So I'm looking to build a lathe and I'm basing everything on the Emco Compact 6 / 120 / 220 lathes. I can't just pick up a used lathe as they are too big and heavy for me to bring get into my garage, so I'll just build one in situ.
To give some context, at a high level I just intend to buy a spindle and turret from one of these lathes. (Already have the 220P spindle on the way and I'm currently looking a either a turret from the 220 or a slightly larger turret from the 320.) To give an idea on size, the larger turret has a mounting base of around 120mm tall by 85mm wide and the work area for the 320 lathe is 176mm for the Z axis and 56mm for the X axis, so only small. The originals use ballscrews and box ways for both the Z and X axis, with the X axis mounted "upside down" with the longest part moving up and down.
My plan is to mount everything to a cast iron surface plate (About 24" x 18") which will give me a nice flat ferrous surface (For magnetic indicator mounts) and proper metal to drill and tap for mounting, then I'd cast some epoxy granite under this surface plate to build the slant angle and add mass / rigidity. For the Z axis, I'll use a ground ballscrew and some preloaded linear bearings, but for the X axis I've found a THK KR46 (https://tech.thk.com/en/products/pdfs/en_a02_116.pdf) which happens to be just about the right size. (It's not a standard length so it must have been cut down or custom made) I'd mount the THK KR46 upside-down (I.e. With the sliding block mounted to the Z axis and the body / rail / X axis motor moving with the turret) so that coolant / chips drain out, but it would be covered anyway. I can't use a larger THK KR linear guide as they are all far too long.
My question is whether or not the THK KR46 will be rigid enough for the X axis ? For reference, the standard Emco 220 spindle motor is a DC 2.6kW motor with a maximum spindle speed of 6,300RPM. It is meant to be constant torque upto 1,700RPM and constant power for the rest of the range, which by my calculation suggests that the maximum torque is 14.60Nm. (2.6kW @ 1,700RPM)
Here's the motor nameplate from the 120:
https://vignette.wikia.nocookie.net/...ns120motor.JPG