Yeoman’s Lathe: Background

Can you imagine taking three months saving money to buy a cheaply made wood plane? While at the Maker Fair in Ghana in 2009, I learned of a young student of a carpentry trade school who had done just that.

Individual people in the developing world face huge obstacles -- and stiff competition -- as they try to start economically viable enterprises. As the carpentry student above found out, tools are expensive and out of reach to all but a few, making the acquisition of tools and the skills to use them one of the biggest roadblocks to development in informal economies. Those who do gain skills are often roadblocked from passing them on due to the lack of available tools -- education alone is not sufficient if people can't put their skills to work.

Imagine a different scenario:

  • What if the barrier to machine tools of acceptable quality were lowered?

  • What if you could build a metal lathe (the key tool in manufacturing almost everything) out of a few bags of concrete and scrap metal?

  • What if you could fill an entire machine shop or small factory with tools made out of scrap and concrete? What if that machine shop made a business out of making more machines, populating other machine shops that made businesses out of fabricating parts for agricultural equipment, repairing auto parts, making lucrative sculpture art, or any of the myriad other niche markets in the informal economy?

  • What if communities with severely limited economic potential could bootstrap their fabrication and manufacturing ability to increase their industry and quality of life, without outside assistance or loans?

  • What if you could cut training time from years to just a few weeks?


These are the sort of what if’s that motivate our Open Source Lathe project.


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[Lathe bed casting ready for bearings and ways to be assembled. Image from 1916 article.]

This 1915, 20,000 pound cannon shell lathe design became this modern lathe that will fit on a bench top and can be built by a mechanic from concrete and scrap metal.


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Basically, this project repurposes Yeoman’s innovations for war materials manufacturing during World War
I for the design of appropriate machine tools in the developing world.



Yeoman’s Innovation

When the U.S. entered World War I, the country suddenly needed to produce millions of artillery shells, guns, and other war materials. At that time the manufacturing sector didn’t have nearly enough tools to produce the materials required for the war effort.
  • “Conventional cast iron construction of machine tools is a slow and laborious process. The iron must be stress relieved and trued by skilled workers. Shell making lathes and gun planers and borers would take months just to get the machines built. The actual production of bombs, guns, and ammunition would be even longer into the future. The United States needed machine tools immediately.”
  • -Mr. Shannon DeWolfe
Lucien Yeoman’s innovation was to reduce or eliminate the curing and machining time by using off-the-shelf manufactured components – bushings and the like – to provide the accurate machine surfaces required for a precision machine tool. The tool-creation process looked like this:
  1. Cast the concrete tool basic structure, leaving voids for bearings/bushings and let the concrete season long enough to become stable.
  2. Using a jig, place bushings, ways, spindles, and other components into perfect precise alignment.
  3. Pour a special alloy of type-metal into the voids, casting the bushings and components accurately in place.
This manufacturing method allowed precise machine tools to be built and ready for production in hours instead of months required for traditional method.
We had to scale his lathe down a bit (95 to 97%). We also had to make it a general purpose screw cutting lathe instead of one for making only artillery shells. We actually changed little in his basic, but until now,almost forgotten design. After the war, Yeomans was awarded the prestigious Franklin prize for his efforts. And then his machines were almost forgotten.

We did had to make a few changes when we shrank the Yeomans design.
  • We did not have a factory, multiple factory alignment jigs or the Yeomans' secret type-metal recipe. Instead, our tools are meant to be built in sheds in rural areas of Developing Countries.
  • We added a general purpose lathe carriage, a movable tailstock and a new version of our proven Multimachine wooden jaw thread follower threading device.
  • We did retain all of the important and long proven parts of the original Yeomans design, a weighted carriage, locking critical parts into a seasoned concrete casting and his use of supported round lathe ways.

Our new design has these features.
  • It had to be movable, this one will weigh about 450 pounds. The concrete frame should weigh about 320 pounds and the carriage and tailstock are easily removed.and replaced with no loss of alignment.
  • It should be able to machine a 5 or 6" steel or a larger aluminum workpiece
  • It should be able to resurface 12" brakes, clutches and flywheels when a ubiquitous 4.5" angle grinder is attached to the tool post.
  • Assuming careful construction, it should be accurate enough for "real world" machining.
  • It should cost at least 95% less than the cheapest available commercial lathe lathe of comparable size.

To understand all this you need to do a little homework and really study these:

These articles from 1916 explain the construction process in greater depth:


Why Concrete?

Concrete is ubiquitous, cheap, and easy to work with. There is precedent for its use, both in Yeoman’s designs and others.
This article on building a 6-in turret lathe with a concrete bed is also related because J.V. Romig, writing in Popular Mechanics and in other magazines, kept the concrete machine tool idea alive (thanks Google).


Where can I find the latest design?

The latest design drawings and draft How-To-Build guides will be kept on this page of the wiki for easy public access.


Who is working on this project?

Pat Delany, inventor of the MultiMachine, has been researching and working on this project for 8 years.
Tyler Disney recently teamed up with Pat to help produce drawings, models, and to visually communicate the design. Although an engineer by degree, Tyler is not providing engineering services for this project (i.e. Tyler doesn't really know anything about lathes or machine design).
The design process for this project is open and collaborative; many many people are involved and actively contributing to this project. Check out the Yahoo Groups sites below and subscribe to the email lists.


Background Resources