Instructables

A modern build of a medieval spring pole lathe

Step 4: Lathe details - building the spring pole

At this point the “spring pole” lathe is almost built. THe reason for all the quotes around “spring pole” will be evident in a moment. At this point, we have uprights mounted on A frame supports, parrallel crossbeams, holding up a moveable head and tail stock with steel centers. Now we need a power source to rotate the object that will be held between the centers.

In olden times, and I do mean OLD, the power source was a springy pole, that would pull the rope wrapped around your workpiece back after you’d pushed down on the treadle to rotate it. This would create a reciprical or back and forth motion of the workpiece. You’d apply your tool on the down stroke, and ease off on the up stroke. This is the wood turning was done for hundreds of years.

Since I could not walk out to the woods and find a springy pole, and more to the point, I had no room in my garage for one, I decided to use a “bungie cord” instead. This would give me spring back enough to do the job, and could take up much less space, while still recreating the motion of the springy pole.

For my lathe I took a couple of lengths of 2×2 and drilled holes about 1 inch down from the top, on one side. I did this for both side pieces. They were about 8′ long, straight out of the hardware store. I trimmed about 6 inches from the ends to get rid of bad wood. I then cut a 4′ chunk, and drilled the ends to accept a 6″ piece of dowling on each end. It stick out about 4″ after sinking it into the ends. These dowels go through the holes in the tops of the side pieces. No need to attach it any better, since the next step is to hook the end of the bungie (mine was purple, very festive) around the 2″ of dowling sticking out of the side piece, and stretching it over to the other side to hook it over the other dowling end. This pulls the two side pieces up agaisnt the ends of the 2×2 middle piece, and it’s all good.

All I had to do was tie a rope around my bungie in the middle, and wrap it around the piece of wood pinched between centers, and voila a “spring pole”!

The last step was to create a treadle from some 1×2 scrap, a piece of leather for a hinge, and a piece of scrap ply wood to stand on. The 1×2 should extend past the end of the crossbeams. I notched the ends and made a sort of A shape out of the 1×2 pieces with two hinges attached to the plywood I stand on. The crossbar of the “A” was placed so my foot had a comfortable place to rest. It works quiet well, and is less work than I expected!

I’m still working on a design for a toolrest. For now I just clamp a 2×2 scrap to the head and tail stock, but that doesn’t work very well.
 
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wizworm3 years ago
Look into traditional bowmaking for your spring pole (think the top half of a bow), I'd find a straight grained red oak 1x2 and sand it down to a taper testing its springyness along the way. There's lots of 'ibles about bowmaking that can help
throwapot3 years ago
you could also make it like a sewing machine where the pedal operates a rod attached to a flywheel. I don't know if they used such devices in the middle ages for lathes, but off center wheel and rod technology has been around for a long time.
The idea of a spring pole lathe always intrigued me -- I was wondering what it would be like to scavange a spare bicycle rear axle/cassette and take advantage of the pawl mechanism to get a spring pole lathe that didn't reverse direction every time you lift your foot. Hrmmm. Then add some spinning weight to help carry momentum. Might really make it even easier to use.
Great idea! I was also wondering if it would be helpful to add some kind of gear or pulley system that would increase the number of revolutions with each step on the treadle.
DaboJones5 years ago
Do you have some more detailed pics of the treadle mechanics? We're looking to make an automaton powered by treadle, but now that I see this I want my own lathe...:) Thanks for the instructable.