Wood selection is not very critical, use something you like (I used a not very hard mystery wood (Magnolia?) and ebonized White Oak). The only concern (if you don’t use the lever) is you use a hammer (plastic, hide or wood, I use a really small dead blow) to drive the wedge in and out so use a wood that won’t split and pop the bulb off. Any hammer will scuff the finish. Both the wedge and bun will be infused (with varnish or boiled linseed oil) to add strength, density, stability and color (the bun and wedge, in this photo, have been infused with varnish. They are from the same piece of mystery wood, the difference in color is from the amount of time in the varnish soak).
A good source of wood is cut offs somebody might otherwise throw out or turning blanks. This piece of Apple could be used to make a wedge and bun but it would be nice if it was taller in the thin part.
- Draw the wedge shape on your wood. I like a “fast back” style ala the 1963 Corvette Sting Ray Coupe (wikipedia)
- I use the mill for a lot of the roughing because it keeps things square, which just makes things that much easier when shaping.
- Square the stock.
- Mill a 7º ramp.
- With the bottom flat, use ½” cove bit to waste out the cavity between the ramp and bulb.
- I use a saw to extend the flat into the bulb (since I’m a klutz with chisels). A 60º dovetail endmill also works very well for this operation (the black wedge was done that way).
- File, file file. Or chisel.
- Sand, sand, sand.
- Plane to width and test fit. The wedge may interfere with the kickers so you may need to trim the nose. It is also a good idea the round over the ramp edges so they mate with the bridge fillet.
- I use the smallest feeler gauge I have (0.0015″) to test the fit. You should not be able to insert it between the wedge and the bridge.
- Tune the wedge before applying finish, unless you like to finish twice (or thrice in my case). If tuning just isn’t working or you would like an easier way, add a lever (part 12b).
The bun is shaped sorta like a chess pawn with the head lopped off. There are two considerations: It’s a small space, there needs to be room for shavings and fingers to remove those shavings. Second, there needs to be a bit of a shelf for your forefinger or thumb (depending on how you hold the plane as you use it).
I like to the run the bun proud (ie higher than the shell). Other than aesthetics, the only reason to do this is if there is any [vertical] wood movement, you won’t notice.
I run the lower back edge just a bit shy of the mouth edge.
The grain runs front to rear (same direction as the wedge). Ease the lower front edge and corners, they don’t do anything and just muck up the fit. If you were slopping welding on the front plate, you pay for it here.
Glue: Epoxy works but make sure you use just enough because it is a major pain to clean up. I’ve been using liquid hide glue because it is sooo easy to work with and clean up. It works so far: I have a piece of wood glued to a piece of steel and after several months was able to twist the wood off with pliers so the bond did deteriorate over time but this is a no stress joint.
I finish before gluing and mask off most of the back and bottom (you can see the mask line in the above photo), which gives the glue something to stick to.
You can etch the metal with Phosphoric acid or garlic (really) for better adhesion. Be careful, if it gets on any polished surface, it won’t be polished any more (although it is easy to touch up).
I apply a bit of glue to the bottom and front and leave a dry band at heel and top (I do not want squeeze out) and maybe a tiny bit to edges down by the front corner.
- For softer and non-tropical woods, I like to infuse the wood with varnish or BLO, which adds color, depth and, with varnish, hardness. I put the wood in the oil, put that in a vacuum jar and pull a vacuum (maybe a half hour or so). The oil foams like a Guinness as air leaves the wood and when the vacuum is released, the wood really sucks up the oil. I let it soak for a half hour to an hour, more is better. It can take quite a while to dry, if you cut into the wood a week later, you will really notice the oil smell.
For oily tropicals (like Cocobolo or Ebony), I just use lacquer or shellac. Some woods, like Maple, can look pretty bad when infused with BLO (although, over time, the color can become uniform and quite nice) so test on scrap.
- I like spray lacquer as a finish because it is quick. But not very durable. Shellac is probably better. I use double stick tape to attach the wood to a stick and spray away.