Build Your Own SLA/SLS

So there's lot's of talk on the internet about shrinkage. Some say it happens and some say it doesn't.

After calibration, my ring came out about a size and a half too small. Is this shrinkage or another reason to re-calibrate?

Any jewellery designers come across this issue?

It happens. Just in varying degrees.
Normally it's only around <3%, but it's highly dependent on design, temp, and material.
If your prints are 150% off then I'd say it sounds more like a calibration issue and not a shrinkage one.

The best way to calibrate would be to print out an object with a known x/y size measure the printed part with calipers and adjust the build dimensions. You can get very accurate prints by adjusting this way.

Recently, I have tried some cheap local (Made in Russia) experimental resin. It was printable, but all models were significantly short in Z-axis, maybe 10%-20% compare to X and Y. And straight vertical walls were not actual straight but curved.

Now, I am printing with FunToDo resins and have no major problems with shrinkage.

Great, I will measure a 20x20x5 block and try this out. Many thanks!!

Okay, so it turns out my calibrations are actually okay on X and Y. My 20x20x5 block is to close tolerations however I'm still getting a ring two sizes smaller than the original.

I noticed though that whilst printing the ring, the supports on the base are almost non-existent. The ring shank seems to bypass the 5mm length supports and just amalgamates with the base? Is this a Z issue?

Could this contribute also to the ring size being two sizes smaller?

Any light on this would be great!

So your calibration prints are all coming out fine but the ring is still coming out way too small?
You didn't mention how the calibration on Z was; be sure to test that as well.
I'd say that's hinting at an issue with the file itself. Maybe the STL is being auto scaled by half somewhere in the software pipeline?