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Discussion Starter · #1 ·
I am doing a mod to my Gretsch 5420t that will require me to drill new tuner post holes in the headstock.

I need to plug the existing holes Then drill the new holes that are in different locations.

I could use any advice on plugging the existing holes. I was going to measure the headstock thickness and
then use epoxy glue. I will buy the closest dowel size and hand sand it to fit. If I can cut them perfectly to the thickness
I could fit them and they won't require sanding.

The Headstock is very glossy and black, and I would assume a very thick coat of poly finish. I know if I use a regular Canadian Tire drill bit it will chip around the outside of the hole on the top, and probably chip and splinter when it breaches the bottom.

What techniques can I use to:

-cut the dowel square and to the correct length
-glue the dowel in place
-possibly spot refinish the old holes that are now filled with dowel

-drill the new holes centred and square
-the type of drill bit to do the best job
-prevent chipping and splintering

Thanks for any advice in advance.
 

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When I drill out the end pin hole on acoustic to install a pickup jack I cover the area that I’m gonna drill with masking tape and the drill doesn’t tear the finish. I use a half inch step drill for this and I realize that the holes you’re drilling will be smaller. But something to consider is whether or not a piece of tape over the area would keep the finish from tearing.
 

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Discussion Starter · #3 ·
When I drill out the end pin hole on acoustic to install a pickup jack I cover the area that I’m gonna drill with masking tape and the drill doesn’t tear the finish. I use a half inch step drill for this and I realize that the holes you’re drilling will be smaller. But something to consider is whether or not a piece of tape over the area would keep the finish from tearing.
I was going to do that, but I don't think it will help with the drill bit going through at the bottom. I was thinking perhaps a brad bit would be better than a typical Canadian Tire titanium coated bit. I have just read that a piece of wood on the bottom can help prevent the tearing and splintering when the drill breaches the bottom of the headstock.
 

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What @Wardo said.

Do you need to plug the old holes - do they need to be smaller or different spacing? Otherwise consider simply enlarging the existing holes.

If you do need to plug the holes, this means you can use a spade bit to drill the new ones. A spade won't chip the edges (has those teeth that score a line around the circumference before it really digs in). Similar idea to the brad bit suggested above but the centre point is comparatively much longer. Still use tape and drill a small 1/8" or so pilot hole - enough to guide the centre point of the spade (the newer style screw thread ones may not be the best here). Start slow (use a variable speed drill) to make the score line around the circumference without chipping the finish (or wood) and then open her up once you're into the material a bit. Don't drill all the way through; use the pilot hole to finish off from the other side to avoid chipping the back of the headstock. If possible use a bit that is a touch smaller than the hole size needed and widen it out that last 1/32 or 1/16th with a round file or sandpaper wrapped around a dowel/screwdriver.

A Fosner bit is a good idea too, but only in a proper drill press and since the headstock is angled you'll have to make a jig to get it to sit there. And the pilot should go straight through in that case as well (not sure what was meant by both sides there)

As for the plugging, don't worry about cutting the dowel exactly right. Get it fitted snug (this may mean enlarging the hole a tad; again use a round file, and go slow). once the dowel is set up in place with ends sticking out both sides (do not try to get it flush on either side - no need and high probability of not getting it right), trim it with a flush cut saw such as a Japanese pull saw. It can be awkward (and dangerous because power vs hand tool) but a long enough flush trim bit in a router (bottom bearing) will work too if you have a steady hand and are experienced using them.

For minor touchups you can use cheap nail polish (it's actually nitro). If the headstick face is black then a colour match is easy; your gothic/emo teen may already have some.
 

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From what I just read about bits they are designed to make flat bottomed holes, nothing mentioned about the chipping.
They make a very clean edge. What I meant was drill partway through from the back of the headstock (following the 1/8" guide hole with the tip) then finish from the top. I've never used one on a guitar, but have used them (both in a drill press and freehand) on lots of furniture pieces. They cut the outside of the hole a little before the inside part, and they do make very nice holes with flat bottoms if you don't go all the way through the workpiece.

IMO a spade bit is the worst option. Both a spade and brad point bit will give a high chance of chipping.

If you can avoid plugging the holes and can just make the existing holes bigger, that would be ideal. You frequently see this done using a reamer on YouTube videos. Most reamers are more suitable for thin pieces so to use one for something as thick as a headstock you'd want to find one with a long taper.

YMMV - this is based on my experience with furniture not your expensive guitar!
 

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@player99, on numerous occasions, I've had to enlarge potentiometer holes to accommodate CTS pots, a task somewhat analogous to your situation if you can avoid the dowelling route. I've had success by first covering the original hole with decent quality masking tape, determining the target diameter of the CTS shaft that has to go through it, and marking that on a good quality step bit. Once this prep is done, I put the drill in reverse, and SLOWLY (repeat SLOWLY) start enlarging the hole through the poly layer. Once I am well past that point, put the drill in the normal rotation and again slowly drill away through the wood.
In the case of tuners, I'd repeat the 'drill-thru-poly' process on both sides of the headstock.
Poly is notorious for chipping, so slow and steady does it! Good luck.
 

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Discussion Starter · #10 ·
What @Wardo said.

Do you need to plug the old holes - do they need to be smaller or different spacing? Otherwise consider simply enlarging the existing holes.

If you do need to plug the holes, this means you can use a spade bit to drill the new ones. A spade won't chip the edges (has those teeth that score a line around the circumference before it really digs in). Similar idea to the brad bit suggested above but the centre point is comparatively much longer. Still use tape and drill a small 1/8" or so pilot hole - enough to guide the centre point of the spade (the newer style screw thread ones may not be the best here). Start slow (use a variable speed drill) to make the score line around the circumference without chipping the finish (or wood) and then open her up once you're into the material a bit. Don't drill all the way through; use the pilot hole to finish off from the other side to avoid chipping the back of the headstock. If possible use a bit that is a touch smaller than the hole size needed and widen it out that last 1/32 or 1/16th with a round file or sandpaper wrapped around a dowel/screwdriver.

A Fosner bit is a good idea too, but only in a proper drill press and since the headstock is angled you'll have to make a jig to get it to sit there. And the pilot should go straight through in that case as well (not sure what was meant by both sides there)

As for the plugging, don't worry about cutting the dowel exactly right. Get it fitted snug (this may mean enlarging the hole a tad; again use a round file, and go slow). once the dowel is set up in place with ends sticking out both sides (do not try to get it flush on either side - no need and high probability of not getting it right), trim it with a flush cut saw such as a Japanese pull saw. It can be awkward (and dangerous because power vs hand tool) but a long enough flush trim bit in a router (bottom bearing) will work too if you have a steady hand and are experienced using them.

For minor touchups you can use cheap nail polish (it's actually nitro). If the headstick face is black then a colour match is easy; your gothic/emo teen may already have some.
The holes have to be moved. D - G and A - B not much, but enough to require redrilling. The E - e need to move around 80% of the size the hole, so a 20% sliver of overlap.

If I use a saw I will scratch the finish, and I don't have the nice expensive Japanese pull saw. I think getting the length perfect ans the ends square will eliminate the problems. I am wondering if I should make the dowels a bit shorter to allow for the finish? The nail polish sounds like a good idea.
 

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Discussion Starter · #11 ·
@player99, on numerous occasions, I've had to enlarge potentiometer holes to accommodate CTS pots, a task somewhat analogous to your situation if you can avoid the dowelling route. I've had success by first covering the original hole with decent quality masking tape, determining the target diameter of the CTS shaft that has to go through it, and marking that on a good quality step bit. Once this prep is done, I put the drill in reverse, and SLOWLY (repeat SLOWLY) start enlarging the hole through the poly layer. Once I am well past that point, put the drill in the normal rotation and again slowly drill away through the wood.
In the case of tuners, I'd repeat the 'drill-thru-poly' process on both sides of the headstock.
Poly is notorious for chipping, so slow and steady does it! Good luck.
There's no way to avoid the dowel steps. For sure on the E - e. If I'm going to do those two I might as well do them all, as it will make drilling way easier and I won't have "ventilation" in the headstock.
 

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when you use a brad bit the tear out is terrible. So you pre drill a 1/8 or smaller hole all the way through, then use the brad from both sides towards the center so no tear out. The pre drill guides the point. Hand reamer is the best method but most hobbyists don't have a set. Or you super glue and masking tape trick and mount a backing board to the headstock so there is no tear out then get rid of the backing board

make the dowels short and fill with epoxy/resin, colored if need be, wet sand to suit. and for wood drilling personally i think one of these is your best friend.

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The holes have to be moved. D - G and A - B not much, but enough to require redrilling. The E - e need to move around 80% of the size the hole, so a 20% sliver of overlap.

If I use a saw I will scratch the finish, and I don't have the nice expensive Japanese pull saw. I think getting the length perfect ans the ends square will eliminate the problems. I am wondering if I should make the dowels a bit shorter to allow for the finish? The nail polish sounds like a good idea.

Then with the significant movement of holes, and your other concerns, the proper thing to do is refinish the headstock. Futzing about trying to get the dowels sized perfect before gluing in and leaving just the right amount of space for finish thickness and then doing multiple spots of touch ups is harder and more work.

Like don't get me wrong, I'd applaud a judicious kludge here, but it sounds like you care more than that.
 

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Discussion Starter · #14 ·
Then with the significant movement of holes, and your other concerns, the proper thing to do is refinish the headstock. Futzing about trying to get the dowels sized perfect before gluing in and leaving just the right amount of space for finish thickness and then doing multiple spots of touch ups is harder and more work.

Like don't get me wrong, I'd applaud a judicious kludge here, but it sounds like you care more than that.
I don't think refinishing the whole headstock is going to work for me because I will lose the inlaid Gretsch logo and the ELECTOMATIC going down the middle of the headstock.The upper 4 tuner holes' damage will most likely be hidden by the new tuner post washers, and I will have to live with the two black dots partially visible from the E and e holes. The less I have to mess around with the finish the better off I will be. As far as the futzing, I have the ability to futz, I am not willing to respray and buff and polish the complete headstock. As I said if I can do a decent job of dowels, drill without much chipping and then use your suggestion of nail polish I will be satisfied. Unless I hire someone to do it for me, but I don't think the guitar is worth it, and once I drill the new post holes I have ruined it's value as an original guitar. I like the guitar, and I will keep it as a modded player for myself.
 

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Discussion Starter · #15 ·
when you use a brad bit the tear out is terrible. So you pre drill a 1/8 or smaller hole all the way through, then use the brad from both sides towards the center so no tear out. The pre drill guides the point. Hand reamer is the best method but most hobbyists don't have a set. Or you super glue and masking tape trick and mount a backing board to the headstock so there is no tear out then get rid of the backing board

make the dowels short and fill with epoxy/resin, colored if need be, wet sand to suit. and for wood drilling personally i think one of these is your best friend.

View attachment 437394
I don't want to sand because I will make more of a mess and I don't want to lose the logos.

Your suggestion with the brad bit is a good one for sure.
 

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Discussion Starter · #16 ·
I have a cheap Craftsman table top drill press. How would I use this to square up the drilling? Otherwise I have to use a hand drill and eyeball it. Which won't work well. The holes will be angled and then the dowels won't be level to the top.

Maybe do it on a couch and use towels to level up the guitar body so the headstock sits flat on the drill press? I can use something to prevent the drill press tray or shelf (whatever it's called) from scratching the bottom but I will probably have to hold it by hand and not use clamps?
 

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I wouldn’t worry about cracking the poly. I’d just drill it and hope for the best and then layer it back on with new poly and knock it back and shine it up even.

The dowel and epoxy should work to fill. I might even just use epoxy. I’d tape off one end and pour it right in.

Another option could be to take a heat gun and scalp the poly off of the entire back of the headstock. Maybe even heat the back and use a razor blade to cut 3 on a plate sized rectangles around where the existing holes are. That might accommodate a crack free drill through area at the back.
 

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If you're worried about loosing logos build up the finish coat. High build clear coat 2k or something like that. More room for error
 

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I don't think refinishing the whole headstock is going to work for me because I will lose the inlaid Gretsch logo and the ELECTOMATIC going down the middle of the headstock.The upper 4 tuner holes' damage will most likely be hidden by the new tuner post washers, and I will have to live with the two black dots partially visible from the E and e holes. The less I have to mess around with the finish the better off I will be. As far as the futzing, I have the ability to futz, I am not willing to respray and buff and polish the complete headstock. As I said if I can do a decent job of dowels, drill without much chipping and then use your suggestion of nail polish I will be satisfied. Unless I hire someone to do it for me, but I don't think the guitar is worth it, and once I drill the new post holes I have ruined it's value as an original guitar. I like the guitar, and I will keep it as a modded player for myself.

If it is inlaid vs paint or decal, then you won't lose it at all. The inlay is much deeper than the finish; and you don't even have to sand all the way though the finish.

But fair if it's mostly hidden (it sounded like there'd be visible bits around 4-5 of the tuners; some machine heads have bigger nut flanges or washers than others with just tiny ferrules).

The epoxy thing above is a good idea for you then, but epoxy can be a bear to sand (harder than wood), especially spot sanding, to level and blend the epoxy into the original finish. You can be there for days with progressively finer grits on the eraser end of a pencil. Tinting it black to match the front of the headstock would be easy, but those Gretshes have a solid colour on the back and that may be a bear and a half to match, but the tuners' gear box will likely completely cover it.
 
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