Re-Cambering a Bow?

[robobass]

Any good FAQ pages for this? I'd like to try it myself this time.

I have an early Sam Kolstien bow that I love but don't use regularly. The last time I got it re-haired (4 years ago), when I picked it up my bow guy told me it had straightened out, and he had re-cambered it for me. I was a little shocked that he would just do this without talking to me first, but I was more than happy with the result. I was comparing bows with some friends recently, and realized that it had once more lost it's camber.

I've seen a bow being bent with heat before, but the guy (a respected NYC bowmaker) just heated up the stick with a torch and sprung it with his fingers. I am more inclined to spring it in a jig and gradually introduce heat with a heat gun (like a paint stripper). I have a couple of worthless warped violin bows on which to practice.

I'm just looking for some pointers from people who have done this before.

Thanks in advance,
Robobass

[Phil Rowan]

I have a bow that's been re-cambered as well. I'm definitely not an expert on this, but I think that, unless you know exactly how to do this, take it to a bow maker (the same guy, or someone new).

[Eric Swanson]

+1 on having a pro bowmaker do the work if you care about the stick. I recently had this done on my bow.

The bowmaker (Eric Lane, in Boston, an excellent bowmaker and apparently a fine double bassist, too!) was very clear about using an alcohol lamp, NOT a heat gun. Something about the quality of the heat, control, etc. Certainly out of my depth...

[davidzgeorge]

you have to be careful when doing a recamber. i had it done on one of my bows once, and it actually didn't help very much. you might have better results investing in a better bow instead of trying to fix one that isn't working for you.

[robobass]

Originally Posted by robobass

Any good FAQ pages for this? I'd like to try it myself this time....I'm just looking for some pointers from people who have done this before.

Well, really, were any of these responses useful? Also, when people start talking about voodoo as relating to any aspect of luthiery, I think of a different two-syllable word. I've seen some bad bending work done by some respected bowmakers. That is why I want to approach this scientifically. It doesn't seem to me like it should be that hard.
Robobass

[JimGullen]

Originally Posted by robobass

Well, really, were any of these responses useful? Also, when people start talking about voodoo as relating to any aspect of luthiery, I think of a different two-syllable word. I've seen some bad bending work done by some respected bowmakers. That is why I want to approach this scientifically. It doesn't seem to me like it should be that hard.
Robobass

Greetings!

On the surface, it's not that difficult...just heat the stick and then bend...and hold until it cools/takes a set.

It's kind of like playing a bass isn't that tough....press a string and pull the bow....repeat as needed.

No flame intended, just making a point... :-)

The issue, I think, isn't so much voodoo, as the need for a lot of experience. Different sticks will require different amounts of camber. Also, the camber needed may vary on different parts of the stick. It takes a lot of experience to now how much to camber, and where to camber. The fact that you've seen some bad (re-) cambering work from respected makers helps my point, I think.

Cambering can be relatively straightforward but if the stick has a twist in it, it can be very difficult to remove.

Plus, if you're working on a finished bow, you have to really worry about not scorching the finish.

If you're interested in doing this, I would recommend getting an write-off violin bow or two and and alcohol lamp and work with those to get some feel. I know you're ulitmately interested in your bass bow, but those take a lot longer to heat/camber....just due to the thermal mass. Starting with a violin bow will give you results faster and you will be able to get a sense of the feel for how a stick feels in your hand when it's ready to take a set. Take the camber completely out of the stick and then put it back in. Put a bend into the stick and then straighten in out. Put a bend in the stick near the head and straighten...put a bend in the stick near the frog and straighten....all of those will feel different in your hands.

Go slow, the stick (when not in the flame) should never get so warm as to keep you from holding the portion being heated in your hand.

In good conscience, I have to tell you that I don't recommend this as a do-it-yourself job. I've had professional instruction on this and I probably wouldn't do this work for someone on their fine bow.

Since you have an interest, experiment on a throw away and then decide if you want to take your working bow to the flame. As a statistician, I can appreciate your wish to approach this scientifically, but there's also some art to it.

Good luck and best regards!
Jim

[Eric Swanson]

Hi Robobass,

Sorry if my attempt at being helpful missed your mark.

What I was imperfectly trying to express in my post is that a well-regarded, deeply experienced, full-time bowmaker emphatically told me that, having tried (and seen the results of) both approaches, he strongly prefers using an alcohol lamp, not a heat gun.

Good luck! Love to hear about the results...

[Marcus Johnson]

Originally Posted by robobass

Well, really, were any of these responses useful? Also, when people start talking about voodoo as relating to any aspect of luthiery, I think of a different two-syllable word. I've seen some bad bending work done by some respected bowmakers. That is why I want to approach this scientifically. It doesn't seem to me like it should be that hard.
Robobass

I also said that it would be worth trying on a bow that you didn't "love"... anyway, I deleted my post telling you pretty much what several other people seem to agree with.

Your bow, dude. Go for it.

[robobass]

OK, That's more like it. Thanks! I plan to research further before starting, and I do have some junk vln bows to practice on. I still question the alcohol lamp thing. A heat gun just makes much more sense to me. Could it be that the lamp has served well enough all these hundreds of years, and no one has thought to try something different?
Robobass

[JimGullen]

Originally Posted by robobass

OK, That's more like it. Thanks! I plan to research further before starting, and I do have some junk vln bows to practice on. I still question the alcohol lamp thing. A heat gun just makes much more sense to me. Could it be that the lamp has served well enough all these hundreds of years, and no one has thought to try something different?
Robobass

Greetings!

I don't know that it's just blind sticking to tradition. I do know that in their book Kuhn and Regh show a method of building a box which will hold the bow(s) and bend them to the camber you want. You then heat the box in an oven until they take a set. Definitely not old school!

I think there are a couple of issues with a heat gun..first having some way to hold it steady on the table (not a real big deal to make some sort of a stand) and the second, I wonder if the gun puts out too much heat over too big of an area. It's been a long time since I've seen a heat gun in person, but I wonder if you just have more control over the heating using a flame. You don't camber a bow all at once, you do small sections.

Since you've got some junker violin bows, try the heat gun, see if you can get decent results.

Is there some reason you're hesitant to try an alcohol lamp...at least initially?

Best regards!
Jim

[robobass]

Originally Posted by JimGullen

Greetings!

Kuhn and Regh show a method of building a box which will hold the bow(s) and bend them to the camber you want. You then heat the box in an oven until they take a set. Definitely not old school!


Is there some reason you're hesitant to try an alcohol lamp...at least initially?

Jim

Second question first: Having open flame near my bows or instruments) seems like a good thing to avoid when possible!

First comment. I like the sound of that. Basically you're springing the bow in a jig and doing a general heating.

If you don't own a heat gun, you've got to get one! They come with different nozzles so you can direct the heat flow how you want it. I've done a lot of plastic bending in the past with them. It just seems like a more controlled way to get the heat to the bow than an alcohol lamp, or torch for that matter.
Robobass