Dimensional thermal test jig (for annealing)

This is a companion for the dimensional calibration tool by LuckyPants. It allows you to place up to 4 of those tools at a 45 degree angle in an oven (or other thermal test environment). I used to for testing how annealing my PLA based parts improves thermal resistance (i.e. can I put these parts in a hot car?). It allows you to use the weight of the part itself to exert a bending force on the middle of the part.

I printed mine in MakerGeeks PETG, but the next time I need to print it I'll probably print it in PLA and then anneal it at 80C for 40 minutes. The PETG did not hold up to temperatures as well as I had hoped.

In addition to this little jig. Here's my notes from my test:

Samples (each sample was 20% gyroid infill, 0.20 layer height):

• Brown Solutech PLA (which is pretty crummy and I expected to do poorly - but it did better than expected!).
• Yellow MakerGeeks HTPLA

• Blue MakerGeeks PETG (this piece was not annealed)
  Test environment:

• A steam oven Sous Vide mode allowed very fine control of temperature and slow heating/cooling

• The PLA and HTPLA parts were annealed in a horizontal orientation in the oven at 80C for 30 minutes. The parts were placed initially in a cold oven, heated and then allowed to cool in the oven.

• The PLA/HTPLA and PETG test pieces were placed on the jig and heated in the oven at a series of temperatures. Each temperature was held for 30 minutes. The test temperatures: 50C, 60C, 70C, 75C, 80C, 90C
  Findings:

• The HTPLA shrunk 1.7% in X & Y and expanded 0.5% in Z during annealing

• The PLA shrunk 3% in X & Y and expanded 0.5% in Z during annealing
• The PETG started to droop very slightly at 60C, drooped to about a 15% angle by 70C, by 75C it was basically limp on the bottom of the test jig
• The PLA had very slight droop (1mm) by 70C, but otherwise resisted the heat just as well as the HTPLA

• The HTPLA had no droop at any of the temperatures
  Conclusions

• PLA does almost as good as HTPLA if you don't mind the shrinkage

• HTPLA shrinks a lot less in annealing than regular PLA

• Annealed PLA has better temperature resistance than non annealed PETG
  Possible further research:

• Try higher temps - I stopped at 90C because that's what was easy to test in my oven (and I only needed my parts to survive in a super hot car - which the internet says is about 75C)

Print instructions

Category: 3D Printing Tests Print Settings

Printer Brand: Prusa

Printer: i3 MK3

Rafts: No

Infill: 20%

Filament: MakerGeeks PETG blue
Notes:

If you want this part to last, I'd recommend printing in PLA and annealing that PLA in an oven.