Pilot hole + countersink bit for #8 screws--am I crazy?

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Forum topic by deadherring posted 08-15-2017 06:57 PM 2148 views 0 times favorited 6 replies Add to Favorites Watch
View deadherring's profile


84 posts in 2530 days

08-15-2017 06:57 PM

Hey all,

I feel like I might be losing my mind. I’ve purchased the bits that have the countersink built in for #8 screws (what i use primarily in the shop) for years. I feel like they’ve always been 1/8” and have worked great for me.

Recently my bits were all dull so I went to restock. I looked at HD, Lowes, and Amazon and they all seem to be 11/64. I bought a few and when I use them at home, it seems to be creating a hole that is too big for #8 screws:

I tried a #6 countersink and it is 9/64, also too big:

I can’t seem to find a bit with a built in countersink that is 1/8.

Have i lost my mind? Did something change while i was asleep? Anyone have a link to a 1/8” countersink?



6 replies so far

View Woodknack's profile


13504 posts in 3267 days

#1 posted 08-15-2017 08:07 PM

DeWalt had some very bad quality control issues on their countersinks right now, that could be part of it.

-- Rick M,

View deadherring's profile


84 posts in 2530 days

#2 posted 08-15-2017 08:43 PM

@Rick M: Just to clarify, what I’m saying is when I’ve purchased a #8 countersink/pilot hole combo bit it’s always been 1/8th. Now, they are 11/64 which makes a hole too big for a #8 screw.

View jerryminer's profile


960 posts in 2328 days

#3 posted 08-15-2017 09:15 PM

Lee Valley has these: Countersink bits

(I think they are made by Snappy)

-- Jerry, making sawdust professionally since 1976

View patcollins's profile


1687 posts in 3752 days

#4 posted 08-15-2017 09:23 PM

Well 11/64 is the through hole size and not the size hole to use if you want the threads to catch any wood. It sounds like they are now designed for a through hole instead of a pilot hole.

Here is a chart that does a little explanation of the 11/64”, I suppose they assume you will use a screw that is long enough for the threads to engage?

View Nubsnstubs's profile


1732 posts in 2617 days

#5 posted 08-15-2017 10:36 PM

If you are using a 2” screw, set you counter sink at 2” . If you’re using 1 1/4”, set it at 1 1/4”. That’s the way it’s designed to be used. It sounds like you are setting the countersink at the top of the bit instead of for the size of the screw your drilling for. Set properly, the taper allows the screw to get a bite, the straight portion allows for a through hole, and the countersink allows the screw head to be flush or hide below any surface you’re screwing into.

  • Drill, countersink and counterbore in one step *

That’s from the description in the second link you posted….............. Jerry (in Tucson)

-- Jerry (in Tucson)

View AlaskaGuy's profile


6118 posts in 3196 days

#6 posted 08-15-2017 10:39 PM

I don’t know for sure if this is any help but, the chart show 11/64 for tappered bits and 1/8 for straight bit for #8 screws.

-- Alaskan's for Global warming!

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