|Continual rotation lathes
|Quotes about turning
|Notes on a 17th Cent. turner
My hand-pumped "turn-bench"
inspired by the illustrations on the Bow lathes page.
A video of my bow lathe in use.
Doing my demonstration in front of our booth at the Minnesota Renaissance Festival with my early version fo this lathe when I still had wooden knobs as handles on the centers.
I used 1" brass round stock for the poppets (-the head & tailstocks). I drilled and tapped the holes to fit threaded iron rod stock bought from a surplus store that I used for the centers and screws. I eventually replaced the threaded rod stock with eye-bolts since I thought they looked closer to the forged handles on center screws in period illustrations than the wooden knobs I originally placed on them. To give the modern screws a more rustic appearance I tossed them into my barbeque grill and covered them with some hot coals to blacken them.
My first attempt at a bow was simply whittled from a piece of scrap oak molding I had laying about. -Obviously not the proper material, but it was already fairly thin and knot-free, and worked for my first experients with this lathe. Since then my bow broke and I have been making do with a willow branch which has been working just fine. To adjust the tension on the bowstring if it is too long, or too short, I carved several notches into the handle of the bow.
The bench and attached clamp that hold my lathe are undocumented for this use. This type of lathe would normally be clamped in a bench vice, as illustrated on the bow lathes page. However, I wanted a portable bench to work at and my idea was based on similar benches with wooden clamps that were used for a variety of historic tasks from stitching leather to sharpening saws so I thought it might be a reasonable compromise. I also decided to clamp the lathe on both ends in the expectation that my portable bench would not be as stable as a metal vice mounted on a sturdy workbench.
Originally, I simply mounted the work between the centers and wrapped the bowstring directly around the piece I was turning. This worked fine, but limited who small I could turn something due to the force of the bowstring pulling on the piece. Inspired by simple chucks illiustrated in Moxon's Mechanic's Exercises, I added a mandrel/chuck and additional poppet, or support so that I can wrap the cord around the mandrel instead of around the piece being turned. This allows me to turn much smaller diameter objects with less risk of breakage since the downward pull of the bowstring is supported between the headstock and the new poppet. It also reduces the waste that you can see on one of the wooden bobbins in the graphic below that has not been parted from the dowel I used as raw material. It also means the bowstring does not polish, or mark the piece I am turning.
I turned my first mandrel/chuck, out of maple and used it as a jam chuck with 3/8- inch tapered hole carved roughly square. I simply whittle the end of the stock I'm turning in a roughly tapered square to match it. This worked fairly well for a while, but eventually the wood in the chuck started getting compressed and wooden pieces I was turning would slip unless I over-tightened the tailstock. Turning bone worked well in it even after it started to get worn, since the bone did not compress, and was hard enough to bite into the walls of the chuck. To solve the problem, I sacrificed an adapter from a cheap socket set, and turned a new mandrel in oak with a hole to fit it the socket adapter. Thus, now I have a mandrel with a metal chuck with a square hole, and won't have to worry about it getting worn out. (I'll be adding some graphics with details soon) I originally used some vaseline to lubricate the mandrel inside of the brass poppet which supports it. But once the mandrel was worn in, a little bee's wax was sufficient to keep it turning freely.
My leather pouch of tools, the lathe, and the "clamps" from the bench all fit into one 18" long box
I've just been using standard mini-lathe tools to turn the bone, and I have discovered it is not as hard to work with as I thought it would be. Although for demonstration purposes at reenactment events, I rough-out the bone pieces on my modern lathe to get them round. I've read that bone should be boiled for around an hour to soften it slightly, and kept wet until working it. But in trying it, I haven't noticed any difference. This might be due to the fact that I've been using sterilized bones for dogs bought at a pet store, and since it has already been boiled, and sterilized, more boiling may not do anything.
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