Posted: 3/21/2026 3:25:15 PM EDT
[Last Edit: Blob][Edited]
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I make a lot of prototype parts out of ABS at work, both printed and machined. The parts are all designed for injection molding and so many of them have features that are either extremely difficult or flat out impossible to machine or print. Here is today's example: Attached File It's a U-channel with an overhanging tab. Not enough room to fit a keyway cutter for machining, and printing with an orientation that is optimized for the rest of the part leaves the tab oriented in the weakest way. Plus you'd need supports inside the channel. The solution is to split the part in CAD so they can both be printed in orientations that maximize strength and then bond them together with acetone. All you need to do is use a small paintbrush and wet the part with acetone and put them together. This isn't gluing, this is chemically bonding the two parts together to make a joint that is basically as strong as the parent material itself. Here you can clearly see the difference in layer lines between the two parts, maximizing the strength of the tab and optimizing the main part body. Attached File Attached File Most of the time I leave the parts like this because it's perfectly functional as-is, but if you want to clean it up a bit what you can do is take a file and grind up some material into powder and use it as "filler" to build up the gaps: Attached File Attached File Then after it dries you can sand it down smooth. Attached File Like I said we use this technique at work constantly and it's great and figured I'd share it here because it could come in handy in one of your projects. 
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This is one of the main reasons ABS is my go-to (along with increased heat tolerance). I use a slurry though, not straight acetone. Brushing the surface with it (I use acid brushes) bonds the layers and smoothes as well. There are times I'll print things a bit thinner and layer-in very thin fiberglass fabric. The slurry acts just as a resin and results in an outstanding bond. If you haven't already, learn to weld with the filament. Cut off a ~3/4" piece and chuck it up in a dremel. Spin it fast and build heat through friction on the mating point. I also do prototyping and have adapter bodies I can run >100psi of air and water through, even utilizing NPT threads, without leakage. |
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Originally Posted By User55645: This is one of the main reasons ABS is my go-to (along with increased heat tolerance). I use a slurry though, not straight acetone. Brushing the surface with it (I use acid brushes) bonds the layers and smoothes as well. There are times I'll print things a bit thinner and layer-in very thin fiberglass fabric. The slurry acts just as a resin and results in an outstanding bond. If you haven't already, learn to weld with the filament. Cut off a ~3/4" piece and chuck it up in a dremel. Spin it fast and build heat through friction on the mating point. I also do prototyping and have adapter bodies I can run >100psi of air and water through, even utilizing NPT threads, without leakage. Interesting tip. I'll give it a try sometime. |