ScotY wrote: ↑Mon Jul 22, 2019 8:41 pm
Thanks, Reed! I was wondering what you made the gibs from...now I know. I understand how you made them and the mounting blocks. How did you do the linear rails? Can you post more pics?
The design of my linear rails are a direct result of what I had on hand and was really intended as an experiment.....
The reason I went with linear rails was because the cross slide to saddle fitment was really far off. I believe when Techno-Isel was producing these machines they took the cross slide off and flipped it around so the gib adjusting screws are on the opposite sides as there were from the factory. They did this so the mounting screws for the ball screw block wouldn't interfere with the gib. I originally was going to re-scrape the cross slide to the saddle but after some checks with I found my cross slide was warped and the dimensions of the dovetail were pretty far off. Not to say it couldn't have been repaired but I wanted to give the linear rails a shot as I have never worked with them before.
To mount the rails, I first took a piece of precision ground shaft (thompson linear shafting) and clamped it into the "V" way in the bottom of the saddle. I then mounted the saddle on parallels onto my mills table and used a test indicator to sweep along the precision shafting to indicate the saddle square to the x travel of my table.
I wrote a simple program in intercon to drill the holes for the mounting screws for the rails and tapped them for m4 threads.
To align the rails to the spindle axis I mounted the rail that was closest to the head stock onto the saddle and placed a test indicator mounted to a magnetic holder on top of the rail truck. I then put a parallel against the chuck body and lightly clamped the parallel with the chuck jaws. To verify the parallel was square, I set my test indicator to read "0" on one end of the parallel and spun the chuck 180 degrees and adjusted the parallel until both readings on each end of the parallel read "0"
I then swept the test indicator across the whole length of the parallel by moving the rail truck along the length of the linear rail until I was happy with the reading. I think I set it so there was about a tenth of taper moving toward the center of the spindle axis. I then mounted the other rail and swept that one in with my test indicator using the first rail as its reference.
All in all it works pretty well. I get a decent finish on aluminum and threading seems to come out pretty good. I do get some chatter when parting however, my parting blade isn't much to be desired.
I've been thinking about re configuring the linear rail design to incorporate 4 trucks for more rigidity. I've been toying the idea of machining off the dovetails on the saddle, filling the void with epoxy granite and mounting the trucks to the saddle and the rails to the cross slide or making a seperate linear stage using low profile hiwin mgn15 style linear rail and trucks that bolts to the saddle as an assembly.