In Shop Blog, Techniques, Tools

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I’m always looking for little tricks to improve dovetailing, especially the part I dislike: transferring the tails’ locations to the pin board.

Sawmaker Mike Wenzloff stumbled across this interesting short entry in William Fairham’s book “Woodwork Joints, How they are Set Out, How Made and Where Used” (available for free download here at the most awesome Project Gutenberg). After describing how some woodworkers use a knife or a saw to transfer the marks, Fairham writes:

“Other workers prefer a pounce-bag instead of a saw. A pounce-bag consists of a piece of fairly open woven muslin filled with a mixture of French chalk and finely-powdered whiting; the muslin is tied up with a piece of thin twine like the mouth of a flour sack. All that is necessary is to place the timber in position and bang the bag on the top of the saw-cuts, when sufficient powder will pass through the bag and down the saw kerf to mark the exact positions of the lines.”

So it was off to the store to buy some pantyhose.

But first, we had to find whiting and French chalk. The French chalk was fairly easy , it’s essentially powered talc. You can find it at the fabric stores where it is used for marking cloth. Or you can go to the pharmacy and buy baby powder, which is talc and fragrance (essence du hinder l’enfant).

Whiting was harder for us to find. It is calcium carbonate (ground chalk) and is used in preparing artist paints these days. After a couple of clueless looks and pointless phone calls, Managing Editor Megan Fitzpatrick found some at an artist supply store.

And then the muslin. Surprisingly, we’re a yard short on muslin in the workshop right now. So Megan suggested I buy pantyhose for the bag. I balked a bit. So she picked out a nice pair of L’eggs Everyday knee-highs (color: nude with a sheer toe), paid the man and we were off to the races.

Now before I ruined a nice new pair of knee-highs, I decided to try some other fabrics. First up: some old surgical rags that former Senior Editor David Thiel brought into the shop about 10 years ago. It actually was too coarse and the powder went flying.

Then I tried an athletic sock (I use them to transport my block planes to shows and classes). Bingo. It deposited a fine dusting of powder when I whacked the sock on the dovetails.

As I was experimenting with the different whacking forces and whacking vectors, I cleaned off the pin board after each whack with a little water and a rag. And that water seemed to make the powder even easier to see.

Then I tried marking some knife lines and just whacking those (seeing knife lines in walnut is really hard for me). That worked, too. The resulting pins were easy to see and to saw. I’m going to have to experiment with the technique some more, but it’s another thing to tuck into your bag of tricks (or your nude, sheer-toe knee-highs).

– Christopher Schwarz

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