Extruder pressure bearing screw loosens during print
Hello all,
I'm new to the 3D Printing world...purchased a triple head 3D Touch a few weeks ago. Thus far, I've been pleased. I'm using SolidWorks to create all my STL files with and have had great success.
I've had a couple of problems (I'll save the other for a ticket or another thread). My configuration is Head 1: PLA Black, Head 2: ABS White, Head 3: PLA Clear. I've been printing with PLA as part, and ABS as support/raft. My problem is, if I have a part that takes more than 3 hours to print, the pressure bearing screw will loosen to the point of no longer feeding the filament through. The result, of course, is my printer happily printing for the remaining hours with nothing there, and support material spewing all over the place since there is no part to attach to.
(Side note for BFB: a rotary encoder wheel would be fantastic for the 3D Touch--could pause the build to indicate a filimant failure or in my particular issue, a pressure bearing issue, so the part didn't have to restart).
Anyway, has anyone else experienced this? Is there a workaround? a fix?
Thanks in advance!
Sounds like it should work--I'm just wondering if there's something else going on...am I missing a piece? I just got this unit less than 5 weeks ago, and if I don't tighten this screw mid-print every 2 hours or so, I'm going to get a failed part. It seems like this shouldn't be happening on a brand new unit.
Other thoughts?
Thanks.
Not really. Do all 3 pressure roller assemblies match? It is interesting that your assembly that loosens is the PLA. I'm on a 2 Ex machine and Ex2, where the PLA is, is the one that used to loosen.
Not sure how I would check to see if they match...they all appear to be the same, and the unit was shipped as a triple head unit, so I would assume so.
One thing I've noticed is that it tends to loosen more when I'm printing a gear rack...perhaps due to the high level of vibration caused by jolting back and forth for the teeth?
I use PLA as my primary part material, haven't had much luck with ABS, so it remains my raft/support.
Thanks for the input.
> Not sure how I would check to see if they match...they all appear to be the same, and the unit was shipped as a triple head unit, so I would assume so.
Can't really assume anything. Mistakes happen. Do all three pressure bearing assemblies have the same parts?
> One thing I've noticed is that it tends to loosen more when I'm printing a gear rack...perhaps due to the high level of vibration caused by jolting back and forth for the teeth?
That and lots of de-string, where the filament is retracted into the extruder while traversing to a new location, will do it. Watch the extruders while printing and you'll see that there is significant oscillation of the pressure rollers when reverse is applied. WIthout any sort of locking mechanism to keep the cap screws fixed to the pressure assemblies as they wiggle, the cap screw backs out a little bit each time, due to this peridoic twisting, and the pressure is lost. Filament stripping follows and your printer is printing on air.
I have the same problem with my 3D Touch. The No. 1 extruder pressure bearing screw loosens about 1/4 turn every 12 hours. I am using PLA in the #1 extruder but I do not think that that has anything to do with this problem. I believe that it is a frequency resonance problem causing CCW forces on the screw. I removed the screw and found the threads to be coated with light oil, probably from the original assembly process. This oil may enhance screw back-off forces. Left handed threads would probably be the ultimate fix but removing the oil film and applying a drop of Loctite thread locking compound would probably slow down or even stop the process. Hope this helps.
Same issue here on my 3dt
My makerbot cupcake was notorius with this problem and it got 5x worse on makerbot thingomatic. The problem is the filament reversal (what you BFB guys call destringing).....over time loosens the bolt. I notice the oil all over my bolt as well. I will try removing it and adding the lockwasher suggested by penske guy.
W
FOUND THE SOLUTION!!
http://www.vibra-tite.com/vc3.php
This stuff is amazing. It's like applying your own lock-tite, but it is resuable. It will withstand numerous removals and still maintain its locking attributes. I ordered a small tube of this stuff and it is amazing!!!
I was going to post the classic 'warning', to not use any form of Loctite type compound near acrylics (causes surface weakening). However I'm not sure about this. MEK, should be alright, and you can (of course) put it on the nut, and let it dry before going near the plastic. May well be worth remembering as a useful anti vibration compound for other parts of the machine. :)
Best Wishes
> I have the same problem with my 3D Touch. The No. 1 extruder pressure bearing screw loosens about 1/4 turn every 12 hours. I am using PLA in the #1 extruder but I do not think that that has anything to do with this problem.
Interesting correlation, here, is that only my Ext2 screw backs out and that is the one running PLA. The simple application of the star washer cured it, with no contamination possibilities. A split washer wouldn't work as well, as they are dependent upon increased pressure to work. You would then have two springs working against each other and the adjustment of the pressure on the filament wouldn't be as positive. A star washer, with its barbs, doesn't compress but provides increased friction on the cap screw head. For that matter, a rubber washer would work. Anything that is not slippery would prevent the nudging of the screw through incremental oscillations of the rollers during de-string.
I had this on my 3DT, only on Ex2, for whatever reason. I put a star lockwasher under the cap screw head and it provides enough friction to maintain the setting.