Is there any negative effect if I enlarge the internal diameter of the PTEE isolater coupler?

[Lofrank 1]

I have some really 3.0 mm (or maybe 3.11 mm) filaments which always jam in the PTEE isolater coupler.

So I want to enlarge the internal diameter of the PTEE isolater coupler from 3.2mm to 3.5mm or even bigger.

Is there any negative effect if I do this?

For example, whether the printing accuracy will be affected?

Thanks.

[IRobertI 516]

Don't do that. The nozzle+heaterblock entrance is 3.2mm so if you enlarge the PTFE, the plastic will be allowed to swell out to be too thick and jam because of that instead.

It's strange that it's so difficult for you to get 2.85mm filament over there in China since sooo much stuff is produced there.

[Lofrank 1]

I only plan to enlarge the internal diameter, keep the external diameter unchanged, which will make the plastic thinner, so won't jam?

In fact, I get a spool of 2.85mm filament yesterday from the sole seller (who sells 2.85mm filament ), but the quality seems not good enough, because I get jam in the PTEE isolater coupler 4 times. Each time I have to move the coupler out and clean it.

I'm sad to say this but it's truth that many things are made in China, but not sold in China, we have to buy from foreign countries.

You said that so much stuff is produced here, could you give some examples? So may be helpful for me to get 2.85mm filament.

Thank you for your help, as always.

[IRobertI 516]

I stole this image from kris:

If you enlarge the inner diameter of the PTFE, the filament will expand into that new diameter (it can get quite soft higher up in the system) and cause issues. One thing I didn't consider is that it will likely get caught at the bowden entrance as well.

I meant that a lot of stuff gets produced there in general, not specifically filament. I'm sorry, but I don't know of a source for filament in China. The filament I use mainly is produced here in Europe.

[Lofrank 1]

@IRobertI

Thanks for your detailed description, it's likely to be happen.

Anyhow I still will try it since I already placed an order for a new PTFE (who's inner diameter is 3.5mm - 4.0mm) this morning

Thanks again.

[phut 0]

It's strange that it's so difficult for you to get 2.85mm filament over there in China since sooo much stuff is produced there.

 

If you look at the history behind it, not at all.

In the early days of 3d printing, the community normed on '3mm' as the nominal reference to the larger filament size beside '1.75mm', and that stuck as the nominal size to the detriment to practical application in bowden based feed mechanisms.

Whereas 1.75mm had more decimal places from the start as well as printer manufacturers that moved rapidly in the 'early days' to exert global influence to make it a de-facto standard the way it worked best for them.

Manufacturers were told to make 3mm filament. And so they tooled up to do so - without knowing the caveats in practical application that the 0.15mm difference makes.

There does seem to be a slow collapse of 3mm nominal market as the standing opinion is that '1.75mm machines perform better'. Certainly as UM owners we know that the contribution of the feedstock diameter to overall print quality is SFA compared to other areas the UM holds advantages in over other printers in the market segment the UM lives in.

I'm just not sure the '2.85mm' market will come to rise to replace it, since 1.75 is now such a well established standard. With feedstock making a substantial proportion of TCO (especially on a relatively reliable printer, like the ones UM make), UM Brand has its work cut out for it in the coming years to maintain supply chain for their filament diameter of choice.

Meanwhile my modified UMO is run on historically available in my region 3mm nominal feedstock achieving perhaps 95% of the total quality one might be able to if I ran 2.85mm feedstock with optimised hardware.