Updated and Re-configured Twisting Machine
I had the twister mounted to a 4' x 8' table before and needless to say it was a hassle to
move about. Now I have made a 'twister truck' which is two light weight "I" beams with wheels.
I had to re-arrange the drive set-up but it is essentially the same.
click the picture for a larger image
The final drive in 1st gear is about 1.25 rpm.
I use 1st gear the most. I use the drum switch to reverse the direction of the motor, rather than using reverse gear on the transmission. I have to admit that there was more luck in building this thing than there was engineering. I pretty much had to use what I had laying around. The goal was to get from 1750 rpm down to about 1 rpm. I started with a 1750 rpm, 3/4 hp reversible electric motor. Runs on 220. (strong) I bought a "drum switch" from Grangers for about $30. The drum switch allows forward & reverse switching of the motor. I took the 3 speed transmission from an old broken riding lawn mower. I used a 3 step, v-belt pulley on the motor and a 3 step, v-belt pulley on the input shaft of the transmission. This allows for infinite speed variation and a link for slippage if necessary. The transmission used a chain drive to power the wheels of the mower. I had a buddy with a machine shop cut down an adjustable v-belt pulley and mount the driven sprocket from the mower to the pulley. I didn't engineer the size of these sprockets,
I just used what I had. The gear reducer was just about new and supposedly came from a boat lift in a small marina near by. I paid a guy $100 for it. I didn't choose 32 : 1, That is just what it happened to be. I couldn't afford a 3 jaw chuck or a 4 jaw chuck from a metal lathe so I found a piece of 3" round stock. My machine shop buddy drilled one end to fit the output shaft of the gear reducer, and bored a 2" hole on
the other end. Drilled and tapped for 4 "jack bolts" that hold the piece to be twisted. This machine has an incredible amount of torque. On larger stock, (1" and bigger) It is harder to get the stock hot than it is to twist it. The vise is a spring loaded affair. The idea is to keep tension on the piece being twisted to help eliminate sagging. A single piece of stock will get longer when twisting hot with the spring loaded vise.
A bundle of stock, will get shorter.