What Size Hole for Tap?

[Ken Robb]

I'm installing my new Vega fence & the holes on my Grizzly 1023 don't match. I need to drill & tap some new holes. What size hole do I drill for a 5/16-18 tap?

Thanks,

Ken

[Bruce Page]

Ken, for the standard 75% thread you want to use a "F" drill (.257)

A 17/64 (.265) drill will give you about 65% thread.

[Dean Baumgartner]

Ken, for the standard 75% thread you want to use a "F" drill (.257)

A 17/64 (.265) drill will give you about 65% thread.

Ken,
When I installed my Vega on a Delta saw the tapped holes weren't the right size either. Instead of trying to tap new holes, there were I think alternate spaceing holes on the Vega front rail so I drilled through holes in the apron of the saw top. Used a bolt all the way through with a flat and a lock washer on the back. This arrangement has been fine for the last 10 years.


Dean