Sidewinder Lathe Project Update

Well, I’ve completed a number of “required” projects and now I can get back to the “fun stuff”.  The Sidewinder lathe is taking on “a life of its own”.  I’ve done some re-examining of my goals for this project.  Here’s the current list of things that I’d like to accomplish by building this lathe:

  • design and construct a lathe that is human powered, but still capable of a range of speeds that will allow for high quality execution of the work on a reasonbly broad range of diameters, up to eighteen inches;
  • be able to turn pieces up to sixty inches in length on a fixed bed (perhaps longer with a bed extension);
  • minimize the footprint, by positioning the driving wheel parallel to the lathe bed;
  • utilize contemporary work holding devices

In short, the goal is to build a big lathe that will be capable of turning large parts using modern chucking while occupying a small amount of floor space and – DO IT WITHOUT A MOTOR!

Okay, so I’ve got to start somewhere.  And, it seems to me that the logical place to begin is with the drive mechanism.  This, it would seem, would consist of the power supply (Me!), the power transmission apparatus, and the speed control system.  Alright, you’re right to ask the question – if I’m using a treadle, which is driven by human power, why do I need a speed control system?  Can’t I just increase or decrease the treadle speed as required?  Well yeah, I could.  But if anyone has every ridden an old single speed bike up a hill, you’d immediately know why some method of speed control (or more appropriately power control) would be so desirable. 

I plan to use a large drive wheel, forty-two inches in diameter.  From working on my springpole lathe, I know that about one hundred treadle strokes per minute is a pretty comfortable pace.  The math is realatively straightforward, I’ll be able to generate a pretty good amount of speed.  Ahh, here’s the problem.  The springpole lathe, you see, is all about torque.  It is a “torque monster” (as Underhill says, great for cutting multiple threads).  The “big wheel, high gear, high speed” lathe won’t be very torquey.  It’ll be kind like when Honda brought out their 250 cc four cylinder motorcycles to the race track.  Everyone thought their little rubber bands would break (but they beat everything in sight).  However, when I’m roughing in a large piece of stock, I’m going want to run at a slower speed with adequate power (torque).  Therefore, the need for some type of gear change mechanism.

So for the past few days, I’ve been thinking about methods of gear changing that I might use.  The whole issue is pretty well complicated by the fact that I have a right angle change of direction in the “power supply” line.  I thought about a step pulley arrangement but that would require the use of some kind of tensioning device (idler, etc.).  That device would not only take up valuable space, but it would also alter the direction of the power transmission (spliced rope or round leather belting).  Then there’s the problem of the type of belting I would use between the two step pulleys, as I invision them as being supported at both ends, not cantilevered.  Then, EUREKA! – a flash of insight.  Why not use two cone pulleys with a transfer idler?  Truly variably speed.  After a little simple mathematics; Speed of drive pulley X Diameter of drive pulley / Diameter of driven pulley = Output speed,  I figure that if I pump the treadle 100 times per minute, I can realize spindle speeds of between 175 rpm and 2950 rpm by simply moving the transfer idler.  Here’s a diagram of the “theory”,

So…If there’s anyone out there in “Lalaland” who’s as goofy as I am, let me know if you think that my theory holds up.  I’d be most appreciative of any input.

Obviously, this little project isn’t going to be completed within the next couple of days, so I’ll keep you posted.

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8 Comments on “Sidewinder Lathe Project Update”

  1. Tib Says:

    Hi!
    We have on display at our gallery three reproductions of Norwegian sidewinder lathes created by Norwegianophile and expert turner, Richard Enstad. I’d be happy to put you in touch with him if you would like, and to send images of his lathes.
    Cheers,
    Tib

    • Don Olson Says:

      I have just been exposed to the sidewinder lathe. The only picture I have is one with Dick Enstad standing by a s-winder lathe but only the top half is showing.
      How can I get images/pictures of it?
      Today I called Vesterheim but the lady did not know but said that Diane, education coordinator, would not be back until Monday.

      • Tib Says:

        Hi Don-
        Much time has passed, but if you would like I can send images. Please email me at tib@woodturner.org

      • D.B. Laney Says:

        That would be great. I’ve spent a lot of time completing other projects in the last year, but the “sidewinder” is still much on my mind. Any pics would be helpful. Thanks Dennis Laney

        ________________________________

  2. Don Olson Says:

    I have just found out about sidewinder wood lathes and am very interested in your design and development of your respective project.
    Looking forward to an update.

  3. Matt Sullenbrand Says:

    Hello again,

    You might want to look into the owner of the lathe on this Web site: http://www.rvp1875.com/index.php/tools/lathe

    Seems like a nice design that may be somewhere along the lines that you are looking for.


  4. Hi,
    I have a suggestion for the drive train.
    The large drive wheel could power a large screw directly from the hub and then a gear would mesh with the screw. The gear would turn the wood.
    This setup would require some extra gearing to step up the speed, and it would avoid the drag of a pulley system. However your lathe ” turns” out i’m sure you will have fun.
    Good on ya for building a lathe
    Like this. 🙂

    • D.B. Laney Says:

      This has been one of those projects that has been on the back burner for a while. That said, it’s still one that I’d like to do. I gave my springpole lathe to a friend of mine several months ago, needed the space. But there’s nothing like working on a foot powered lathe, so I’m sure there’s another one in my future. If you’ve got a minute and could make a little diagram of what you have in mind, I’d sure like to see it. Thanks for your interest.


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