I'm going to convert my 10x22, 2 axis lathe to CNC, conversion images please

I recently converted my knee mill to CNC, I now want to do the same for my 10x22, 2 axis lathe.

Lathe is a Craftex CX706 which is identical to a PM1022

I would like to see how people have mounted their steppers / servos to give me some mounting ideas, so if you have done a lathe conversion, please post an image of the stepper/servo mounting.

I measured required cross-slide torque at 0.5 Nm (just to move cross-slide), not sure how much extra is required for actual cutting?

I'm leaning towards 7i96S for a control board. Comments welcome.

Much appreciated.
 

What's your intent/desire?  CNC as fast/cheap as possible, or as much lipstick on that thing as it can handle?

Are you replacing the lead screws with ball screws?

How much aversion do you have to butchery? i.e. removing bits and making permanent holes in castings?

Just asking, because my first suggestion would be to:

• Z-axis ball screw right down the middle of the bed with a direct-drive motor under the spindle.
  • Gearbox in the bin, sheet-metal in the bin.
  • Ball nut bolted to carriage right under the centerline where you're cutting
• X-axis motor to the rear, direct drive
• Cuts down on overall size envelope, keeps you from bumping in to the X-motor or having to figure out a belt drive, and - more importantly - puts both ball screws in tension during the typical cutting directions.

You don't have room for 'beefy' ball screws, and you can get away with smaller screws (maybe 20mm on that lathe) if you aren't attempting to bend long, poorly-supported screws by putting them in compression.

Downside - you no longer have a friendly-looking little lathe with cute handles.

Upside - you'd be showing Rotary SMP what Mini-lathe Pimping really means.

slowpoke wrote:

I'm leaning towards 7i96S for a control board. Comments welcome.

 

(slightly more serious answer)

7i96 is a great board, I've got one in my lathe.

Spumco,

I don't want to make this irreversible, and I will try using the existing lead screws (backlash and all) at least for now. Not sure how well the backlash compensation will take care of that, I guess I will find out.

slowpoke wrote:

Spumco,

I don't want to make this irreversible, and I will try using the existing lead screws (backlash and all) at least for now.
 

Understood - if it wasn't obvious, I was kinda engaging in a little 'what-if' fantasy as if it were my lathe...

Nice thing about lathes, the backlash isn't quite as big a deal as on mills.  It's rare that you have to cut in both directions on one axis in the same toolpath (think circle on a mill).  Just write your programs with enough retract so that the backlash is taken care of when the next cut approach is made.

Regarding motor mounting, I think you'll want to mount the Z-motor outboard on the right, probably with a belt drive.  Keep the gearbox, and just leave it disconnected.  X-motor up front, and hang it under the cross slide with a belt up to the leadscrew.

Rotary SMP's minilathe series would be a good starting point for mount ideas - just scale it up to fit.