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Question TPU issues


Active member
I am having a major issue with TPU. The first 30 layers are OK but then the next 70 or so are rubbish and the print is ruined, after that it prints perfectly for the rest of the job. I have tried different` levels of cooling but no difference. I don't understand why it can be good, bad and then good again with no change in settings or environment. If it was progressively getting worse then it could be cooling etc but why does it come good again. This is reproducible on every print. Any print up to about 30 layers is perfect. I print 98 shore TPU at 230, 50 and 70% fan with doors open. The hotend is an Afterburner, Clockwork 2 with Rapido and 0.4mm nozzle. Sub 30 layer prints come out perfect with no blobs or stringing. ABS(30% fan, doors closed and 50C chamber) and PLA(100% fan doors open) print perfectly and are consistent over any height. Any help would be appreciated.


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Did you *really* slow down the print? TPU, being what it is, is flexible. So you need to move slowly so you don't start the print vibrating. Like ~30-40 mm/s speed vs. ~150-ish mm/s? Granted, a 2.4 has a fixed bed, but the toolhead still imparts a load on the part as well as just the mass of the print.

Looks like you also have an overhang? Are you doing the walls inside out, or outside in? Inside out will perform better on overhangs.
Hi, thanks for your response. I am printing with a volumetric flow rate of 4, which equates to 50 mm/s which I thought wasn't too fast for a voron with TPU. I can try slower, also I am doing wall inside out. I am still baffled as to why it goes good, then bad, then good again. I would have thought speed would not make this variance and be constantly good or bad. Any other thoughts welcome.
Just add, re the overhang. I can print the same part in ABS or PLA with no support and no issues and also with a flow rate up to 20 which is over 200 mm/s. My accel/decell is 5400/2700 which is lower than what input shaper suggests.
Hmm that's rather weird, if you look at gcode preview, does something change there above those layers? VFR? Speed? Cooling?
I tried different slicers, firstly S3D but that's too ancient to get a print but SuperSlicer gave a much better result which I think would suggest settings within the Orca slicer. Strange though as the Orca settings were transferred from SS initially and it is based on SS as I believe. There are still some heat issues but the back is unseen so I can use this as the front is clean. There are indentations at each edge for a bolt head so it is nearly right, the edges are deformed which are very thin so maybe it is a cooling problem with the Afterburner, maybe try a mantis type with a mini sherpa i.e. Xol2, any suggestions welcomed.


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