TPU is simply not printable with the MK3s  

RE: TPU is simply not printable with the MK3s

Is your filament fresh? could it have absorbed water?  Maybe dehumidifying it would help, 
I have an electric oven which I put some old Sainsmart TPU into at about 60C for some hours... that improved the bobbling and stringing.
I now have a fruit dehumidifier, but I haven't tried TPU in it yet.

Have you tried a temperature tower? 
Stringing is an issue with TPU, a lower temperature may stop the stringing. 
you could try increasing the travel speeds to maximum, which I believe is 200mm/s

regards Joan

RE: TPU is simply not printable with the MK3s

I am trying print a small tire at this point since the duck was successful. the issues is that theres stringing across the hole on both sides. ill apply the updates and report back. 🙂 Thanks again.

RE: TPU is simply not printable with the MK3s

@the-sh1z

Good luck, 
with tyres, you may be able to use the command - Avoid Crossing Perimeters

Do one tyre at a time

if you do two or more there will always be hairs between them!
regards Joan

RE: TPU is simply not printable with the MK3s

i gave up on the priline. i ordered some saintsmart tpu since it already has a profile in prusaslicer. i kept getting spaghetti strands across the holes in the tires regardless of the settings.

RE: TPU is simply not printable with the MK3s

Just to chip in a bit here.

These are the settings that work reasonably well for me, although the stringing is still quite annoying (so, if anybody has any clever ideas...). Slowing everything down a bit and funny enough an extrusion multiplier of 1.1 were the things that helped me getting consistent results.

The filament is a local brand and unfortunately they don't publish proper data sheets, so I don't know it's hardness and other properties.

Most importantly, do not print on the smooth sheet. Adhesion is so good, it almost cost me the sheet.

Don't give up, once it works TPU is really an interesting material and well worth the effort.

P.S. Joan, the printed little wallet is a nice idea...

RE: TPU is simply not printable with the MK3s

@ros-cogitans

If you have seen this tip before, my apologies! The 3 key things I found are... 

To stop TPU spilling out the side of the extruder... simply LOOSEN both gear screws on the extruder (from a normal PLA, PETG filament setting) by winding OUT the screws by 1 turn or 360 degrees. It will then stay put and feed through just fine.

Keep the temperature high... I use 255 degrees for most TPUs and they come out nicely. Start from 'Generic FLEX' and work from there.

Also always DRY your filament... I dry all my filaments before printing by using a modified food dessicator, they are much cheaper than specialist dryers you can buy on the internet, but they do EXACTLY the same thing! Look up 'make your own filament dryer' on YTube and you will see how its done. Its very easy to do and costs about a quarter of a 'specialist' filament dryer. For the temperatures/times to use for different types of filaments - just visit the website of the 'expensive version'. All the best.

RE: TPU is simply not printable with the MK3s

I so envy all of you that succeeded in printing with TPU in the MKS3. I found this forum and tried again. But I´m stuck in the problem that the printer does not realize the filament is loaded and flowing off the noozle, therefore never starts to print. It works fine with PLA. When I tried to loosen or tied the screw from the nozzle feeder, I ended up with a mess in the nozzle. I don't know what to do anymore. Would you have any tips to fix this? 

RE: TPU is simply not printable with the MK3s

Hi Leslie, yes it absolutely is possible to print TPU with a Prusa Mk3s. If you get TPU spilling out the extruder, then just loosen off the screw that tightens the grip to your filament by one full turn - if you have been printing PLA for example. TPU needs less grip to extrude. 

I print my own Flip Flops with TPU and tyres for my partners wheelchair on a regular basis - so it most certainly can be done. Give it a try!

Simon

RE: TPU is simply not printable with the MK3s

I have printed for the first time with flexibles recently, Fillamentum TPE 90A, actually. To make it work I had to trick out the MMU though (as I don't want to uninstall it and am to lazy for adding a kill switch). It absolutely refused to load or messed up the string around the extruder gears. I deleted the MMU extruder loading g-code and now simply pause and load manually (also purely manually by turning extruder gear and feeding filament). Works flawlessly. 

I have all printing movements at only 12 mm/s to be on the safe side. I see zero chance of getting the filament to work with MMU in regular operation, maybe 96A  is a different story, but 90A is just too soft for that.

PS: TPE has the fun feature of being PP like in its adhesion profile, which means it basically sticks very poorly if at all to anything other than PP, PE and the like. But luckily the warping is much less severe. 

RE: TPU is simply not printable with the MK3s

I too had issues with getting flexible filaments to print beyond a few layers and tried all the suggestions for print settings / cooling the extruder stepper / using 0.6mm nozzle all with no luck.

I was about to give in and order an extruder more suited to flexibles when I came  across a youtube video explaining how the MK3 uses a non-standard heat break design to improve performance with the MMU and that this can lead to blockage issues with HTPLA.  So I replaced the heatbreak in my MK3S+ with a standard E3D part and it proved to be an instant fix - I can now print all flexible filaments without issue including the very soft TPE types with no other mods required.

Seems to me that Prusa should ship the MK3 with a standard heatbreak and offer the modified one as an option for those wanting to use the MMU2 rather than only shipping the modified one that can cause printability issues....

RE: TPU is simply not printable with the MK3s

I recently started printing with Sunlu TPU making aids for people with mobility and gripping issues. Just loosened up the tension on the extruder a few turns and printed 30mm/sec with temps per manufacturer specs. Worked very well for me even on tall thin items. Granted it's hardness is at the harder end of the TPU range but not having any issues at all. Very happy with it. If I ever need the softer hardness that might be more of a challenge so we will see if the need arises.

RE:

Hi,

Thats great to hear SailorEric! My partner has reduced mobility. I heve designed and printed both replacement wheel hubs in PETG and TPU tyres for her wheel chair and rollator. I have not published due to Health and Safety Regulations etc. It's absolutely fantastic that you are doing this and helping someone with your skills.

My rationale was to reduce the cost of these essential items for her.

Wheels for a wheelchair, cost us 80GBP - mainly because the wheel and tyre is bonded together. I designed a reusable split hub with a seprate tyre - I can print tyres for around 7GBP, work just as well and save us a lot of money.

I think people with reduced mobility are ripped-off... for pretty much everything. Anyway if my designs are in any way helpful to you, I will be happy to share my designs - just with you. All the best and keep helping, one day we may need this equipment ourselves.

RE: TPU is simply not printable with the MK3s

Agree on the rip off! My wife was in a wheelchair for ten years. Crazy prices! We are currently in Guatemala. Wheelchairs and other mobility aids have a hard life out here and parts are often impossible or very expensive at best. Would love to see if I can use your design here. Everything we do for people here is donated free of charge t those that need them!