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UM2Go - feeder skipping - but how?

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Hi everyone,

sadly it is my first post on forum (but I'm reading many topics before, but more in incognito mode:)) and it is troubleshooting issue.

I have UM2+ and UM2Go. I am very happy with these printers, but UM2Go is constantly have a problem with feeder skipping. I have read many topics with great advices, but any of these work with my printer.

What I already did:

1) Atomic pulls - so many many many times.

2) Loosen 4 screw on top printer head a little bit

3) Installing |roberts| feeder (Oh man, I love your design)

What you have to know:

1) Skipping is not happening on bottom layer - (it is on every one)

2) My settings:

2.1) 0.2 layer height

2.2) 40mm/s^2 speed (is so slow comparing to UM2+ :()

2.3) 225'C temperature

2.4) Filament: Innofil White PLA

Firstly, I thought it may be clogged nozzle. After many Atomic pulls - it make no difference - still skipping. Bed calibration? No, because skipping is happening on upper layers (funny - because on first layer I never got problem with skipping).

I was experimenting with temperatures, but still the same. With 215'C or 230'C feeder still is skipping (maybe more or less regularly but still skipping).

I exluded a issues with printer head blockage, because of this:

 

As you can see - it skipping being free in bowden tube. In this video you can see, that feeder is skipping only going forward. But it happening also when I moving it backwards - not on this video (then only solution is pulling filament with hands with quite force).

I honestly admint - I don't know what to do next. This skipping issue is killing me. And it results with underextrusion and it's baaad.

Guys, I'm looking for your help!

PS.: I printed |roberts| feeder using PLA - I think ABS is better option, but back then I didn't have any spool of ABS. Maybe there is a problem with skipping?

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The little blobby disk in the bowden is likely causing the extra friction making it difficult to move the material forwards or backwards.

In this case, you should actually move the material forwards, cut off the little deformed disk part and THEN rewind the material.

The usual cause of these evil disks is often the PTFE has developed a lip/cavity, or something is not seated flush between the hotend system (brass tube, PTFE and bowden)

How long have you been printing on the Go? it might simply be time to change out the PTFE. I would recommend the new ones from the + if you have a choice.

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My runtime statistics on UM2Go is 350h of printing. But feeder skipping issue starts earlier.

I print for 16h daily, so changing PTFE coupler too often is not an option for me (but maybe it is necessary). I think I got spare parts included in my GO package from distributor.

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My runtime statistics on UM2Go is 350h of printing. But feeder skipping issue starts earlier.

I print for 16h daily, so changing PTFE coupler too often is not an option for me (but maybe it is necessary). I think I got spare parts included in my GO package from distributor.

 

And you're printing in regular PLA?

350 hours is not unheard of to need to change out the PTFE, it depends on a lot of factors like what you're printing, how long and temperature.

There should have been an extra PTFE coupler that came with the machine so I would try to install that first to see if that solves the problem.

There are new couplers now, they last a lot longer so after you wear out your second one, get a TFM coupler.

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PLA only (Innofil).

350 h in only one month. Let's say, GO was busy :)

I started to looking for a good replacement for old PTFE coupler. I found this nice set: http://shop3d.ca/product/ultimaker-tfm-coupler-and-tfm-isolator-bundle/ (I just looked on your profile pic :))

Second option is to buy PTFE rod and make coupler on my own. I have good friends in workshop, so they probably can do it for me. I was thinking about PTFE mixed with coal or fiberglass. I read this type of PTFE will last longer.

But buying this set is also good idea. I have to contact shop3D.ca and eventually order it.

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PLA only (Innofil).

350 h in only one month. Let's say, GO was busy :)

I started to looking for a good replacement for old PTFE coupler. I found this nice set: http://shop3d.ca/product/ultimaker-tfm-coupler-and-tfm-isolator-bundle/ (I just looked on your profile pic :))

Second option is to buy PTFE rod and make coupler on my own. I have good friends in workshop, so they probably can do it for me. I was thinking about PTFE mixed with coal or fiberglass. I read this type of PTFE will last longer.

But buying this set is also good idea. I have to contact shop3D.ca and eventually order it.

 

You are in Poland though? we're in Canada, so you could probably find the part cheaper (shipping) closer to you. But those are the right parts to go with however!

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You are in Poland though? we're in Canada, so you could probably find the part cheaper (shipping) closer to you. But those are the right parts to go with however!

Unfortunately, shops in Europe are out of stock. So you are my only option :) I have just sent you a PM about ordering bundle to Poland.

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Have you looked at www.3dsolex.com ? They have TFT couplers that will last longer then the standard one.

The one that came in your UM2go should be glass reinforced PTFE but these still don't last a long time.

 

This is where I recommend too. But I don't think they're the official UM2+ couplers. I'm not sure of the difference maybe Gr5 Knows. Either way they will be better than the standard PTFE ones.

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Have you inspected your bowden tube for wear and tear? Especially if you're printing on it heavily, you can end up with damage either at the feeder end of your bowden tube, or on the interior of the tube, which would cause significant extrusion issues. The feeder end should be widened out to about 45 degrees, but look clean. If it's chewed up looking you may need to cut a couple millimeters from the end and widen out the end again. You can check for damage on the interior of the tube by removing both ends from the printer and running a clean piece of filament through by hand. If there's damage inside the tube, you'll feel resistance at certain points pushing it through. If that's the case, you'll want to replace your tube.

Also, are there any ground up pieces of filament in the tube? That would impede the filament's progress. If I end up with filament debris in my tube I usually push a little bit of paper towel in one end, and push a piece of filament through. It should gather up and debris and push it out the end so you've got a clean tube again.

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Have you inspected your bowden tube for wear and tear?

Yep, bowden tube is clear, without any debris etc.

Yesterday I changed PTFE coupler, and after few fast prints, skipping is gone and underextrusion issue is no more a problem. Feeder skips sometimes, but it hasn't such a visible impact on my prints.

In the end, I could say that worn PTFE coupler was a reason for skipping, so you we're right. New coupler minimalized skipping significantly, but not completely :) Anyway, I'm happy with the results :)

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