I started out by adding a stepper to my wood turning lathe spindle and an xy table onto the lathe bed you can see this here (blog is a bit sparse). I recently bought a small mill to help with my construction of version 2 of my cnc run ornamental turning setup and am currently busy building this. I am also writing software to generate gcode to drive my setup which I feed into emc2 to control the steppers.
I also want to add steppers to my mill which is a 20vsm with DRO bought from RDG and have a question about this. I am ok with converting the table (but if someone has already converted this type of mill and has drawings of brackets then I would use them to save me designing my own).
But I really want advice about converting the Z axis. My mill has both coarse and fine vertical feeds. The coarse feed is operated by a large wheel attached to the vertical slide and traverses the whole of the column; the fine feed is via a little wheel on the front and is 50mm depth range.
So my question is which feed should I add the stepper to? My inclination is to go for the coarse feed, because there is access to the thread at the top of the column. However I have two concerns 1) balancing the weight of the mill head so I do not need to use an extra high torque stepper and 2) would I get a fine enough vertical movement with the stepper directly connected to the column screw (even microstepping the motor at x4).
I had planned to use the same type of stepper on the mill as I use on th OT setup (about 4Nm torque bought from motion control products ltd) mainly because I already have the drive electronics built for these and can share that one controller between my OT setup and the mill, but I have doubts that the steppers would be strong enough to drive the head vertically.
I would appreciate any advice on the mill conversion