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.

RE:

I just printed Recreus TPU 60a with no problem at all (Prusa MK4).  I slowed the print speed down to minimize stringing, and covered the build plate with blue painters tape.  If you don't cover the build plate, you'll likely ruin the build plate trying to remove the print.   The only difficulty was loading the filament - it took several tries to get it past the sensor. 

Next time, I'll try freezing the end of the filament to make it stiffer.

70a and above print with no problems or adjustments at all.

I don't know if it's necessary, but for all my TPU spools, I made an adapter with bearings so the extruder pulls the filament smoothly without stretching the filament followed by uncontrolled unwinding of the spool.

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

Bonjour, 

Pourrais tu me dire a quel vitesse tu imprimes pour le 60A ? J'ai la même marque de filament que toi !

Et est ce que tu desserres les vis avec ressort pour avoir moins de tension ?

Je serais curieux de savoir comment tu as reussi

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

Here we are printing Varioshore TPU from colorFabb at 230º and 70% flow rate, wich must be very close to a 60A with the Prusa MK4 and Prusa XL, and until now we haven't experienced any problems at all.

We always print it at 30mm/s in all parameters and we use a textured print sheet for avoiding to ruin the build plate. We also mark the "avoid to cross perimeters" tab for geting the less stringing possible and print the models one at time for the same reason.

I don't know what kind of devices you are going to print. In our case none of them is more than 50mm high and take more than 5 hours to print.

I hope this can help to you.

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

To avoid excesive stringing and random clogs with TPU, be sure that your filament is free from moisture. If you keep the spools in a sealed box/bag with desiccant, check often if the silica gel balls start changing color, even slightly. If that happens, dry your filament at once. Believe  me, it makes a real difference in the print.  

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

I ultimately slapped a Bondtech LGX Shortcut Copperhead ( https://www.bondtech.se/product/bondtech-lgx-shortcut-copperhead-hotend/) on my Ender 3 S1 using NBR's modder board ( https://www.nathansellsrobots.com/products/modder-board-for-ender-3-s1-1) and it has been awesome. Prints everything down to Filaflex 60A at 40 mm/s, and could even go faster if you use very aggressive pressure advance.