drilling tech, chipping of coating

[chalie]

Hi Guys,
Wonder how many technique we have for drilling a hole on the finished guitar body without damaging the top coat.
Thanks.
Chalie

[ma4rk]

Put some masking tape over the top & drill through that however, someone might have an even better suggestion...

[Scott in Dallas]

In my experience, tape usually works. A few layers of masking tape will usually do, but be careful pulling it up. If you can clamp a block to it that would be ideal. Also use a very sharp drill bit. Brad point bits and forstner bits would probably be your best bet. A drill press is better than a hand drill, and going slowly and letting the drill do the work is essential. I tried to cut a corner or two drilling into my Squier '51 and made a hell of a mess of it.

[chalie]

Thanks. I found that not a good way as it still chipping but I use a milling bits to sloping the outer side of the hole step-by-step before enlarging the hole with next drill bits. This is a very time consume method and can not keep up my delivery.

Originally Posted by ma4rk

Put some masking tape over the top & drill through that however, someone might have an even better suggestion...

[mech]

If you have a drill press and can secure the body this works well with a good drill press that has very little runout or spindle play.

Use a brad point bit that is the correct size. Angle point and Forstner bits do not work well. The work surface needs to be as perpendicular as possible to the drill bit.

Set the drill press for a moderately slow speed. Bring the bit down to the surface and while applying moderate to light pressure, turn the chuck by hand until you get down into the wood. Too much pressure can crack the paint and cause a chip. With the bit firmly against the wood, turn the drill press on and drill the hole. Turn the drill press off when you reach the desired depth and back the bit out while turning the chuck by hand.

You may be able to do this with a hand drill if you are very steady. Any sideways pressure by the bit against the paint will probably cause a chip.

mech

[Means2nEnd]

High speed dremel if it's to widen pot holes. Goes so fast is goes through any finish like a hot knife through butter. I have done it a bunch of times no chipping. Reamer tools shred a finish.

[Bruce Johnson]

The best way to avoid chipping the finish is to use a fitted hold down block. It's a block of hard wood, like maple, with a hole in it the size of the drill bit. If you're trying to drill into a curved surface, the bottom surface of the block can be contoured to match. This block needs to be clamped down on the body. The idea is that you are pressing down on the circle of paint surrounding the hole, so that it cannot lift up. Drill the hole down through the block with a sharp brad point bit, running very slow.

If this is a production job (large quantities), make up a special tool/fixture that's like a woodworking clamp. It clamps onto the body, and the upper jaw is maple with the hole for the drill bit.

[rojo412]

For smaller holes, I just use the bit and spin it with my fingers to "drill" through the paint. This is great for mounting bridges or pickguard screws.

And if I needed a bigger hole, I'd probably chose a Forstner and do the same thing. Have it cut a shallow "practice" hole and then use the drill for going through the body.

Pre cutting the chipable surface seems to keep it from chipping.

But I've also used masking tape. And I think the block of wood with the hole in it to guide it through sounds like a fantastic way to do it as well.

[Bassman62]

The faster the drill speed the better.