The conversation of fixing the body to the chassis when finished with your build has come up quite a few times around here, most recently in the Rookie Rally thread and, thankfully, its come to my attention that I wasnt the only one frustrated by trying to drill and tap, the tapping part specifically.
I was having issues until I dug out a really good handle that fit the tap nicely, but even then I was sweating breaking the tap off in the post...which inevitably happened. It WON'T happen if you're slow and deliberate, but honestly, I'm rarely those things. I was about to throw in the towel and go back to JB Welding them shut, but I wasn't quite finished with weight placement on one of the Datsuns I was putting together so I decided to try and let the screw self-tap the hole and BOOM.
I went from frustration and a 1-in-3 or -4 car failure rate to nearly 100% success. It's so stupid simple that it makes me laugh but redlinederby asked that I post up about it and I know it woulda helped me in the long run so here goes.
The SIMPLE and successful way.
1) Drill down the middle of the post with the tiny drill bit supplied in the 2-56 tap and drill kit. Dubro makes one cheap as do many many others. Most, if not all, newer castings have a little dimple in the middle of the post rivet to act as a guide which is awesome. If you're doing an older casting without it, definitely use a punch to make a guide hole. The tweak that has helped me the most with this step is to chuck the drill bit so that only a small part of it sticks out. This makes your life so much better. No more broken bits and your less likely to drill too far. Also, go slow initially. The diecast is very, very soft and doesn't need alot of speed to drill out. Go slow, then bump speed up to middle speed and you will have a quick easy hole.
2) Drill out the rivet with a bigger bit like you already do in order to remove the chassis from the body.
3) Clean up the post (if needed) by filing the top flat and making sure the body and chassis go together cleanly.
4) Drill the small hole again to make sure you have enough room for the screw to bottom out and not strip out. If you drilled far enough in Step 1 then this is not necessary but it usually is for me.
5) This is where things used to go south quick but not anymore. Instead of tapping the hole in this step, put a 2-56 screw on your driver and slowly but with a little but of pressure, turn it into the hole. The diecast is soft enough that even a non self-tapping screw will tap the hole nicely. Couple things I've learned though...having a nice handled driver will make your life so so so much easier and also, make sure the hole is drilled deep enough that the screw head bottoms out before the threaded portion which can cause it to strip out the hole.
Remove the screw and you should have a nicely tapped post
Thats it. You're done and HOPEFULLY will be far far far more succesful than before. At least I have been. This is a much better way to secure your chassis to the body than epoxy or glue as you can now test and tune, take it apart and make adjustments all you want without issue.
Hope this was helpful to those who arent already doing so or maybe tried it and got frustrated!