Extruder "clicking" and underextruding - RepRap Afinibot Prusa

Hello!

I´ve been asking around for tips regarding som feeding and extruding issues I have on my Afinibot. The short version is that the extruder stepper starts to click and retract att feed rates of 0,2mm / 50mm/s and above, resulting in poor prints. I had bigger issues before I realized that the filament that shipped with it seems to be of lesser quality, it bunched up in the nozzle (or rather, bunched up in the PTFE tube).

But still, the problem persists. I´ve solved it to an extent by cranking down my feed rates, but there is something wrong somewhere. This is my first printer so I´m learning as I go... I´m also pretty good at root cause analysis but feeding issues has so many variables it scares the crap out of me

My conclusions so far:

- PLA temps. I have tried lowering my temps, was up at 210 degrees, and now at 195. Don´t really know if it has made a difference. I use Plastech PLA.
- Stepper motor current. I can´t figure out how to send gcode commands to the printer to get a readout of the set currents. I use Repetier Host which has Gcode send functionality (I think) but I can´t make it accept the M906 command. What do I need to type and more importantly, how do I increase the voltage to the stepper a little? I have an Afinibot with a Melzi board as far as I know.
- This is whichcraft and impossible to solve without sacrificing my firstborn. Something I´d rather not do...

/Stefan

clicking on the extruder could be a result of filament slipping on drive gear or your stepper motor isnt getting enough power so when feeding through the bowden tube when the pressure builds up, the actual motor hasnt got enough torque to feed at the selected rate.
if this is happening you will need to increase power on the driver pot, will be little screw on board. you can google how to google this.

oh be careful on increasing power, do it with small turns as this will also increase the heat on driver and the nema stepper motor.

Edited 1 time(s). Last edit at 12/19/2015 05:55PM by Bradles.

Thanks, a pot you say? I thought I could do it by adjusting firmware. Also, the stepper is completely cold now so I can´t feel any heat buildup as it is right now. Should be good for some "tweaking" (said me who has no experience, aka a "hold my beer and watch this!" situation )

edit: There is no slippage, I have tightened up the idler for the extruder with no difference.

/Stefan.

Edited 1 time(s). Last edit at 12/19/2015 06:03PM by Steleei.

I´ve been googling trimpot adjustment for Melzi boards but I can´t find a proper resource... Do any of you have a link? My board is a Melzi V3B if it helps.

/Stefan

In general a clockwise turn increases the motor current and anti-clockwise reduces it.
Only go higher by about 30° on the dial and keep an eye on the motor temp as well as the temp on your drivers.

So I´ve been working on this problem... I adjusted the pot for the extruder stepper, to a litte over 20 degrees. Clearly it works better, but I can still experience very little clicking at 50mm/s. So it´s not okay by any stretch, but now I feel I can atleast produce pretty reliable prints.

I actually went over 30 degrees (quite a bit) but it didn´t help and in the end the stepper started to click all by itself. Apparently there is such a thing as too much power...

So what to do next? Change the PTFE tube? What temps do you recommend for easiest extrusion? PLA in this case...

/Stefan

If the extruder is still struggling I would check where the filament gets stuck and fix the issue for good.
Usual culprits are the area where the cold end meets the extruder, from the bowden coupling (if on the cold end) to the inner hole of the cole end, the area where heat break and cole end meet and last but not least the overall hole diameter from cold end to melting chamber.
You want one smooth ride all the way from the extruder bearing down into the melting chamber.
Especially once the filament has the usual chew marks on it every tiny gap, corner or burr can and in most cases will cause trouble.

I recommend 600 grid or finer snad paper rolled on a bike spoke or similar.
Put into a cordless drill it will remove all bad spots quite easy.
The heat break can be a pain and often takes over an hour on its own, stainless steel is quite hard to work with....
Once done and happy the last piece of sandpaper should be useless and blunt anyway, so add some metal polish and continue until everything is shiny.
You don't want to see any rings or changing diameters where parts meet, if the heatbreak is of low quality you won't be able to sand it down enough to get rid of the small holes on the drilled walls - don't worry about them once snaded and polished these tiny holes won't harm anymore.

I have a different board then you, but when I am adjusting the pots on my stepper drivers, I normally use a multimeter to read the voltage passing from the potentiometer (metal) to the ground on my power supply. Based on the resistors used, I believe I want something in the neighborhood of 0.6-0.8V in order to stay under the amp limit of the stepper driver.

The issue I had with "eyeballing" the pot adjustments is that after a certain point, the pot would reset and start over from turning it too far.

If you overturn those tiny things you got a problem, they offer around 270° of motion.
There is a mark that shows you the position, this mark can be from where the left leg is to where the right leg is - on the upper circle part but never at the bottom where the legs are.
You are lucky they still work once you forced them too far.

Thanks for the tips! I´ll definately polish the hardware to make it as smooth as possible. I´ll report back with my findings!

Regarding the pots, I´d read beforehand that they only have 270° so I did´nt go very far, I just realized pretty quickly that it didn´t make much of a difference...

/Stefan

There is a Melzi tutorial here. [reprap.org]
Basically you shut off power to the board, unplug the usb cable, switch the position on jumper connector, plugin usb cable, wait until led turns on, ground your volt meter at the board supply ground and touch pot adjusting screw with red lead. Should read .5 volts. Can safely be raised to .7. Check all 4 pots. When done adjusting, unplug usb, switch jumper back, plugin usb and power up.

Thanks for the short and easy to understand guide, elwood127. Appreciated!

I´ve been printing quite a bit the last few days, and have come to the conclusion that filament colour also makes a difference... Printed a large car body and some other stuff today in clear, worked like a charm. Switched to black with the same settings (PLA, 200 degrees C), and it extruded for maybe 15 seconds before clogging. I´ve also taken the heat end apart to clean as per you recommendations (it had also leaked a bit) and found then that some filament was stuck in the PTFE tube about 10mm from the bottom, I assume that is the zone where the filament expands during melting. Appears to me that darker filaments expand more or something, atleast I have found that they extrude more poorly than lighter och clear ones...

Is it a temperature issue? Maybe I should turn the temps down on darker filaments...say 180? Should I change the PTFE tube (I don´t have a replacement, looks like I need to source PTFE tube here in Sweden...) What are your findings?

Regards,

Stefan

For every new roll of filament you have to check the properties and where required adjust them.
If you have more than 2 or 3 rolls around it pays off to make numbered profiles for them and to makr the rolls accordingly.
The best in terms of quality is natural filament without any colors added, black is basically the dumping ground for plastic as you won't see what is in there.
I had white PLA that was next to impossible to print with a good surface finnish, always looked rough and with poor dimensional accuracy.
Was about to take the entire hotened apart to check but tried a different filament first and it printed great - so the white PLA went in the bin.

Ok... I have a few rolls and bad memory so marking them up seems like a good idea

I´ll try to heat up my hotend to 170C and upwards and try to coax the jam out if I can, I don´t look forward to tearing everything apart again... But as a rule of thumb, should I start with lower temps and work my way up? I seem to remember reading somewhere that hotter temps can burn the filament in the PTFE tube.

/Stefan

I tried both ways, starting high and going down as well as the other way around.
All I can say is that not enough enough heat only causes the extruder to struggle while too much heat can cause all sorts of problems.
Now I do it this way:
Start with a low temp that should work from experience with the type of filament.
Check the layer bonding and if too weak increase the temp by 5° to try again.
Final check is with some bridging as too high temps here make it all sag and too low temps will cause problems bonding.

Hi, I've been working on 2 Afinibot Prusas from two friends. One of them purchased the printer around March 2015 and the other purchased it around October 2015. I managed to get the afinibot from March 2015 working with ease, but with a slightly buggy firmware called Zonestar and repetier host recognizes it as "Marlin v1.3v." Nevertheless it prints okay.
However, the Afinibot purchased around October 2015 had smoother rails, and it communicates better with the latest repetier host. BUT, I am also having a problem with the extruder. The steppers seem to be clicking and the filament isn't extruding continuously as compared to the older model. The older model had a different design for the extruder and idler, however the idler was 3d printed with lower quality but it works.

I've tried various solutions by cranking the pot on the melzi board from 0.8v to 1.5v above. Unfortunately the steppers only clicked and slipped louder. So adjusting the current didn't seem to help.
I've also tried checking the steps in the eeprom from repetier host. To no avail, even setting the acceleration, max extruder feedrate to 1mm/s didn't help. It lessened the frequency of the clicks, yet it didn't change anything.
I also checked if the nozzle was clogged, so I tried flushing down filament at 240 degrees, then to 260 degrees, yet it didn't help again. I tried cleaning the nozzle by dipping it in pure acetone, and still no progress.
*oh and I checked the ptfe tube, and it looks fine. It only has trouble pushing the filament down when the nozzle is back on.

It would seem that the afinibot they shipped around October has a design problem. I was hoping if anyone has made any solutions for this printer.

Seems like we are experiencing the same issues, niccoreyes. My Afinibot is from november, so I assume it might be similar to your newer version.

My printer is printing right now beside me, it´s working but the clicking persists. I didn´t notice much difference either adjusting the pot...

I´ve noticed something different though which might be a total red herring. When you look at something for too long the crazy might kick in... Anyway, I´ve noticed that the clicking occurs at similar points on each layer, and some streches of print at the same speed (which then should click as well, same extrusion and nozzle pressure) does not. Is it possible that this behavior is firmware och slicer related? Since this is my first printer I don´t have any previous experience to compare with, and I have only used the standard firmware, Repetier host and Slic3r. Either way, I am observing a behaviour that is not consistent with the clicking only being dependent on feed rate...strange.

But perhaps I´m just going crazy. That´s also a real possibility

/Stefan

Oh, and it has no problems whatsoever feeding filament by manual control when I change filament colours. I don´t know the exact feedrates, but it feeds pretty quickly when I give manual commands, it feels to me that it feeds slower during normal printing and still clicks. That´s with the nozzle in open air, perhaps extruding against a previous layer creates much higher nozzle pressures but that shouldn´t be since it´s also suspended over the layer by say 0.2mm.....

The plot thickens....

/Stefan

Edited 1 time(s). Last edit at 01/06/2016 01:12PM by Steleei.

I think I´ll order a new connector between the cold and hot end (the screw holding the PTFE tube) with a heatsink. The stops I´ve had seems to be clogging in the tube (leading to higher pressures) so a more effective cooling of the tube might help. Perhaps it´ll remedy the issue a little.

I´ve also tried to contact the seller but he seems to have trouble communicating in english so I don´t think that´ll do me very much good... Ah well, I´ll chalk it up to experience!

/Stefan

You can get knock off E3D clones with fan for under 20 bucks on Fleabuy.
They do require some work on the stainless steel tube and some fine sanding / polishing throughout but after that do a surprisingly good job.
Mine had not a single failure throughout the last 3 rolls of filament.

I´ve realized that most heatsinks won´t fit on the Afinibot, with the distance betewwn the hotend and extruder being som small. Perhaps I can just redesign the colling duct a little... ah well.

/Stefan

Had a small breakthrough, found a supplier of PTFE tubing here locally and replaced it. It runs the entire length of the screwed tube from the heat block and up, and it made a world of difference. I had a jam later, but I´ll come to that...

Appears that it´s vital to have a fresh and clean PTFE tube (duh), but especially with PLA. Is this correct? Seems like PLA is very temperature sensitive when it comes to expansion in the PTFE tube, as I learned the hard way. Did some awesome gecko test prints in orange Plastech PLA at 200 degrees C. Came out great. After that, I started an overnight larger print in grey Plastech PLA with the same settings but it clogged after about three hours. Took the hot end apart and saw that filament had oozed up out of the top of the PTFE tube (25mm from the bottom), so it appears that it melted way too far up the tube. Granted, I have 4mm of retraction so that would pull up some filament but it should not melt. It created a blob over the tube that prevented any feeding...

So I guess I´ll have to crank down the temps on the gray, 5 degrees perhaps? I´ll try it later today, any other tips or recommendations are welcome!

/Stefan

Yes, pla is particularly sticky and prone to jamming in the heat-break. So is TPE I recently discovered...

If you get molten filament all the way back up the heat-break that suggests you need more aggressive cooling on the upper part. You have a fan running continuously up there?

Hi.

I don´t have a cooler for the heat break, though I thought about adding some M6 shims and create my own cooling fins but the thread length is pretty short between the hotend and the extruder block so I left it as is.

But results from my tests and repairs are in! I´ve experienced big improvements since changing the PTFE tube to a fresh one, and also lengthening it so there´s no gap between it and the extruder block. In short, making the filaments way through the extruder and heat break as smooth as possible. Right now I have practically no clicking issues. But the melting of the PLA at the top of the PTFE persists to some degree, which annoys me. To the point where I have ordered a completely new hotend, a E3Dv6 universal hotend with integrated cooling fins and fan.

This carriage will fit my bearings and the extruder and E3Dv6 should be a pretty easy fit...

[www.thingiverse.com]

I even have the option of going bowden later if I want, the hotend accepts both. Hopefully going with a quality hot end will end my troubles and let me focus on other things (such as auto levelling... )

/Stefan

Sounds like a great choice, I'm sure that will improve things.

Ok, so probably my final post on this subject...but we´ll see

So I changed to an E3D, works well as an extruder. But I´ve come to realize that the clicking very much seems to come as a result of an overheated stepper driver. Also, the current was too low to the stepper from the get go.

To remedy this I´ve mounted an 80mm fan over the board and drivers, using mount

[www.thingiverse.com]


I searched for other posts regarding board cooling but it doesn´t seem to be a big problem for people, found very litlle.... I´ve also cranked up the voltage on the pot, now that I have better cooling. Sometimes it clicked because of low voltage, sometimes because of overheating so I had some trouble figuring out what was really going on... What used to happen was that the beginning of the print went fine, but extrusion deteriorated over time (say about an hour later) when I guess the driver got too hot (too hot to touch).

Anyway, I connected the fan to the extrusion fan connection on the board, I´ll attach and power both the board fan and extrusion fan off the same connection, seems to work fine.

/Stefan