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What’s The Tightest That A Dovetail Joint Should Be?

Dovetailed jointSome days ago, a woodworker put together a dovetailed officer’s trunk for members of the San Diego Fine Woodworkers Association. A number of the people watching were astounded as they watched him drive the carcase dovetails together.

The thing that amazed them was the tightness of the fit between the pins and tails. In order to seat the tails into the pins, he had to hit it using a dead-blow mallet several times.

The association members were curious about why he used this method. Here’s what he told them.

“I see dovetails as a self-clamping joint. When the joint is well-made, it shouldn’t need any clamping. (Of course, if you’re still mastering cutting the joint, clamps are a necessity). Several years back, after reading up on older workshop practices, I came to the decision the make my dovetails tighter.

In the past, iron clamps were very costly, even more so than they are today. When looking at inventories of older shops, you’ll see that they had very few, if any clamps. One of the oldest major workshop books, Joseph Moxon’s 1768 book “The Art of Joinery,” doesn’t mention clamps at all. In the 17th century, the English referred to clamps as “cramps,” but they were typically a single piece of iron that was used to keep a structure together.

While that’s not a definitive piece of evidence, it’s a sign that woodworkers in the past didn’t rely on clamps the way we do today.

When you read about dovetailing in the past, you’ll find very few mentions of clamping. In another older major book, the 1830 title “The Joiner and the Cabinet Maker,” they mention driving the clamp together with the mallet the same way I did, although they do use a scrap piece to protect the joint. Clamps are mentioned in other parts of the book, such as when they discuss pilling up mortised-and-tenoned frames.

In the 1950 Charles H. Hayward book “Woodwork Joints,” there’s nothing to be found about clamps. When he describes assembly, he says that he taps lightly with a hammer. He’s able to keep the joints protected using a piece of wood.

The Complete Dovetail by Ian Kirby, which was published in 1999, does talk about clamps, but he uses them only to pull the joint tightly. Afterwards, he releases them.

After seeing that so many people were able to get by without clamps, I made alterations to my sawing so that I wouldn’t need to use clamps in order to keep my carcases together. I began leaving a little extra waste wood after cutting the second half of the joint, which gave me enough compression to avoid using clamps in the majority of cases.

As an answer to your initial question, the joint is too tight if the wood splits. (I was thinking “Duh” to this myself – Ted Leger)

I’ve started using a number of tricks like this, including drawboring and rub joints, so that I can cut back on the amount of clamps I used in my job. I don’t think that people need to stop clamping dovetails; this is a personal choice. With that said, it can be beneficial to learn these techniques so that you can still work if you’re out of clamps. This is a great technnique to use with hide glue. If you use white or yellow glue, the fit is likely to become tighter.”

So all in all – the joints need to be tight enough where clamps wouldn’t be necessary, but if you start hearing any cracking….they are a little on the snug side.


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Ted Leger –


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Updated: December 21, 2014 — 11:27 pm
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