Bridge pin sizing shop hack
 

A DIY shop hack that I came up with and found to be useful and wanted to share. I'm using embedded uploaded photos so will post them all together in two messages.

Reaming a bridge pin hole larger is easy but there may be times when you want to reduce a bridge pin diameter, like I had:

I had a situation where I could not get the optimum bridge pin fit. They were either too loose or too tight. This may be common in a guitar showing a little wear in the holes, but not enough to go up to oversized pins.

Conventional wisdom says to step up to larger pins, then ream the bridge holes to get the proper fit.

In my case, the match was just slightly above the normal pins, so I would have to ream quite a bit to get up to the oversized pins. Also, I did not want to make that invasive surgery on the guitar. I did lightly ream the holes to the same size by using a common pin to compare them.

Reducing a bridge pin is very difficult. You can't chuck it up in your lathe very easily and there is no good way to grab it.

I used my drill press with a 1/2" chuck.

I had some heavy wall rubber tubing 1/2" O.D. (.190 I.D. in my case). I cut little rings about 3/8" tall.

I then placed the head of the pin in the ring, which expanded the O.D. of the rubber hose material.

Leaving the chuck all the way open, I was then able to lightly press this up into the chuck. Do not tighten the chuck - that will just push the rubber grabber out.

With a slip of sandpaper I gripped the pin and turned the drill press on.

It might wobble but my fingers immediately held it centered.

There is an inherent safety check and any binding by the sandpaper will pop the pin out.

To operate simply squeeze the strip of sandpaper as shown, then slide it up and down to follow the taper.

You can apply light pressure and sand easily. The pin might pop out a couple times. If so, I used a little hook tool to yank the rubber hose piece out and reinsert it.

I was very surprised at how well this light press fit held the pin for sanding.

I used a Drafting circle template to watch my diameter under the collar and gauge when I was almost done. Then I switched to fine sandpaper to smooth/polish the pin.

I resized all six bridge pins in about 20 minutes on my first try.

I custom sized my pins to fit my older Martin perfectly without making any mods to the guitar.

Instead of reaming and permanently modifying a guitar you can very easily size the pins for the perfect fit.


In the pics I used a white bridge pin just so you can see where it fits.

more uploaded pics

Very clever. Thanks for the demo.