MatterHacker PVA Adhesion

I am a beginner as far as 3D printing goes, but I talked my Boss into purchasing a Lulzbot Pro for prototyping. It prints PLA wonderfully, but I am having a bit of a problem when I load PVA into Extruder 2. I Have MatterHackers PVA which does run cooler than most… their site says 185 plus/minus 15 Deg. C I baked it by default when it arrived so it would be known low moisture content, and keep it in a polybox.
I have modified the Poly S1 profile for temps and the first layer adheres to the print bed beautifully the second layer starts to pull away and by the 3rd or 4th it is delaminating… Help i need support for my support.

Thanks… P.S. would provide pics, but no camera’s allowed.

ok, after watching the printer change heads and temperatures during a print I believe Cura is overwriting the temps in the material profile at the time it slices, I did not put any temp in the profile at 200 C but that is what cura is printing at. I can test it again by doing a reverse print… using the PVA as the model material and the PLA as support.

The auto-nozzle offset function on the Taz Pro is flawed at best, completely wrong at worst for the Z offset. Mine TPro does an ok job of X and Y but completely misses the Z.

Solution: Print two squares, 20mmx20mmx5mm each with PLA (NOT PVA!!!) but in the two extruders and about 40mm apart. When done, inspect the bottom and make sure the #2 extruder square has identical squish. Adjust the Nozzle offset Z index to make them identical.

Helps to use different colors in the two extruders so you don’t get mixed up. Number each set for each print so you can see over time the results.

Thank you, I will try this… it also looks like Cura is consistently adding 10 C to the temps in the PVA material profile for the second nozzle… since I made a copy of the Polymaker S1 PVA profile and modified the Temps, I wonder if it’s hidden somewhere in there… There is another Generic PVA Profile, I’ll try that one too.

ok, it appears that there are 2 problems going on … Heat and nozzle #2 Z height. I finally tamed the heat problem MatterHacker PVA Cooks fast at and above 200 C and starts to discolor and extrude like a string of pearls.

Now on to the Z height, if I adjust the Nozzle offset Z height setting am I adjusting only the second nozzle or does it adjust both nozzles in the program? the reason I am asking is I tried printing the Vernier and the PVA appears to be printing to high above the PLA and does not stick, but when it starts
to print the round for vertical test it appears to slightly burry the tip of nozzle 2 causing a divot . I ran the autocalibration again and I then tried to print the TAZPRO Calibration and everything looked fine until the 3rd layer… again the PVA seemed to want to print to high above the surface… it is Z or retract problem?

Its a weird setting and hard to get a handle on but I would assume yes. I treated it as such and it seemed to work that way for me. Sorry for the delay, this forum doesn’t send me notification.

So clean the nozzles, take the filament out. Do the nozzle offset calibration. Put two PLAs in the extruders (two different colors works best). Make two 20mm square cubes and print them with the two different PLAs in the same printing session. Take them off and inspect the squish on the bottom of each cube. Make the cube from extruder 2 look like the cube from extruder 1.

When I do it I get extruder 1 cube squish to the way I like it. You can see the lines and there is a faint ridge you can tell from a fingernail scraping it. You use the main Z axis offset for this.

Then I print the two cubes, two different extruders and match extruder 2 to extruder 1 using the nozzle offset Z value. Once 1 and 2 match the regular Z offset will move both up and down whereas the nozzle offset will just move extruder 2.

At least mine worked that way :wink:

Best of luck.