PETG translucence different between printers

I’m printing translucent PETG with great success, and my prints look fantastic. On my TAZ 6, the finished parts have a crystal look which reflect the light, and allow a little transparency. So far so good. I’m starting to print the same pieces using the same spool of filament on my Flashforge Creator Pro, but the end result looks different. The parts are more opaque with a satin finish. I’ve tried increasing the temperature by 20C on the Flashforge, but it doesn’t affect the look. The only other thing I can suspect causing the difference is the nozzle size. Any ideas?

Important things to note:

  • The filament is 1.75mm
  • The Taz 6 has the 3mm hot end with 0.5mm nozzle
  • The Flashforge has a 1.75mm hot end with 0.4mm nozzle

The attached pictures don’t show the differences well, but hopefully gives you an idea. The Taz 6 part is on the left, and the Flashforge on the right.


Is the flashforge nozzle steel?

I had a very similar issue with PLA in my FFCPro. PLA on the FFCPro would come out a very good looking Matte finish while the Lulzbot with similar settings would be a glossy finish. I was never able to get matte finished on the Lulzbot.

I’ve been playing with PETG on my Taz5. On two different prints of the same object/same filament I did notice a very different surface sheen. I’m pretty sure that my extrusion temperature was different. These were both experiments and now that I have a good starting point, I can do some test pieces to figure out what effect correspond with different parameters. I also imagine that it’s dependent on the brand of filament.

I sometimes drive myself crazy by changing too many parameters at one time.
When testing for optimal parameters, I have started to follow the methodology described in this video -

https://www.youtube.com/watch?v=N-7uX6Dw-7A

(He talks about printing ABS at 120 degrees, but I think he must mean 220…)

Parameters you can test

Extrusion Temp
Extrusion Amount
Speed
Cooling

Other things to tweak from simple observations

Retraction
Bed Temp
Fill
Wall thickness



Best regards,
PCH

I’ve spent some time today working it out in a more controlled way, and have determined that it really is about the temperature, or how much time the plastic can stay molten. Setting the temperature of my Flashforge to max (around 265), and turning off the fan, I’ve gotten prints much closer to the quality on the Taz. Slowing down the print (from 40mm/sec to 25mm/sec) also had similar effects.

On the Taz, feeding 1.75mm filament through the 2.85mm nozzle causes the plastic to stay in there a bit longer than if it was a 1.75mm nozzle. The heating element is probably a bit beefier too. I think that may be giving it a significant edge in final finish quality.

I’ll do some more experience to see if I can get identical results between the printers, or at least good enough similarities.

I found that on my FFCPro, plain PLA in a matte finish (205c) would have poor layer bonding. Upping the temp to 215c would give better bonding, and would give that glossy look too. I like shiny tho. :smiley:

I did try replicating the matte finish for PETG on my Taz. Lowering the temperature didn’t change anything. Lowering it even more just resulted in a blocked nozzle.