I have a Hardinge HLV-H that I plan to convert to CNC. Yes, I know it is a great manual lathe and a shame to Frankenstein it, but I got it cheap and I think it is a great machine to convert. it is very rigid, is set up for flood coolant, and it already has a collet closer that can easily be automated.
My plan is to remove the cross slide and mount two linear rails on the existing saddle with the carriages mounted on the saddle and the rails themselves mounted to the bottom of a Tormach long gang plate. the single rail I have in the picture was just for an example since I had it sitting around. Instead of using that type of round rail I plan to use something like Hiwin square type linear rails.
I will use ball screws for both axis. For the X axis I will keep with the existing dovetail ways instead of the linear rails.
My first question is what size linear rails would be appropriate for this? They publish calculations based on load, but I really don't know what type of loads will be on the rails when cutting. Anybody know what size rails are typically used in this size machine in a factory built CNC? I am guessing 25mm or 35mm would be good, but that is just a guess.
Other comments, criticisms, suggestions for this build welcome. I will be adding more info as I go.