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Building a Frame Saw
Forging a Copper Kettle
Making a pair of leather work boots
Forging and Fletching a Bodkin
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Friday, December 11, 2015

Restoring a Tenon Saw

For some time now I have had an old tenon back saw in a rather poor state of disrepair. Although sharp, the blade is heavily rusted in places, the spine little better, and the handle loose. While functional, there is a tremendous amount of friction from the rust buildup and overall needed a fair bit of work to get back into a serviceable condition.

While the glue dried on another project, I took the opportunity to finally restore this saw. I had to make a specialized screwdriver to remove the nuts, which looks a bit like a flathead with a slot cut down the centre. One of the past owners of this saw evidently tried to use a regular screwdriver on only one side of the nut, which does not work overly well and leaves deep scratches in the soft brass.

This 'restoration' will not be heavily involved, merely cleaning what can be cleaned with what I had on hand to bring it all into a usable condition. I know what works for me, and it does not need to be factory perfect to do the job.

First, I cut strips of 120# sand paper and used spray adhesive to attach it to a steel block whose corners I rounded slightly on the belt sander so they would not dig into the blade surface.

Several sheets of paper later, the blade is smooth and the worst of the rust spots removed. While the cosmetic state is less than pristine, it is flat, and that is what really matters. Most importantly, the area just above the teeth is infinitely better than it was previously. Holding the spine off the edge of the bench ensured I had a flat surface underneath where I sanded, and when satisfied, I moved onto the back itself. By how the rust developed there, some spots kept their patina a little more strongly than others, but this area never contacts the work piece so I did not give it too much attention.

Next up were the brass screws. This was a purely aesthetic step, as they do not have any influence over the functionality if the tops are a bit tarnished. Had their natural oxidation been the only problem, I would have kept them that way. However, as mentioned above, they saw some abuse from improper maintenance, so I sanded them back to a flatter surface than before.

The nuts saw the worst of it, that centre one bearing the heaviest scar where an ill suited screwdriver bit into the brass.

The final step before reassembly, which could have been done at any time really, was to sharpen the teeth. They were not too dull, but could use a new edge anyway. Periodic maintenance for tools that require a finer level of precision is never something I actively avoid. This was the most time consuming part, as I also brought the depth of each tooth to the same level, which will make future sharpening easier and the cut more predictable.

Finally, I gave the the metal a coat of Renaissance Wax, a micro-crystalline wax that was developed for museum pieces. For application on tools, it both protects against rust and reduces friction while cutting without leaving a surface contamination which might conflict with subsequent finishing products. For saws, the latter is less important, but I also use it on the soles of planes.

Here is the saw before and after. Not perfect, but far better than before. Since its cleaning, I have already used it more times than every other time combined. The cut is much cleaner, there is less friction, and it is far less likely to pinch in the cut. Although it has already had generations worth of use, it can now stand for as many more years of use with proper care.

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