Countersink bit question, screw sizing

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Forum topic by Roux posted 08-15-2014 02:59 PM 996 views 0 times favorited 2 replies Add to Favorites Watch
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3 posts in 1828 days

08-15-2014 02:59 PM

I apologize if this is not in the right place, I tried searching for my question but didn’t come up with much. Thanks!

I’m working on some Oak furniture, with #8 wood screws.

I have a #8 countersink, as well as a #10 countersink. (Counterbores? Countersink+bit for pilot hole).
I have just purchased 1/4in and 3/8in Plug Cutters, and neither are filling my need.

My #8 countersink for some reason has two tiers (? and 3/8), but I can’t get deep enough in this wood (Thin) to get to the 3/8 “shoulder” on this bit, it’s just drilling a nice deep hole on the smaller “tier” of the bit. A 1/4in plug is too small to fill this hole, and 3/8 too big!

My #10 countersink makes a perfect 3/8 hole, but I’m worried about putting #8 screws in a #10 pilot hole, even though the seem like they’re quite snug to me.

At the moment I’m considering using the #10 bit to drill all my pilots, even though I’ve got #8 screws… Or, I could put the #8 drill bit inside the #10 countersink, but that seems like it might be a really bad idea and introduce a lot of wobble or weirdness….

2 replies so far

View Hammerthumb's profile


2949 posts in 2422 days

#1 posted 08-15-2014 06:59 PM

Drill a 3/8” hole with a forstner bit for the plug hole, and then use the #8 countersink.

-- Paul, Duvall, WA

View TheFridge's profile


10858 posts in 1933 days

#2 posted 08-15-2014 07:02 PM


-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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