jon r said:
i just had a cool idea!
how about a push bike pedal driven lathe. you could have different gears and everything. I know its not strictly bushcraft but i thought i would run the idea past you guys!!
The wood would only turn in one direction too!
Yes. It's not new though, been around for a hundred years or more.
Basically, you make the pole lathe like normal except you fit an extra leg on one end, just far enough from the outside leg to mount a bike rear wheel. Use one with a single gear and make sure the thing can free wheel if you know what i mean (I mean it shouldn't be a fixed gear wheel).
You run a bike chain from the foot treadle up and over the gear and down to a heafty spring so when you press the treadle it makes the bike wheel spin. When you lift your foot, the spring pulls the chain back again, but the free wheel gear allows the bike wheel to keep spinning. Add some lead weights to the spokes evenly distributed and it acts like a fly wheel.
So imagine your lathe, you are standing in front of it. The bike wheel is below and to the left of you. There's a chain draped over the gear connected to a hinged stick. The hinged part of the stick is attached to the base of the lathe leg on your right, so the stick goes up from bottom right to the chain maybe a foot high on your left. Behind the chain there's a spring strong enough to pull it back again (bungee would do as well). The bike wheel is heavy with all the lead flashing you've wrapped in and out of the spokes (lead flashing in a long 6" wide strip from B&Q). You lift your foot and place it on the higher part of the stick and push down. The wheel spins. You repeat that a couple of times and the wheel is going at a good pace now. It doesn't slow down quickly on account of all the lead. Now you can move your foot to the right of the stick and just push with your toes, not a lot of effort once the wheel is going, and you can just keep it spinning with a push of your toes near the right lower end of the stick.
That's the mechanics of it sorted. Now you need to find a way of transferring all that torque to the workpiece. Traditional pole lathe poppets (stocks) won't work efficiently. You need to find a proper head stock to put the work in. You can make one, scrounge an old one from a power lathe or buy one of the cheap ones from Machine Mart that are designed to work with an electric drill (probably your best bet).
You'll need to clamp the stock to your lathe bed (and screw it down as well). Then you'll need something on the piece that would normally be held in the chuck of the drill. Something a strong cord would be able to go round. Machine Mart also sell pully wheels of all sorts so you should be able to find something to fit.
Then you'll need a cord to go round the pully wheel and round the bike wheel (Of course, you did remove the tire first?) The cord can be elasticated (rubber band, old inner tube cut down and pieces glued together to make it long enough), or rope of some kind. If using rope, you'll need another pully wheel and a spring behind it to put tension on the rope so it'll grip the other wheels enough to keep the work spinning.
So, you have your lathe, a method of turning the work in one continuous direction, a method of holding the work and spinning it. The right hand poppet can have a normal pole lathe point on it and it would be best to fit the threaded crank on the right so you can tighten it on the billet without having to move the left hand headstock. After setting it all up, you really don't want to have to move it. Move the right hand popper only so it travels in and out for long or short work pieces and have a piece of threaded bar bent like a crank handle for fine tightening adjustments to hold the work.
Another advantage of using the Machine Mart head stock is you can mount a bowl plate on it and turn plates and bowls without the need for mandrels.
It was historically a natural progression for wood turners once the bike wheel was developed and once free wheeling gears appeared on the scene. I've built one and they work very well, but as I mostly do demonstrations in period costume from the middle ages, I have to stick with the traditional pole lathe. However, if history isn't important and you just want to turn wood, this is a good way to go. You get the best of both worlds. Continuous spinning and greater efficiency, without the racket of electric motors and dust masks and ear defenders etc.
I'd not worry about changing gears though, just pump faster or slower on the stick.
Hope this helps.
Eric
