I have a Dremel, a router, a drill etc.

I have a project that requires me to open up a space inside an existing hole in wood.

Think of a 2x4 with a 1 1/2" hole already going through 3/4 of the board but not out the other side. Also, the entry hole cannot be widened. The carve out would be completely inside. I need to open up a pocket in the bottom of the hole but not break through the other side. This pocket would be to give an electronic component a bit more space to fit.

Ideas on what I might be looking to get to do this? It doesn't need to be pretty, just functional and effective.

Does the enlarged area need to be flush with the bottom of the existing hole?

I was going to suggest a slotting or rabbeting bit for the router but the ones I'm seeing have pilot bearing which wouldn't allow for making it flush with the bottom.

Perhaps without the pilot bearing? Or a T-slot bit?

you didn't mention if you need the deeper hole to also be 1-1/2" in diameter. If it was me, I would use a fostner bit, since they don't have much of a lead point and cut a flat bottom hole. I would figure out exactly how deep I wanted to go and wrap enough tape around the body of the bit to prevent it from going through. (I often use electrical tape for quick, simple depth stop on drill bits. just build it up pretty thick) Assuming the hole was already 1-1/8" deep, you could probably get another 1/8" to 3/16" without going through. If you use a smaller diameter fostner bit (they are not inexpensive bits), you could drill a number of shallow holes and just clean-out between them (probably just break-off the bits with a needle nose pliers). However, test your depth setting on a scrap board before working on the main project.

Ken

quote:

Originally posted by KenS:
you didn't mention if you need the deeper hole to also be 1-1/2" in diameter. If it was me, I would use a fostner bit, since they don't have much of a lead point and cut a flat bottom hole.

This ^^^^^

But a 1-1/2 in. Forstner bit in a hand drill might be tricky. (N.B.: I've never tried it, so I don't know for sure.)

If you're close enough to me to make it worth your while, you're more than welcome to bring the piece over here and we can do it on my shiny new drill press. Hell, I'll even buy the Forstner bit

Maybe a rotary rasp in a dremel if you're wanting to create an internal pocket. They come in various shapes and sizes.

The problem with the forstner bit is the center punch would impact too close front side which is quite thin. Rethinking this, I may just use a straight bit on my router.

Ensigmatic, I am about as far east in Michigan as you can get.

If you want to see pics of what I am working on, lookup Les Paul switch and control cavity. I am working on a imported copy and the newer, better quality pots and switch are a bit larger so I need to make some room for them.

The forstner bit sounds like the right solution to me.

If you can't open the entry hole at all (I would put blue tape over the opening hole and cut out the opening with a razor knife, and you can't go any deeper and just need to open the inside of the hole.

I would use a wood rasp bit on a Dremel or drill, will take a while, but will be more precise. Dremel will be the most precise and you're only removing 1/4" of material all of the way around. Paint the bottom of the hole white, and that will help to let you know if you're getting deeper.

I’m confused. Wouldn’t the forstner bit widenthe hole, which was against what was asked in the OP?

I was thinking more like Paul, with a piloted straight bit on the router. Bearing rides the edge of original hole, bit carved out underneath it.

quote:

Originally posted by Oz_Shadow:
The problem with the forstner bit is the center punch would impact too close front side which is quite thin.

Gotcha.

quote:

Originally posted by Oz_Shadow:
Ensigmatic, I am about as far east in Michigan as you can get.

So probably about an hour away, if I'm understanding your correctly.

quote:

Originally posted by SigJacket:
I’m confused. Wouldn’t the forstner bit widenthe hole, which was against what was asked in the OP?

A 1-1/2 in. Forstner bit wouldn't widen-out a 1-1/2 in. hole if it was guided well.

How much material do you need to remove or widen?
Centering a Forstner might be challenging.
A Dremmel is only going to take a small amount.
A router bit or a larger sanding cylinder attached to a drill is what I would consider.
But it really depends on how much you need to remove.

Ball type rasp.
If it could be mounted to turn on a lathe, there are tools to open up the inside quickly.

quote:

Originally posted by Oz_Shadow:
Think of a 2x4 with a 1 1/2" hole already going through 3/4 of the board but not out the other side. Also, the entry hole cannot be widened. The carve out would be completely inside. I need to open up a pocket in the bottom of the hole but not break through the other side. This pocket would be to give an electronic component a bit more space to fit.

You need a burr grinder bit. You can get them with 1/8" shanks for using in a dremel, or larger for use in a router or die grinder.

how about a router bit with the bearing mounted above the cutter bit area.... this would allow enlarging area below hole opening without enlarging top of hole opening..... have used such a bit while employed as a cabinetmaker..... might be hard to find such a bit.... drill sgt.

I am assuming the deeper hole needs to be the same diameter as the original hole?

If that is the case, the Forster bit will work. This is how I would do the job :

Mount (clamp) work to a drill press table, centering it with the bit in the chuck with the machine off.

Adjust table height so the bit cannot go too deep when the bit is at full depth.

Grind slight point off from the center of the bit. Bit will now make a flat bottom hole.


If the desired hole is not cylindrical - use a router with a straight bit. Make a wood pattern in the shape of the desired hole. The pattern needs to be oversize by the radius of the router base minus the radius of the bit (this sounds right). The pattern should not let the router bit cut larger than the desired shape & size. The pattern gets clamped to the work, the router can only move around inside the pattern. The bit needs to reach the depth of the desired hole. Start by plunging carefully into the center. Slowly do a spiral cut, taking a very light cut, until in contact with the pattern. Final pass around perimeter cuts hole to final size.

Hammer and a Flathead Screwdriver, right?

I would use a rabbiting bit. Chuck it in a router or a drill press. Drill press would be my first choice if the work piece is small enough.

Thanks all. I got it with a straight router bit. I want to say it was 5/8. With the 1/4” shank it gave me just the right amount of cut into the side and the length was perfect. Any farther and it wouldn’t have cut deep enough.

I was re-wiring my first guitar - the one I learned on. I re-did everything with quality components and pickups. Now it plays better than it ever did. 50s style steel braided cotton pushback wire is interesting.

I would suggest a Die Grinder and a ball shaped carbide burr. With that you can go inthru the entry hole and enlarge the cavity quickly and easily. However I will caution that these burrs are intended for shaping steel and they cut thru wood like warm butter knife thru room temperature butter. SO be very careful with how quickly you feed the burr in the opening because it would be dead simple to punch a hole all the way thru.

BTW, I used this setup to carve some grooving in the forearm for my Beretta 686 to get the forearm bedded so it didn't rattle.

Dermal has a sander bit. A wider drum in the shank. Perhaps that extra 1/4 inch width on the inside chamber will suffice.