Thursday 12 June 2008

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Bucksaw Rebuild

Advertise Yet another tool rehab (or rebuild in this case) entry. It's almost as if I spend most of my time working ON the shop rather than IN the shop. Hmm. We might be on to something here...

Anyway, a while back I wanted a bucksaw. Why? Well, the wooden bucksaw would be for bucking wood on a sawbuck. You just gotta love English! The only problem was that the vintage ones I could locate all had similar problems that made their further use unlikely - but as I was told on at least three different occasions "That would look great handing on the living room wall!" (Blasphemy! Tools are for using, not decorating!) But really, bucksaws are very cool. They are wonderful contraptions of wood and metal, and loose mortice and tenon joints, that balance the physics of leverage, compression and tension.

I finally realized that I was going to have to make my own - but in order to keep things simple, I decided to salvage the blade and hardware from an existing saw and just rebuild the wooden frame, using the original parts as models - a direct, and therefore simple, fast process. Yeah right. Like I could ever do that.

Here's the donor buck saw:


As I disassembled the saw, I took a good look at the problem areas. First, the grain on the short arm did not run parallel to the length of the arm. So, as the turnbuckle was tightened to tension the blade, the stress of the load ran across the arm at an angle rather than down the arm. This weakness developed into a crack that threatened to completely sheer off the arm along the grain run-out. In the photo, the blade is only slightly tensioned:


Second, the two part stretcher was held together in the center by a pin. The hole for this pin created another area of weakness and it too cracked:


So, as was inevitable, I decided to "improve" on the design. The first problem was easy to fix. I just selected my stock (local birch) to allow for layout with the grain running the full length of the arms. The second problem I solved by replacing the two-part stretcher with a solid one piece design. No hole; no weak point. As a bonus, I only had to chop two mortices instead of four.

Here's what my version of the saw looks like on the bench:

And with some of its buddies:

Side note: The small spray bottle is full of bleach water - as the chopping block (aka: birch stump) sat on the concrete floor it would mold on the bottom. A quick spray from time to time took care of things until the stump finished drying out.

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