violin bow rehairing – savemaple.org

This is the first time I’ve ever rehaired a violin bow. In this case, it’s a cheap fiberglass bow. Nothing much will be lost if I screw it up.

This is orders-of-magnitude harder than I thought it would be. I very nearly gave up when I finally figured out everything the task entails.

Good sense would dictate abandoning this project. Pride goads me onward. I refuse to call it quits and admit my mistake.

We’ve fought lengthy wars based on more-or-less the same rationale. So don’t judge me.

In any case, this entire post is about carving and fitting tiny little wooden wedges. The critical wedges that keep the horsehair in place, on the bow.

Crafting precisely-shaped pieces of wood the size of popcorn kernels, using full-sized hand tools.

It’s every bit as hard as you might imagine. This is the step at which I balked originally.

Consult the checklist:

Do those little pieces of wood go flying across the room when you cut them with a chisel?
Are those flying proto-wedges then virtually indistinguishable from waste wood chips that litter your work area?
Will you sand a couple of strokes too much, thus rendering the object uselessly loose?
Will you sand your fingertips to the point of pain, as you try to shape the wood on sandpaper?
Will these tiny fragments of wood occasionally shatter, as you try to cross-cut them with a chisel?
Will you have to re-cut each one several times, in an attempt to get the fit just right?

I assume you get the drift. Making and fitting the wedges, for the first time, is the worst kind of fiddly work.

An infinite number of monkeys, with an infinite number of chisels and an infinite amount of time, will eventually carve an exact replica of the Statue of Liberty.

And yet, that is not a recommended production technique if you run a gift shop.

I’m sure there are artisans who can knock these out in a trice.

Me? Start to finish, it took me about three hours to make and fit the wedge that goes into the heart of the frog.

The first trick is to know your limits. It’s just not possible to cut a piece of wood, to the required tolerances, using hand tools, in one go. Not for me, anyway.

In my case, I first split inch-long shards of wood of a segment of quarter-inch ~~basswood~~ poplar board, until I got one that was a snug fit for the width of the hole into which the wedge must fit. Then cut an over-long piece off that, and went to work with sandpaper, on that tiny fragment of wood.

Work it until it fits, or you’ve lost it on the floor, or you’ve made it too small and have to start over. Whichever comes first.

With enough monkeys, chisels, and time, you will eventually get one that fits. I think my winner was maybe my fourth attempt.

Wordless workshop.

A few further observations.

Some people start at the tip of the bow. Seemed like most started at the frog. Frog wedge looks much easier to do than the tip wedge. So that’s where I started.

You can buy ready-made “wedge blanks”, for just a few dollars. That is, you can buy the chips of wood, roughly the right size and shape. But my take on it is that the bulk of labor is in achieving the exact fit. You’ll put in that labor whether you buy a ready-made blank or make the rough chip yourself.

You cut the wedge so that the grain of the wood runs parallel to the length of the bow stick. This is to prevent the wedge from falling out in drier weather. Wood shrinks as humidity falls, but (essentially) only across the grain. Cut this way, the width of the wedge may vary, but the critical length dimension should remain very nearly constant, regardless of humidity. I kept losing track of which which direction was which, on the wedge, so I eventually colored the top face of the board with sharpie, so I would know which end was up.

Only one end of the hair comes bound, like that. The other is free because you have to cut the hank to size, to fit your bow.

You have to shove the bound end of the hair, into the cavity, so that the hair makes a right angle turn and the bound end of the hair sits flat on the bottom of the cavity. To make the end of the hank of hair more flexible, wet it, give it half a minute, then towel it dry. Use a sliver of wood or other dull object to press the end of the hank into place. I assure you that a screwdriver will cut horsehair under these conditions.

The frog slide — the bottom plate of the frog — has to slide over the hair, as it sits on top of the wedge. This means that the top of the wedge must be more-or-less flush with the top of the hole in which it sits. I lubed the frog slide with powdered graphite (sold as lock lubricant). That was a mess. I now see that savvier people get the same effect just by running a pencil down the slot into which the frog slide sits (reference).

But, ultimately, the wedge is what holds the horsehair in place. So, at the end of the day, you have to answer the following question:

Why are they called wedges?

This little wooden plug, inside the frog. Why is that called a wedge? It’s not obvious. Why is this a “wedge” and not a “plug”, say. Sure looks like a little wooden plug.

The reason is that you don’t insert the wedge vertically into its respective hole. Like a plug or a cork. Wrong-o. These are not plugs or corks.

In fact, if you cut it just right, you can’t insert it vertically. It should be just a hair too long for that. You insert the edge of the wedge furthest from the horsehair first, leaving the wedge tipped up slightly, high end resting on the hair. Then you press it flat, and in.

That motion — like closing a trap-door, as you push the wedge into place — locks the hair firmly against the wood of the bow or frog.

That’s what makes it a wedge. And that’s why the length dimension is critical, but the width, not so much. The distance between where the wedge meets the hair, and the back of the cavity, has to be just right.

That’s the theory.

In practice, expect some trial-and-error. The wedge is too big, so it won’t fit. Or too small, so it pops right back out. Or it pops out and gets lost in the rug. Or it fits, but you can’t squeeze the flat plate on the frog over top of it. And repeat.

Conclusion: That was the easy one.

Good news: Just three hours later, and one wedge is done and fitted.

Bad news: That’s the easy one.

Engineering-wise, the modern violin bow frog clearly has a lot of safety and redundancy built in. Multiple systems keep the horsehair in place. The hank of horsehair is both bound to itself (so individual hairs can’t pull out), and mechanically attached to the frog (so the entire hank can’t pull out, once the bottom plate is slid back into place.) And there’s yet another wedge — with glue, yet — to be driven under the ferrule of the frog. The pressure of the internal frog wedge merely aids those existing systems.

In short, this looks like overkill, for a modern bow frog. I’m guessing it’s done this way because this is the way it has always been done. Perhaps for older styles of frog, or those lacking the precision machining of a modern frog, or with horsehair that did not come pre-bound, the internal wedge fit matters more. But for this frog, from an engineering standpoint, it sure looks like any hard object that fills that hole would have kept the hank in place just fine.

The bow tip, by contrast, has zero redundancy. All that stands between the violinist, and performance disaster, is a single, tiny, carefully-fitted wooden wedge.

Which, by itself, is a reason to start at the frog, if this is your first bow.

Finally, in hindsight, I completely understand why the manufacturer glued the tip wedge in place, on this cheap bow. I may end up doing the same. We’ll see how it goes.