After shaping the frame parts, all that was left was construction of the two handles and the winding toggle shown in the picture above. Unfortunately, I’m not fond of trying to photograph while using power tools, even the lathe, so I’m afraid you’ll have to settle for my descriptive prose.
The toggle starts life as a ½” diameter cylinder easily made from offcuts from the saw (at least in my case). The ends are rounded and a cove us turned near one end. The cove retains the tensioning strings and allows the toggle to pivot when under tension. After parting off, the opposite end is flattened into a paddle shape. There were several ways this could be done, but I chose the stationary belt sander as the most expedient – 60 seconds start to finish. Just hold by the grooved end and press the opposite end to the belt. Flip and repeat.
Yes, the handles are cocobolo. I didn’t have any thick hickory, and didn’t care for putting a glue line right in the middle of a knob. I know the wood is still strong, but it bothers me for some reason. Besides, I had some leftover turning squares laying around by the lathe. I started to use mesquite, but found a cocobolo blank that was just the right size. I grabbed one end in the chuck, bored a ¼” hole for the blade pin, and shaped a handle. The form is simple, and makes a good turning exercise. Again, precision is NOT required. The second one quickly followed.
After completing the handles, the blade pins are glued into place. The butt end of the pins has a series of concentric grooves connected by a lateral channel – perfect for gluing. I followed the recommendations and used a slow-set epoxy. I dribbled some into the holes and then pressed the pins into place. You might want to have some sort of clamping device standing by if the fit is a bit tight. That little bit of extra pressure can make all the difference. This is when you find out what that channel is for. As the pin presses in, some of the epoxy is squeezed back around the flange in the middle of the pin. Just be ready with a paper towel and wipe as it appears. This works better than trying to get all the squeeze-out at once.
My choice for a finish was my usual shop-grade one – diluted boiled linseed oil flooded on and wiped off in two coats. Simple and effective.
All that remained was to assemble the final product. The stretcher fits into the mortises, and the blade is hooked into the pins just like a coping saw. I followed the recommendations for stringing and used 50lb braided fishing line. It had been a long time since I bought braided line, and I was unprepared for the change. This stuff looked more like monofilament, than the braided nylon I was used to, and I was more than a little skeptical about it. After all frame was assembled and the blade was in place, I made four slightly loose loops around the two horns and tied the ends together. The toggle was placed on the inside of the loops and twisted to tension the blade.
A word here about tension: The notes on the TFWW website are vague about the amount of tension required, and after a bit of fiddling I understand why. Tension is a very subjective thing. I’ve been very conservative so far, after reading the dire warnings about the perils of overtensioning. How much is enough? I’m not yet sure. For now, I’m playing with the following numbers:
“Slack” is considered to be the point where, when released from the stretcher, the toggle won’t unwind on its own (about three turns). “In tension” is five or six additional turns beyond that. “Overtensioned” is the point where something cracks – something I don’t really want to find.
I’ll spend a little time with the saw, learning its quirks and finer points, and then report back with what I’ve learned. Till then, I highly recommend that you try one for yourself. It’s a fun and simple project that yields an inexpensive fix for your saw problem.