Full Chisel Blog

November 1, 2008

Dovetail Bow Saw Blade

Filed under: Dovetails,Historical Material,Of Interest,Proper Tools,Techniques,Uncategorized — Stephen Shepherd @ 2:40 pm

 

There was a recent discussion over at WoodCentral on the Hand Tool Message Board about the cranked bow saw blade used for making dovetails, well at least the pins.  I first saw the blade in Salaman’s Dictionary of Woodworking Tools and put an illustration of the blade in Shepherds’ Compleat Early Nineteenth Century Woodworker in 1981.

I have made several of these blades and as a matter of fact I made two this morning and took some pictures.  These are 11 ppi band saw blades, not the greatest blades in terms of set but the number is good and the steel is good.

Blade in Vise

This is the setup in the vise, this is a shorter vise than I have used before by 1/2″, this one is two inch.  I heat the blade to cherry red to remove the hardness, allow it to cool slowly and it is annealed.  I then heat the blade between the marks, use chalk or soapstone to mark the blade in the center, and place it in the vise as above.

First heat

 This is the first bend, which I do with a small square face hammer, then heat the blade again and pound it over until it is about 45 degrees.

 Second heat

I heat the blade up again in the vise, be careful as the vise does get warm.  I then beat the blade flat over on the top of the vise making the 90 degree bend.  I use a brad punch to drop the teeth at the heel down to the vise top.  I then work over the teeth with a brad punch (nail set) to get some set back to the teeth I have just hammered.

I then sharpened up the teeth as needed and it is ready to go.  It is not that hard, you can use a forge or a gas torch to heat the blade, a vise and a square face hammer and nail set.  You will also need a triangular file to touch up the teeth.

 

 Dovetail Bow Saw Blade

Here are the two blades I made this morning, it took less than an hour to make them.  I had intended to make only one, but the first one is cranked the wrong way.  Make sure you are bending the blade in the right direction.  I had one in my bow saw in front of me and still got it wrong.  The odd angles of the blades is normal, when put under tension in the bow saw it straightens out.

I don’t harden the blade again after I am finished, because I don’t think it was that hard to start with.  Now while most of the work I do is in pine, it works well on poplar, so I am not too concerned about hardening the teeth again.  The first part of the blade is rip, when I do touch up the teeth at the bend I do put a bit of an angle to them, I also whet the entire blade, both sets of teeth to insure a smooth cut.

The hardest part of making the blade is getting the crank in the right direction.  Give it a go, it is easy.

I had problems putting up this post, I got dumped a half a dozen times and thought it might be an omen, but I don’t believe in omens.

Stephen

 

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