Filament Friction

WayZada
Posts: 38
Joined: Thu Jul 30, 2020 2:39 pm

Filament Friction

Postby WayZada » Wed Aug 19, 2020 3:26 pm

Friction on the filament seems to be ruining my prints.

I am printing on my E2 using MatterHackers PRO PLA (linked below). Occasionally the friction on pulling the filament to the extruder becomes too high and the filament stops being extruded. Of course, the machine doesn't know this so i get very thin or even missing layers when this happens. I've had this experience with 3 different spools of filament.

The root of this seems to be that the hole where filament passes through from the spool to the PFTE tube is very small and has sharp edges. When the problem occurs, I simply pull the 'hung up' portion of filament through the gap manually and then everything works again.

My question - what can I use to alleviate this? I would like to install a larger 'pass through' that the one that has come stock, which would help filament not get stuck passing through. I see one user mod on the forums, but I'm not sure i'm ready for this level of machining. Is there somethign simple I could to do remove the narrow orifice or otherwise help get filament from the spool to the extruder more readily?



Filament:
https://www.matterhackers.com/store/c/1.75mm%20PRO%20Series%20PLA

One user mod:
https://forum.raise3d.com/viewtopic.php?f=20&t=20793

Blue21
Posts: 115
Joined: Sat Jun 06, 2020 8:04 am
Location: Switzerland

Re: Filament Friction

Postby Blue21 » Wed Aug 19, 2020 8:42 pm

Hi
On the post you mentioned, I didn't have done it directly for that purpose. It is possible it helps.
I had similar issue with friction and lost several prints as the extruder stripped the filament.

One issue I had was the PTFE tube is 4mm diameter outside and 3mm inside, so it is weak and easily damaged if bent during the load/unload process. I tried 4/2 mm with no success, it is too small. 4/2.5mm seems not bad but 4/3 is ok when not damaged.

Second issue is that I was using cheap PLA most of the time and it comes on cardboard spool. Several spools had small bend that come in contact with the spool holder and almost stopped the print due to the extra friction. I have machined the spool holder rolls so that the side of the spool never come in contact with the fix part of the spool holder. Since this modification, I had no issue anymore. Also I ensured that the spool holder rolls can freely turn.

Ideally would be to detect that the filament is no more advancing and connect such sensor in parallel with the filament detection sensor or combine them together. That would pause the printing and the print could be maybe saved. Maybe it is not really possible for any kind of print (especially the one that have a small XY surface), at least if would avoid risk of the machine running in a faulty condition.

Your spool seems to be rigid plastic so a part of my issues is most probably not applicable to you.
It can be also some issue with the extruder itself (dust or other near the gear).
Can be also an humidity issue. If it was a "fresh" spool, then that don't apply.
E2 + Prusa Mini <- UM 2+ <- Replicator2

WayZada
Posts: 38
Joined: Thu Jul 30, 2020 2:39 pm

Re: Filament Friction

Postby WayZada » Wed Aug 19, 2020 9:10 pm

Thanks for the tips. This is reasonably high quality and consistency filament and on a plastic spool. Still, I wonder if it is friction on the spool or friction on the filament. I have swapped lots of colors in and out (all same brand filament) and the problem is pretty irregular, so I am thinking it is the filament making it through that fairly small and sharp-edged orifice.

The filament is freshly opened, and I store in a dry box, so I don't think it is humidity. PTFE tube is intact with no kinks nor other visible damage. I'll look into friction on the 'rolling' of the spool as another possible cause.

Any suggestions to remove or replace the part that is hanging up my prints? I see that you've machined the part, but I'm hoping for something I can screw in our out instead of machining a part myself.

For Raise3D folks, here are some photos. The dark and light green should be printing side-by-side, but the light-green hangs up and stops advancing.
IMG_1597.jpeg

IMG_2802.jpeg

WayZada
Posts: 38
Joined: Thu Jul 30, 2020 2:39 pm

Re: Filament Friction

Postby WayZada » Wed Aug 19, 2020 9:31 pm

Taking to heart the possibility that the friction is coming from the spool rather than the filament path. To that end, I've...

1 - removed the rubber stoppers from all of the holes (no rubbing of these against the spool), and
2 - switched the provided holder to a configuration that has the spool hanging via the center instead of 'rolling' on the outside of the cylinder.

Preliminary tests by hand indicate much less friction with this setup, and a new (smaller) test print is started.

Any reason I would want to reinstall the rubber 'plugs' that separate the filament spool area from the main build area? I guess maybe some added gasses will vent out through those, but the door and top aren't airtight and I vent out a window for anything other than PLA.

Here are two shots of how my set-up currently looks:
IMG_2254.jpeg
IMG_9595.jpeg

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Vicky@Raise3D
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Re: Filament Friction

Postby Vicky@Raise3D » Thu Aug 20, 2020 3:37 am

For printing PLA the rubber plugs should not be needed. But if you were trying to fully enclose the machine to print a higher temperature material they will be needed.

WayZada
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Re: Filament Friction

Postby WayZada » Thu Aug 20, 2020 12:16 pm

Ok. Beyond frustrated here. Even with my 'low friction' spool set-up, my print overnight failed yet again. This is not a clog in the extruder or hot-end, it is a matter of the direct drive not being able to pull the filament. Here's the failure, where the bright green color simply stopped printing:
IMG_1602.jpeg


What I believe to be the problem here is the extremely narrow opening in the filament sensor, pictured below. The tolerance between the filament and orifice is just too tight. I'm printing with 1.75mm +/- 0.02mm (per manufacturer and tested with calipers on my end).
IMG_7418.jpeg
IMG_1550.jpeg


3 questions for @Vicky or Raise3D support:
1 - Can I drill out this part to yield a larger 'orifice'? Will this damage the sensor?
2 - Can you please send me a replacement part where this orifice is larger and will allow filament to pass with a larger tolerance for diameters?
3 - the inside diameter of my PTFE tubes as installed, and the backups, is 2.5-mm. Other posts suggest a 3-mm inside diameter may generate less friction. Which is the size that your company suggests.


At time of writing I have had the same print fail 3 times for this reason, cumulatively with about 45-hr of printing into those failures (and, of course, the filament cost). This design flaw is costing me time and money, and I need a resolution. PLEASE HELP!!!

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ccclarke
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Re: Filament Friction

Postby ccclarke » Thu Aug 20, 2020 4:35 pm

I'm not saying you're wrong, but when troubleshooting, always follow the data. Pictures are subjective. What is the ID of the hole?

If it doesn't match the drawing, (bad parts happen) a new part is warranted. If it does match the drawing, then either there's a design flaw, (and you're the only one reporting it) or you have an alignment problem. I doubt Raise3D is going to have larger diameter parts if the one you have is the proper part.

I've always thought the off-center hang of the spool on the roller post was a poor design as it takes more effort for the spool to roll when it's hanging by the upper side of the arc. A roller bearing surface would reduce the amount of effort for the extruder gears to pull the spool.

Another obvious oversight: On the Pro2Plus, a Raise3D filament spool (mounted on either post) scrapes against the clear acrylic door, scratching it more and more over time. A 1/4" of clearance would have made it a non-issue.

CCC
Male Modeler / Sub-Human

WayZada
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Joined: Thu Jul 30, 2020 2:39 pm

Re: Filament Friction

Postby WayZada » Thu Aug 20, 2020 7:46 pm

@ccclarke - Thanks for your thoughts! I cannot measure the tolerance of that hole with the calipers i have at home due to the geometry. I can tell you that it is VERY tight around 1.75mm filament. As an example, when filament is unloaded and the very end of the unload has even a minor bulge, it cannot retract through that orifice (but can through the silver tube holder that screws into the block).

The orientation of the filament pull seems to allow for all sorts of friction both on the spool and also on the filament. With the part removed I have manually pulled a few meters of filament back and forth - when you get at more extreme angles, the filament 'catches' or 'scrapes' on the orifice in question here.

One thing i've noticed - i can get through shorter prints without issue, but this is happening on longer prints. I believe this is because as the filament is unwound back and forth along the spool, the entrance angle to the block is changing. That seemingly minor (and entirely predictable) chagne is altering the filament path and leading to scraping. This is a working hypothesis, for sure, but it is my best guess.

All of this to say - I appreciate the advice from the community and will keep trying, and will keep posting on this tread for others who are troubleshooting the same.

BTW - current set-up has the spool rolling on a single spindle through its middle (as above), but now have removed the aluminum block, filament sensor, PTFE tube and am running filament 'bare' to the extruder. This test will at least let me isolate that the problem is friction within the block in question as all other configurations to-date are failing.
IMG_6550.jpg


Thanks team. As I work with support i'll also post their feedback here for others to see what i'm going through and learn from this.

WayZada
Posts: 38
Joined: Thu Jul 30, 2020 2:39 pm

Re: Filament Friction

Postby WayZada » Thu Aug 20, 2020 7:57 pm

Wait! I CAN figure this out. Filament measuring 1.8-mm or less is fitting through without issue. Filament measuring larger is getting hung up. What I think happens is not that the filament itself is actually too thick, though. It is that when the angle is too extreme the orifice isn’t smooth - it has sharp edges and the filament catches.

The silver fitting that screws in and holds the PTFE tube in place is more like 2.2-mm ID. So the black block where the filament sensor mounts is the choke point if my theory is right on the issue.

WayZada
Posts: 38
Joined: Thu Jul 30, 2020 2:39 pm

Re: Filament Friction

Postby WayZada » Thu Aug 20, 2020 8:06 pm

One more. Here is a short length of Raise3D filament that has some minor bends in it. Nothing extreme. This moves readily through the PTFE and through the silver tube holder. However, not the black filament sensor “block” in question. I suspect that any minor imperfection in the filament diameter or straightness is hanging up inside the block.

Easy fixes for Raise3D would include: (1) larger ID in this block, or (2) switch to a mechanical sensor if the larger ID will prevent the optical from working.

0C8C49DC-EE7C-405D-AE4B-8AE8B98266EE.jpeg

Bikeracer
Posts: 88
Joined: Sun Jun 28, 2020 11:54 am

Re: Filament Friction

Postby Bikeracer » Thu Aug 20, 2020 8:36 pm

Would something like this help, pics at bottom of thread.
https://forum.raise3d.com/viewtopic.php?f=20&t=20776

Blue21
Posts: 115
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Location: Switzerland

Re: Filament Friction

Postby Blue21 » Thu Aug 20, 2020 9:30 pm

Just my thinking:
In case you really want to drill large the hole, you have really to remove the electronic board from it, easy one screw. If you fully go through, it will be bigger but inserting the filament will become harder than what it is currently.
Seems from your pics that it is the "light green" filament that stops each time, did you try to swap filaments between the extruder. Ideally you would found a way you can have the same problem (I know you want to get ride of it, no make it again ;) but with a minimum of filament used (smaller print). Troubleshooting is the art of being able to reproduce the issue with confidence. This is usually based on some hypothesis and their verification at the minimum cost.
How looks your filament after it stop extruding if you take it out from the extruder, mine was really stripped and I even don't need the unload function to be able to easily take it out.
From your pictures it seems to fail at the same Z height, maybe a sign? Z height has an impact (little) on the PTFE tube position in the machine. As you mentioned earlier can be related to the filament position in the spool too.
If you do a print with only the extruder that has the "light green" filament, would it fail?

In general I also think that the entry to the filament sensor is not that perfect for hard filament but its diameter cannot be too big to keep the sensor detecting a broad range of filament, including semi-transparent like PETG. For such price tag machine, they could have designed a better filament sensor that not just try to detect its presence (almost transparent filaments are a problem for the E2, it is logical as the E2 sensor is designed). A wheel and a switch would allow to detect filament presence and feeding, cheaper would be just a wheel. It seems that the E2 if ready for a lot of modding despite its price :lol:
E2 + Prusa Mini <- UM 2+ <- Replicator2

WayZada
Posts: 38
Joined: Thu Jul 30, 2020 2:39 pm

Re: Filament Friction

Postby WayZada » Fri Aug 21, 2020 1:29 am

@Blue21 - thanks for the tips. I have had this happen always on the left extruder with multiple filament colors and brands. And also with the PTFE tubes completely removed to ensure that isn't the issue. I do have failure on prints of one color using the left extruder as well, so i think it isn't just this model or the Z-height.

After extruding, filament is not stripped - I can't pull it out and need to use the unload to remove it.

agreed on the better filament sensor! ;)

(finally - why keep printing in this color scheme and this model for testing? Because I owe it to a paying client and i'm LATE thanks to this machines continued failing. I cannot replicate the fail on command - it is random during print jobs of a few hours or longer, so i keep attempting a print I need in hopes the failure goes away!)

WayZada
Posts: 38
Joined: Thu Jul 30, 2020 2:39 pm

Re: Filament Friction

Postby WayZada » Fri Aug 21, 2020 3:06 am

I have removed everything from the filament path to the extruder, I have disassembled both hot ends to ensure there is not clog nor blockage in the gears or filament path. I am using high quality filament (MatterHackers PRO PLA). I have tightened tension on both extruders. With lots of watching I have found the extruders sporadically begin ‘clicking’ and then this goes away. Of course, that clicking is a failure of the filament to properly move through and extrude from the hot end. To be totally clear – I have had several successful prints using both your supplied PLA and the MatterHackers PRO PLA. However, failures are apparent on both extruders that happen randomly in space and time (i.e., not always a specific layer or duration into a print job).

See video of the latest failure linked below where you can see and hear the ‘clicking’, and also the failure to extrude the gyroid infill that should be printed in dark green in one video.
Video Link: https://www.dropbox.com/sh/vg9ti739120rb41/AAARTbewILBvRsomHMpc0y_0a?dl=0

I understand the clicking is indicating filament isn't advancing properly. I have removed all friction or possible holdups along the filament path and am still getting this. I have printed hotter and cooler than the current extruder temps. I have disassembled and cleaned the hot ends (no clogs found, no visible dust nor debris in gears).

Ideas? Support? Is this a defective unit?

Blue21
Posts: 115
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Location: Switzerland

Re: Filament Friction

Postby Blue21 » Fri Aug 21, 2020 5:52 am

From your videos, I would say that the motor of your extruder is not working correctly, seems it should turn constantly and it is just going forward/backward but maybe I misinterpret what it is supposed to do during the print. In any case such noise is never a good sign. From your videos with direct feeding of filament in the extruder the problem is not before the extruder, it is the extruder itself or the main control board that has an issue.
E2 + Prusa Mini <- UM 2+ <- Replicator2

WayZada
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Joined: Thu Jul 30, 2020 2:39 pm

Re: Filament Friction

Postby WayZada » Fri Aug 21, 2020 1:46 pm

Having serviced both hot-ends to confirm there was no clog, I went back through the entire calibration procedure this morning. I swapped the filament to prove here that it isn't simply one spool giving trouble. Attempted to print a temperature tower, but the left extruder continues to fail. It seems the friction on the filament may not have been the key to this problem. Both extruders exhibit 'clicking', meaning they are not able to advance the filament through the hot end (See videos linked above).

Failed temperature tower (dark green = left extruder):
IMG_7817.jpg


Failed prints using Raise3D white PLA that shipped with the printer:
IMG_9591.jpg


Failed test print when dark green was on the right extruder:
IMG_9375.jpg



The problem is not the filament - it is the E2 extruders. Both have failed, both have the 'clicking' (videos above).

For a machine of this cost, these are major issues.

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Vicky@Raise3D
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Re: Filament Friction

Postby Vicky@Raise3D » Fri Aug 21, 2020 10:53 pm

All of the fialment pathways should be able to accept 1.75mm filament with a deviation of +/- 0.05mm. Something that you will need to take a look at to ensure that the filament is being extruded properly is to ensure that the extruder tension is set properly. We can not recommend modifying any component of the machine as it can lead to issues down the line not only with the machine but with warranty claims as well.

WayZada
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Re: Filament Friction

Postby WayZada » Sat Aug 22, 2020 1:07 am

Team - wait a minute. Look at this issue:
https://forum.raise3d.com/viewtopic.php ... ers#p52808

It is the filament? I've had good success along with failure of the MH PRO PLA, and the Raise3D has at least a few fails. Still, the filament is suspect...

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eXcelonPrime
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Re: Filament Friction

Postby eXcelonPrime » Sat Aug 22, 2020 3:03 am

FWIW I haven't had any issues using MH PRO PLA, but I haven't been impressed with it either. To me, (anecdotally anyway, I didn't put caliper to every mm) I don't think they're hitting their tolerance claim of +/- 0.02mm.

WayZada
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Re: Filament Friction

Postby WayZada » Sat Aug 22, 2020 2:06 pm

@eXcelonPrime - this is good to know. I see others having issues with MH PRO PLA and I have been as well. I've got some spools of MH Build PLA and others around that i'm trying today.

To keep the thread updated - Raise3D technical support is offering the following:
1 - they reviewed my serial logs and identified several error codes related to temperature
2 - I unplugged, inspected, and reconnected the extruder cables and then ran a test for stable temperature (it was)
3 - They are sending me replacement cables for the extruders as they suspect a problem there led to the temperature error codes.


After step 2 i successfully printed with Raise3D filament, then failed with MH PRO PLA. Then overnight successfully printed a large job with MH Build PLA. I am continuing to suspect this is the filament, but want to succeed/fail several more times in a systematic way before i'm ready to draw that conclusion.


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