Feasibility of sharp internal corners in CNC-machined

Yes, I’ve machined similar parts in ABS before. I recommend reconsidering some of your internal geometry. ABS is easy, it’s got low cutting resistance and it holds detail well, but sharp internal corners are essentially impossible. You can’t get a perfectly sharp 90° internal corner with a standard tool because of the cutter’s corner radius. Even with 0.5 mm diameter cutters, there’s still going to be rounding in the corner.

Chamfers as small as 0.2 mm can be very challenging. The variation in a typical chamfer tends to be more than 0.2 mm! If the tooling isn’t dialed in precisely, small chamfers can either be skipped or deliver inconsistent finishes, especially in a softer material like ABS. You’re more likely to get better results with a larger chamfer, or a fillet that shows the variation less.

If your design can tolerate slight fillets in those internal corners – say 0.5 mm radius – you’ll improve machinability and process times. That said, a good CNC shop can advise based on their tooling and precision level. I’d suggest sending them the STEP file and asking for feedback before locking in the order. It’s better to tweak the design slightly now than to get a part back that doesn’t meet expectations.