Hand Tools Archive

Subject:
Re: ...Hey, John, how about...

John Aniano in Central NJ
Hi Joe,

The thickest bow stick that I've ever cambered was about 16mm. It was for an oversized bass bow in pernambuco. I taper the sticks before bending them, so only one end was this thick, the other was around 9mm. The length was ~26" long.

The rough cambered thickness was 16mm but the final planed bow was 14.5mm so you bend a bit oversize to compensate for any twist that might occur. I usually use about a 1.5mm oversized blank.

I initially bend bows using dry heat with a large wick alcohol lamp. Later tweaks to the straightness or camber are done with a smaller wicked alcohol lamp. The larger has a ~5/8" wick, the smaller about 1/4". Other bowmakers use a very soft flame of a Bunsen burner, hot air guns and small electric hot plates. Traditionally, small charcoal braziers were used. I once used a small hibachi grill!

Pernambuco is relatively easy and forgiving to bend with dry heat. I also make bows with figured and unfigured snakewood and other alternative species which are much more difficult. If you overheat any bow blank, especially a thick one, you can get cracks that form that will appear to close up once cool, but they are still there. You have to heat the stick up slowly.

I only bend a small portion of a stick, say 4-5" maximum at any one time. If I was using a larger heat source, like a hot plate, I guess you could heat and bend a longer section.

I mark off the region I wish to add/remove camber or to straighten with white chalk. Easy to just wipe off when done. The chalk marks show my extents to heat the wood and I hold the stick and play it constantly through the open alcohol flame. When it is hot enough, and this takes experience, the bow is ready to bend. The stick is bent against a curved wooden form, but the resulting curve is gauged by eye.

A thin violin bow (5mm) might take only 15 -20 seconds to heat to effect a small change. The 16mm thick bass bow would take several minutes to heat up, again going slowly to prevent overheating the outside "skin" and developing cracks.

Not sure how these techniques might help your gunstock straightening - sounds like you have a method that works. Especially since the cross section you are working with is much larger than a typical bow blank.

John

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