strange things happen printing large vase on XT and NGEN ColorFabb

[ili_olo 0]

Hi, with my UM2 I'm testing new materials to improve heat resistance of my objects.

The object is a lampshade (similar a big vase) approximately 20 cm x 20 cm x 20 cm, wall 0.8 mm no infill, no top, 0.4 nozzle, 0.2 layer height.

with PLA (colorfabb or Ultmaker or others) everything is fine, but using xt or ngen I have a few issues.

main setting:

xt: temperature 245, speed 40 mm\s, fan 50%,

ngen: temperature 230, 40 mm\s, fan 50%

issues:

over to a certain height (around over 16 cm), things start to go bad..

---the shape is deformed, the circular shape becomes oval

---strange surface artefacts appears, a sort of blobbing (particullary in xt). It seems a sort of scar

---layer adhesion gets worse

the bottom part (first 16 cm) is good, so I tried to divide the object into 2 different file....

and inexplicably if printed separately the upper part is ok!

I think the problem is also related to the specify shape (overhangs and changin angle), but do not understand why it only occurs over a certain height and only using XT and NGEN (with PLA no issue).

any suggestions on how I could approach to this?

now i'm thinking to try a larger nozzle (0.8) and spiralizing the contours

thanks for any suggestions.

filippo

www.filippolosilab.com

[Labern 775]

Use spiralize to stop bobbing etc.

Can you not rotate the item so the large bit is at the bottom?

[ili_olo 0]

thanx Labern, It could be a good idea to mirror the object and to shift large part at the bottom. In this case I have to make some changes to the design, since now in the small part there is the fitting for the lamp holder, and as it is now i can't print it at the top.

Anyway i hope that spiralize and large nozzle could fix the problem.

[peggyb 171]

spiralize only works with solid models, and will also destroy your lamp holder.

Spriralize can only spiral one outer wall, and you model has an in and outside wall.

[ili_olo 0]

So to use spiralize I had to make a solid model and generate two separate gcodes: one for the first 20 layers (lamp holder) without spiralize and another for the rest of the lamp with spiralize. Then i had to mix the 2 gcodes with swap at z plugin (or with my text editor) and cross my fingers...

It might work?

[peggyb 171]

Was thinking about that also, but did not know if you could handle this

Can you see in the layer preview if it is working? (it should)

[ili_olo 0]

yes, in the layer preview it seems to work without any problem.

i'll test soon to print with the large nozzle 0.6