MMU Nextruder mod tension screws
Goodday,
I installed an MMU3 on my core one.
Since the beginning i have trouble with the tension screws. Somehow the bite/scratch in the aluminum heatbreak.
At first i printed an other screw holder (right after the screwshead) that was shaved off 1 or 1.5mm. Because this holder was rubbing so hard the tensioner would not come back to its original poistion.
I added 0.1mm shims to avoid the heads being pulled in the plastic thingy because of temps. (other problem)
Today i check after a few mmu prints and there is a lot of metal shavings on the heatbreak.
When i undo the tensioner or bolts everything seem to run fine. I always press the bolt when i open tensioner and they seem to move freely.
Now i have altered the bolt threads so they don't act like an jigsay in the holes.
Now it is really smooth but....
this is not normal right??
RE: MMU Nextruder mod tension screws
I would say yes, not normal. I have the CORE One (assembled) with MMU3 (kit) and see no issues like this.
this is not normal right??
RE: MMU Nextruder mod tension screws
Maybe my tensioner arm is too short?
So the bolts are not in line with the holes?
RE: MMU Nextruder mod tension screws
I am sorry, i mean the swivel should be pointing up. Mine is pointing down
RE: MMU Nextruder mod tension screws
It's unclear which metal parts the two tension screws could come into contact with.
In your case, I recommend completely disassembling the Nextruder into its individual parts.
This will also determine which part is causing the metal abrasion.
Then reassemble strictly according to the assembly instructions
https://help.prusa3d.com/de/guide/9d-core-one-nextruder-mod_111779
It's important to use the MMU version of the main plate! (I've made that mistake before, too).
RE:
Yes.
I think i reprint the parts. Maybe there is something dimensional off.
In the idler fs (magnet thing) maybe the screws are to tight together. I have one new from prusa in the packaging which i ordered earlier.
I did not bought this set new in box so maybe the previous guy printed the parts himself.
I have the black mjf mainplate tough.
Anyway. I ordered some m3x50 screws. I will cut them to exact length.
I really dont like threads going in and out off holes all delay long. It is just not right.
I did this mod on the mmu3 tensioner screws to. So the thread are not scraping on the idler body. This way tension is always correct en there is no scraping or binding whatsoever.
I dont modify the original screws btw. I keep the originalsin a seperate printer/mmu bags.
RE: MMU Nextruder mod tension screws
The metal wear can only be explained by the screws rubbing against the heatsink holes.
But there's actually enough play in the screws' holes, unless there's a misalignment.
Can you see from the holes which side the wear is on?
The idler nut is hollow, except for the part into which the screws are screwed.
And the screw guide provides the clearance to the gearbox.
So there's no risk of resistance from those parts.
Did you use the "new" longer screws (M3x35)?
The Mainplate has to lie flat on the heatsink, or is there a small gap between them ?
This mainplate !!!
RE:
I don't know. I use thew MJF printed plated.
The front screw is tilted a little downward.
This is the holes with the idler nut fs in front of it. It seems correct. An new idler nut fs measures exact the same distance and hole places with an caliper.
It seems the front hole is scuffed on the downside right and upside on the left (swivel side)
Because of all this it made this mess in ~1200 toolchanges
I also have an clicking sound. It seems the filament is retracted by the extruder motor then, ratatatatata for 1, 2 second before mmu decides to pull filament out.
Is this value fixed? or is it depending on the idler fs hall sensor? So when filament is unloaded and sensor noticed it the mmu unloads it furter?
I would like to alter this value becasue retraction is way to long now.
Is it somewhere here?:
Seems ok:
OK:
Normal screw guide:
Shaved off screw guide for clearance on top of heatbreak:
Anyway i am gonna place the cut m3x50mm or m3x45mm screws. The unthreaded part is 31 or 27mm. Maybe print an other size screw guid to get exact same length as the m3x35mm's.
So the bolt is round and smooth all the way through the holes. I am not gonna let this eat my heatbreak away.
