Step 8: Hand File the Center Holes
Using a hand drill limits your drill bit size to about 1/2 inch diameter, so the 3/4 inch hole needed for each disc will have to be done using a hand file. This actually works out well since the holes are not perfectly centered as can be seen in the comparison with the hub adapter in Photo 8. Using the paper template and a round file, the 3/4 holes will be hand filed. This procedure only takes a few minutes per disc but is extremely accurate.