Drilling volume pot hole

Hi. This is the only forum where I get great, consistent answers. I'm about to drill a hole for my volume pot on my newly painted guitar. I was going to use blue painter's tape to protect the finish.

My question is do I drill going from inside the cavity out, or from the front of the guitar into the cavity? Which way is safest for the finish? I have made holes bigger by going from the cavity out, but this is drilling an entire new hole. thanks in advance,
Pete

It would have been better to do your drilling before finishing, but since that horse it out of the barn you should put the masking tape on top of the body and drill from the top. The tape will help prevent finish shipping. Happily, the washer and knob will cover any small finish chips around the edge of the hole.

Thanks for your input. Yeah, hole first would have been better. Any other advice before I get the drill out?

I think I'd use the pot's flat washer (ID) to draw an outline of the hole, then carefully score the finish just a bit larger with a sharp hobby knife (don't slip!). Also use a punch to mark the center and hold the bit. That might keep the finish from lifting up etc.

Drill using 3 progressively larger bits as well, and from the front.

I'm not an expert, it's just how I'd do it if I forgot to drill the hole before painting :wink:

If you can fit a block of wood into the cavity to give the drill something to continue into, it'll minimize chipping.

Use a sharp FORSTNER bit.

A lot of times, I finish the guitar before I drill holes, so I don't have to worry about them getting nasty or absorbing water during the buffing process. I simply lay down a nice piece of blue painters tape, center punch where I want to dril, and drill very slowly using a forstner bit.

Use a sharp FORSTNER bit.

If you don't have a set of Forstner bits, get one, it'll be the best drill bit investment you'll ever make. Home Depot has a decent set that goes on sale regularly for $20.00, and they're pretty decent.

Awesome. Thanks for the bit advice. You start small and work up to larger bit size right? How many bits would you use if you work up?

No, use one forstner bit slightly larger than the size of the shaft. A forstner bit has a point in the center which hits first. Next it cuts the circumference of the circle and begins hogging out the material inside the circle. As mentioned above center punch where you want your hole to be & go slow, let the bit do the cutting. Also mentioned above, if you can, get a backer board where the bit will exit, which gives you a perfectly clean exit cut. If not, go very slowly, let the bit cut the circle as it exits. If you push hard it will tear out, risking the flat surface your pot sits on. Take a practice run or two on some scrap.

Good luck

Richie

Oh, also, if your bit is the same size as the shaft & the shaft won't fit thru the hole, cut the hole. Next, get a dowel smaller than the hole, wrap some light (220) grit sandpaper around it. Enlarge the hole until the shaft fits, using DOWNWARD strokes, from the outside (finished side), working your way around the hole. Again, take your time. If you cut on the upward stroke the paper could grab the finish & lift it up. On the downward stroke the wood acts as a backer. This whole show only takes a couple of minutes but you really need to be in the zone. Make it take longer than it should.

Richie

I advise against working.your way up in size. Do just as others have suggested. Use awl to mark the hole and then drill with a forstner bit. If you were to drill a smaller hole first you would not be able to center the forstner bit.

I was suggesting going up in bit size only if you use standard twist bits.

If you get a forstner, just use it.

http://www.amazon.com/dp/B005HTQQQG/ref=asc_df_B005HTQQQG2014869?smid=ATVPDKIKX0DER&tag=hyprod-20&linkCode=asn&creative=395093&creativeASIN=B005HTQQQG&hvpos=1o1&hvexid=&hvnetw=g&hvrand=21291025901201450012&hvpone=&hvptwo=&hvqmt=

I advise against working.your way up in size. Do just as others have suggested. Use awl to mark the hole and then drill with a forstner bit. If you were to drill a smaller hole first you would not be able to center the forstner bit.

When you use the awl to mark the hole, just a little tap? Sorry, never used one before

When you use the awl to mark the hole, just a little tap? Sorry, never used one before


Right, just a tap to make a small mark or dimple in the wood. Then you can set the point of your forstner bit in that hole.

Unlike a centre punch used for metal, a proper carpentry awl (bradawl) has a screwdriver type handle, you push and twist it into the wood. Straight edge blade for screws, spear-point or needle point for drilling. You can use an old dart head.

One more vote for using a Forstner bit. Any time I want a clean hole in wood this is what I use. Even a spade bit would be better than a regular twist drill bit for your situation, but a Forstner bit is better yet. The sharp cutters will make a clean cut through the finish, as long as the finish was properly applied to the wood.

Harbor freight carries a decent set of Forstner bits at an affordable price: http://www.harborfreight.com/16-piece-titanium-nitride-coated-forstner-bit-set-39812.html

-Gnobuddy

I'd stay away from the spade bits. Those things just tear wood up and shatter it underneath.

Picked up the forstner bits. Thanks for the advice. I also bought a regular awl at the store. It has a pretty sharp point. If I'm drilling from the top of the guitar finish, just a dimple in the finish right? I'm nervous the awl might do damage to the finish. I may dive in soon so let me know! Thanks again for the ideas.

I'm not a woodworker by any means but I've had luck by getting the hole started by drilling backwards. This gets you started without risk of tearing. This could be terrible advice so take it at face value but it works for me without having the best possible bits

I'd stay away from the spade bits. Those things just tear wood up and shatter it underneath.
I've never had a problem with them as long as I:

(a) Back the item I'm drilling with a piece of scrap wood and let the bit cut into the scrap as it finishes going through the workpiece.

(b) Keep the rpms low.

(c) Feed the bit with light pressure and let it cut its way through the wood, no forcing.

The larger diameter spade bits have two sharp "teeth" at the outer corners, and these cut into the material before the main bulk of the wood is removed. So the bits tend to make a clean cut at the periphery of the hole (which is where the guitar's finish is), even if the wood removal inside that periphery is a little sloppy.

I'm not a luthier, but I used to build model airplanes and that involved some delicate woodworking from time to time. I have hole saws, spade bits, and Forstner bits, and depending on the particular circumstance, any one of those three might be the best choice.

One nice use of the Forstner bits was cutting clean, shallow holes in which to insert and glue small rare-earth magnets. The magnets are so strong that this is a convenient way to attach removable battery hatches and so on to the model. It just snaps on and stays there due to the magnetic force.

-Gnobuddy

It has a pretty sharp point. If I'm drilling from the top of the guitar finish, just a dimple in the finish right? I'm nervous the awl might do damage to the finish.
I use a spring-loaded center punch:
http://www.harborfreight.com/spring-loaded-center-punch-621.html

Set the wood surface level, position the tip of the punch exactly where you want the hole, make sure the punch is vertical, and push gently down.

If the wood is soft you'll get the dimple you want with very little pressure, and you can stop and remove the punch when you see that you have enough of a dimple.

If the wood is hard, or you're working with metal, as you continue to push down on the punch, at some point the spring-loaded mechanism inside the punch will trigger, make a little "thwack!", and effectively deliver one sharp hammer blow to the punch, from the inside. And you'll have a nice little dimple in the workpiece.

There are also center punches which don't have the internal spring-loaded mechanism, but in all but the softest materials you have to tap those with a hammer, which is a little more risky than simply pushing straight down on the spring-loaded type of punch.

As always, practice on some scrap wood first. Best to use some wood similar to the wood you used for the guitar body, so it will have a similar feel.

-Gnobuddy

Those auto-punches are great but they are for metal, not a carpentry tool.
You do not use a hammer in woodwork except to bash nails in.
Use a wood drill for drilling wood, several designs all intended to stop chipping and ripping.

Push the bradawl into the wood through the finish. Don't be frightened of it. Practice drilling some scrap.

If you are enlarging an existing hole then you do need a set off good sharp twist drills ("straight jobbers") but use slowly in a hand powered wheel brace. Too much reliance on power tools overlooks that hand tools have greater control.

Those auto-punches are great but they are for metal, not a carpentry tool.

I use them on both metal and wood. With wood you get a deeper dimple, perfect for positively locating the drill bit and making sure it doesn't slide sideways as you start to drill.

I wouldn't use one if I was drilling a truly tiny hole (1/16" dia, say), as the dimple would be too big and would still show after the hole was drilled. But for the OP's purposes a bigger dimple is no problem, as it will still be much smaller than the hole he eventually drills, and will vanish during the drilling.

Too much reliance on power tools overlooks that hand tools have greater control.
Very true. A tapered reamer is another tool good for slightly opening up an existing hole that is a little too small.

-Gnobuddy

I'd drill with a 5/16 bit then use one of these (T-Handle reamer) to finish it.
http://drillsandcutters.com/images/products/detail/116dwrrtr.jpg

I use them on both metal and wood. With wood you get a deeper dimple, perfect for positively locating the drill bit and making sure it doesn't slide sideways as you start to drill.

I wouldn't use one if I was drilling a truly tiny hole (1/16" dia, say), as the dimple would be too big and would still show after the hole was drilled. But for the OP's purposes a bigger dimple is no problem, as it will still be much smaller than the hole he eventually drills, and will vanish during the drilling.

Very true. A tapered reamer is another tool good for slightly opening up an existing hole that is a little too small.

-Gnobuddy

Argh! you luddite! :wink:

You do not need to bash a scribing awl - that's the pointy one with the fat "sail makers" handle for pushing the point into wood, very accurate it is too.

Again we see a perfectly good tapered reamer designed to cut metal whereas a wood reamer has a fluted cut to cause less chipping and tear-out. Violin and lute makers use them for the wooden tuning peg holes.

At one time drills for wood and metal had different blade attack angles for better cutting and clearing. You can still re-sharpen a HSS metal drill to cut wood (or any other material) more efficiently, but these days twist drills are so cheap they are disposable items. You can still get wood-specific twist drills, I don't like the little ears on them - they tend to run off-centre if you try to broach out an existing hole. A metal twist drill has a ~120 degree point but a wood drill wants a 90 degree point or even 60 degrees for a self-counter-sink.

Use a sharp FORSTNER bit.

A lot of times, I finish the guitar before I drill holes, so I don't have to worry about them getting nasty or absorbing water during the buffing process. I simply lay down a nice piece of blue painters tape, center punch where I want to dril, and drill very slowly using a forstner bit.


Excuse me for very slightly hi-jacking the thread, but I have a quick question that is almost the same as the OPs:

I had intentionally not drilled PG and strap button holes on my current (first) build yet, planning on leaving until after it's finished, for exactly the reason Colt says. As these are only small holes (as opposed to the OPs), am I doing the right thing?

It's a swamp ash body, with a translucent blonde finish (well, it isn't yet.....but it will be........)

Excuse me for very slightly hi-jacking the thread, but I have a quick question that is almost the same as the OPs:

I had intentionally not drilled PG and strap button holes on my current (first) build yet, planning on leaving until after it's finished, for exactly the reason Colt says. As these are only small holes (as opposed to the OPs), am I doing the right thing?

It's a swamp ash body, with a translucent blonde finish (well, it isn't yet.....but it will be........)

Yes.

Use a very sharp twist drill to pilot the holes through the finish. Do not go too deep for these small screws, you only need a starter hole. Turn the drill bit slowly as you go through the finish to avoid chipping. I would be inclined to use a wheel brace or a pin chuck for the pickguard, lining up on the holes in the thing. It may help to make a bore hole just through the finish so the screw shank does not split it wide, try a using small countersink here.

The screws for the strap buttons are larger, the one in the upper bout is difficult to get at with a drill with the neck on but a bradawl does the job nicely. The bradawl is the correct tool to pilot holes this size, this is the one with the little sharp chisel blade to sever and separate the wood fibres but without extracting wood and so making the hole loose fitting.

Yes.

Use a very sharp twist drill to pilot the holes through the finish. Do not go too deep for these small screws, you only need a starter hole. Turn the drill bit slowly as you go through the finish to avoid chipping. I would be inclined to use a wheel brace or a pin chuck for the pickguard, lining up on the holes in the thing. It may help to make a bore hole just through the finish so the screw shank does not split it wide, try a using small countersink here.

The screws for the strap buttons are larger, the one in the upper bout is difficult to get at with a drill with the neck on but a bradawl does the job nicely. The bradawl is the correct tool to pilot holes this size, this is the one with the little sharp chisel blade to sever and separate the wood fibres but without extracting wood and so making the hole loose fitting.

Thank you, jefrs. :smile:

Argh! you luddite! :wink:

You do not need to bash a scribing awl - that's the pointy one with the fat "sail makers" handle for pushing the point into wood, very accurate it is too.

And where exactly did I say anything about bashing an awl? :confused:

-Gnobuddy