Squaring a hole for Recessing a Screw-head

[Ed Barker]

When recessing the head of a screw in either a bolster or wood handle, I've been using just a regular machine drill bit. However, this does not leave a squared, flat bottom base for the screw-head to lie against. How would I go about accomplishing this? Would I just use a reamer or can I actually grind the tip of the drill bit to make it flat without ruining it?

Thanks,
Eddy

[jimroe]

How I do this is instead of using a drill bit or a reamer, I use an end mill; this leaves the corners completely square.

Of course end mills only come in certain sizes, so it's sometimes necessary to trim the diameter of the head of the screw so that you get a good fit (I pick a slightly undersized end mill and keep a supply on hand to use for the various sized screws I use).

Just a "demon trick" with this process; I will start the counterbore by using a drill just slightly smaller in diameter (".005 or so) than the end mill I will be finishing the counterbore with; I drill only a little bit so that I can still finish the counterbore with the end mill. The point of the drill will follow the hole already there and make sure the counterbore starts concentric. Then when you finish with the end mill you will end up concentric; end mills have a tendency not to follow the hole (they're actually designed to make their own hole rather than follow one already there) and this process keeps things right.

I also use a 4 flute end mill as they seem to work better than a two flute one for this purpose.

[SharpByCoop]

Good suggestions above.

Here's another:

FYI, KnifeKits.com sells a series of drills with a pilot hole bit and a larger squared countersink ground into the bit. Fantastic for scales or bolsters. But then that would make it TOO easy...

Coop

[Ray Rogers]

Those other methods all work great but if you want to use a reamer, here's how I do it.

Chucking reamers have a bevel on their leading edge. I first grind the end of the reamer flat until this bevel is ALMOST gone. Next, I cut down the shaft as much as possible on the reamer to make it short and stiff.

Then, I like to drill my initial hole with an undersized drill. This is the hole the shaft of the screw will pass through and it acts as a pilot hole. Next, drill the hole that will be the countersink for the screw head. After that, run your modified ream into the hole and flatten the bottom. This will leave a small drill point divot at the bottom of the hole. Finally, run the proper sized drill through the hole to make the correct sized hole for the screw shaft to pass through. This last step generally removes all of the divot leaving a perfectly flat bottom in the countersink.

All of these methods work, some easier than others. Reams are available in literally any size you could want and at reasonable prices. Sooner or later you'll run into a situation where you won't be able to get the results you want because the end mills or countersinking drill bits aren't available in your desired sizes. That's when you pull the reams out of your bag of tricks...

[Don Robinson]

I make piloted counterbores and flat bottom drills to order. Whatever sizes you need.

[Jeff Higgins]

Originally Posted by Don Robinson

I make piloted counterbores and flat bottom drills to order. Whatever sizes you need.

I'm using the counterbore drill bits from Knifekits at the moment. I think they are using the recommended clearances for buttonheads and socketheads, and I find them largely unsuitable for my needs. I'd like them to have a little tighter tolerances, so I need to get with you on making some better sizes of these for me.

[Don Robinson]

Any time, Jeff.

[Jeremy Krammes]

I have been using Brad point bits. DeWalt makes them. I picked them up at LOWES. They are about $3 and are basically the same as the step drill bits that are $14.

Jeremy