Worn out extruder gear?

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pyronaught
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Re: Worn out extruder gear?

Post by pyronaught » Tue Oct 04, 2016 3:42 pm

I found something else about worn out filament drives that can cause jams when feeding in a new spool. The two holes in the drive that the filament feeds through actually becomes worn and elongated over time as thousands of feet of filament rub the walls. The inherent curvature on the filament caused from being rolled up on a spool results in it pushing against the left wall, since the curve is always in the same direction. Over time as the exit hole gets bigger, the filament no longer exits the hole straight down, but rather off to the left. The images below show what the exit angle looks like for an old drive compared with one that has just been printed. That's a pretty extreme offset! I might try putting a brass tube insert into the holes to prevent wear. Brass is a very low friction metal and you can get tiny precision tubes made from it in a large variety of sizes.

Old drive:
old_drive.jpg

New drive:
new_drive.jpg
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jimc
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Re: Worn out extruder gear?

Post by jimc » Tue Oct 04, 2016 4:31 pm

Damn i have never seen that much wear BUT i dont use abs for my drives. Try printing them in epc.

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sthone
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Re: Worn out extruder gear?

Post by sthone » Tue Oct 04, 2016 5:38 pm

I can see PETG causing that if you run a lot of it as it has those ridges like a file. It's going to depend on the infill used too... I printed one in epc and I don't remember the infill but it must have been rather low because the 45° angle on the filament actually poked right thought the side of the bottom part like a spear. I since print everything at 80% and only use 90° cuts.

I was actually going to mill a filament drive out of aluminum I just never got around to it but the brass tube idea sound like something I might have to incorporate into it if I ever find the time.
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pyronaught
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Re: Worn out extruder gear?

Post by pyronaught » Wed Oct 05, 2016 1:01 am

I did run a big PETG job through it earlier in the year where it was printing 24 hours a day for about a week straight. It's been all PLA since then.

We've got 18 M2s on the team now between various locations (they just bought five more today), so I may just make new filament drives with the funnel mod and brass tube mod and send them out to everyone. Haven't tried ePC yet, this sounds like a good application for it.

I'm working on a filament splicer/winder to help with the mountain of partial spools that has been building up. I get too many print failures by not being there when the spool runs out, so I really need a jig that splices and then winds from one spool onto another in order to make full spools from partials. I can't believe nothing like this currently exists on the market, I'd much rather just buy it than make it.
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ajmadison
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Re: Worn out extruder gear?

Post by ajmadison » Wed Oct 26, 2016 4:42 am

pyronaught wrote: I'm working on a filament splicer/winder to help with the mountain of partial spools that has been building up. I get too many print failures by not being there when the spool runs out, so I really need a jig that splices and then winds from one spool onto another in order to make full spools from partials. I can't believe nothing like this currently exists on the market, I'd much rather just buy it than make it.
There's a splicing jig on thingiverse.

http://www.thingiverse.com/thing:1052283

Believe there are others, but can't comment on one being better than others.

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zemlin
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Re: Worn out extruder gear?

Post by zemlin » Wed Oct 26, 2016 12:21 pm

I keep a couple empty spools around, so if I'm concerned about running out of filament I can tare the scale with an empty spool and then get an accurate weight of what's left on the material spool. That keeps me from starting a print when there isn't enough material on the spool - but I have also considered splicing. I have a cheap hot-knife which would probably do the job.

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pyronaught
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Re: Worn out extruder gear?

Post by pyronaught » Thu Nov 03, 2016 5:21 pm

I'm just running out of places to put these things. I can't use them with the amount remaining because there is not enough to do even one of the large parts I'm making. I noticed PLA gets brittle after about a week in open air too. Not sure if it is just the first layer of filament or if it gets into the whole spool, but I'm wondering if I will even be able to use this stuff. I've lost prints from the filament snapping off in the tube already.
spools1.jpg
spools2.jpg
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jimc
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Re: Worn out extruder gear?

Post by jimc » Thu Nov 03, 2016 5:41 pm

When i run low i just keep printing. When the spool runs out i dont even stop the printer. I just feed the new filament in right behind the old. It just keeps right on printing. I only have a snag maybe 1 in 30 times. As the filament disappears down i to the drive i just stick the new end right in top if it. Just make sure both ends are cut straight with a razor blade.

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sthone
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Re: Worn out extruder gear?

Post by sthone » Thu Nov 03, 2016 6:26 pm

If I've ever seen someone in a need of a filament splicer it's you Pyro. :D

Chasing filament works great I hardly ever retract filaments back out any more it only leads to more problems for me. The only down side is you have to be there to catch it if it's in the middle of a print. This comes in handy for making sure the cuts are straight though if your going to try chasing the spool swaps.

I've miss a few swaps and it sucks to have to start a print all over. I just ordered a spare heater cartridge yesterday to try and make a filament splicer. I'll post my results if I actually get one to work.

Edit - Jules did a great write up on swapping.
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jimc
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Re: Worn out extruder gear?

Post by jimc » Thu Nov 03, 2016 6:45 pm

yes you have to be there of course, BUT if you know your going to leave and not be around then before you go just cut the filament off where you are at, feed a new spool in then continue on with what is left another time.

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