Dimensional thermal test jig (for annealing) by punkgeek

Last crawled date: 3 years, 1 month ago

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)