[cadandcookies]

Last year, 2220 had our chassis powdercoated by one of our sponsors. We certainly haven't been doing powdercoating for a long time (I'm hoping to see 254 get in on this thread), but there were a couple of things we learned:

For hole tolerances, if we dimensioned it as a clearance hole, it was completely fine (we just used the clearance hole setting in Creo for that hole size, you can look up whatever size that gives you to find drill bits for that size, otherwise if you're having a CNC sponsor do that for you they should be able to easily recognize it).

We didn't do any major surface prep because our sponsor handles ridiculous volumes of powdercoated parts, so they basically have the entire process from intake through application to baking automated.

For dimensional tolerances, powdercoats can vary in thickness, so talk to your sponsor-- depending on the application method, they can be 1 mil to 10 mil in thickness* (though in our experience it tended towards the lower end of that). Definitely talk to your sponsor about their recommendations.

*might be wrong on this, main point is that it varies