Hi there! I've been using regular drill bits (numberd 1-56), the veray only in few thousands of the inch. Here is the chart: Bridge Pin Size Drill No. #6 #48 #7 #45 #8 #42 #9 #36 #10 #30 Also I have used high speed drill (DeWallt brand) with PRECISION DRILL GUIDE, I bought it from Woodcrafters store ($41.95). With that GUIDE, you can adjust angel and depth of your drilling to keep it firm. Also, IT is VERY handy tool in any woodworking projects. I hope it helps. Vlad.
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