Stepper Sizing

Looking for info about stepper sizing. Anyone know of any good sites with advice on stepper sizing? Need x and Y axis sizes for retrofit on an old 10" x 24" lathe. Using ballscrews on both and possibly linear slides on x-axis. Thanks

wiki.linuxcnc.org/cgi-bin/wiki.pl?Stepper_Formulas
wiki.linuxcnc.org/cgi-bin/wiki.pl?Steppe...or_Speed_Limitations
wiki.linuxcnc.org/cgi-bin/wiki.pl?Mechanical_Spreadsheet

All of those pages are on the LinuxCNC Wiki

wiki.linuxcnc.org/cgi-bin/wiki.pl

JT

As a data-point I have a lightweight Chinese 9x20 lathe runing with NEMA23 steppers. It has 3.5Nm on Z and a 20mm ballscrew and , 2.5Nm on X with an 8mm ballscrew.

The X is slightly more acceptable than the Z, though parting is a bit of an exercise in frustration. Toolpost drilling is not really an option with anything bigger than 6mm.

It's a perfectly usable lathe, and has made some decent parts but on the basis of that machine my latest conversion (a Holbrook Minor 10 x 20) has 1kW servos on both axes.

For a stepper machine I think I would be looking at 3.5Nm NEMA 23 on X and 5+ Nm NEMA34 on Z.

Thanks! Having a reference point is a big help! I noticed you refer to the carriage axis as 'Z', while others refer to it as 'y'. Is this interchangeable?
What are your opinions on hybrid steppers? I was also concerned about going too big as others have said that sizing too big can result in rapids being too slow.

what are your thoughts on drives? My impression is that the higher voltage drives are preferable and will provide best performance.
Do you have any favorite brands of steppers and drives?

andypugh wrote: As a data-point I have a lightweight Chinese 9x20 lathe runing with NEMA23 steppers. It has 3.5Nm on Z and a 20mm ballscrew and , 2.5Nm on X with an 8mm ballscrew.

The X is slightly more acceptable than the Z, though parting is a bit of an exercise in frustration. Toolpost drilling is not really an option with anything bigger than 6mm.

It's a perfectly usable lathe, and has made some decent parts but on the basis of that machine my latest conversion (a Holbrook Minor 10 x 20) has 1kW servos on both axes.

For a stepper machine I think I would be looking at 3.5Nm NEMA 23 on X and 5+ Nm NEMA34 on Z.

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Robotwizard wrote: What are your opinions on hybrid steppers?

If you mean the ones with integrated encoders, then that is what I would use if I was building a stepper system.
But, recently, I have been using second-hand industrial servos.
One of these ought to be pretty good on your Z, perhaps something shorter on X.