I’ve been toying with the idea of using ball screws on my little Sherline. Unfortunately the only way this could remotely make any kind of economic sense is if I went with the 5/8″ dia screw from Mcmaster. http://www.mcmaster.com/#ball-screws/=jwpffz The screws are $18.65 a foot and and the nuts are $29.90, which is cheap…..
I was thinking I could get that to work until I took a look at a nut… It’s an inch square. I might be able to figure out a way to squeeze it in on the Y-axis, but it would be a little crazy on the x. There just not enough room. one possibility might be to make a new saddle, but that was really more work than what I wanted to do. In addition it would reduce the work area on the Z axis. The distance between the table an the bottom rail would be reduced.
I ran across a link on cnc zone which led me to this sight which talks about makeing lead screw modifications. 5bears offers some interesting techniques on turn down a lead-screw. (I’m going to want to check this out more in detail later.
The 5/8 ball screw on a Sherline mill is probably as really dumb idea. The existing lead screw is 1/4-20 threaded rod. The price is right, but the size isn’t for a 5/8 ball screw.
The original CNC retrofit done by D&M was really shlock. Had I known this in my original bartering, I think I would have traded for a few more goodies Anyway.. D&M long since out of business..
Here are a couple of pictures of the Sherline disassembled.
I don’t like where the y-axis lead screw is. It’s too close to the table. The existing motor motor mount is higher then the table. I really don’t like that. On the current Sherline CNC the motor mount is tapered for clearance.
Well, on the motor blocks. D&M basically slapped the motor mounts over the exist manual system.. Not bearings. I guess it was a way to make a quick buck.
This is also a very early model Sherline. and it has the original anti-backlash system which well it sort of sucks… The new system is much nicer, it’s meshing gears. Unfortunately retrofitting is a difficult because the center distance has changed.
So the plan for the moment to to get the rest of the components modelled in Freecad. I can use the practice with solid modeling and it will allow me to experiment with a few wacko idea without having to physically modifying the Sherline.