About the lathes, Yeomans' and ours.
You may have to shift mental gears a bit.
  • The machine is not meant to be an efficient machine tool. It is meant to work fairly well and to be affordable almost anywhere in the developing world.
  • It is meant to be built and used by a mechanic in a shed rather than a machinist in a factory.
  • Although it can't be built as accurately as a commercial lathe because of a probable lack of precise measuring devices, it can be as accurate as a lathe that has had a few years of use and abuse.
  • Construction should require only concrete, common sizes of pipe and steel bar and a little automotive scrap (nothing "hardened and ground").
  • A main requirement is that it is easy to build and align. Our latest improvements are still being drawn but should make construction even easier. Cheap, easy, accurate alignment methods are have been developed.
  • Forces involved in cutting a piece of poor quality steel by a non-expert machinist using a dull or poorly adjusted cutting tool are immense. Concrete and scrap steel are cheap, so vast over design should be used on our machine as long as it does not add too much to the final cost.
  • High turning speeds should be avoided because the spinning workpiece becomes a blur as it turns and death or injury to a poorly trained worker may be hidden inside this blur.
  • High "efficient" turning speeds also require carbide cutting tools (expensive and easily broken) and a coolant system -- items that may not be either affordable or available.
  • The machine is not meant to last forever in it's first configuration. Instead, it is meant to be able to repair and improve its own parts. The lathe "ways" can be easily rotated to unworn areas or replaced. Although every common machine tool can wear to the point that it can't be repaired, this one might be made to last almost forever.

Even though the only Yeomans shell making lathe dimensions that we could find were for a 10 ton machine meant to turn 3400 pound projectiles, it was not hard to scale it down to a 16" swing shop lathe. It was more difficult to scale it down to to a 12" swing 450 pound lathe because some of the components in the carriage get a little crowded

Nearly every machine builder will want to leave his imprint on his machine. This is only natural and is a good way to improve the design, but I hope most early adopters will discuss their changes with other builders before they commit to steel and concrete. Our first goal is a design that can be documented in a "How to Build". We need pictures of the actual construction process that will correlate with the drawings. We will be happy to adapt the drawings to important improvements but I don't want to take advantage to Tyler Disney's being such a good guy.

Slow turning speeds really work

Check out #18 and #19 to see the great power of slow machine speeds. Also see the primitive chucks that were used and the change gears we were able to get away from by using a few simple bicycle parts along with a drill chuck from a broken drill.

Steps in construction
the size we chose and why
lathe bed and form
an almost no fastener version (not to be shown) where the form is held together by pegs and blocks, adjusters will be replaced with hardwood wedges, way stabilizer bolts replaced by holes in the form. 4 studs around the spindle will be retained as a way of mounting a temporary lathe mount.

ways


carriage
cross slide
Temporary lathe to be used if no outside machining is available
spindle