I need to make a 3/4" bolt hole for a Ruger #1 stock. A pilot hole and modified spade bit didn't work out well. Anybody have the specs for a gundrill that I can make? Thanks

You only need a partial 3/4" hole and the rest can be 3/8 or 1/2. Get a piece of drill rod and mill a quarter flute about 23-3 inches long, sharpen the tip at 90deg and relieve the back side for clearance, then heat treat it. I drill mine from both ends toward the middle. I use a pilotted 3/4" twist drill for the bolt head big enough for a socket.

By the way, I drill it all using the lathe with the drill in the headstock and the blank supported by the tailstock center.

Jim

I do it exactly as JK describes; in the lathe and make the drill as he describes.

Thanks guys. Do you let the wood blank "float", but not rotate, between the drill bit and tail stock? I tried clamping it on the lathe and think maybe that's why it went off center.

Don't feel bad...I've drilled a bunch of these holes you describe..I'm yet to have one end up"dead nuts"

I now drill the bole best I can and use the hole as a pilot for the inletting

I drill the hole then shape the stock around it.

I found a drill collar that clamped to my bit.

Drilling those holes can be an exercise in futility until you get the hang of it. The key is proper drills, sharp drills, short feeds and correct speeds. I use augers with heavy flutes that can be held accurately in the chuck or collet. The first thing you have to do is cut the threads on the pilot so that they can no longer pull the auger forward through the wood. The simple way is to hold it in the 3 jaw or collet and cut them almost away using the compound set to the same angle as the thread. Leave a little bit of the thread there (about half thread depth to grind the pilot hole as you drill) Next you have to establish your centers on the blank using a punch and then drill the centers between centers in the lathe with a center cutting tool. After that set your speed to 150 to 200 RPM. Extend the drill about 1 inch out of the chuck or collet and start the hole between centers as shown in the picture. Then extend the drill another inch. After you are in a couple of inches you can begin extending the drill 2 or 3 inches per crack. If you try to extend the drill to far it will bow between the chuck and work piece and the hole will begin to go crooked. keep going until you are within 1/2 inch of your tailstock center and then stop, reduce your speed to 50 or 90, pull the tailstock away and push it through the remaining 1/2 inch by hand.

If you extend the drill to far between cuts it will go crooked.

If you drill at super slow RPM it will go crooked. (150 minimum, 200 maximum for safety)

If you don't remove most of the thread on the front pilot screw it will go crooked.

If your feed rate is too high it will go crooked (feed just what the drill will cut comfortably and smoothly)

If your cutter gets dull it will cut crooked.

You should not be fighting to hold onto the wood at any time during the drilling. It should drill smooth and almost grab free.

You can not enlarge an existing hole with these drills. This just gives you the pilot hole. There is a learning curve here.


wood augers2 by Rod Henrickson, on Flickr

wood augers1 by Rod Henrickson, on Flickr

Having nothing to do at the moment and just to prove that I'm not completely mad. Rather than the mock-up I posted above, I grabbed an old piece of stock, set up the drill in the collet lathe (it holds the drills truer than the chucks) and poked a hole. The hole came out EGGFAWKINGZACKERY in the center and the drill slides up and down the hole with no resistance. So it can be done with the proper equipment and a few hundred of past experience.

I drilled from the pistol grip to the butt. You should always do it that way in the rare event that the drill wanders 1/8th of an inch or so.

stock drill1 by Rod Henrickson, on Flickr

stock drill2 by Rod Henrickson, on Flickr

stock drill3 by Rod Henrickson, on Flickr