Independent lead screw power on a 7x12?

[websterz]

I know it's possible to add a separate power feed motor to the lead screw for ultra-fine feed, but is there any advantage to be had by disengaging the lead screw from the gear train and powering it independently? Torque is always at a premium on a smaller lathe and I figure that anything I can take off the motor's shoulders, so to speak, would only leave more torque for the spindle. I don't single-point threads, I know how I just don't need to, so having the lead screw coupled to the gear train is not that big a deal to me. By using a small motor like the one I got out of the old sewing machine last night, I believe I can jack-shaft it down from 6000 RPM to something more usable to drive my lead screw. Converting that much speed down to under 100 rpm ought to really up the torque, but will a 70 watt 110 AC motor hold up? I can get another motor, whatever, I am just pondering the benefits of the project. Please, share your thoughts.

 

[bogstandard]

Websterz,

I think Steve (Cedge) is going to do, or has done, exactly what you are envisioning, so it might pay you to drop him a PM about it. Just in case he misses this posting.

Bogs

[rleete]

I'm not sure which site (but one I found through the minilathe.com) has a mod using a cheap surplus gear motor to drive the leadscrew.  He used bamboo skewers as the shear pin, too.  Showed how to mount it, and several suppliers.  I'll try to remember to dig up the site and post it.

The finishes he got on aluminum look as though they've been polished, just from the super-fine feed.

[websterz]

I've seen the site, that's how I knew the fine feed would work. I will have to have a beefier set-up for what I want to do though.