Prusa XL - Soft TPU printing modification

Prusa XL & soft TPU

With soft to very soft TPU filament, the resistance in the PTFE tubes is too high and cannot be printed even if the filament sensor being deactivated.

I created a bypass with ball bearing rollers for this purpose. I use the 6th spool holder, which is not in use on the 5 head printer. If needed you can find a modifiyed spool holder part in my account.

The bearings are a bit fiddly as everything has to be very small and light, but my TPU printing results are now excellent.

All parts are printed with PETG from Prusa. With PLA the ball bearings would be easier to free, but that works too.

Here is a version with metal ball bearings

Print settings:

• Print profile: 0.10mm
• Infill: doesn't matter

After printing, place the ball bearings on his front side (this is the side which the part was on the print bed) and use the 3mm Allen key to press it through the hexagon. This one is running very tight, but that's ok. Please make sure that the hexagon is pressed through the center of the axle in the correct position.

Bearings (V4):

The best choise, because it is very easy to seperate the balls from the housing:
Simply use small scissors to cut off the connections between the balls and the move the roller a while until it runs easily.

Bearings (V2 & V3):

Hold the part with the Allen in it, then bend the ball bearings back and forth so that the parts can separate from each other. There are 3 parts that move against each other. Then move the roller until it runs easily. This can take a while and is a bit of fiddling, but if you have patience you will be rewarded with a very easy-running roll...

If you can't cope with printing a bearing, I have created several different ones, just test which ones are best for you

Assemble:

Move the right hotend approximately to the middle of the print bed, then replace the original cable clips with the printed ones and align them so that the filament routing makes sense.

The modification is only created for the right extruder. If you want to use the one on the left, you should adjust the clip accordingly so that the rollers are on the left.

You can download the PTFE holder on the hotend (seen on pictures) here from Bernd.