Originally Posted by
Maxturbo
That arrangement will only be as good as the quality (precision) of the manufacturing of the bolts & nuts, which can run the spectrum of very poor to right on.
That and the condition of the frame to tool contact surface. (a machinist here)
Allen head bolts as you have chosen are a better shot at quality. You can also increase your chances by going with NF (national fine) threads n' nuts, as they are typically of higher precision!
If I had a lathe I could probably turn down the heads a smidge and square up the edges to make them a bit more precise. For now I just swap sides and turn them a couple of times to check them. To tell you the truth, I'm not one to be super worried by absolutely perfect alignment. This close is close enough. I'm sure someone will become all verklempt over that statement, but oh well.....