Questions Regarding Converting a Lodge & Shipley Engine Lathe to CNC

[NickB]

Relatively new to the forum but have been getting great help on another project, so I figured I would seek some advice on a new project. We are looking to convert an old Lodge and Shipley 20.5” x 78” Powerturn Engine Lathe Model 2013 to be a CNC using the Acorn board. We do not use the lathe for actual turning operations as we only use it to bore center holes in round stock. The lathe is already equipped with a Vacon VFD for the spindle motor. I am looking to only control the Z axis, as we never move the X axis.

My main questions are should I use a stepper motor or a servo motor to move the Z axis and what size should be suitable? I am not concerned really about the speed as we do not need to drill extremely quickly, but just want to make sure we use something with enough torque.

To go along with this I was wondering if it would be suitable to drive the Z axis from the feed rod using a belt and pulley system or something similar? I am trying to avoid having to switch the feed rod out to a ball screw if possible as we do not have to be critically precise on our depths. I was not sure if the backlash compensation of the Acorn would be enough to account for this?

Thank you for any help in advance and I apologize for all the questions, however I am very new to these types of projects. Please let me know if I can provide anymore information.

I also apologize for the sideways photos, however if you click on them, they appear properly.

[cnckeith]

size of Z motor depends on the screw and belt reduction you use. i would install a 5 turns per inch ballscrew and use 2:1 htd belt reduction so overall turns ratio is 10:1 and use a 1KW AC servo on Z