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kvones

UM+ material feeder falls apart

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Hello,

I have just finished building my UM+ and have encountered a weird problem while doing first test prints. After each 5 or so prints, the material feeder literally falls apart - the big metal nut on the end comes off, and then the gear wheel falls off, stopping extrusion. Is this something that 'just happens' or did I make a mistake somewhere putting it together? So far I have fixed it by just screwing the gear back on and fastening the nut but it keeps happening....

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do you have a photo of your assembly - has not happened to me on either of my machines in years of running.

Do you have a washer between the nut and the cog?

I only put them on hand tight - so that is not the issue.

The whole assembly (plus nut) should be spinning with the retractions.

Worth just checking that your stepper motor is parallel with the cog so that it is not driving it off axes - check that they are not too tight - or you can get binding and I guess an off centre drive - so pull the stepper slightly away, they don't need to be tight.

 

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It sounds like you don't have the locking part in place. There is a little black plastic piece that looks like a bone with a C on one side. This is suppose to clamp onto the knurled bolt after it's been inserted into the extruder. There's a slot for this on the opposite side of the gear.

This prevents the whole gear/knurled bolt assembly from winding it's way out. You might have missed that part in the instructions.

*edit* found the picture:

UM-parts_46.png

Make sure the black plastic piece is clipped onto the bolt. See the slot on the right of the knurling?

 

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I got the same problem last week just after finishing the assembly. I don't know if I was right since I am just newbie to this printer.

I noticed that even the bolt v.s. screw were tightened, if you spin the gear backward, it will unscrew the screw. So then I tighten everything, remember to put the black plastic into the gap, and then don't dial back the gear even a little bit. You should be fine for printing.

 

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I will take a photo of my assembly to post. I have used the black c bone piece on the end groove of the knurled bolt as per instructions. How tight should this piece be between the feeder and bolt? If I screw the feeder wheel on I can adjust it so it's either quite tight or looser, but it doesn't seem to make much difference. It just works its way out after a few prints, especially ones with lots of retraction. I have used the two slightly fatter washers inside the assembly, and then the slightly thinner washer on the end before the nut. However, I have also tried leaving the washer off, to give the nut more screw space. Currently using it without the last washer. The nut definitely turns with the feeder gear, I have tested for that.

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I noticed that even the bolt v.s. screw were tightened, if you spin the gear backward, it will unscrew the screw.

 

Then it is not tight enough...

When your assembly is correctly done, pull out the C clip, then the axis and use a wrench to tight the 'end-bolt' on the gear. I would even recommend to put some thread-lock before tightening.

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Hmm, the feeder continues to work itself apart when I print, even when I tighten everything as much as I dare. This is really getting a bit annoying - after a long print, I basically have to take the nut off, screw the gear back in and put the nut back. On the up, I am getting great prints :-P

 

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After reading about this with others I realized I really just needed to hold the gear (and it's cover) tight and tighten down the nut...I did this a couple times after letting it run for a bit and now this problem seems resolved for me. If not I'll put some loc-tite on it but for now I think I'm in good shape.

 

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This image might help in explaining:

http://wiki.ultimaker.com/File:Bolt_assy_v3bolt.png

I had this same problem 3 years ago when building my first machine. I recommend taking out the bolt. Screwing on the nut quite far, put 1 ring on it, put the capnut on it. Screw the capnut tight against the bolt.

Now screw the nut back, until it clamps the ring. Take 2 wrenches, and screw the nut and the capnut together as tight as you can. Did this 3 year ago, still going strong today.

 

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