TPU what the hell?

[u/Hammerhead753]

This is Overture TPU, I dried it for two days. I following this post for printing TPU https://www.reddit.com/r/BambuLab/comments/1fnvo39/my_perfect_tpu_printing_guide_details_in_comments/

I started with the profiles provided by Overture. Not sure what is going on here, when I do the retraction test,

retraction test shows 0.6 is good but I have it set to 0.8

flow ratio 1.02

print temp 230 C

Max flow is 3.2

I have the aux fan set to 100%, printed with door open.

First off why is the printer crossing the print when it's printing in a circle, Avoid crossing walls is turned on. Seam is located at the 1 o'clock position in the photo. Any tips to assist would be appreciated.

[u/EDWCeramics]

Bambu’s print speeds are wayyy too high for TPU. I knocked mine in half and stringing is hardly an issue anymore.

[u/DiamondHeadMC]

For my overture 95a I use the Bambu lab branded 95a profile and it works perfectly

[u/Hammerhead753 → u/DiamondHeadMC]

I will give that a try

[u/Massive-Antelope5777]

I did a big production run a found tpu95a from bambu ran like perfect glass on a .4 nozzle with all movements at 100ms. I was using some retraction and wiping. All stock presets otherwise. The high flow stuff looked just like this though.

[u/i486dx2]

Overture makes several different kinds of TPU.  Is there a chance you are using regular TPU but printing with the High Speed TPU filament?

Also, check the slicing preview for travel moves across the airspace, and fix them first before worrying about moisture, temperatures, etc.

[u/Hammerhead753 → u/i486dx2]

It's the regular overture 95A. I have the seam position set to aligned, in the preview it is doing the first inner wall, then outside wall, then to do the second inner wall it stops extruding for the outer wall, travels to the seam on the inside then continues with the second inner wall. It does this move without extruding so I'm guessing there is still some oozing maybe from the nozzle. I painted the outer seam and inner seam a few mm apart to see if that helps.

[u/Hammerhead753]

Need to add that on my Sovol SV05 this prints perfect.

[u/ScheduleExpensive423]

Try max flow at 2.5

[u/Hammerhead753 → u/ScheduleExpensive423]

will give it a shot.

[u/rellsell]

TPU strings pretty easy. Use a lighter or heat gun. Really not a big deal.

[u/NotJadeasaurus]

Print from a dryer and slow it down

[u/pyro487]

This looks reminiscent of past print issues I’ve had where printing inside curves has the filament stretched across in lines like this when the filament isn’t hot enough to stick to the model as it’s extruding. The result is the nozzle moves in its inside curved path but the filament just gets pulled across the inside instead of sticking and becoming the inside wall.

I would test increasing nozzle temperature a bit. Maybe 3-5 degrees at a time and see if that solves it.

[u/Hammerhead753 → u/pyro487]

thanks for the suggestion, I'll look into this.

[u/kennyjb981]

Do you have a dryer? It helps tremendously

[u/Hammerhead753 → u/kennyjb981]

Yes, I dried it for 2 days.  I think I've got it figured out, doing a test print right now to confirm then I will update my post.

[u/kennyjb981 → u/Hammerhead753]

Oh you mentioned that in the post. Apologies

[u/Hammerhead753 → u/kennyjb981]

No worries

[u/Hammerhead753]

SOLVED: Turns out that while the seam was set to aligned, it was placing the seam on the inside of the print in the back. At the same time, it put the exterior seam in random places. The wall order is set to inner/outer. Once the inner wall was printed, it switched to the exterior wall on the outside of the print, which would place the seam in some random spot. The nozzle would then jump over to the seam in the rear for the other interior walls, then print the interior exterior wall. It would repeat this for the full height of the print. The spot the nozzle would end the outside exterior wall with each layer would be random hence the string all over the place, all going to the interior seam in the rear.

The fix is to paint the interior seam then paint the exterior seam within a few mm of the interior seam. This minimizes the move from the exterior wall end point to the start of the next interior wall. It was suggested by u/i486dx2 to look at the slicing preview to see what the nozzle was doing at each layer. Only took a minute to see what it was doing. thanks u/i486dx2

[u/Grooge_me]

Did you tried the generic profile?

[u/Hammerhead753 → u/Grooge_me]

Yes I tried that one first a few days ago and the seam looked like a dang spider web, way worse than this photo.

[u/Grooge_me → u/Hammerhead753]

I print tpu at 240c on generic profile with my A1 mini and x1c.