Drill holes for pistol grip

[Matt Roth]

I'm stumped. I need to drill two holes, one in the middle of the other. The inside bore is 15/64, and the slight counterbore is 9/32. How would you accurately drill these? 2 stage bit? Jig? Help!

[Jamie Buxton]

Drill the larger hole first, with a bradpoint bit. It will leave a flat land for the medallion to sit on. Then drill the smaller hole. Use a regular twist bit. It will center on dimple left by the tip of the bradpoint.

[Matt Day]

Agreed....


Drill the larger hole first, with a bradpoint bit. It will leave a flat land for the medallion to sit on. Then drill the smaller hole. Use a regular twist bit. It will center on dimple left by the tip of the bradpoint.

[Matt Roth]

I tried that with a Forstner bit...the regular bit still had a tendency to walk a little. Will the bradpoint leave a better dimple?

[John Coloccia]

I tried that with a Forstner bit...the regular bit still had a tendency to walk a little. Will the bradpoint leave a better dimple?

I usually drill the counter bore a Forstner and then follow up with a brad point for the hole. You can also drill the center hole however you wish, and then follow up with a piloted counterbore, but I think that's serious overkill for this application.

[pat warner]

Piloted counterbore, top right (http://patwarner.com/images/drilling_tools.jpg). Not cheap but almost no risk to the work.

[Prashun Patel]

You'll get the best results with a drill press. This will also insure the hole is perfectly vertical.

[Sam Layton]

First, clamp/secure your grip to your drill press table where the hole will be drilled. Use a braid point bit and drill the large hole to the proper depth. Without moving the grip change the drill bit to the smaller bit and drill the second hole. If you have the grip secured to the table, both holes will be properly aligned.

Sam

[Bob Wingard]

+1 on the firm positioning of the piece on the drill press table ... I don't think the sequence of large vs small hole is all that critical, but all things being equal, I would also do the larger hole first ...at least to break the surface ... then go to the smaller clearance hole. With the piece still clamped up, you could then check for proper depth of the larger hole and deepen it, if necessary.

Unless you're doing LOTS of these, I wouldn't even consider specialized ($$$$) tooling. There's more than one way to perform this task without throwing a lot of $$$$ at it.

[Kent A Bathurst]

I usually drill the counter bore a Forstner and then follow up with a brad point for the hole.

Bingo.



1010101010

[Larry Frank]

I would drill a small hole first which is the center of where you want the two holes. Use this to drill the larger hole and then the smaller hole. The small hole will help to keep the bits centered properly. As others have said, the part must be securely held for the entire process.

[Myk Rian]

Use high speed to drill. Reduces wander.
That's what a "Sensitive" press is used for.

[Matt Roth]

I would drill a small hole first which is the center of where you want the two holes. Use this to drill the larger hole and then the smaller hole. The small hole will help to keep the bits centered properly. As others have said, the part must be securely held for the entire process.

Thanks all. For sure more than one way to skin this cat. I think I'll use the small hole idea...I forgot this hole needs to be counter bored from both sides, so the small through hole will allow for this, along with a couple brad point bits.

[John Coloccia]

If you need to do from both sides, do the show face counterbore first with the forstner (or brad point...forstner leaves a flatter bottom, though). THEN drill the the small hole, then flip and do the other counterbore and center hole. The reason for this is it removes as much material as possible between the front and the back when you drill the small pilot hole. Small bits tend to wander. The less you have to drill through the more accurate it will be.

[Matt Roth]

Thanks all, here's what I wound up with: