How much play is normal in the bearing of the extruder burred gear?

[gdog 4]

Servicing one today that was a mess.  It had been serviced before (as the adjustment screw was on top of the housing due to incorrect reassemble) but the fact is it was grinding filament and I expect fixing the tensioner adjustment screw will help but it still seemed to have a lot of slop in the bearing.  Like almost 0.5 mm of play side-to-side. 

 

EDIT:  ***  JUST TO ADD, I assume this is the original gear, and the machine has about 2800 print hours on it  / 2400 ft of material extruded.  So would that be still inside the normal service life on the original extruder assembly?

 

Also, is it possible to save the burred gear and just replace the bearing?  It doesn't look particularly serviceable but you never know... 

 

 

Edited January 28, 2022 by gdog

[gr5 2,173]

So you are talking about the 2 gears in the UM2+ feeder?  I believe 0.5mm of play is too much.  Not sure.

 

@fbrc8-erin - what do you think?  Does he need new feeder gears?  (his profile says he has a UM2+ ext).

 

 

As far as 2800 hours and 2400 meters of filamnt - it's common for those numbers to be similar - that's a lot but we've seen printers hit 10,000 meters.  You might want to change the belts now.  Definitely change the teflon part if you haven't done that (the teflon part in the head - the white part.  Called sometimes an "isolator" I think?)  That should be changed every 500-1000 hours.

[gdog 4]

I just rebuilt the head / hot end - new block, isolator, teflon thing + nozzle.  With that done, attempted to get a test print out. (This machine was a salvage project).  The first go was a fail - the material failed to load and instead a very nice crecent was chewed in my filament as soon as it got to the print head.  So I'm thinking, "Yeah, that extruder is worn out", but then I inspect and the teeth marks in the strand up to the crecent look Goldilocks, so I try again.  This time, I disconnected the gear with the release lever and push manually through the extruder till material was coming out.  At that point, I reingage the gear, and it worked fine.  Did the mini-cal test print.  The bottom layers came out beautifully.  But at the first infill stages, it got ugly like blobby and stringy.  I ended up slowing down to 50% print speed and it seemed to help.  But when I tried to remove from the print bed, the thing broke on those first few infill layers. 

 

Good news - the circles and shapes pretty much came out prefect - there was no x-y shift or x/y belt/motor skipping which is what the person who gave away the machine was complaining about.  I am going to post some pictures in a bit.  I am thinking basically that the failure to load had something to do with the Bowden tube, but I'm not sure.  It seems like maybe the filament was getting stuck on the lip of the teflon thingy after exiting the bowden, but I assure you I use all the force appropriate to cram that bowden tube all the way down in the print head. 

 

EDIT - ADD PICTURES (1) chewed filament that failed to enter nozzle on "change filament"... got hung up and just litterally chewed a bit out of it in <1 second. (2)   MINI-CAL (broken)

Edited January 29, 2022 by gdog

[gr5 2,173]

I haven't used the "insert filament" option on my UM2 printers in years.  I always slide it in manually.  That feature is only needed for the original "non plus" feeders.

 

Always cut the filament to a point.  Two cuts should do it.  Not at 45 degrees but much steeper angle.  That will help the filament find the hole in the teflon.

 

[fbrc8-erin 272]

Could we see photos of what you're seeing on the gear?