John Mickelson's
Bridge Pin Slotting Fixture
© Frank Ford 2003; Photos by FF


Designed by the self styled Fossil Ivory King himself, and machined by Stewart MacDonald's Don MacRostie, this is a "must have" fixture if you do a lot of bridge pin custom fitting. (Unfortunately, it looks as though this is a product that will not be in general circulation, so I suppose it's best to think of this article as a suggestion for making a fixture rather than an actual review. If making this fixture seems a bit daunting, take a look at Dan Erlewine's simpler, "shop built" bridge pin slotter.)


This nifty tool was built around one of those high tech linear bearing slide units that John bought as a surplus item on eBay:

The bearing has essentially no friction and no side play at all, so it makes a perfect rail on which to guide the slotting fixture. These things turn up all the time in salvage, so if you're not picky about dimensions, you can get them for far less than their retail prices. John bought a lot of about 20 identical ones for this project. Don MacRostie did the precision machining of the tapered bridge pin holder and the slot track. (Before you ask, I have not heard whether this will be a standard Stewart MacDonald item, but it wouldn't hurt to give them a call and request that it be put into the catalog.)

Here I have the fixture mounted in my drill press vise. It works just as well clamped to the drill press table, but my vise was already bolted there, so I decided to use it that way:

I spent some time precisely aligning the 1/8" ball end milling cutter with the 1/8" slot in the brass fixture. Once I had it centered, the slide worked smoothly from one extreme position to another. I used a small auxiliary chuck for this little milling cutter because my big 5/8" drill press chuck really doesn't like to close down that far, and the thing is so big it would obscure the view

Then to slot an unlsotted ebony pin, I simply held the pin in place, and shoved it gently into the rotating cutter:

The cutter makes a perfect groove, neat and clean:

It's a snap to lower the quill a bit to deepen a slot, and the fixture is so rigid that the cutter doesn't chip the ebony at all. I ran this one at only 300 RPM and cut the full depth in one pass!

I guess this is one more reason John Mickelson is the King. . .

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