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PIB polybenzimidazole Isolator Coupler

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10 hours ago, meduza said:

I have a early generation I2K somewhere, i took it out because of too many feeding problems with PLA where it increased the feeding pressure quite a bit compared to the stock PTFE. PLA does stick a bit too well to PI for it being a one-stop solution for printing if you ever want to use PLA.



I think this is an issue I am having, I have underextrusion issues lately and well posssible that this is the actual reason. Can't tell if the underextrusion happens mainly with PLA, but I am printing PLA 75% of the time. Though it was the nozzles in service for longer, but I should try to remove the I2Ks.
The any other material than PTFE doesn't make sense if this is the only one PLA doesn't stick to. So in this case rather accept the wear than have underextrusion...

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You won't find many materials that molten PLA sticks to as little as PTFE (TFM is a modified PTFE), since it is one of the most non-stick materials known to man, and it also has some of the best high-temperature properties.

The reason for hunting other materials is mostly about not having the wear problems that PTFE experiences. To be honest though, as long as you are printing sub-250C materials, the TFM + rigid spacer that was introduced with the UM2+ lasts so long that i honestly don't see this as a problem anymore. The old PTFE + spring could deteriorate in just a few hundred hours, but the TFM is in the multiple thousands of hours range, mine last one was swapped after 2000 hours (even if it would have worked for quite a bit more time) and i really beat that coupler with running some high-temp filaments at up to 275C for a few hundred hours, and bunch of kilos of abrasive filaments, i have seen couplers doing 5k+ hours and still being totally fine.

But if you want to go for 280C+ printing with the UM2+, you do need to look for replacement materials since the PTFE/TFM will be degrading pretty fast, but getting the same performance with PLA as with PTFE will be very hard. PBI seems like the best alternative, but it is still not as slippery as PTFE/TFM, and it is also very costly, both the material and the machining. To make a commercial PBI coupler, it would probably have to sell for at least 100€.

I believe that the best solution for higher temperature printing is a hybrid style hotend like the UM3 Print Core, where it is TFM lined to just above a very short and sharp metal heat break, that makes sure the TFM does not get hotter than 100C or so, where it basically will last forever (there is of course other factors that also affects the wear, but the thermal degradation and compression effect goes away)

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That makes sense! Thanks for your exhaustive input.
I have not too much need to print beyond 250/260 degrees currently. It would not be worth on compromising on the non-stickiness.
I was just looking for something universal that would cover higher temperatures and last long. But it seems the TFM / PTFE is already a reasonable compromise. So I think I'll remove the I2Ks and otherwise stay with the TFM/PTFE couplers.

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15 hours ago, ataraxis said:

Oh man, that's really sad... I was really impressed of his creative drive.
But to be honest: I do not really understand why they have deleted his designs - they would have been some kind of legacy to his community in my eyes.


I have 2 new versions that work better than his old design. We developed a holder behind the bed (like skis) that keep the weight distribution better. Gudo also on his last version of the gudoXYCore made a new bed stabilizer that mixed my skis design with a compensation system. I will dig into his step files and try to come with a version to publish.

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5 minutes ago, ataraxis said:

Hey neotko, thanks you very much for that! I am owning an UMO, therefore I will have to modify it a bit anyway I guess ?


Most probably, specially because umo+/um2 use square flanged bearings and the aluminum has holes where we screw to to distribute the tension. But nothing too hard to adapt for yours

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