Vapor polishing 3d printed parts

[MrBasse]

As has been mentioned before, the shape will change slightly. However, the material isn't really being dissolved, it's more akin to melting. You will be left with the same amount of ABS unless a chunk drips off before you remove it, but in my experience by the time it gets to that point your part no longer resembles your part anymore...

If you orient things properly to allow gravity to pull as straight down as possible, you shouldn't have issues with maintaining tolerances on holes and locating pieces. But they definitely have a tendency to lose round a little.

Start small and play with it, it takes some effort to make a chamber that I would feel safe using around kids on account of flammability issues of acetone and the heating of said flammable liquid. On the upside, when it does start on fire it is a pleasant slow burning flame that gives you time to move before too much goes bad. That said, take a lesson from me and don't do it for the first time in front of a class full of students over carpet. Ours went fine, but we learned that this process works very quickly and continues to work after you are done with the vapor bath.

What do you want to smooth out and why? If it is just for appearance, you can't go wrong just trying it. If it requires holding dimensions it will take some trial and error to find the right times and heat, then very good consistency to repeat results.

[jagoldman]

There is a lot about this on other 3D printing sites but if you are concerned with how much you are melting off and hazards, there are multiple methods that you can use. Heating the acetone will be faster, a lot faster, but that releases noxious fumes. You can also not heat the acetone and get a more controlled melt and no fumes.

[NWChen]

Originally Posted by techhelpbb

If all you want is to make something shine - you can sand the pieces and get a nice shine back with shellac. This trick does actually work with PLA as well.

Originally Posted by jagoldman

In the past, my team has used PLA on our robot without any problems, and if the tolerances were off, we would use sandpaper, files, and drill bits to correct. I see no real purpose of polishing a part like that or any reason to use ABS instead of PLA.

Originally Posted by MrBasse

What do you want to smooth out and why? If it is just for appearance, you can't go wrong just trying it. If it requires holding dimensions it will take some trial and error to find the right times and heat, then very good consistency to repeat results.

Thanks so much for your help. I'm looking into smoothing a structural PLA piece for appearance purposes, so tolerances still apply - I didn't know acetone vapor polishing wouldn't work for this application.

[techhelpbb]

Tetrahydrofuran and M.E.K. can smooth PLA. I've used M.E.K. but it tends to take a long time with Inland generic PLA spools (there are different formulations of PLA so be aware that not all PLA is the same). I would strongly urge anyone considering these chemicals to use them near ventilation

I should add - Tetrahydrofuran and M.E.K. make short work of latex gloves. Were suitable gloves when handling.

[Design mentor]

There is one use of Acetone vapor polishing that I can recommend that is quite useful:
When a part is used in conjunction with rubber, maximum friction can be obtained with smooth rubber contacting a vapor polished part. This process was used in the production of a squeeze actuated slip-clutch ratchet-like screwdriver that I invented and licensed to Sears. The screwdriver handles were machined on a lathe then run through an acetone vapor chamber. This drastically increased the friction between the inside of the rubber grip and the acetate handle. The grip was slightly oversized and mounted on snap bushings over the handle - when the user squeezed the rubber grip it deformed and contacted the screwdriver handle. Even with the grip contacting only about half the normal contact area of a handle that a hand would have, the friction was so great that the overall torque of the screwdriver was about one and a quarter times normal.