We have all seen drilled backing plates, and we all like them...well most everyone. I was looking at a pair on a ride at a show recently and i could see that the holes were not all inline, and kind of wandered, still funtional but not as cosmetic as they could be. Being a rodder on a budget as most of us are, i came up with a simple solution to help with keeping the holes in line so to speak. I know that any general machine shop has the fixtures to do this, but this is for the home builder on a budget. I had a buddy at a local shop turn a s**** steel slug, round with a step in it and a threaded 1/2" hole in the center. He then made a ring that holds the clamping disk above the backing plate register, i did this to be able to drill backing plates with different center holes. I welded a piece of rectangle tubing to the steel slug so i could clamp it in the mill vice, the mill works better than a drill press as it has the X and Y for lining up the bit, but a piece of steel plate will work to clamp it to a drillpress table. Use a cloth tape to lay out your design around the outside, and tighten drill, loosen adjust tighten drill, repeat. This doesn't help with all of the drilling, you still have to make sure that the holes are the same distance apart each time, but using this will make sure that the holes around the narrow outside edge as well as all the other flat areas are in perfect circles. Total cost less than $25.00....NOW GET DRILLING!
If you have a mill, you should really treat yourself to a used rotary table. I got a used Troyke(USA made) from Ebay for less than the cost of the shipping.
The Jalopy Journal
