A few months ago I acquired my very first lathe! Even after boundless hours of research, hindsight is always 20/20
The lathe I picked up (BT250F) has all the power and size I could fit through my door and heft down the stairs to my basement shop, but it's pretty spartan on features. Like most hobby lathes it lacks a geared head and features those marvelous change gears we all know and love, but it also lacks a powerfeed separate from the leadscrew. While I read that it's best not to powerfeed with the leadscrew regularly due to wear causing inaccuracy for threading, I was more annoyed by having to swap out change gears to go from threading to powerfeeding and back.
After trying and failing half a dozen designs I found a post I have since lost on a forum I have long since forgotten about using a stepper motor to drive the handwheel. So I went ahead and tried that.
The Nema 23 Stepper Motor mount will fit in between the handwheel and half nut lever.
The mount was modeled in Rhino and 3D printed for fit before routing from 6061 and mounting to the Apron. There is a slot for a belt tensioner and the apron was tapped for m6 screws
The original handwheel has a recession for a spring that puts friction on the handwheel dial. The new handwheel needed an additional area for the belt pulley. The belt pulley was threaded onto the shaft and the threads staked in place. Then the replacement handwheel was milled from 6061 and attached to the belt pulley with m6 screws. A collar was also created to sit between the handwheel gear shaft nut and the handwheel to prevent it from tilting under the tension of the belt. I would have liked to add a thrust bearing between the handwheel and apron, but the gear shaft just wasn't long enough and this seems to work fine.
Instead of key I used an m5 grub screw ground to a square profile at the end which fits beneath the handwheel dial
When I want to run the carriage longitudinally by hand, the grub screw in the pulley on the stepper motor can be loosened, and it runs pretty smoothly (as long as it's oiled!). A few turns of the grub screw and flicking the motor driver switch and I'm ready to power feed. A lot quicker than swapping change gears!
The stepper motor driver fits in a molded aluminum case mounted to the rear guard and can drive the stepper motor anywhere from 1 - 999 rpm cw or ccw.
In the future I would like to add some kind of guard to keep the belt clean but still gives me access to the dial, and a bearing beneath the stepper motor pulley so it spins without being oiled. The challenge there is that the stepper motor shaft is pretty short, but I have some ideas. Anyway, attached is a short demo of it in action.
Comments and criticism, or any ideas to improve it?
Anyone else made a similar novel upgrade to a low feature set lathe like this?
The lathe I picked up (BT250F) has all the power and size I could fit through my door and heft down the stairs to my basement shop, but it's pretty spartan on features. Like most hobby lathes it lacks a geared head and features those marvelous change gears we all know and love, but it also lacks a powerfeed separate from the leadscrew. While I read that it's best not to powerfeed with the leadscrew regularly due to wear causing inaccuracy for threading, I was more annoyed by having to swap out change gears to go from threading to powerfeeding and back.
After trying and failing half a dozen designs I found a post I have since lost on a forum I have long since forgotten about using a stepper motor to drive the handwheel. So I went ahead and tried that.
The Nema 23 Stepper Motor mount will fit in between the handwheel and half nut lever.
The mount was modeled in Rhino and 3D printed for fit before routing from 6061 and mounting to the Apron. There is a slot for a belt tensioner and the apron was tapped for m6 screws
The original handwheel has a recession for a spring that puts friction on the handwheel dial. The new handwheel needed an additional area for the belt pulley. The belt pulley was threaded onto the shaft and the threads staked in place. Then the replacement handwheel was milled from 6061 and attached to the belt pulley with m6 screws. A collar was also created to sit between the handwheel gear shaft nut and the handwheel to prevent it from tilting under the tension of the belt. I would have liked to add a thrust bearing between the handwheel and apron, but the gear shaft just wasn't long enough and this seems to work fine.
Instead of key I used an m5 grub screw ground to a square profile at the end which fits beneath the handwheel dial
When I want to run the carriage longitudinally by hand, the grub screw in the pulley on the stepper motor can be loosened, and it runs pretty smoothly (as long as it's oiled!). A few turns of the grub screw and flicking the motor driver switch and I'm ready to power feed. A lot quicker than swapping change gears!
The stepper motor driver fits in a molded aluminum case mounted to the rear guard and can drive the stepper motor anywhere from 1 - 999 rpm cw or ccw.
In the future I would like to add some kind of guard to keep the belt clean but still gives me access to the dial, and a bearing beneath the stepper motor pulley so it spins without being oiled. The challenge there is that the stepper motor shaft is pretty short, but I have some ideas. Anyway, attached is a short demo of it in action.
Comments and criticism, or any ideas to improve it?
Anyone else made a similar novel upgrade to a low feature set lathe like this?
