Counterbore holes don't match standard plug sizes

[Chris Nolin]

I'm attaching ship-lapped beetle-kill pine siding to an old trailer, and have been counterboring the screw holes to be covered later by plugs cut from the same wood.

I've been drilling, countersinking and counterboring all in one step with one of those quick-change bit sets (Makita, in this case). The counterbore bit I've been using is stamped with an "8" on the shank (#8, right?) and I'm driving #8 deck screws.

I bought a plug cutter set last week and discovered the counterbored holes don't match the size of any of the cutters in the set. The 1/4" plug is too small, and the 3/8" plug is too big. I have hundreds of holes to plug, and I fear having to remove all the screws and redrill each hole.

Anyone know what I'm doing wrong and/or how I might fix it?

[glenn bradley]

Bad time to find out, eh? I hate that ;-) Does Makita sell matching plug cutters? I couldn't find any. Metric, me thinks. Funny that they would be specific on the screw size and casual about the counterbore. Please let us know what you find out.

[Jamie Buxton]

Maybe the 8 is millimeters? That's very close to 5/16".

Lee Valley offers both 5/16" and 8 mm plug cutters..http://www.veritastools.com/products/Page.aspx?p=153

[Chris Nolin]

Thanks Jamie and Glenn! I guess my head was stuck in Imperial. Never even considered that it would be metric. But you must be right! And thanks for the link to the LV cutters. I'll probably be ordering today. You've officially gotten me unstuck. :)

[george wilson]

No,your head is stuck in IMPERIAL.:)

[Chris Nolin]

I caught it just as you were typing your post, George. Thanks, though. I should really know better, as I often make fun of others' grammar mistakes (especially those of Bush 43). Now I'm guilty of the same. I'm not having a good day, I guess! ;)

http://grammartips.homestead.com/empirical.html