Making a Saddle
Here's how I use my 1x42 sander to make an acoustic guitar bridge saddle.
First, I flatten the bone blank on a marble slab with silicon carbide paper:
I can slide just a bit of the end of the saddle through my thicknessing sander:
I make repeated small cuts and try the fit into the saddle slot. If I cut too deep, I can lower the table and switch ends to try again. Since the blank is longer than I need, I have a bit to spare, and can even shorten the blank to try a third time, if necessary:
Once I'm confident of the trial fit, I'll pass the entire saddle under the bottom wheel of the sander to bring it to uniform thickness:
At this point the blank should just fit the saddle slot.
After the thickness of my blank matches the slot in the bridge, most of the work is over. Now, I'll mark it for length and sand the ends off to the marks. I can round the ends on my sander to match the rounded ends of the routed slot in the bridge:
I've got the ends rounded and the length cut so I can insert the saddle into the bridge slot to check the fit. Notice how the saddle fits tightly enough so I can lift the bridge by it:
I mark the height and lengthwise contour on the saddle and sand freehand against the vertical platen. I can even round the top of the saddle while I'm at it:
Because the sanding belt is only one inch wide, there's lots of clearance all around and very little danger of injury in "offhand" sanding.
Now my saddle is finished. All I have to do is clean up the belt sanding scratches with some 600 grit paper and buff to a fine finish. I'll avoid the areas that actually insert into the bridge so I don't change the fit.
Usually I can actually lift a guitar off the bench by its saddle. That's the ideal fit. It presses easily in by hand, and holds well against the string tension. I'll loosen the fit slightly if there's to be a pickup element under the saddle.
If I'm making a saddle for a Martin guitar from around 1920-1965, I'll have to deal with removing an old saddle that was cut through at the ends and glued into the bridge. Here's how I get that old glued saddle out!
By the way, that third wheel happens to be exactly the same radius (1") as the radius of Martin bridge tips. It's a snap to finish the end of a through cut Martin saddle. I just mark with my half pencil:
and trim the saddle on that little back wheel:
