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kitwashere

UM1 Can only get a certain amount of correctly extruded filament

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So I've been frustrated with my UM1 for some time now.

 

Smaller parts seem to print okay, but anything relatively large will print the first few layers fine and then start heavily under extruding.

 

All of this is on V1 everything, hotend and feeder (which I would love to change but I can't print anything worth while! Have an UBIS hotend sitting right next to me and all of the vitamins for this feeder http://www.tridimake.com/2013/04/rollerstruder-filament-feeder-driver.html)

 

I did manage to get Bertho's bearing feeder thing (http://www.thingiverse.com/thing:26094) printed so I've got that going for me. I am pretty sure the feeder is at fault here. The filament is always chewed to all hell. I've tried light pressure on the spring holding the bearing to the filament, up to almost fingers bleeding tight.

 

Any help solving my issue is greatly appreciated. I actually checked Ponoko to price out having that feeder printed for me! That is how frustrated I am with this thing.

 

IMG_20140511_123020.jpg

 

IMG_20140511_123052.jpg

 

IMG_20140511_123124.jpg

 

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Have you checked that you don't have a partial bowden pop? If you do, that could be one possible explanation to why it works ok at first but then starts messing up later as more and more heat is transported upwards and makes the plastic at the junction point gooey.

Could also be worth checking for a partial clog in the nozzle.

Would also be an idea to check the temperature readings during the print. Perhaps there's a perfect storm of glitches that makes the temperature reading go wonky at some point causing underextrusion.

That said I had a somewhat similar issue with my printer way back. The first 1-1.5mm of print was always fine but after that it underextruded slightly. No matter what I did or what parts I replaced it just kept happening. Never figured that one out...

 

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The bowden seems really solid at the push-fit connector at the hot end, and I've never noticed it moving on either end. This all happens on parts with no retraction as well so I don't think it's that. Any certain way to test this you can think of?

In the printing wizard in Cura the graph with the temperatures seems very stable, I'll grab a screenshot next time I give it another try.

I have disassembled the hotend recently and found no faults there, but I'll check it again and see is anythings funky.

When I read this out loud it seems the problem would have to be at the hotend though. The filament gets all chewed up so the feeder is trying. Maybe I'll try zip-tying my UBIS in there and see if I get any improvements.

Thanks for the suggestions

 

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yes, upgrade to the latest version, especially hot end. feeder can be printed afterwards. I have a very similar issue with my UM1 just at the moment. Check @ http://umforum.ultimaker.com/index.php?/topic/5227-problems-extruding/.

I am sure that on mine it's the teflon coupler. So take it out and inspect it carefully. Do not rip it out with pliers, be gentle. Hope you can resolve this soon. hte pice is rather easy to replace and rather ok with regards to price... 15€. I will test it in the coming days once the replacement arrives.

 

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Well Cura prints the first layer slower by default and then slowly speeds up over 3 or 5 layers to "full" speed. So keep the speed the same and that should help. Also keep the fan off maybe. This will reduce quality but it will be good enough to print some replacement feeder and such.

Also I recommend printing hotter. Try 240C. That's around the hottest temp you want to print at but should be okay. That way you need much less pressure from the feeder.

These 3 things (less fan, more heat, print slower) all are for the same purpose - less force needed to print.

Another thing you can do is this test here (even though it was done on a UM2, it is perfectly applicable here):

http://umforum.ultimaker.com/index.php?/topic/4222-pulling-force-of-um-extruder/

You can play with this test with different spring tensions. Measure the compressed length of the spring or position of the screw or whatever it is that adjusts tension and compare that to how much weight the feeder can pull before the filament gets chewed up and stops moving.

 

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So I tried with no fan and still got the same results, tried again making a kapton tape "duct" to make sure air doesn't get blown on the nozzle and got the same again. This was all last night, today i'll take apart the hotend again, check for plugs and try again with a super slow speed (been doing all of this on the default 50mm/s) and up the temperature (been at 210 or 220 during these attempts)

@gr5

I know I have a postage scale lying around somewhere, if I can dig that up I will give that test a try.

And that is very generous of you! I haven't been up to Boston since I was a kid, might take you up on that. Filament, lunch, and beer on me of course :)

@everyone saying to buy from UM

The base price for the parts is extremely high and with the shipping to the US it makes it unreasonable.

From what i can tell the major improvement made on the hotend is the teflon piece, no? If it comes to it, maybe I can hack something together with some teflon tubing from McMaster.

Thanks to all, wish me luck

 

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So after a lot of messing around with settings, I am actually getting usable prints at the moment! Very exciting! 260C with the fan on at 25mm/s takes forever but gives me decent results, a little blobbing but nothing some elbow grease can't take care of. Maybe my thermocouple is out of adjustment or something because 260 seems very high for PLA but whatever, it works.

I am getting random connection loss between the printer and my PC, but this seems to be a somewhat common problem with printing over USB. Placed an order for some parts to make a controller to sort that out hopefully.

Thanks to everyone who posted, I finally feel like I own a 3D printer instead of a very expensive, smelly box (tung oil takes some time for the stench to wear off)

I was trying to turn an old GameBoy into a controller for the thing, and also had plans to make a filament "pre-heater" to try and reduce friction in the bowden tube, and I've got some motivation to pick those up again!

Ubis Mount (First decent print!)

 

Thanks again to everyone!

 

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