publicly available table). Or could you name some significant variables that I'm forgetting? --- And you're probably right about my question being unclear. I'll try to rewrite it a bit today.

Spoken like a true PHD student. I encourage you to be the one to create such formula. If I have not seen it then it is not known to most. This is an open source movement!

I'm not a PhD student anymore, but thanks for pointing out that my SE profile is out of date. ;-) Anyway, I may tinker around a bit on this, but I don't have all that much time. Mostly I'm surprised this work hasn't already been done. Seems like low-hanging fruit.

Thats the exact issue. A lot of people now use 3d printers but sadly there are few who actually do research for the community. Frankly I am unaware of any recent advancements FROM reprap foundation in the last few years. There is much that can be done. I do what I can here on SO. But most seem to want to create blogs and beg for free toys instead of doing Nophead style research and development. Even if it is done unless they add it to the Wikis it is more or less lost.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Connecting an inductive sensor to the Anet A8
I bought an Anet A8 over christmas. When I bought my printer from Gearbest, I also bought the inductive sensor that they sell.
It doesn't seem to work, and I think it might be broken. However, I have no idea how I can test if it is broken. This is what the wiring looks like and how it's connected to the board
I'm not sure if I need to modify the wiring in order to hook it up to the A8's motherboard. I have no idea what the pinout is on the A8's mobo, and it's not indicated either. Most guides deal with using RAMPS when it comes to installing such a sensor. I'd like to know how to connect this to my board, if possible.
The printer works fine otherwise, so I don't think the board is broken or anything. For now I've resumed using the normal endstop, but I would like to enable bed levelling by installing this sensor. (or a different one if necessary)
How do I get this working?

Those connections don't fill me with confidence, the wiring colours are unusual. Hard to tell unless you can track down the actual sensor datasheet (the vendor has likely just put this together speculatively from off the shelf parts)

@SeanHoulihane I've managed to connect it using instructions I've found on Youtube after looking up stuff related to Tom's answer. I went for the voltage divider option.

I am not entirely familiar with the ANET A8 electronics, but it's very unlikely it's any different from how any other mainboard works, so any instructions that work for RAMPS should work for your board as well.
The sensor you linked to has an operating voltage range of "6V to 36V". However, the endstop connectors (on any mainboard I've come across) only provide 5V - not enough for the sensor to work. You could verify that this is also the case for your ANET board with a multimeter.
(Assuming the colour coding is standard) you'll need to connect the black wire to GND, the red wire to 12V, and the yellow wire through a diode to the signal pin of the endstop connector. The anode of the diode should connect to the signal pin and the cathode to the wire coming from the sensor.
The diode is required, because otherwise the 12V signal from the sensor will damage your electronics, which can only accept 5V. Any ordinary diode will do (for instance 1N4148). You should enable endstop pullups in your firmware when using this method (though if your board already has physical pullups this is not necessary but won't hurt either).
Note that if the sensor is inductive, it will also need an appropriate (metal) surface to trigger off. Unfortunately, it is not clear from the product description what type of sensor you have bought, and (amusingly) gearbest doesn't know either:

Question:
Hello, is this Sensor capazitiv or induktiv? Thank you verry much.
Reply:
It is an auto leveling sensor for 3D printers

I believe its a non-standard mainboard from a firmware point of view, and people seem to be changing the firmware when they use this inductive sensor. I know when I switched to an opto sensor, I needed to invert the signal to the mainboard.

You will have to:

Find and print something on Thingiverse to mount sensor;
Change firmware to Skynet and change the offset values accordingly, in order for the new sensor to recognize the bed.

There is official Facebook page of Anet A8 printers as well as Skynet firmware. You can ask there if you need further help. Though the above steps are easy.

Thank you for the suggestion. I don't use facebook, and I'm not about to start though.

I don't use facebook. In the end I managed to hook it up using a voltage divider and Skynet, as I already mentioned in the comments on the question.

For those who read this old answer, Skynet3D was a girl of Marlin firmware, the changes for Anet printers have been merged into Marlin firmware.

I'm guessing you have the Anet sensor? If so and you are using the stock firmware that came with your A8 - it's not going to recognise the sensor  but you can download and flash the Anet A8L firmware that is designed to run with the sensor from the Anet site -  I stumbled on this while searching for stock firmware.
I hope this helps you out.

Do you have the link? The Anet website does not offer any downloads currently. I found this link, The Firmware Links You May Need, which links to dropbox locations. Is that what you mean?

I used Skynet, as explained in my comment on the original question dated Jan 30th.

authors: เฟ๊อะฟ๊ะ อาหลิว


text:
Calculating extruder motor steps for 1 mm
I would like to calculate the amount of steps to turn the motor to have 1 mm of the filament.
I did the following (using approximate values):
The gear on the outside of the teeth as a diameter of 11mm.
Therefore the circumference is 34.56mm. Divided into one degree i get 0.096mm / degree. The stepper does 1.8 degree per step which results in 0.1728mm per step.
To get 1mm of filament pushed into the extruder I will have to do 5.787 steps.
The same extruder is in a Geeetech i3. The firmware there is configured to do 93 steps per millimeter.
I don't have any experience in working with stepper motors but in theory, this would be my approach with a huge difference to an existing firmware.
Where is my mistake?

Microstepping. Your board likely has 16x microstepping, so that each step is divided up into 16 parts. Your 5.787 figure, when multiplied by 16, comes out to 92.6 steps/mm - matching the value in your firmware.

Ouhhhh yeah, i read about this months ago when assembling... Omg didn't remember thanks for the info ;-)


text:
Identifying PLA/PETG or ABS
I received a roll of Black filament as a present, and struggled to print with it, experiencing extreme under-extrusion (and slippage of the hobbed gear). Higher temperatures seemed to work better, particularly in freeing up the extrude rate.
The filament is advertised as PLA, but without any temperature recommendations that I can find on the vendor's website (or the amazon listing). Amazon reviews have a fairly wide range of temperatures, but the listing aggregates several colours. There is a suggestion that the filament may be PETG, or ABS.
I have tried using acetone, and it dissolves roughly the same as some ABS I have, my PLA shows some weakening but doesn't dissolve.
Below about 215°C, extrusion is borderline non-existent. I printed at 225°C with a fan, and it extruded kind of OK, but adhesion was poor. 240° without a fan seems a bit on the hot side (see photo). Even 255°C seems to extrude OK without burning. There is no smell I can observe (but I have a cold). It burns with a small blue flame, and minimal smell (kind of like natural gas).
One factor against it being ABS is that with the bed at 60°C, printing both a benchy and the heat tower below, there was no warping. Bed adhesion remained good.
Is there anything I can do to better identify this filament and decide the best combination of fan/temperature without wasting too much time?
255° to 225° heat tower, seems different to the ABS i've used:

There is a trick. However I would like to mention that chances are that the random spool you pickup from most stores, especially no name brands, are either completely lying to you about its material or is mixed / cut with cheaper fillers. All about finding a good brand. Course rarely does one actually need pure PLA, a mixed material will often perform as well without you even noticing. Aside from the temp difference. Not to say it is right.
Now the trick is this. While I don't advise ever breathing in potentially carcinogenic plastic smoke. You take a lighter. Burn it. If it smells sweet it is PLA.
From this link from digital trends about PLA VS ABS you can see why it has this smell.

The thermoplastic is also more pleasant on the nose, as the sugar-based material smells slightly sweet when heated opposed to the harsh smell often associated with ABS. However, while PLA might seem like a better overall choice at first glance, it features a far lower melting point than ABS.

Also not responsible if you burn yourself or your property. At your own risk.
Just warming it with lighter might work too. But just burning a small section. It will be real clear.
Or you could just drop a bit into aceton and see if it melts. PLA will mostly just look like crud after being treated is aceton. ABS is 100% dissolve.
We see from these forums that PETG does not dissolve via Aceton. So you can test you material. If it does disolve it is ABS. If it smells sweet when burned it is PLA. If it melts at 240 and does not dissolve it is likely PETG.

Solid forums
3d printboard

We are a bit lost on a test for PETG. However we do know its melting point. Which is 240-260c. I would say it is likely you have ABS

Once we know the material we can get to the meat of your question.
Best way to proceed is to start with simple calibration prints. The thin wall. Cube, and part fitting. Once those pass you are good to go. Other than buying simplify3d I do not know of any short cuts. Back when I used slic3r I kept a spread sheet. I would change a temp by 5 degrees and give it a quality score. Repeat with speeds. Far as fan, I would expect that it wont effect much. Maybe need to calibrate your PIDs.
Once you have it dialed in, all you will need to do is calibrate the temp when switching materials. Remember you need to calibrate even between different colors (okay its best to.. I often skip) I usually do the temp adjustments live on the printer. Increase and degrease a few degrees. For me the goal is to have the plastic as cool as possible. That allows for highest quality prints (ie less oozing and such)

At 190 I can barely push it through the extruder at all. 210-215 seems to be where it starts to flow.

Pla melts at 175ish so I am sure you do not have PLA

I use a hot solder iron. Lower temperature than a lighter and still releases the PLA smell.

Well your thermal couple / thermizistor might be over reporting. Updating answer.

I assume you mean ABS in the middle of the answer? How about PETG? Is that eliminated?

@SeanHoulihane I am afraid I do not understand your comment about ABS. No I do not say PLA and meant ABS in my answer. We have ID it as PLA from to the smell. Again not to say it is pure or of good quality. Here is more on PETG https://www.reddit.com/r/3Dprinting/comments/3mef9i/so_tell_me_about_petg/

There is no pla smell...

Its also very flexible (at least in a single layer), which doesn't seem to point to PLA.

Yeah but you didn't actually burn it.. but if you burn it and it does not smell sweet the. No it won't be pla. Anything is flexible at 1 layer.

"I have tried using acetone, and it dissolves roughly the same as some ABS I have" ----
Well this is the answer: If it dissolves completely in acetone then it's ABS. Neither PLA nor PETG dissolve in acetone. Some ABS brands have reduced styrene content to reduce the smell, also ABS doesn't smell much at lower temperatures. It takes 250C to make some of my filaments to really stink.


text:
3d prints come up with ribbing on one side
The right side of my prints always have the standard ribbing effect given by a bent z rod, however I have replaced the rod and there was no change. Here are pictures of one of my more recent prints:

and the left side of that same print:

As you can see the left is almost unaffected the right is the only side with the error. Anyone have any ideas about this?

Looks like your axes still aren't quite aligned properly. What speed is your extruder moving at when doing shells?

Hmmmm In my experience when a printer has that bad of wobble it is still the Z axis. Your rods might be good, but are the two Z axis the exact correct distance and equal distance on the printer frame? Imagine that you had one a few millimeters too far out. How might the rods act? Mayhaps, over the course of several layers, they would slowly drift back and forth? Creating a period effect on your print? What do the top of the rods do over time? Do they move a lot if you go from height 0 to 100mm on z?
I have a few ideas. What happens if you loosen you Z motors so they can move around their mount? I had to do that on my Prusa back in the day. I think for that machine the Belt was actually too tight causing the issue. Current printers are usually better designed so its unlikely that is your issue. Also measure the distance between the top of the rods when the carriage is at 0, and at max. You should see very little variance.
If it was on both sides I would say it was bad PID calibration. IE this simplify 3d link
Though you can see on this forum the fellow had a bad coupler. So still mechanical.
Also could be back lash / belt lash.. but unlikely

+1 hit most of the points I was about to comment for. Any idea if the machine uses a worm gear or some sort of nut? Is it possible that a nut would not be concentric or be cross-threaded?

Thanks @tbm0115! Yes photos of the machine would likely help as well.

hey thanks it was the z axis coupling, just had to readjust it, thank you so much.


text:
Blow vs suck air over hotend's heatsink
I've build a 3D printer from sourced parts and mounted the hotend cooler to blow air over the heatsink.
Talking to a friend, he said it's better to reverse the airflow over the heatsink, but couldn't give me an argument other than everywhere he saw it was like this: all coolers are mount to suck the hot air away from the heatsink.
Is it one way better than the other way ? And if so, why ?

I think it also depends on th design of the radiator and how the fan is mounted on it. Some pics?

I am very confused if this radiator talk. A radiator like my car has in not in my printer. Do you mean the heater element? Ie the hotend or heated build plate? Or do you mean the cooling fins? That could kind of be called a radiator. In that case blow on not suck. Does sucking at your hand cool it?

It is unclear to what you are referring to, by your use of the term "radiator" - Could you add a photo of the "radiator"? Do you mean heatsink? Or have you installed an additional cooling mechanism?

Sorry, yes I mean heatsink. I'll edit the question

Getting hot air from the radiator is definitely wrong idea because of few reasons:

hot air can damage your fan (as they are usually not heatproof). Cold air cools the fan
cold air is denser so fan can suck more cold air than hot air so cooling is more efficient (fig A)
in terms of plug of radiator (with dust) it's much better to try to push cold air into plugged fan (fig C) than to suck the air from it (fig B). When flow is decreased there is higher possibility to damage the fan as it doesn't cool itself

Of course we are talking about 3D printers with small plastic fans. Please notice (almost) all fans construction: they are designed to get air from the top of the fan and push it to the bottom (this construction prevents damaging/plugging fan motor by dust)... and their mounting wholes (or clips) are usually... naturally suggesting to direct air to the heatsink)

In the case of 3D Printing, it's going to be faster to cool the radiator by blowing out the heat from the source.
The idea is that you're trying to get rid of as much heat as possible in the quickest means possible. By blowing away from the radiator, you're allowing the ambient temperature to cool the hot air being blown out.
If you were to blow the ambient air towards the radiator, the blown air will warm slightly as it is overwhelmed by the heat of the radiator. Even though the ambient air may be cooler, it will take more time to cool off the radiator.
Example of bad airflow, which will take much longer to cool the radiator:

Example of good airflow, allowing the hot air to be quickly cooled by the ambient temperature of the build space:

I don't dispute the conclusion, but I think its misleading to talk about ambient temperature. All that matters to the heatsink is the air passing its fins. Both cases mix 'new' air with the already heated air.

@SeanHoulihane I see what you're saying and I think I agree more with darth pixel's answer. I was coming from the perspective of a machine with a heated build plate, where the ambient temperature is still about 90°F (more if enclosed).


text:
Silver Solder specifications for hot end heating element
In this question I was told that I should use silver solder to connect the heating element to the power supply.
(I was also told that a ceramic extruder head was the way to go, but I'm working with what I have)
I bought two types of silver solider from Radio Shack:

96/4 Silver-Bearing Solder, Lead-Free 0.62" diameter.
62/36/2 Silver-Bearing Solder, 0.15" diameter.

Is there any reason I should use one of these over the other to power the heading element of the J-Head extruder?

The first is not suitable. ASTM96TS Sn96Ag4 has a melting point of 221–229 °C according to Wikipedia. Pb96Ag4 would be OK, but that is not lead free so doesn't seem to match your description. Update from comment to explain the letters and numbers: the data comes from wikipedia, the numbers are Tin(Sn) 62%, Pb(Lead) 36%, Ag(Silver) 2%, for example, see below for an electronics solder compound.
Sn62Pb36Ag2 is an ordinary expensive electronics solder (but not lead free), with an even lower melting point.
You need to find a high temperature silver solder, with a melting point of about 305 °C (which confusingly might be a soft silver solder), for example one of these. Hard silver solders melt at 600 °C, that would be excessive in this application.
The nomenclature 'silver solder' came about before lead-free electronics solder was introduced, since when more alloys containing silver have become popular as general purpose solders.

Use ferrules to join wires, and on your board either solder directly (it doesn't matter what solder you use because it's not going to get hot if your wires are gauged properly).  Or use soft copper wires and clamping terminals without the wires being tinned or risk a fire hazard.
Tinning makes the surface harder which makes for less contact area.  If it deforms from heat , it can come loose and cause arcs, which is where the fire hazard comes from.

or risk a fire hazard - could you edit your answer and clarify that point? If the wires are tinned, is that a fire hazard? What exactly is the fire hazard in this situation? It isn't really all that clear, and considering that it is an important safety aspect, it would be worth being expanded upon...

My (uneducated) reading is that this tinning increases the risk of a high resistance joint, compared to clamped soft-copper. but I agree, clarification is important.

Tinning makes the surface harder which makes for less contact area.  If it deforms from heat , it can come loose and cause arcs, which is where the fire hazard comes from.

The terminal blocks are rated for wires terminated in a particular fashion. If you find one that's rated for tinned stranded wires, go right ahead, but those are few and far between and are usually spring loaded terminals, not screw terminals. For screw terminal blocks (female), there are usually only two approved termination types: directly to solid copper wire, or to a stranded or solid wire in a ferrule.

I can't comment yet, but for those wondering, the issue with tinning the wires is when you are clamping them. Tinning them actually increases the resistance between the wires and terminal, due to making them harder and not getting squished out to make more contact with the terminal. This increased resistance means increased heat, and enough heat means fire.

The reason for the prohibition is that when you fully tin a multistrand wire fully, the solder wicks between the strands of copper and forms a solid block, part of whose volume is metallic solder. When you clamp the solder and copper bundle you tighten the screw or clamp against the solder block, and in time the solder metal "creeps" under the compressive forces and the join loses tension. The wire can then either pull out or cause a high resistance connection with heating.

Source


text:
3D printing a cardboard box
Is there an FDM 3D printing material that looks similar to a cardboard box? I guess, and understand, it would not be possible to 3D print a cardboard box but would there be something similar?

The closest thing you will find is Woodfill plastic. As time goes on we are seeing more and more PLA that is infused with other materials. Woodfill will look and feel like waxy wood. We are pretty used to seeing fiber boards and the like so this will not come off as odd. However it is not quite cardboard, except that it is also a wood product. It will also smell of wood.
Here is a close up of a beyond exceptional wood fill printed piece. There is also other types of wood fill including bamboo.

I mean if you want Cardboard.. Why not a laser cutter? While you can get a MUCH cheaper laser cutter, the glowforge comes to mind.


text:
Why do I have problems trying to get Slic3r to load a config file?
I decided to fire up my 3D Printer again after a while.  I have new PCs, so I had to download Slic3r fresh, so I got the latest version (1.2.9).  Then I went and found my old config file.  It's really old, from 2013!
And Slic3r did not load it when I told it to, and consequently, when Octoprint was telling my Printrbot LC (custom) to print my things off Thingiverse, it was not in the bed, and the x axis skipped a few nubs, as would happen when you tell it it's too far away.
I recall having to double and triple check Slic3r to make sure that it actually loaded the configuration I spent time crafting and honing.  However, it's obviously been 3-4 years since I last played with this stuff, and this is a very low level feature that should have been fixed at Day 0 or 1.
I presume that I'm doing something wrong.  Do I need to stand on 1 leg and hold my mouth just right?  I don't even know how I could screw it up...
Update
I changed from "Simple" mode to "Advanced" mode, and the config imported fine.  Though, I don't think it was my most recent config.  C'est la software!

I changed from "Simple" mode to "Advanced" mode, and the config imported fine. Though, I don't think it was my most recent config. C'est la software!
Also, I switched to Cura after this.


text:
How do I enable Expert mode in the Craftware slicer?
I'm using craftware, and I'm trying to figure out how to enable expert mode so that I can adjust the extruder/bed temps. I looked all over the application, the user manual, and googled it, but I cannot find the setting to enable it. Any help is appreciated.

I figured it out, you must click the slice button, then among those options, there is s button to switch to Expert mode. Hope this helps someone in the future.

Welcome to the group! Glad you found a solution. While we were not much help this time, be sure to give us another shot in the future :-)


text:
Padded Sketch comprises too many solids (FreeCAD)
Under FreeCAD, I sketched on the face of a solid as follows :

My problem is, when I use "Pad a selected sketch", the solid created comprises also the original solid.

It prevents me, for instance, to get the difference with the first one.
Any idea what may be causing this? How to prevent it?
MyFreeCAD config:
OS: Ubuntu 16.04.1 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.15.4671 (Git)
Branch: releases/FreeCAD-0-15
Hash: 244b3aef360841646cbfe80a1b225c8b39c8380c
Python version: 2.7.11
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 6.8.0.oce-0.17

Ok, I got help on this forum thread
Using Part Extrude instead of Pad a selected sketch on the sketch will create an independent solid.
It also turns out that, instead of creating the second solid to do a boolean difference, the good way to "cut" my solid is using the PartDesign Pocket tool.

If you just select the face, and pad the face (versus padding the solid), you should not have this problem.


text:
Prusa i3 jerking during printing
I have a Prusa i3 and during the print, it will start jerking which makes a noise that sounds like something is going wrong. At first, I thought it was the infill since there is a gap in between the layers which this picture shows (I have ripped off the bad layers to see if I can get any use out of it. The video shows the bad layers). For reference the "wall" along the outside is 2.1 mm.
 Then about 70% of the way through the print, the Y layers started to shift so I thought that the jerking was a result of this. This is a video of what is happening https://www.dropbox.com/s/g1afjwyzl8hqej9/IMG_0403.MOV?dl=0
So is this the infill that is causing the jerking or is there something that I should fix on the printer that will stop jerking?
Thank you!

Well that is unique. I would say if you only see this after the printer has been running a while then your electronics are likely overheating. Put a fan on it and report back.
Otherwise and also I would reflash the electronics..

Should I put the fan on the main board?

Yeah see if that fixes it. If so 3d print a case that has a fan holder.


text:
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.

Hi welcome to the group! Are you asking about how to RENDER a wheel or how to slice the stl?

My question concerns the actual 3d printing.  I've made several attempts, which have all warped.

Are there any particular reasons why you want to ue ABS over e.g. PLA?

Much more experience with ABS.  Is PLA much better with regard to the thermal contraction of the printed material?

I had pretty much this exact situation when printing a disk for a rocket avionics bay.  It seemed to come down to getting the basics of bed adhesion: Heat bed, ABS temp, bed composition, and a "primer" layer.  I found the FF Creator Pro to work well with a bed at 110, filament at 230, printing on a glass plate with ABS slurry.  Then adding the brim 6 orbits wide held it down very well.  I found that printing on the stock FF blue plastic was inconsistent with adhesion.  Also, keep the door closed while printing and for something this size don't run the cooling fan (if you're printing on the left nozzle).
And, of course, the right infill helps with the thermal contraction and strength.  I found through testing that the rectilinear patter in S3D gave the best structural support in multiple dimensions.  I also end up typically printing infill at about 15% to ensure a good surface on the upper face.  Any lower and I found a lot of sagging in the top finish.
If you're using this as a platform, then the layer size matters a lot also.  You don't need .10mm layers, as .25mm or .20mm layers would probably work better.  Then make sure you print enough top layers to get a good finish.  At .20mm I usually print 4 top layers with a 15% infill.

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?

Worth a try.  I think that is an option in Simplyfi3d.  The wheel is to be the platform for a 3dscanner ala SuperMakeSomething's youtube video.  Don't really expect it to hold more than maybe a kilo.  Thanks.

Well then 10% is probably overkill.  I would do 5-7%.

For a 6" disk I'd also suggest a wide brimmed raft around your part. In my experience something that wide and uniform with ABS will likely warp. The wider the brim the better chances you'll have of your part staying flat. My vote would be for 7% infill too, lower than that you may have an issue with the top surface being slightly wonky.

So you just want a short, wide cylinder? Just print that, with low density infill (20-30%) and 6-8 solid top layers, three bottom, and three perimeters, and you'll be fine. For bed adhesion with something this wide, use a 10mm brim, one layer thick. And a heated chamber will help a lot.

Thank you for your answers.  I printed with a 20% honeycomb infill, 3 layers top, bottom, and around, 5 brim thickness, 225 extruder, 105 bed, on acetone scrubbed Kapton tape.  What was different per your suggestions was lower % honeycomb infill and more brim and 3mm thickness for the part.  Earlier attempts had been 5mm and 40% infill, 2 pass brim, and rectilinear infill.


text:
Marlin, end stops, and position report - possible bug?
Am seeing the following behavior in Marlin:
When moving the printhead, if an end stop is hit, a position report (M114) erroneously reports the print head position as where it was trying to go, as opposed to where it's position actually is.
For example (using pronsole):
> M114
X:1.00 Y:1.00 Z:1.00 E:0.00 Count A: 142 B:0 Z:1260
> G0 Z100
endstops hit:  Z:16.88
> M114
X:1.00 Y:1.00 Z:100.00 E:0.00 Count A: 142 B:0 Z:21263

In this example, the Z endstop was hit at (z:16.88), but the printer appears to think it is at the target location (z:100).
The "Count" Z appears to remain accurate however.
Question: Is this a bug in Marlin, or is this correct behavior and I am misunderstanding something?

If it a bug you should make a report to their github page.

Thanks, and yes I will if it is.  First just seeking confirmation that this is a bug - I would be surprised that this would exist in something as mature as Marlin, as it would clearly throw the whole print job off - so I am first seeking confirmation from those smarter/more experienced that I if it is indeed a bug, or am I just misunderstanding something?

I understand the concern to want to be sure that you have an issue before reporting it. However in this case they would be the best people to report it to. If you think about it, really, you just did a report, but to the wrong people :-)! It is likely the same amount of effort for us to look and not have an answer as it is for the guys who wrote the code. In my opinion the best use of effort is asking them.. I open bug reports all the time at companies like google. No big deal to do a report. Just don't think we will have the detailed knowledge to answer. But I could be wrong.

Some info on the subject: few stepper motors have any way of knowing their exact position during operation, which means Marlin will have to assume the steppers always are in the right place.
In other words, all g-code commands are executed relative to their current position, not with regards to the real positions. So if you forcefully move the printhead during print, the printer will just continue printing the same patterns in mid-air (this is basically what is called layer shifting).
The only way the printer can know the real position of the steppers is when the endpoint switches are triggered. This is why the homing action is done to before prints in order to reset the internal positional bookkeeping of the steppers in Marlin. So if the endpoints are triggered without the printer actually being at the endstops, you will seriously confuse Marlin.
I agree that is sounds weird that Marlin does not reset the positions of it's steppers when an endstop is triggered (during print?), but then again, if it happens accidentally (and not as part of a re-calibration procedure), I believe the default actions should be to abort all operation since this would indicate the printer being out of control. Perhaps there simply is no routine to handle movement after the program has been aborted - a situation where probably nothing would be right anyway..

Thankyou, well said & informative.  I can now understand why this has, perhaps unintentionally, been unhandled.  I am not sure what the advantages of having this work correctly could be, but I will submit a code fix and bugreport to Marlin if naught than for the sake of completeness.


text:
How are things like a USB casing designed for 3D printing?
How are professional or regular products designed on the computer for manufacturing?
Do they do it by making a 3D model and then getting it made by manufacturers/plastic factories, or the process is different?
If it's by making 3D models then what kind of programs do they use - Regular 3D software like blender?
I also understand that you can get a 3D model printed by 3d printing services, but are they the same as mass manufacturing companies, by that they make the product by 3D models.

3D printing provides a faster method for prototyping and have always been labeled as prototyping machines. Until recently, it has been rare to see 3D printers used for "mass manufacturing".
Yes, most mass-produced products start the manufacturing process with a 3D model. 3D models can be created in many different applications such as Solidworks, AutoCAD, Unigraphics, Blender, even Sketchup just to name a few.
In product development, the 3D model will then go through prototyping. Rapid prototyping can be done using a 3D printer by utilizing cheap materials and almost no labor cost.
Here are a few costs that can be associated with the different prototyping methods.
Traditional Prototyping
(Typically involving "traditional", subtractive manufacturing methods such as CNC mills, lathes, routers, etc.)

CAM programming
Fixturing
CNC Machine Setup
CNC Operating/Labor

Rapid Prototyping
(Typically involving a 3D printer or other additive manufacturing methods)

Model preparation (for slicing)
Printing Operation
Object post-processing

Removal of supports
Curing/Cleaning of part (for non-FDM/FFF printing methods)

Once a prototype is produced, the designer will adjust the 3D model accordingly based on results of the prototype. This process will be repeated until the prototype is adequate for the purpose of the end product.
When the product design is ready for mass production, it will go through traditional manufacturing methods such as:

CNC Machining (subtractive)

Mill
Lathe
Router
Laser
etc.

Injection Molding
etc.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
Why am I not seeing an effect from an M42 command on Marlin?
I'm trying to use one of the RAMPS GPIOs to control an external device that requires a 5V low-current logic level signal from Marlin. In order to do this programmatically, my host software (Octoprint) is sending an M42 command. I am using the following syntax:
M42 P4 S255

according to the pinout in the following image:

However, the pin appears to not be driven to a logic HIGH level. Is there firmware-level configuration I need to do as well, or is my syntax/pin number incorrect?

Post your firmware settings. Also verify your source for the board. If it is a cheap knockoff board...

@StarWind I'll follow up with the printer vendor regarding board source. There are no configuration elements specific to pins or GPIOs that I see in Configuration.h or Configuration_adv.h.

I'd try M42 P4 S0 just in case it's somehow inverted. If so, then and only then I'd worry about why.

@Greenonline Unfortunately, the printer is no longer in my possession (I no longer work in that lab and am in a different city hours away altogether), and the issue was worked around by somebody else in a manner unknown to me. Mark's answer does seem sensible but I can't confirm that it works--shall I select it regardless?

Maybe not then, in that case. Thanks for the update. I'm not sure what to do in this situation... it seems like it will be forever uncertain whether it worked or not. Not to worry :-)

I looked at the current Marlin code and the P24 command should work as you expect it unless the pin you are trying to use in listed as the "SENSITIVE_PINS" list:
#define SENSITIVE_PINS { 0, 1, \
X_STEP_PIN, X_DIR_PIN, X_ENABLE_PIN, X_MIN_PIN, X_MAX_PIN, \
Y_STEP_PIN, Y_DIR_PIN, Y_ENABLE_PIN, Y_MIN_PIN, Y_MAX_PIN, \
Z_STEP_PIN, Z_DIR_PIN, Z_ENABLE_PIN, Z_MIN_PIN, Z_MAX_PIN, Z_MIN_PROBE_PIN, \
PS_ON_PIN, HEATER_BED_PIN, FAN_PIN, FAN1_PIN, FAN2_PIN, CONTROLLER_FAN_PIN, \
_E0_PINS _E1_PINS _E2_PINS _E3_PINS _E4_PINS BED_PINS \
_H0_PINS _H1_PINS _H2_PINS _H3_PINS _H4_PINS \
_X2_PINS _Y2_PINS _Z2_PINS \
X_MS1_PIN, X_MS2_PIN, Y_MS1_PIN, Y_MS2_PIN, Z_MS1_PIN, Z_MS2_PIN \
}

These pins are printer specific; so, without access to your Marlin build, I can't see if pin 4 corresponds to one of these.  If this is the problem, the command should be returning an error.  If there is no error, I would look closely at the hardware.

Might be because servo pins are not connected to 5V. use Jumper as shown

Does this affect the ability to drive the GPIO? I don't need a 5V power supply, just a TTL signal.

I cannot say for sure. Tomorrow I will check on my board. If you want to check the working of M42 using marlin, send 'M42 S255since no pin number is given, by defaultLED_PIN(pin number 13, RAMPS LED is attached to this pin.) pin will turn ON. You can send M42 P20 S255` and get gpio output from 20th pin (In your image I2C section pin 20 or 21). I have checked this. it works.

It's not a strong concern regardless; I haven't had access to the printer in question for a number of years now (since I graduated/moved), but I suspect that because the atmega2560 drives the pins from its internal supply, setting that jumper would power the fixed 5V pin but not affect the IO/signal pin.

May be that pin is already used by firmware for some other purpose like servos are enabled


text:
How can I print gears using very high resolution material like nylon
I'm trying to gear down a servo even further. I notice that the majority of the gears are made of nylon, and I want to create new gears that come close to the resolution and strength of the existing gears. I have a Replicator 2, but the resolution does not seem to come close to what I need. Any suggestions on how I can create nylon or other hard material parts that might work?

perhaps you mean nylon?

oops, yes, corrected

Fred seems to have you covered.
That said way too much work to get a replacement part.. Just buy mass made after market parts. I am sure you can get them on ebay for cheap for such a common printer.

Just because you mentioned how to create metal parts. Look up Lost PLA casting.

His term was "hard material" not hard metal, but any form of casting would require to have a decent resolution in the original part. One can now purchase also wax casting filament if burning out PLA isn't practical for the casting operation.

Proceeding with the expectation that you mean nylon rather than vinyl, there are a few options open for you. What resolution are you seeking? Layer thickness of 0.100 mm is quite good, allowing for ten layers per mm of part thickness, with infill adjusted as required.
If you've already determined that your printer will not print at the resolution required for your gear design, you would perhaps purchase a higher resolution printer. Of course, that may be an expense you would like to avoid.
If your parts count is small, you could consider to print samples of the parts to confirm fit, but not worry about strength and then use an online service to have them printed via SLS method.
Selective Laser Sintering places nylon powder on the work surface, then selectively melts the powder into a solid. Each layer when completed is covered with another layer of powder and fused to the previous portion (or not) until the part is complete.
Because the un-fused powder provides support, there is no requirement for the model to have supplemental support structures. There is a requirement/objective that the part have "drain holes" in areas which might otherwise be solid. Any surface that entraps powder is charged to the purchaser as if the space within is included in the part.
An example would be a cube that can be printed as six square faces only. The cube wall thickness can be specified and if a drain hole is incorporated, the cost would be the volume of the walls only. No drain hole would mean the cube would be charged for the entire volume.
For gears, which are typically low profile/flat items, that's a minor consideration.
The same concept applies to SLA printing, which uses a laser in a vat of resin. If the model is a solid with no drain holes, the interior will retain the resin. It is possible that the interior can be cured with strong UV light and/or sunlight, but opaque resins would not accept this work-around, nor would it reduce the cost involved. Also note that SLA printed items would lack the necessary strength.
If farming out your parts is the direction you intend to travel, ensure the dimension stability reference in the vendor you use. Nylon sintered parts will shrink a known amount during the fusing process. The vendor should provide the appropriate reference, or the vendor should confirm that he adjusts the model appropriately for shrinkage.
I have one very tiny part constructed from SLS nylon and it's amazingly strong for such a thin wall. Nylon wears well too.

They likely would only need to buy a e3d hotend or the like to increase their resolution. but 0.1mm is great for any hobbyist level printer. Though SLA / powder prints are a bit overkill when he just needs replacement parts? we also need to know more about his exact needs and budget.

@StarWind0, I'd like to know more about user379468's requirements with respect to the resolution of the model. Your suggestion of a different hot end would be practical or a replacement smaller diameter nozzle. A smaller diameter nozzle has its own complications, but may be the right answer overall. Regarding the overkill aspect, he may have requirements not met by off-the-shelf stuff. That's one aspect I enjoy about my printer, the ability to create exactly what I need, or at the very least, take a stab at it!

If changing the nozzle to a smaller diameter is a viable alternative for your printer, then that may give a major increase in your X-Y-resolution.
You can think of it like drawing with a pencil vs. a thick crayon: a fine tip allows for fine details.
Personally I have done some printing with a 0.25mm nozzle,  which was a bit of a challenge to find good slicer settings for,  but otherwise went very well, giving much better resolution than my 0.4mm nozzle (nearly twice a good to be exact).

This approach is true up to the point where the mechanical quality of the printer is less than the nozzle size, after which it's not getting you anything if your printer won't put the nozzle exactly where it's supposed to be. My cheesy Delta is somewhat past this point with a 0.3, I suspect. A Cartesian printer with quality parts should be able to go quite a ways in this direction.


text:
How to straighten PTFE tubes?
PTFE tubes are typically delivered coiled up. And because they are quite stiff, they always want to spring back to their original curvy shape, making them harder to route properly.
Is there a way to straighten them out?

I've considered using a heat gun, but I'd like to be sure I can do it without damaging the tube. Has someone tried this before? (If you have, go ahead and create an answer, rather than replying with a comment.)

I just live with the bent-ness. If they are in the extruder, the tube straightens them. If they are a guide for the plastic then the filament straightens them as much as matters.. If you are having issues you might have too thick of a tube. Heatgun likely wont help due to the super high melting point.

@StarWind: I guess I don't like how they bend. In my setup, they sometimes get caught behind something while the printer is working. So I would like to exercise some control over that. One way would be to use a drag chain, but that seems overkill.

I hated the tubes! I ended up ditching them and mounting my filament directly above the printer to avoid using the tubes.

@tbm0115: But there are practical advantages to using the tubes, like [1] You can feed your filament from an almost entirely sealed container to keep out moisture, and [2] the moving print-head won't experience sudden forces pulling on the spool from various directions (causing artefacts in the print and tangles on the spool).

I just plugged the ends of tube and soaked it in real warm water for 5 minutes then stretched it out on a table. That helped then the hard part I spooling it up against the arch and soaked it again. This seem to work the best.

You could use a hairdryer to introduce a spot-bend where you need it.

Hi and welcome to SE.3DP. SE is a Q&A website. Could you expand upon your answer a little as it is a bit terse? Also, I've made it more of a statement, rather than a question.

A colleague of me puts spring steel wires in the tubes and leaves the tubes on the central heating for a certain amount of time (probably hotter than 60 °C).


text:
Extruder skipping/clicking (brand new printer)
I just got a GeeeTech Rostock 301 mixer head delta printer and am having trouble honing in on why the extruder is struggling with my first spool of ABS.
Being the main parts of the printer came assembled I am unsure of where to start taking things apart. I have a read a multitude of possible causes and am hoping for some direction on which is most likely so I can start there.
Symptoms:
Extruder clicking. The extruder makes a low grinding noise every time it tries to extrude more than 1mm of filament using the manual controls. Again I am working with ABS so I have the hotend heated to 250 degrees C. The extruder had no trouble when I was first putting the filament in and using the extruder to push it thorough the Bowden tube.
But when I tried using the manual controls to extrude a small amount of filament it seems to be fine, just a small time delay between the extruder moving and the plastic coming out of the hotend.
Things I have read to try
Again this a kit printer and the involved components came assembled (see below) so I am not sure what I should look at first. I assume that if it came pre-assembled then it is most likely done correctly.

Clean out the hotend, do a cold pull
Take apart the extruder and realign the driving cog, check for shaft slippage
Replace your Bowden Tubes
Tweak slicer settings

For the first 3 I think its new so it should be clean, in working order. And for number 4 I put what was in the manual except for the temperatures (because the settings shown in the manual were for PLA but it is a PLA or ABS printer)
Assembly:
The printer being a kit came with the print head completely assembled as shown in the picture.
Not shown in the picture it also had the Bowden tubes in place. It also came with the extruder assembled as shown in the picture.
So aside from wiring and mounting these pieces the only thing I did was cut a clean edge on the Bowden tube and connect that to the extruder.

A hotend like this should always have 3 filaments loaded, or else molten plastic will clog up the unused inputs. Are you using only one colour (and leaving the others unused) by any chance?

Yeah, I only have one loaded... I imagine I have to clean it out now that I heated it up with only one color? What would be the best way to go about that?

@Evan, I would use cold pulls. Heat up the hotend, push filament through manually. Let it cool to ~100 deg C. Pull out once the filament is still somewhat soft. Repeat until clean.

@Gunslinger, even on a new hot end?

Still having trouble? Can you see if it is extruder gear slipping against the filamen? Or is the extruder motor jumping back and forth? If you can see the extruder gear, paint it striped with a marker.

@Gunslinger Yeah, I cleaned out the hot end best I could and it was still difficult to push filament through by hand. Hooked up to the extruder it worked of the extruder took small steps but there was a a delay between filament in and filament out. The extruder gear was not rotating when it was slipping so it is gripping the filament well enough

My experience with a different system: clicking was the hobbed gear slipping against the filament. Cure was slowing the feed rate and raising the hot end temperature.  Essentially the flow resistance was too high for the speed and T setting. YMMV.

@JKEngineer Yes, I did try just slowing everything down but it didn't really help, I think there might be a manufacturing Defect in the head and have ordered a one color hotend to get me by while i work with the company to get a replacement

First you have to see if nothing jams the filament (blocked nozzle or anything in its path, PTFE tube not good, etc).
Second, the temp for ABS is about 225°C to 230°C. At least that worked for me.
If none of the above, then go for the motor. The problem could be from bad settings, low power or a motor malfunction. Maybe the motor is no good to begin with.
Good luck !!!

This is worth pointing out as it hasn't been said yet, make sure your stepper driver isn't overheating. If it overheats, it will cause the stepper to temporarily shut down, and it will click when it happens. This could be caused by inadequate power or by insufficient cooling.

Would this happen on the first later of a print? also the extruder steppers have cooling fans

I've had the same problem, nozzle was just too close to the bed and motor required a little bit mode power so I turned a little bit a pot on stepper controller.
Since then no problem, also is good to rise a bit a temperature ;)


text:
New thermistor isolation, how?
We are trying to repair an Ultimaker Original+. One problem is a missing resistor isolation. The Ultimaker Original+ prints with up to 260 Degree Celcius.
Which kind of isolation products are suitable to resist the heat and are fitting on the thin wires of the thermistor?

"Where can I get them" is rather dependent on your location, and on StackExchange, we like to avoid opinion-based answers (such as recommending a particular supplier of a product).

The most common choice for insulating thermistors is glass fiber sleeving. It tolerates very high temperatures, and is commonly rated for up to 600 °C.
Teflon is also used but has a rather low upper limit on its working temperature; it shouldn't be used at temperatures exceeding 260 °C - which rules it out for your purpose.

I have never seen FBG sleeving small enough for the hair size wires typical on a thermistor. Do you have a source? I just used Kapton tape.

@DLS3141 E3D carries some.

I'm not sure if it fits the use you're describing, but Kapton (polyimide) tape is stable to about 400 degrees C. It can also be used as a build surface, so generally useful to have some.

Kapton tape is used all the time for electronic work, both to secure fine wires (for example patch wires on a PCB) and for insulation. It's not so great for thermal insulation since it is thin, but I have my hot-end wrapped in it, and that has saved some burnt fingers.

I used Kapton tape to insulate mine.

There are many materials you can use one that came to my mind is this High Temperature & Pressure Sealant and also the best way to apply it so it can be removed easy is this . take a kitchen food very thing nylon cover you know the very thin elastic one or cover the parts with some type of release agent (dont use something that inhibit silicone like sulfur or sulfur containing staff) and apply it over it then when is solid cut it and release it it would be like a glove i hope ;)There are silicone that are really high temp 1000 f to 2000 f good luck :)


text:
Smooth transition between a PTFE tube and the back of a push-fit coupler
I'm creating a reverse Bowden setup to guide my filament from spool to extruder, through a path which contains two couplers in the middle as follows:
[spool] --- |#= --- =#| --- [extruder]
So I have to connect a tube to the back of a coupler (---=#|) and not just to the front (---|#=). That's the end that contains the screw thread, and it's not designed to take a tube. I can't manage to make it a smooth transition. When I try to push my 1.75 mm filament through, it will often get stuck there. After it's through, the extruder seems to have no problem with it anymore.
Is there a trick to making this a smooth transition?

The solution might be to countersink the opening at the threaded portion within the tube. There are various angles available for countersinks, although the more common angles are 82 degrees and 90 degrees.
Drive the countersink to the point where the wall thickness is zero, unlike the drawing below showing some material outside the beveled area.

For your purposes, you'd want the steepest angle possible, the 60 degree tool.  If you decided to purchase a countersink, pick a diameter slightly larger than the outside diameter of the wall thickness of the coupler. You could use a countersink of the same diameter as the outside diameter of the threads.
Center drills are available with 60 degree angles as well:
Amazon specific item

The second smallest center drill listed here has a 1.5 mm center point with a 4 mm drill point. If your coupling is larger than 4 mm, the next size up will not work as well, as the center point is 2.5 mm. You'd have to resort to a countersink only.
If you are near a machine shop or have a friend with a mill or even a decent drill press, those resources may be able to perform the countersink for a minimal (or possibly zero) fee.
I have a mini-mill and a collection of countersinks as well as center drills. I found my bag of unused couplers. They are for 5 mm tubing and were flat on the threaded end. This is the result after a quick trip to the mill. It appears in the close up that I could have driven the center drill deeper into the fitting, and also cleaned off the swarf a bit as well.

That makes sense. :-) Thanks for the great answer. As it happens, I am finding some 60 degree center drill bits with 2mm tip on Amazon, so those should do the trick.

An alternative to chamfering the connector is buying a different type of connectors with a larger bore hole all the way through the connector and let the tube pass all the way through. These are used in my similar spool to extruder setup (reversed Bowden setup in OP's terminology).


text:
Has anyone used a Shield Buddy (en lieu of a Arduino Mega2560) as the RAMPS 1.4 host board?
I have read a few times1 that the Arduino Mega can struggle to perform the tasks required for 3D printer control, as the AVR chip is working at its limits, and this is why some manufacturers have moved away from the ATmega2560, to make custom (and integrated) controller boards using ARM processors.
Having just seen the latest answer to this question, Multithreading with the Arduino, on the Arduino SE site, I wondered if anyone had used a Shield Buddy in conjunction with the standard RAMPS 1.4 board?

It is pin for pin compatible with the Arduino Mega (and Arduino IDE compatible - once the appropriate add-ons have been installed), but it has a much faster three core processor. Obviously only one core would be used, leaving the other two idling, but even so the performance is apparently much better.
See Bringing Multicore To The Arduino World With ShieldBuddy TC275.
If anyone has experience of using this board, I would like to know whether it was successful or not? I don't see why it should not, although the Marlin firmware would need recompiling, for the Aurix TC275 processor. Would any improvement be seen? Is it worth paying the high price tag of £89?

1 One of the places was 3D Printering: Electronics boards:

While they work for what they’re intended to do, there are a few
  limitations. Arcs and circles are a little weird to program, and using
  these boards for something other than a cartesian 3D printer – a CNC
  machine, or a laser cutter, for example – is a bit out of the
  ordinary.

It's not just a matter of recompiling Marlin. You'd need to rewrite large parts of it. It may be compatible with the Arduino IDE, but that doesn't mean you can just run firmware intended for the AtMega2560 on it. All the timings (e.g. those of the pulses sent to the stepper motors) would be off, if you managed to get it to compile at all.

@TomvanderZanden - oh ok thanks. I haven't looked at Marlin's source code, as yet, so I wasn't aware of that.

I am currently trying to port the Marlin RC6 to the ShieldBuddy. I have managed to get most of it to compile and I have converted a lot of the AVR assembler to C (the TC275 is so fast that assembler code is not needed!)
What I am having difficulty with is the interrupts. I can see that there is an interrupt for the serial receive and there is a timer0 interrupt for the stepper driver. Are there any others? Also, what frequency does the timer0 interrupt run at?
I am doing the work in Eclipse but using the Arduino/ShieldBuddy HAL.
I would welcome any help anyone can give!!!

@MikeBeach This is not really the place to ask such questions.

@MikeBeach - Nice work, I would definitely like to hear how the work pans out. Once you get it working, your should post an answer to my question... :-) However, in the meanwhile, your question, may be better suited for StackExchange Arduino, there are some clever chaps there, who may know the answer (although they maybe more ATmega oriented)... Or failing that maybe StackOverflow?

It's not quite as simple as you would suggest.
You can't just recompile Marlin for another device. You'd need to rewrite large parts of it. It may be compatible with the Arduino IDE, but that doesn't mean you can just run firmware intended for the AtMega2560 on it. All the timings (e.g. those of the pulses sent to the stepper motors) would be off, if you managed to get it to compile at all.
As some examples, here are some pieces of code from Marlin that would be broken, as they're written directly in AVR assembly:
#define DELAY_1_NOP  __asm__("nop\n\t")
#define DELAY_2_NOP  __asm__("nop\n\t" "nop\n\t")

[...]

// ensure 100ns delay - a bit extra is fine
asm("nop");//50ns on 20Mhz, 62.5ns on 16Mhz
asm("nop");//50ns on 20Mhz, 62.5ns on 16Mhz

[...]

#define MultiU24X32toH16(intRes, longIn1, longIn2) \
asm volatile ( \
             "clr r26 \n\t" \
             "mul %A1, %B2 \n\t" \
             "mov r27, r1 \n\t" \
             "mul %B1, %C2 \n\t" \
             "movw %A0, r0 \n\t" \
             "mul %C1, %C2 \n\t" \
             "add %B0, r0 \n\t" \
             "mul %C1, %B2 \n\t" \
             "add %A0, r0 \n\t" \
             "adc %B0, r1 \n\t" \


text:
What slicer settings would produce the strongest part?
If a part is wanted to be made the strongest possible, what slicer settings should be used?

3-5 shells vs  all shells, no infill?
100% infill vs  some other % infill?
Thin layer height vs thick layer height?
Any other relevant settings?

If your real question is what would be the strongest then I say - the solid would be the strongest - no doubt.
But if the question is:

what be the strongest in comparison to weight or
what is the strongest in comparison to the cost (amount of material)

then these are good questions!
You can of course find many tutorials and comparisons on the net and there will be many answers - which all of them could be good/bad ;)
If these are your questions then instead of simple answer you can ask more questions like:

in which orientation or
for what purpose or
for continues stress or maybe for variable stress or
for bending forces / shearing forces or maybe tearing forces

all these forces and circumstances could require other answer... which could also lead to other questions :)
But according to my experience, the strongest settings (for general purpose) is 3 outlines (and the same number of first/last layers) and triangle infill 20-25 %
Why I think this is the strongest, 3 layers gives good chance to have well stickiness even if there are geometric/design issues and triangle infill gives good (and common) way to carry and spread forces.
But as I said it depends on many input data.
Let's look at these figures:

in figure A we have the strongest composition for compression; this is because all working forces try to damage material particles which is of course hard to do (depending on material density and length of polymers and the way they are tangled and so on - in general - material strength only).
If we consider figure B where forces try to tear apart layers then we know that we base on stickiness between layers which can vary on printing parameters (as is temperature and speed).
Finally, figure C shows shearing forces - in terms of layered structure it doesn't really differ from tearing apart but the results (the resistance of and object) is even weaker - it's because we base on stickiness and we additionally have less effective field of working stickiness) which reduces endurance of an object.

I had seen some information (can't link from login required chat groups) that stated something like 95% infill would actually be stronger than 100%.  This was the source of the question.

@EricJohnson this could be very interesting. I can imagine such situation but it would be really precise issue I suppose. 95% is so close to 100%. I can suspect this 5% (of empty space) gives some extra room to compensate bending so fibers can bend without tearing connections among them... it's possible for sure.

This question is practically unanswerable without the load case or the part being known.
Input for the "strongest" part is depending on:

Load case (compression, tension, shear)
Part design
# of perimeters
Filament type
Infill percentage (incl. local increased infill for e.g. fasteners; see e.g. "Different infill in the same part")
Part orientation when slicing
etc.

Do note that 100 % infill does not guarantee the strongest solution, from ahoeben:

Final note: 100% infill is not always the strongest or best quality. If you overextrude by just a little bit, that will quickly add up with 100% infill. With a lower % of infill, the overextruded material has somewhere to go. There can also be issues with cooling with high amounts of infill; you are not only putting more material on the print, but also more heat. On the other hand printing a layer is going to take a long time, so there should be time to cool. But shrinking/warping while cooling is also something that is affected by the amount of material.


text:
How drastic is reversing the polarity of the power supply to a RAMPS board?
If I accidentally reverse the polarity of my power supply to the RAMPS board, what exactly will be damaged?
Will it harm my:

RAMPS;
Arduino Mega;
Stepper motor and/or drivers, or;
Any other electronic part(s)?

Will all or some of them be permanently damaged?

Edited and reopened. Is this on-topic? It would seem a possible scenario, if due care was not taken, during assembly. Would just the fuses blow, on the RAMPS board, and that would be it?

@Greenonline I did it twice on a RUMBA board accidentally...still works. But that is no guarantee for a RAMPS board.

Polyfuses on the RAMPS
Fire appears to be the immediate issue, in the poly fuses.
From Reddit: reversed polarity, RAMPS on fire

Sooo I made the dumb mistake of reversing the polarity from my psu into the RAMPS 1.4. As warned the ramps did not like this and smoke began to rise from the board. I am pretty sure I saw smoke only coming from the two ptc fuses (big flat yellow ones).

Replacing poly fuses
Note: Older RAMPS 1.4 have easily replaceable large poly fuses, whereas the RAMPS 1.5/1.6 use SMD poly fuses, see 0scar's answer to RAMPS 1.4, 1.5 or 1.6?

Arduino
According to this user, the MOSFETs and the Arduino Mega's regulator can be fried as well:

it most likely fried the mosfets next to the fuses and probably the voltage regulator on your arduino.

However, the fried regulator would only affect the Arduino's operation if powered through the power socket, or VIN (which the RAMPS board uses to power the Arduino Mega). However, via the USB it should still work. See this post, on the same thread:

The voltage regulator is only needed if you supply power to the arduino via the Vin pin or with a separate power adapter. The RAMPS board does supply the Vin pin with 12V.

So, you would probably have to rely on powering the Arduino via the USB and not the RAMPS
Regarding the Arduino, on Arduino.SE there are a number of users who have fried their Arduino in this manner, and many of them suffer slightly different failures, although most are centered around the regulator. One case I remember was that of a capacitor burnout, see Is my Arduino dead? - although the use case was different. There are many other cases on the Arduino.SE.

Protection Diode
According to this post on RepRap - Reverse Polarity, there should be a reverse polarity protection diode (although it appears not to have work in the above example):

If it was a ramps, those have a reverse protection diode across the input that normally needs replaced after such an incident

Stepper drivers/motors
The stepper motors themselves should survive, as should the stepper drivers.
However, each case can be different and it would depend upon the quality of the board (is it a cheap clone or branded?), and the quality/tolerance of the components used - these factors would determine where in the chain of modules the failure occurs. Obviously, the earlier the failure's location in the chain the better.

MKS Base v1.2
As an aside, this user fried their regulator (the fuses were fine) on a MKS Base v1.2 (not RAMPS), by reversing the polarity, which caused the stepper drivers to fail. However, replacing the regulator fixed it, see this post:

Replacing the regulator chip did fix the board.

Rather helpfully the self same user has posted an Instructables of the repair: MKS Base reverse polarity repair.

RAMPSXB
There is no protection diode on the RAMPXB. From RAMPSXB:

Do NOT reverse polarity on the input pins, as there is NO PROTECTION DIODE. Reversing polarity will not only fry your steppers and FETs, but may even damage your Arduino and possibly even your computer. Triple check to make sure the polarity on your power input is 100% correct!

See also

Arduino Forum: Checking the RAMPS 1.4 for some handy troubleshooting tips for the Arduino and the Stepper.

This user on post #5 of Arduino Forum: Checking the RAMPS 1.4 did manage to fry their stepper drivers, but not due to reverse polarity, by from a loose wire:

I didnt connect the power backwards, but either I had a defective Mega2560 clone, or some stray bit of wire somehow shorted something out, and the Mega2560 literally went up in smoke (almost caught on fire !)
Every stepper driver was destroyed, but the power FET's and other components survived

Assuming the (most common and standard) RAMPS 1.4 board, the power input section looks like this:

There are two 12V input sections: one for the heated bed (with an 11A fuse) and one for the rest (with a 5A fuse). If only one of the sections has reversed polarity (and the other one is connected correctly) the power supply (assuming a single supply is used) is shorted out directly through the board (without any fuses or any other protection). This will in principle not damage any components on the board, but it might damage the power supply or melt the wires. In the following, I assume both sections have polarity reversed consistently (or one of the sections is not connected at all).
The bed input section basically has no protection. If polarity to the bed is reversed, the bed MOSFET's body diode will conduct - basically shorting out the input through the fuse. The current that will flow will initially only be limited by the power supply's ability to supply current. Eventually the fuse will trip, but these poly fuses are quite slow and in the meantime it is possible the bed MOSFET will be damaged (which might cause it to permanently conduct, i.e. the bed might always be on, or the MOSFET might become a short circuit and short out the power supply even if the polarity is corrected).
The 5A section has a bit more in terms of protection. After the fuse there is a diode (D2) that shorts out the power supply if polarity is reversed. This is similar to how the diode in the bed MOSFET shorts out, but in this case the diode is dedicated for just this function. The diode has a relatively low forward voltage, lower than that of the MOSFETs for the heaters, so in principle these components will be protected. However, the diode is not really rated for the kind of current that would flow in this scenario, so components such as the heater/fan MOSFETs and stepper drivers might be exposed to a reverse voltage (albeit around -2V at most). They would probably survive.
As in the heated bed scenario, the diode D2 would probably be damaged - it would likely end up short circuited and thus needs to be replaced (or at least removed, but this is not advisable since it's required for polarity protection) before the board will function again.
The Arduino Mega 12V input is protected through a blocking diode (D1) which will fully protect it. This diode will not be damaged, because it won't conduct any current in a short-circuit scenario.
It might seem kind of strange a diode is used to deliberately short out the input in case of reverse polarity, and you might ask why the design doesn't simply use a diode to block the reverse flow of current (like is done for the Arduino). The reason for this is that all diodes have an associated voltage drop, which would cause a lot of power loss (especially for the heated bed), requiring a large diode with heat sink. The way the diodes are placed (i.e., shorting out the power rails in the event of reverse polarity) avoids this loss and still somewhat protects the electronics down the stream (even if the fuses/diodes are blown). Note that this is still a less than ideal solution, if you're trying to design your own reverse polarity protection solution then I would recommend to go with a MOSFET-based solution.


text:
Bad PEI plate adhesion to heated bed
I'm (surprisingly) having a problem getting my PEI substrate to stick to the heated bed surface.  The ABS item being printed stuck great to the PEI surface.  I've not seen anyone else post on this problem, but perhaps someone has seen it.
Note, this is the PRINT SURFACE warping, not the item being printed.  That part went great with no delamination even on a large flat bottom.
I'm using 3M 468 adhesive to attach a PEI plastic sheet directly to the heated surface of my Flashforge Creator Pro printer.  The heated bed is anodized black and the adhesive is a sheet cut to the requisite 6" X 9".  It seemed fine and looked pretty good with few air bubbles when first attached, but the first print caused the edges of the PEI plastic to warp up from the corners of the bed.
It appears that the weak link is that the PEI detached from the adhesive. While this was not uniform, removal of the PEI sheet showed that 95% of the adhesive was still attached to the print bed.
The PEI has one glossy side and one matte side, and I chose to apply the adhesive to the matte side to get the glossy surface.  Does this make a difference?
I applied the adhesive to the PEI surface just as it was after removing the protective plastic coating.  I figured this was a clean as it was ever going to get.
I'd definitely appreciate some ideas on this.

Did you clean the surface of the PEI?  You also may need to sand it a bit to get it to stick to the tape but I haven't had any luck in finding someone else with the same issue as you.

I appreciate the thought.  The PEI was very clean, but as someone else pointed out this may be due to different thermal expansion between  the PEI, aluminum plate, and fairly large ABS footprint on the bed.  I'll try attaching the PEI to a glass substrate as that's what many do.
Gotta say, that this really surprised me as I'd not seen this sort of thing in the last year of printing.

Perhaps this is due to the aluminum build plate warping/crowning as it heats?  I use a PEI print surface on my Monoprice Maker Select (Wanhao Di3), which has an 8.5"x8.5" build plate, and I've had no issues with the PEI coming unstuck.  However, instead of attaching mine directly to the aluminum heated build plate, I attached it (using 3M 468) to a piece of Borosilicate glass, which is then attached to my aluminum build plate using silicone thermal heatsink pads.  The rational for using a Borosilicate glass print surface is that a heated metal build surface is going to warp or move some, as the heat is coming from one side; the glass will not warp and so you have a completely flat surface on which to print (and the heatsink pads help make up the difference in surface geometry).  I used this 3dprinterwiki article as the basis for my glass bed mod, and applied the PEI/adhesive using another source (which I've forgotten, possibly the RepRap wiki).  While the first link is Wanhao Di3 specific, it covers the idea.  Make sure you tweak your z-endstops if needed on your particular machine, as adding the glass plat raises the bed height by several mm.
Please note that I'm theorizing - I did not ever try applying my PEI directly to my aluminum build plate, so I have no direct comparison.  But the use of glass to eliminate build plate warping/crowning is fairly well documented. See also this 3DPSE Answer.

Excellent points, and with a bit more investigation I think this is almost entirely related to the aluminum heating and expansion.   I know others have also bonded to glass substrates (not even borosilicate glass) with good results also.  Just got it stuck down last night and will give it another shot today.

As a follow-up on this topic, I've since remounted the PEI plate on the glass plate, but after sanding and reattaching using liquid to avoid air bubbles.  I am not convinced that this problem was caused by the warp in the PEI sheet.  It's not large, but PEI is not very conformable and the constant tension consistently lifted the edges.  Mounting with the warp down has worked so far.

I never used one, but the thing that makes two parts stick together is the atmospheric pressure. The glue is just a thing that, even if it does not make any chemical bond, is keeping the air out. A pure example of that is if you put water in a glass and then put another one on it. Although the water is not glue you can't easily pull it up and if the surface is big you can't at all. It is the atmospheric pressure that keeps them together and the water keeps the air out ;). I suggest try the other side and see I'm just guessing . Good luck!!!

Well since adhesives are all about chemical bonding with different strengths, the atmospheric pressure is a minor component to this.  The cup experiment works not only due to pressure but also surface tension of the water.

Well Not all adhesives are all about chemical bonding.Also i don t think that the issue is the heat expansion. Also the atmospheric pressure is underestimated here when you put your hand to a house vacuum,for example,the force that makes you hand stuck to the vacuum s end is the pressure of the atmosphere...
https://en.wikipedia.org/wiki/Adhesive

Is there any reason you needed to make two answers rather than one? You can edit your answer if you have something to add. Also, please proofread your answer. It is suffering from run-on sentences. Lack of appropriate punctuation makes it very difficult to read.

The second is a respond to the guy that said all adhesives are about chemical bonding.Now to you :English is not my mother language it took me much time to found way to write my answer as best i could...Please try to focus on the meaning and what matters.....

@Odysx2 I understand that, but in any case, please try to make shorter sentences. If you put a lot of things together in one sentence like this it makes it very hard to read because you have to mentally break down the sentence in to parts and it is very hard to do that if there is no punctuation and the sentence just goes on and on without ever giving you a visual indication of how to split it apart.

Odysx2, I do appreciate your response and trying to help, but I find the claim that adhesives work due to atmospheric pressure completely unsubstantiated.  Even the wiki article you point out indicates only chemical bonding effects.  Empirically, I know that this is certainly not the case with similar adhesives like masking tape.  I've flown rockets to 75K ft with masking tape still stuck to the body when recovered.  I don't think it helps to state a false scientific premise as fact.

What exact is the false scientific fact ?? You fly rockets i lift tons with suction at a marble facility... do some basic physics lessons please before you accuse someone of false scientific premise .....


text:
gcode to move the printhead up for maintenance
I've got a Monoprice Mini Select (15365) and it takes FOREVER for me to manually spin the dial to get the printhead to raise all the way up so that I can perform maintenance (clear blockages in the nozzle or apply new tape to the bed, etc).
So, I was thinking about writing a snippet of gcode that I could just run which would contain the commands necessary to do that for me. I'm a n00b to 3D printing, but I'm an old programmer so I figured it would be too hard. However, before running this code on my printer, I wanted to get some experts to double check me to make sure I'm not going to hurt anything. :)
Here is what I have, please let me know if I've done anything wrong or if you have any suggestions.
; Move print head to center and top to prepare for cleaning/maintenance

M107    ; fan off
G28 ; home all axes
G21 ; set units to millimeters
G90 ; use absolute coordinates

; full dimensions of the print area are 120mm x 120mm x 120mm
G0 X60 Y60 Z119 ; move to center X,Y and just below the max height

M84     ; disable motors

I grabbed a few lines from gcode generated by Slic3r and used the gcode wiki entry to understand each of the commands and fill in the extra ones I needed.

Yes, on machines which will execute "standard" gcode, this will do what you request. Some good resources are http://reprap.org/wiki/G-code and https://en.wikipedia.org/wiki/G-code

It really depends on whether you currently have something half printed on the bed when you need to do maintenance.
For example, you may have a blockage mid-print or need to reprime the nozzle.
So with that in mind, personally I would separate the line that does the move into two different lines.
Move vertically first, then in X Y. Otherwise, the print head may move diagonally and hit your object. This is because the head will move all three axes at once.
Otherwise looks good.
Edit: Another suggestion is that if you use repetier host to control the printer it will be easier to return to the print in-progress automatically.
Also take a look at the S parameter, for moves it can control how fast the move is.