Two Steps Forward, Two Steps Back

16

bench top lathe A lathe is pretty straight forward. You get a bit of wood spinning, and then gracefully shove a sharp implement into it.
As it spins, material is removed evenly from around the centre point, and you end up with your turning.
How we get the wood spinning though is the interesting bit. We have a few decisions to make.

Modern lathes have electric motors that turn the work continuously. You turn the thing on and it starts spinning towards you, continuously in the same direction. As long as your tool is touching the wood, it’s cutting.
bungee latheThe most common type of human powered lathe works quite differently. It’s known as a reciprocating lathe. You have a batten on the floor with a bit of string lashed to the end. That bit of string goes up and is tied to a long bendy stick that has one end screwed to the celling. When you push the batten down with your foot, it pulls on the string and bends the stick. When you let your foot off, the stick springs back and pulls the batten up to the start spot. Wrap a bit of wood around the string in the middle, and every time you push down on the batten the wood spins one way, when you release it, it spins the other. Hence the term reciprocating. One spin forward, one spin back, repeat.
foot powered lathe

As a result, the tool is only cutting on half of the rotations so technically speaking, it’s a lot less efficient. If you want more spins per cycle, then you can increase the length of the batten to give the string more travel.

There is another type of human powered lathe which commonly goes by the name of a treadle lathe. You basically have a pedal that’s is attached to a sod off flywheel, that’s then connected to a driveshaft via a flat belt. The shaft connects to the wood that you want to spin. You get the pedal going, get the flywheel spinning, and your off. You have a continuous rotary lathe that’s human powered.

Whether or not I choose to replicate Roubo’s exact lathe, one thing will be for sure; what I build will be stout. As a result, it would be able to be powered with either method, or if I wanted I could even shoe-horn an electric motor onto it. But I’ve decided that I’m going to go for reciprocating. There’s just such a charm to turnings that come off such lathes, not rough or imprecise but wholesome. Much like the light scallops that are left from a hand plane.
I also love the full body rhythm that they create. Every time you power down you engage the tool, and on the back stroke you back off. It stops the second you stop, it starts the second you start, none of that winding up.
And despite the fact that I would never call myself even remotely experienced at turning, I’ve never found them that inefficient.

On top of all that, a reciprocating lathe is far more simple to build, and more reliable that the treadle lathe.

So that’s half the battle of how to power our lathe decided. Next, it’s pole vs bungee, vs anything else that bends.

reciprocating lathe

These photos are of my small bench top lathe which is a reciprocating lathe, powered by bungee.

16 Responses

    • Jasper

      The whole thing being stout is the most important.

      I guess a “sod off flywheel” is a flywheel that is not balanced and mounted poorly. Hence it flies well and sods off easily.

      Have you considered an electrically powered reciprocating lathe? It has more or less the same rhythm. It could have a foot switch for easy operation.

      Reply
      • Mike Ballinger

        I believe it’s more likely to be around its size. In New Zealand we would say its a huge f**k off fly wheel. Meaning it’s really big.

        Reply
        • Jasper

          Yes.

          The fun thing is that a light flywheel spinning fast can have the same effect as a heavy slow one. It just could add some resistance.

          P.S. Don’t let the people in “Old” Zeeland hear those words… 🙂

          Reply
  1. Bob Vogel

    And, if you get good with your spring pole lathe, you can turn a cup, and leave the handle on. (Don’t ask me to demonstrate, my lathe has a motor 🙂

    Reply
  2. TaDaMan

    To be clear, the lathe is actually going to be powered by the Maguire hoof. And the bungee, pole, steel spring, etc. is just the return spring for the lathe.

    What needs to be balanced is a return spring that has enough power to reset the work quickly, while not resisting the power stroke of the operator too much so they tire out fast. A design I like the look of (have not built or used mind you) is a hybrid pole/bungee where there is a rigid pole set up like a teeter-totter and on one side is the drive rope and the other is a bungee. This setup allows you to adjust the power of the return spring by moving either the rope or bungee in or out from the pivot. So a small piece can have a lighter return than a large one. Quickly tuned for the job at hand, just like the length of the batton for spins per stroke.

    Reply
  3. Matthew Collicott

    Could this be a video build? Been wanting to build one for a long time now.

    Reply
  4. Tom Angle

    All this lathe talk made me build a bungee lather this weekend out of some scrap wood. I do have to say that there is something about turning wood that is hypnotic in a way.

    Reply
  5. Allan Davis

    What about a weight on a pulley? That way the amount of effort to spin spindle is adjustable.

    Reply
  6. Joshua Klein

    I just built a new pole lathe based on Roubo’s out of 12/4 white oak. It sure beats my 2x white pine Roy Underhill design. Go for mass, Richard!

    Reply
  7. Frank C Joseph

    My first turnings where on my grandfathers old lathe it was power by half of a long bow, the heavy lim was mounted between rafters over head. A cord ran down to a pully mounted on the floor. And then up to the drum on the end of the lathe, the drum was about six inches wide and 12 or so inches round. This gave more revaluations and more speed, the drum could be changed, to adjust speed and turns, it was a reciprocating, the drum was not a flywheel it only adjusted speed and number of revaluation s just food for though
    Good luck on this build
    Frankj

    Reply
  8. Antonio

    Hi Richard and Helen…

    I did it… And tried it… And now have a new handle for my (older then me) hammer!
    And also dis a blog post with pictures. (just in case)

    But more important, May I suggest a blog post about the gauges and chisels that combine with this lathe?
    I’m under the impression that my 1″ Aldi chisel and 1″ Faithfull Straight Gouge Carving could be improved.

    Thanks you both
    All the best

    Reply
  9. Dave Chamberlain

    Hi Richard, do you work seasoned timber on your pole lathe? I always thought that they were for green woodworking.

    Regards Dave

    Reply

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