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Merak 11-10-2019 04:02 PM

Taper a straight bridge pin hole
I have an Alvarez AP70 with straight drilled holes and tapered pins, has anyone gone to the trouble of tapering and installing larger diameter pins?

charles Tauber 11-10-2019 04:47 PM

Depending upon the size of the holes, they need only to be reamed to match the taper of the pins. In most cases, oversized pins aren't required. It's a common procedure.

Merak 11-10-2019 05:12 PM

The holes are the same diameter as the wide end of the pin so to ream the holes would require a larger pin.
Maybe I wasn’t clear, the hole is straight, the pins are tapered so the pins only bear on the outer edge of the hole. Has anyone used a tapered reamer to make a tapered bore out of a straight bore and what size pins did you end up with?

charles Tauber 11-10-2019 07:21 PM

Most guitars that I have encountered that have straight holes have holes that are 3/16" or equivalent metric size. Standard size pins don't bottom out in those holes. Reaming them larger fits the pins.

If your situation is that the pins bottom out in straight holes, the question is why? Are the holes larger than typical or are the pins smaller than typical? I'd start by measuring the diameter of the holes.

If the holes are larger than typical, you can make the holes smaller. One way to do that is to coat the bore of each hole with epoxy or CA glue, then, after the glue hardens fully, ream to fit the pins. It is easy to do.

If the pins are smaller than typical, you can purchase standard sized pins and ream to fit those after receiving the new pins.

The disadvantage of using oversize pins is that they are a non-standard size. That said, several luthier supply houses sell oversize pins, including and probably Either way, you'll need to know what size holes you have to determine if you can get pins that large.

fazool 11-10-2019 07:23 PM

This is how I sized oversize pins

Merak 11-10-2019 08:05 PM

The pins are from .189 to .196 diameter so smallest size, calculations says I would add about .026 to the diameter, so might just try a set of .210 pins.

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