Monday, July 16, 2012

Drawboring a Chest Lid?

As I was building the lid for my tool chest, I liked the idea of over-building it to last. Drawboring came to mind as a possible method of improving the lid. Drawboring is a bit of a lost art, although it is regaining popularity. For those who do not study woodworking lore, this is a rather old method of driving a peg through two very slightly offset holes, so that as the peg is driven, the pieces are pulled tightly together and stay that way. This is how I will attach my workbench legs to the top.

I asked Christopher Schwarz what he thought about this, since I was using his overall concepts to build the chest. I figured if it were a good idea, he would have mentioned it. While awaiting his reply, I looked at every image I could dig up of traditional tool chests, and did not see much evidence of drawbored lids. However, I found this photo from Peter Follansbee:


If you view the image full size, and pay attention to the corners, drawbore pegs are visbile. While this chest is only a few months old, I do trust Peter's understanding of traditional joinery and his use of the joint backed up my hunch that it might be a good idea.

Christopher then responded with his ten cents:

Before glues became reliable (think early paste glues) drawboring was very common in furniture, regardless of its position in a project.

As the work became thinner in frame-and-panel constructions and hide glue became the norm, the joinery changed a bit. Instead of pinning the joint, the joiner would make the joint a through-tenon and then wedge it from the outside. This created a good mechanical bond – if not as fantastic as drawboring. But it had the advantage of being able to be easily disassembled and easily reassembled.

Why the switch?

I don't know for sure, but I can guess. I've tried drawboring everything -- even lightweight joints. As the material becomes thinner, the joint is much more likely to self-destruct when you drawbore it. For example, in about 2003 I built a seed cabinet from the Enfield community. I drawbored all the joints in the frame-and-panel door. If the six joints, three exploded. I had to make a new door.

When I make a bench with heavy components, it's almost impossible to destroy it via drawboring. And I have tried.

I wedged my through tenons on my tool chest's lid. If that's not in the book it's an omission on my part.

It's a thoughtful question.

and then this update:  
I took a different approach to wedging the tenons – one that is found in heavy-duty doors. You wedge from the outside of the tenon. Against the edge cheeks. If the primary wood is soft, the oak wedges will compress it, making the mortise a bit trumpet shaped. See the attached photo. This shows an interior panel for the chest that I decided not to use. But it shows the wedging clearly.

You can split the tenon with a chisel if you like. This method has the least risk of all of the options. It's traditional. Reparable. 

He supplied this image:




 It clearly shows the wedges on either side of the tenon. I decided to use this approach, although I was glad to know that at least one studied woodworker had also decided to use drawboring.

In the end, I was just cruising along with the joints and completely neglected to do the wedging step. I guess in 15 or 20 or 50 years I will know if that was a mistake.

4 comments:

  1. The ancient, about 1850 or so, stiles and rails of the doors in the decrepit old house I live in were draw bored. I'm at work and can't check but I think the doors measure about half an inch thick and look like they were made by Sam not Thomas. Even shoddy work can last a long time.

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  2. Keep up the good work, Rob :0)

    @K P - Even shoddy work can last a long time, eh? Good to know. I volunteered to build a door for my parent's house recently. Never tried that before. Maybe I should drawbore it?

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  3. I thought about drawboring my lid, but I was afraid that I might split the wood...my only experience with drawboring is with the treetrunk-like legs on my Roubo. I ended up wedging the tenons...by accident. I did a somewhat sloppy job with chiseling out the mortises by hand, and the ends ended up being "square-like", but not square. So I had to put small wedges to fill the gaps. Yeah...I planed it that way...

    Very nice looking work on your chest. I think it's great you were able to make it with local materials.

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  4. If you look at the picture of Chris's wedged joint, doesn't that look like a peg in the middle of the face of the joint?

    Did he do both methods?

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