Quote Originally Posted by awerby View Post
These guys don't seem to have very high standards for their castings. If one of mine came out that poorly, I wouldn't be celebrating; I'd melt it down and try again. Burning the PLA inside the sand mold evidently disrupted the surface significantly, so any crisp detail was lost. I just hope nobody watches this video and hurts themselves badly trying to do it themselves.
For staters they are sand castings - which will never quite have the same detail as investment castings. You are incorrect about any crisp detail being lost - many of the original print lines are evident and you can't expect to do any better than that from a 3D print.

Next, these casts are straight out of the sand - no touch up work at all was done to them. It only takes very minor work to sand things into shape.

Finally, where they came out a little rough it was only because the sand wasn't adequately packed tight enough - but a little learning is to be expected with a whole new technique. These are literally the first casts as we learned the new process. We didn't think of it at the time, but all we needed to do is flip the sand mold over and repack the sand from the other end.

And we take safety very seriously! I pour in a full fire proof proximity suit (with full head protection), we pour in a dry sand box, the molten metal is never lifted above waist level, the building is adequately ventilated, we use proper tools, etc. and so on.