Hot End Isolator Coupler

[printerfan 5]

Is the hot end isolator coupler of the UMO a consumable?

I've been having issues with underextrusion and noticed filament grinding, so I was wondering if the isolator coupler could have become deformed and is causing underextrusion and back pressure on the extruder motor. (though I only print PLA and only go above 210C to remove clogs using a modified atomic method).

[neotko 1,389]

Indeed it is. 50-200 print hours should be enough to wear it down, deforming it or just burning it down due heat.

TFM is the plastic used on the um2+ and is available for UMO on 3dsolex resellers, it should give you much print hours. Ofc the standard PTFE glass filled coupler is sold by any UM reseller.

If you remove it inspect it you should be able to see if is done for good or is the bowden moving out from the clip, feeder needing a metal brush cleaning or other possible issue.

[printerfan 5]

I'm trying to systematically work through all the issues that could be causing the underextrusion and the bowden tube is also on the list... However, I've definitely hit at least 50 hours of printing.

When I disassemble the hotend, will the isolator coupler look burnt and deformed if its ready to be replaced?

What is the difference between TFM coupler and PTFE? Which do you recommend I purchase?

How can I visually tell if the bowden tube needs to be replaced?

[neotko 1,389]

TFM is a material that's alike PTFE but that last longer (doesn't deform at 250C+) (but your peek can, so don't print at more than 250-255). So... umm Yea, TFM is a better material, google 3dsolex umo coupler, probably some of the many 3dsolex resellers can link to their shop.

The tip, the part touching the brass barrel, should look like this (more or less, since this an image of a um2 coupler)

Bowden should be ok if you only printer 50h I think. Just check everything is tight and well inserted (inside the coupler). Check that the bowden doesn't move out/in if you pull it a bit (don't force it since there's no need).

[printerfan 5]

Well, I've printed at LEAST 50 hours since I replaced the entire hotend including the coupler. I bought the printer used, so I do not know how many hours were on it before I bought it and I myself had put on prob 100 hours before replacing the hotend. As for the temperature, I don't think the control settings let me go above 250C nozzle temp.

The bowden has been with me since I bought it and who knows how many hours the previous owner put on it. Debating on buying a new bowden, but the official tube is ridiculously overpriced. I've seen posts of others recommending different brand of bowden, but what length is ideal?

[neotko 1,389]

Why you replaced the whole hotend? The only prt that should be replaced is the coupler, unless something broke while changing nozzles or something alike it should be fine. And I really doubt a bowden can't last a good year of print time.

[printerfan 5]

I replaced the entire hotend because I was desperate to get my printer working properly. I've had issues with my UMO since I bought it. Even now I'm having significant underextrusion and I can't figure out why. I tried loosening the screw on the extruder driver (bc I noticed filament grinding), it did not resolve the issue, so I tightened it and its still underextruding. I'm printing at 50m/s, so I'm not printing too fast.

Maybe the coupler is deformed, but just seems like its too new to be deformed especially considering I have only been printing PLA with it.

As for the bowden, I assume its the factory bowden, which the previous owner had been using since 2013-2014, so it could be as old as 3-4 years. Also, should I be using the blue clip on the coupling where the bowden attaches to the exdruder drive?