Sunday, November 8, 2009
Making A New Turning Saw - Part IV - Now With Bonus Fun Attached!
Well, the new turning saw is almost finished. There were only two things left to work on, the tensioning mechanism, and the blade (or web) assembly. Really pretty straight forward - which of course, in my shop, just cannot be tolerated! It was time to make things "better".
My first idea on improving things was by changing the way the rods that hold the blade were attached to the knobs. On the couple of turning saws I've made before, the rod was simply epoxied into the knob. Very easy to make and works fine - or did, until the epoxy lost its hold on the rod in the prototype saw. This started me thinking; could the rod be mechanically fastened to the knob? I played around with numerous versions including threaded inserts, jam nuts, all thread, etc. etc. I even build a mock-up to test a couple of these ideas:
Finally, I decided to just use a carriage bolt that passes all the way through the knob. By squaring the hole with a chisel, the squared shank of the bolt (just under the head) will keep the rod from turning independently of the knob. I didn't however, like the look of the bolt head - especially the raised three letter part code. So, as frequently happens, one solution created another challenge. I ended up heating the bolt head red hot and peening it in the pritchel hole of my small anvil to create a "hammered" look. Then I tried something new, which I had only read about - darkening the steel with an oil patina.
Here's what I did. I put a thin coat of Tried and True Original Wood Finish (linseed oil and beeswax) on the bolt heads. Then, holding the bolts in a machinist's vise, I heated the shank below the head with a torch until the oil began to smoke and darken. It took a little practice to get the heating just right. Too much heat (the first time, I heated the bolt head directly) and the oil burnt off completely - too little and it just looked bad and didn't harden. In the end, I had bolt heads that were black, with dark amber highlights. Cool! I really like it when a project takes me into new territory - especially when it works out well.
At this point I should have been almost done, but after looking at my curvy, rounded saw parts, and the straight, faceted design of my knobs I knew it was time to break out the spring pole lathe and make some rounded knobs.
Here's a shot of my spring pole lathe in storage:
And here it is in action:
Several years ago I started building a fly-wheel treadle lathe ala St. Roy. It was slow going and mid-build, eager to see if I even enjoyed turning, I converted it to a spring pole set-up. I rigged up a shock-cord spring on the ceiling and built an overly complex (hmm...) treadle. It worked well enough for me to make the shaker pegs for the peg board coat rack that now lives under the medicine cabinet; and I haven't finished the fly-wheel part - yet.
After turning the knobs, I drilled the holes for the bolts, cut the knobs to length, created a square mortise for the carriage bolt shanks, and they were ready to go:
Now all that is left to do is cut the slots and pin holes in the rod ends to hold the blade, cut the blade to length, and mount it. Then wrap the cord and use the toggle stick to create tension. That's it!
Oh, well that, and actually test it and see if it even works! Details, details...
Continued and CONCLUDED (I swear!) in Part V.
While you are waiting for Part V, here's a random tool shot and a bit of fun. Can you name the 16 hand tools visible in this photo? Ubergaloot status granted to the first commenter with the correct list! Or the closest list; this might be harder than I think. Click on the image for a larger view and give it a shot!