Best dual color cat print ever :-) (and the learnings)

[conny_g 251]

Hi all,

 

I upgraded my 2nd UM2+ to Mark2 recently and had some issues initially. Took me some time to fix the hardware issues (Ultimaker mainboard blown, expansion board broken, nozzle jammed), calibration issues and now to find the right settings to get good dual print results. As it was a mix of things it was at times a bit difficult to understand what was happening.

My first "cats" were really ugly and I took a few weeks (not full time, of course) to identify the issues and improve the print. I think I printed some 10-15 cats ?

Here's the latest and best now, the best dual print cat I ever printed ?

After some hardware issues the rest to tune and improve was print temperature, speed, acceleration, calibration.
 

Temperature: with the 3DSolex Matchless nozzles I needed to go down to 180 C at 30mm/s print speed to get rid of overextrusion in small details and blobs. I think I never dared to print that low.

Speed: at 30mm/s and lower (this cat was printed at about 25) seems to be the sweet spot.

Acceleration: Interestingly this setting to control acceleration in Cura is really negative for prints with fine details. As the speed/acceleration goes down in the corners of small details, but the extrusion does not go down that fast it creates really bad edges and blobs. Best for this cat was to turn that Cura setting off and set the printer to 2.500/15 for acceleration/jerk.
I was never looking here for an issue as this setting really improves prints with large straight areas and sharp corners. But obviously this is killing objects with small details.

Calibration: I did the "dual meter" prints one complete evening calibrating the last fractions of millimeters, but still the cat print was off by 0.1-0.2mm. Still don't understand that, but with a few more cat prints, changing the extruder offset 0.05mm each time it got better and better. Also the Z-offset makes a big difference. Print first two layers in two colors and measure them with a caliper. Adjust Z-offest. Repeat until it's <=0.02mm accurate. Overall: it's worth to spend a few hours to a day on calibration, the prints will be much much better if you have fine details like this cat.

See zoom photo attached on the "acceleration control" issue below.

Hope this helps. I was quite mad and desperate in the middle of this process, really didn't understand why it was better with my first Mark2. But it's simply many parameters to get right and if you don't document them in detail....

Cheers,
Conny

Pic of this best ever dual color cat print:

Zoom image of the best cat, with accelaration control off.

 

Zoom image of one of the earlier tries with acceleration control on:
(see the edges of the colors, terrible!)

 

Edited April 27, 2018 by conny_g