MK4 with super soft TPU (60A)?  

RE:

Good question. From the pictures, it doesn't look like it would support flex materials at all. At least auto load (and therefore MMU mode) might be difficult.

RE:

In the Prusa Live, they indicated the new extruder could handle flexibles.  

Posted by: @lichtjaeger

Good question. From the pictures, it doesn't look like it would support flex materials at all. At least auto load (and therefore MMU mode) might be difficult.

RE: MK4 with super soft TPU (60A)?

IF the picture above shows the real geometric situations, i would expect problems...

Because: The end of the steel tube is too far away from the filament drive gear, giving soft filaments the chance to miss the tube...

Second concern is, as there is no teflon tube any more but steel instead, there might be more friction between the tube and the soft filament.

RE: MK4 with super soft TPU (60A)?

In the technical data for the MK4 there is written:

supported materials

PLA, PETG, ABS, ASA, Flex, HIPS, PA, PVA, PC, PP, CPE, PVB, NGEN, composites and more

RE: MK4 with super soft TPU (60A)?

Most printers claim to be able to print TPU, but what they mean is 95A TPU, which is deceptive because 95A isn't much softer than regular filament. Unless they specify the shore hardness it means nothing. I guess I will just have to wait for someone to review one with soft TPUs.

It does look like there is a lot of contact area in the new extruder, but my concern is that it looks like the contact area is asymmetric. I'll build one of these in the meantime: https://properprinting.pro/product/proper-extruder/.

RE: MK4 with super soft TPU (60A)?

That extruder is very impressive.  Thanks for the link.

RE:

In a recent interview, they said that it's compatible with 40D. That is just about 85A.

Flex: 13:23

Hardness: 14:36

RE: MK4 with super soft TPU (60A)?

85A is pretty good.  I will still have to have a dedicated printer for 60A.  

Posted by: @lichtjaeger

In a recent interview, they said that it's compatible with 40D. That is just about 85A.

Flex: 13:23

Hardness: 14:36

RE: MK4 with super soft TPU (60A)?

so the best way to get answers currently is to bug the live support team?

i seriously hope there will be an update blog to address all the questions popping up so interested people dont have to scroll through miles of blog replies and dozens of forum topics to find the answers to 5 questions...

RE: MK4 with super soft TPU (60A)?

On the few instances that I use flex filament, my choice is Esun TPU-95A, which works fine on my MK3S+. I tried once TPU-70A and the print started well but I got progressive under extrusion after one or two hours. My guess is that TPU-85A filament would be OK on a MK3/S/+, so it seems that the MK4 isn't significantly better or worse than a MK3/S/+ regarding this matter. 

RE: MK4 with super soft TPU (60A)?

I've managed to print quite a bit with FlexFill 70A on the mk4. I had to loosen the pressure on the extruder idler a lot for it to work though. With the factory calibrated spring tension, the filament kept creaping into the space behind the large extruder wheel and jamming. Staying slow at an even 20mm/s for all features types is giving me a good result. It's probably the flexiest tpu I will ever bother printing with. The filament hangs like overcooked soggy pasta. Makes for really good springy rubber wheels.

RE: MK4 with super soft TPU (60A)?

Does it have to be a Pursa? You can consider other options, read the article https://www.linkedin.com/pulse/10-best-3d-printers-get-comprehensive-buyers-guide-david-bronson-x5zce

RE: MK4 with super soft TPU (60A)?

I have been printing with 85a for 200 roof grommets, shoe insoles, plumbing rubber seal replacement etc. I have a mk3s+. I found patients is your friend. First layer speed 10. External perimeters 10-15, and all non visible print surfaces 20. Whenever I tried going faster that I would get issues. Hope that help.