# Hole Size for Tune-O-Matic bridge anchors



## sick-strings (Mar 6, 2008)

Hi all,

Just purchased the following for my project:
http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&rd=1&item=130210694911&ssPageName=STRK:MEWN:IT&ih=003

Anyone know what size hole needs to be drilled for the anchors? I tried 1/2" but it was too big - tried 3/8" but too small. The diagram shows the hole size as 2 - 06.3 (where the 0 is a symbol) but I don't know what that means.

Any suggestions?

Thx everyone.


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## Joel Rainville (Apr 21, 2008)

The diagram only shows the hole diameter in the bridge itself (6.3mm), not the required size hole for the anchors.

I just installed a cheap, chinese made wraparound tailpiece yesterday, and I had to use a 31/64" drill bit for the anchors. But please don't take for granted that's the one you need, you will need to either measure your anchors or buy a drill bit set in 1/64" steps (i.e. every size from 1/4" to 1/2" in 1/64" steps) and test in scrap to see which one fits. 

Your gonna need the drill bits for future builds anyway, and a digital caliper is very handy, so I'd get both if I were you. It's money well spent. ;o)


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## 1PUTTS (Sep 8, 2007)

sick-strings said:


> Anyone know what size hole needs to be drilled for the anchors? I tried 1/2" but it was too big - tried 3/8" but too small. The diagram shows the hole size as 2 - 06.3 (where the 0 is a symbol) but I don't know what that means.


I agree that a caliper is a good investment - that way you're not guessing. Mine isn't digital but it's still very accurate if used carefully.

Having said that, I have a 7/16" bit that works for those types of bridges (but I always check first). And note that you're measuring the diameter below those "fins" on the post. The fins are a bit wider and are meant to dig into the wood to hold them securely. Also, it's probably a good idea to "step drill" the holes (start smaller and work your way up - don't try to do it all in one shot) just to avoid any cracking or tears.

And finally, you want to make sure you get a 90 degree hole (or as close as possible). I have a bunch of jigs that I made using long bolts with a washer glued to the bottom (to keep it flat). I use whatever bolt-jig is just slightly larger in diameter to the bit I'm using. It just helps guide the bit in straight.


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## sick-strings (Mar 6, 2008)

Thx guys. My bridge/tailpiece showed up last week and sure enough 7/16" pretty much does it. It's a bit tight but I can do some light sanding with a smaller dowel+sandpaper to make it a better fit. I might try a suggestion to put the anchors in the freezer overnight to make them shrink before installing them. Then when they come back to size, the fit will be nice and snug for sure.

Cheers.


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## 1PUTTS (Sep 8, 2007)

Good news. Keep in mind, it will be a tight fit with the fins. As long as the part below the fins fits, that's what you want. Then you just mallet them in. If that part doesn't fit - then, yeah...you'll need to tweak it a bit.


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## Guitardave73 (Sep 30, 2021)

1PUTTS said:


> I agree that a caliper is a good investment - that way you're not guessing. Mine isn't digital but it's still very accurate if used carefully.
> 
> Having said that, I have a 7/16" bit that works for those types of bridges (but I always check first). And note that you're measuring the diameter below those "fins" on the post. The fins are a bit wider and are meant to dig into the wood to hold them securely. Also, it's probably a good idea to "step drill" the holes (start smaller and work your way up - don't try to do it all in one shot) just to avoid any cracking or tears.
> 
> And finally, you want to make sure you get a 90 degree hole (or as close as possible). I have a bunch of jigs that I made using long bolts with a washer glued to the bottom (to keep it flat). I use whatever bolt-jig is just slightly larger in diameter to the bit I'm using. It just helps guide the bit in straight.


Do you have plans that you're willing to share on making one of these jigs that you talked about?


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## sulphur (Jun 2, 2011)

Guitardave73 said:


> Do you have plans that you're willing to share on making one of these jigs that you talked about?


This thread is 13 years old.


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