Um2 hotend design questions

[LePaul]

Oh that's the worst spending so much time debugging instead of printing

I noticed a few posters saying they have the Bondtech feeder and it works well for them

[Neotko]

Yea I think it's a good solution if you want a more assured grip on each filament movement. This mk7 that I don't trust has the tendency of slipping just barely enough to cause a bit more blops. Ofc um2 diamond shaped has much more grip but also for 1.75 it flattens the filament way too fast.

I see this issues because when you make 3d fonts with a 0.4 nozzle and you simulate 0.33 nozzle, if even one filament move isn't perfect I get a very visible error.

Good think also my other 2 umo+ do work. But the quality on the umo+ hotend it's slightly worse.

With a double (and grooved) feeder the precision should increase since it actually has more grip on filament at any given time.

Anyhow I don't really need the planetary gear and they have a kit for nema 17 5mm for 50€ or so. But that would mean that I need to design a feeder + holder = more time lost on prints & tests.

[Dim3nsioneer]

The I2K might have a serious impact on temperature distribution inside the hotend as it blocks heat transfer to the teflon. Have you tried with the I2K at a bit lower temperature to get the gloss back?

[Izzy]

I think neotko had a slightly stressful day
Our thoughts are with you at this difficult time
na bugger that, more coffee, more coffee,
I did find with my I2K I was not getting correct feed at the start or a print, I gently increased the bore diameter to the same as the PTFE spacer and it is now better.
I know many would love to be able to print PLA at 75+mm/s with a 0.2 mm layer height and a 0.4mm nozzle, but we have to obey the physics. I get my best results at 45mm/s, 0.1layer height on a 0.4 nozzle, "slowly slowly catchier monkey"
But this is still quicker and better quality than a lot of other printers.

[Neotko]

The I2K might have a serious impact on temperature distribution inside the hotend as it blocks heat transfer to the teflon. Have you tried with the I2K at a bit lower temperature to get the gloss back?

It really seems like it.

I just forgot... The I2K I had previously was a thinner 0.5-0.7mm.

With the thinner I2K I had less problems and more prints.

@Izzy I really print at that speeds all my stuff for my shop sugarpop-store.com like all the time. That's why I changed all my machines to misumi shafts with gt2 belts to keep printing fast with ok quality. That and with some s3d tricks I can print really nice without visible problems (but a 3D printer would notice micro errors). Also that's why I prefer 1.75 because it needs less heat to print.

The other um2 hotend it's working really nice since I installed it. And this other also has the I2K that's why I tryed to repeat the very same setup. Ofc on this other um2 hotend that made me loose 4 days the main problem it's the feeder but also the I2K.

And yeah @izzy I need a break. This error debugging was a freaking nightmare.

[Neotko]

Well. Been doing today that I had sometime to spare, more test with & without the I2K. But this time on a more steady and calm way, because last time I was on a tight scheduling and hurries doesn't help to properly debug the problems.

First of all, the gloss change does exist but it's a 3-5C difference, so no real issue since it manageable. So the thermal differences inside are quite small.

Second. It does add some degree of friction to the filament, visible by how much it twist or it doesn't.

So, I2K + a Geared feeder = no problem at all, specially this won't be of much notice for 2.85mm filaments since they are much harder to bend. But also I suppose that it gives some degree of extra pressure on the prints (retract blobs).

I suppose the new nozzles from 3dsolex with a I2K should work quite ok. Also, the bondtech it's helping to debug this, since I can clearly see that there's no slips and the tooth marks have a perfect repetition (so far).

Next test someday this week, PIB with bondtech without geared motor, and if it doesn't work I'll try with the full bondtech that has the planetary gear.