Posted By Bill Tindall, E.Tn.

Date Monday, 17 January 2022, at 9:04 a.m.

Bill Tindall, E.Tn.
Materials- walnut, quartered white oak, flat red oak.
Bits- Irwin sharp 3/4 and 1"
Pilot holes- none, 3/32", 7/64,1/8"

Summary- I experienced no significant difference in force required to drive the bit into the wood, with or without a pilot hole. I did experience a significant difference in ability to control the brace; it stayed more vertical with pilot hole as I struggled to rotate it. Would I use a pilot hole in the future; yes, for it made it easier to start the drill in a hard wood and control was better. Would I use this means of drilling holes in hard wood, no. If I have to use a power drill to make the pilot hole why not use the same drill to drive a spur bit.

For my strength 3/4" shallow holes are practical; 1" are not.

Walnut experiment

Both 3/4 and 1" drills drilled successfully with and without a pilot hole. The 3/4" hole was easy to drill. I was struggling with the 1" hole. No pilot are left holes, pilot are right holes

Quarter sawed white oak

The 1" bit only began cutting with the 1/8" pilot hole. The thread pulled out from the force of cutting in other cases, top 3 holes. I was barely able to turn the brace once the bit fully entered the hole.

Flat Red oak

3/4" hole was successful with or without pilot hole. With a pilot hole I had less of a struggle keeping the brace vertical. I was just able to turn the 1" bit in red oak with or without a 7/64" pilot hole

 

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