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Idiot proof tool to enlarge a tuning key hole

#21
A while back, I had to enlarge a hole in a guitar body. The hole was not a through-hole in my case, so a reamer was out. What I did was set up a drill press with a drill bit that matched the existing hole, and used that to carefully center on the existing hole, then swap out the drill bit for the new larger one.
 
#22
rudy4444 said:
24997174[/URL], member: 216453"]Hipshot Ultralights come in two string post sizes. Make sure you have tuners in hand to verify the hole size. If the old holes are close to what you need then you can carefully sand using abrasive wrapped around a dowel that's slightly smaller than the existing hole.

If you have the "licensed" import versions they require different holes than the regular Ultralites.

"Licensed" Ultralites (from Hipshot's website):
  • The 3/8" diameter version fits basses with a headstock hole size of 14mm (9/16")
  • The 1/2" version fits basses with a hole size of 16mm (41/64")
The standard Ultralites use 9/16" and 11/16" holes for the 3/8" and 1/2" string post tuners.

Enlarging a hole in your case would depend on what tools you have available. It's also possible to slightly enlarge a hole by using a small sanding drum in a Dremel rotary hobby tool. I've used a standard twist drill in a hand held drill, but ONLY with the drill running in the REVERSE direction.
You can also make a hardwood guide with a properly sized hole drilled in it. You clamp the guide over the hole with a undrilled block of hardwood on the back side of the hole and you can then safely use a Forstner bit that otherwise needs solid material under the center spur to guide it.

As mentioned, a reamer can be used, but unless the reamer maximum diameter happens to be the exact size you need you end up with a tapered hole which I'm not fond of. The Hipshot tuner doesn't have a lot of wiggle room on the body side of the tuner, so if you drill a straight through hole that matches the bushing size the tuner body doesn't cover the hole by much. I'm surprised more people don't use a stepped size hole for mounting them.

In any case, it's usually not difficult to enlarge a hole safely if a little common sense and care are exercised.
Click to expand...
That’s what I did. I used a Dremel tool with a small sanding drum. You have to go slow and keep testing your fit so you don’t remove too much wood.
 
#24
Different idea: remove a current tuner. Measure that hole with a caliper. Get tuners that fit that hole. Deal with screw pattern- if it doesn't match, patch screw holes and then screw. If it does, you're good.

Avoids the whole tuner hole problem (tear out, cracking, too big, too small, no drill press, have a drill press but can't clamp neck in a good position, etc, etc.). And if you need to go back, you can.
 
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#27
dwizum said:
Just to be clear - both the USA and the Licensed versions are available with either string post size. So, knowing you have Licensed doesn't imply a specific hole size is needed, you still need to verify the post size in order to know the required hole size.
Click to expand...

Yep, thanks for that. It’s the larger of the two sizes. I can confirm that.
 
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#28
I only skimmed, so pardon me if someone else mentioned it.
But there absolutely is an easy, cheap, idiot proof way to make your tuners 1/2"
It's a cheap 1/2" step bit.
https://www.amazon.com/Neiko-10182A-Titanium-Drill-Speed/dp/B001CBNPBW/ref=sr_1_4?dchild=1&gclid=CjwKCAiAyc2BBhAaEiwA44-wW4NmsP79TgFKKp5drkSvlj12YvF32tqvEH-fyyP6ZswFU5QcXeLpCBoCI-wQAvD_BwE&hvadid=176316013145&hvdev=c&hvlocphy=9002537&hvnetw=g&hvqmt=e&hvrand=17186115180626205354&hvtargid=kwd-122220078803&hydadcr=21915_9585368&keywords=1/2+step+bit&qid=1614033496&sr=8-4&tag=googhydr-20

just do half from one side, and half from the other side to make sure there is no ugly 'chip out'. a cheap drill (no drill press required) can do this no problem in a couple minutes.
 
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#29
I used a router with another neck with the hole size I wanted as a template. It was on a fender-style neck and I get that wouldn’t work with what you’re doing. But it would be very easy to make a router template for a 1/2” hole. If you can get it to work on the neck of your bass, I think it’s a good option. It also allows you to move the center of the hole slightly if it’s close to the edge or something.
 
#30
And do this before you shove anything in the holes, just for the heck of it ;);

Tuner Holes.jpg
 
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#34
Dan_reeves said:
I bought a bass that has 2x2 Y style tuning keys that are I believe 3/8 in diameter on the headstock. I want to swap them out for some Hipshot Lic Ultralights which I think I need to increase the hole size to either 1/2 or 5/8. I will measure to make sure once it arrives. Is there an idiot proof way to enlarge the holes? I don’t have a drill press - I do have some nice hand drills with forstner bits, etc. But what is the easiest way to do it without potentially jacking up the headstock?

Sorry if this is the wrong place - I wanted to ask the woodworking experts. Thanks!
Click to expand...

Here's one way to do this:
Bore a hole of the desired diameter in a squared block of wood that's large enough to clamp securely to your head stock and thick enough (at least 3/4") to successfully guide the same bit when used with a hand-held drill. Use a sharp Forstner or brad-point bit in your drill press to drill the hole, making sure to run the bit at the RPM recommended for the type and size of bit being used.

Next, clamp the block securely to the head stock, and use the same bit to drill slowly through the head stock. You may want to face your clamps with cork or leather to help prevent slipping.

I strongly recommend practicing on a head stock facsimile before drilling the actual headstock.

Good luck! :)
 
#36
Bruce Johnson said:
This is the best tool: A straight reamer with a pilot. It makes a clean counterbore of the exact size, with no splitting or chipping. I've made them up in many different sizes for different Luthier jobs. I have a couple sized just for bass tuner bushings. I normally use them in a drill press, slow speed, but they can also be turned in by hand.

It's a simple design, easy to machine with a lathe and a mill. I usually make them from stainless steel, and don't even bother hardening them.

View attachment 4178135

View attachment 4178136

I don't understand why you guys are recommending taper reamers? A taper reamer is great for enlarging holes in thin stock, but in a headstock it will cut a tapered hole. A tuner bushing needs a straight hole, a counterbore of a particular diameter and depth.

A straight reamer, like I've shown above is the best way to cut a precise straight hole. A pilot on the front makes it easier and neater. But, you can also use a standard Machinist's Reamer of the right size.

You can also use a large straight drill bit, gently, turning it by hand.

If you don't have any of those tools, the safest thing is a large round file. Slowly and carefully, checking the roundness and diameter.
Click to expand...

I dont actually disagree with any of this in general practice but there is an argument for a tapered hole with ultralites because the threaded cap is bigger than the shaft of the tuner. Because of that a hole sized for the cap leaves a fairly large gap around the shaft of the tuner on the back side of the headstock. If your hole isn't perfectly centered and square it gets very close to showing from under the casing of the tuner. When I install them I drill a smaller hole on the back of the headstock sized for the shaft and then a larger hole on the face of the headstock to accommodate the threaded cap.

20201114_021559.jpg


An added benefit is that drilling the hole in both the front and back face drastically reduces the chances of tear out. This may or may not be useful in OP's case but its something I put some thought into recently. Reaming from the front with a tapered reamer would leave a smaller diameter hole on the back of the headstock and with the right size reamer might be an easier and more elegant solution than mine.
 

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