M2 nightmare with soft filiment

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airscapes
Posts: 219
Joined: Wed Jan 31, 2018 11:36 pm

Re: M2 nightmare with soft filiment

Post by airscapes » Mon Jul 02, 2018 3:41 pm

I have given up on the grooved sleeve. I guess the printed version was not consistent enough as the groves in the filament from the drive were not consistent and I assume this was due the sleeve being plastic and not perfectly round? I was also testing with PETG and PLA not soft filament.
I know I can print with soft if I get the tension correct and print very slow as has been said by others. So I switched gears and created a Dial indicator so I can adjust the tension for a new filament, write the number on the roll and next time I use that roll there is no guessing or testing time wasted.
viewtopic.php?f=10&t=6748

Gwhite
Posts: 197
Joined: Tue Jul 11, 2017 3:38 pm

Re: M2 nightmare with soft filiment

Post by Gwhite » Tue Jul 17, 2018 12:26 am

I machined an aluminum grooved sleeve using the drawing I posted earlier.
Sleeved Bearing in Drive.jpg
It pressed onto the bearing very nicely, but when I installed it in my worn out factory housing, it wouldn't turn. I recently converted the factory SLT into a Fusion 360 solid model, and when I checked it, I discovered a gotcha. The clearance around the bearing in MOST places is 18 mm in diameter, but at the bottom of the cutout on the "inboard" side, it is down to just under 17 mm, which is the diameter of my sleeve.
Sleeved Bearing Fit in Factory Drive.jpg
Sleeved Bearing Contact Location 2.jpg
You need a little extra clearance to allow the bearing to squeeze the filament, so I don't think you can use this approach with the factory drive housing. You would have to reduce the OD of the sleeve, which would probably reduce the depth of the groove too much.

You might be able to get into the appropriate spot with a needle file to clear out the interference, but it's in a very awkward location. It's probably easier just to print a drive with proper clearance. I have been planning on using sthone's hinged design anyway, so modifying the clearance there (if it needs it) will be fairly straightforward.

jferguson
Posts: 133
Joined: Mon Mar 30, 2015 7:26 pm

Re: M2 nightmare with soft filiment

Post by jferguson » Tue Jul 17, 2018 1:01 am

Gwhite,
That is really slick. How well does it work?

Gwhite
Posts: 197
Joined: Tue Jul 11, 2017 3:38 pm

Re: M2 nightmare with soft filiment

Post by Gwhite » Tue Jul 17, 2018 1:55 am

It doesn't (yet...). I will need to print a new filament drive housing with appropriate clearance so the sleeve/bearing can rotate freely. I plan on using black ePC, but I want to finish at least a few sides of my enclosure to help maintain the high temperatures required.

No one has responded to my query about black ePC printer settings, so I expect a period of experimentation until I get that process dialed in. It's very humid here this time of year, and although I have a dehumidifier that keeps my shop at around 40% RH, I don't want to open up the sealed ePC package until everything is ready to go.

I've already modified the factory drive design to fix the clearance issue.

airscapes
Posts: 219
Joined: Wed Jan 31, 2018 11:36 pm

Re: M2 nightmare with soft filiment

Post by airscapes » Tue Jul 17, 2018 4:11 am

When experimenting with my PETG printed sleeve I used a dremil with a tiny round bit and needle file to adjust the oem drive housing.. Hopefully metal will work better that a plastic sleeve.
Good luck and keep us posted

Gwhite
Posts: 197
Joined: Tue Jul 11, 2017 3:38 pm

Re: M2 nightmare with soft filiment

Post by Gwhite » Sun Jul 29, 2018 12:08 am

I've modified the factory drive model to give the added clearance required for the grooved sleeved bearing, and printed one up in PETG. The sleeve & bearing combo now spins freely until you really crank on the tension screw, far more than normal.

The next time I change filament, I'll swap this drive in. I don't expect it to make any noticeable difference immediately, but with normal filament, the drive should last much longer by keeping the filament confined to a straighter path. I don't have any plans to work with more flexible stuff any time soon, but it should help a lot with that as well. Here's a photo of the new drive with the sleeve/bearing installed:
Filament drive w Grooved Bearing Sleeve.jpg
It was hard to get a clear photo with good contrast between between the black PETG and the shiny aluminum sleeve. I put a short scrap of filament in so you can see how it lines up with the groove in the sleeve.

Gwhite
Posts: 197
Joined: Tue Jul 11, 2017 3:38 pm

Re: M2 nightmare with soft filiment

Post by Gwhite » Fri Sep 14, 2018 10:38 pm

Quick update: I installed the filament drive with the grooved sleeve today when it was time to install a new roll of filament. I've been slowly using up a spool of PETG on various small prototypes, and have been tied up a lot on the CAD end of things, which is why it's taken so long.

The drive installed normally, and I got the roller pressure making nice gear grooves in the PLA I'm running now. Basically, swapping it in was a non-event (so far).

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