More Adventures with PETG

I decided that I was going to use the Mini Delta to print off a bunch of small circuit board clips (only 20 mm wide) and fired it up to do the job. The big advantage of the Mini Delta is it's speed. It's easy to run PETG at 80 mm/sec as opposed to the Ender 3's 50 mm/sec. Other speeds are also correspondingly faster. I was going to be using the PolyLite PETG (orange) and had had some good success on the Ender 3 so I sliced the model and printed a group of 6 of them.

Well, that didn't go well. I had terrible layer adhesion and the part turned out to be junk. What went wrong?

There are a LOT of differences between the profiles on the Ender 3 and the Mini Delta so I started tweaking the Mini Delta settings to match the Ender 3 as much as possible. I think the biggest problem was the temperature. The Mini Delta was set for 235 and the Ender 3 was 240. I know, 5 degrees is not much but after a bit of research I found that even higher might be better. So I set things for 245.

The other problem is that the Mini Delta struggles to make a bed temperature of 50 let alone 60 so I settled for 50 at the start and lowering to 40 after things get started.

There were other things that didn't seem right either:

  • A line width of 0.35 mm instead of 0.40. I changed it to 0.40.
  • Retraction on layer change was turned on - I turned it off.
  • 105% extrusion on first layer - I changed it back to 100%. It probably didn't make a difference though.
One of the other things about the Mini Delta is you have no control over the part cooling fan - there isn't one. Well, there is but it's the same fan used for the hot end so you don't really have control. I'm stuck with it the way it is - always on.

After these changes I got a good print. I had to correct the hole in the part though. I had squished the part width in MeshMixer after I put in the hole - which makes for an oval shaped hole.

I have a set of 3 sliced and waiting to try out tomorrow and if they work I'll expand that to 6. I'll need to print at least 3 sets of 6 to get the quantity that I need.

Stringing is still an issue but it's the way PETG is. I can live with it as I'm not looking for a beautiful part so much as a functional one. A little quick cleanup with a deburring tool does the trick.