Quote Originally Posted by 3DTOPO View Post
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.

[If you were setting out to demonstrate the utility of this process for creating small detailed castings like the one you attempted, you have not succeeded. This process might be okay for rough castings, but since there's no way to introduce a core, it's not going to work too well for most of them either. Solid lumps cast poorly, and some of the problems in that one might be due to shrinkage porosity. If you try it again, use a chill and see if it works any better.]

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.

[As someone who's done my share of that "minor work", I'd say melt it down and start over.]

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.

[I think the process, such as it is, would be improved a lot if you used a refractory coating on the part before packing it in the sand. People who do the similar lost-foam process with aluminum use dry-wall compound, but there are lots of better ones that might stand up to hotter metals.]

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.
[Yes, I noticed that. (Nice induction furnace, by the way! Is that home-made?). But I worry about the people who watch You-tube videos and go out to try this at home, in t-shirts and tennis shoes, with the kids all crowding around. You could shake off that "bottle rocket" explosion you got on your first attempt, but it might be a life-changing event for them (and not in a good way).]