Some of you may remember my Clausing CNC conversion from here:
http://www.cnczone.com/forums/vertic..._100_mk3a.html
Once I got "done" with it, I wasn't happy with the tolerances and only ran the lathe a few times before I stepped back and took another look at it. Since this was a total rebuild, I'm starting a new thread on it. I held off starting a build thread until now, because I was not sure this was even going to work.
The main problem was that the lathe would not hold consistent tolerances. I could not get it "tuned" no matter what I did. I think the big reason for this was the wear in the bed. If I got the carriage adjusted within a few inches of the chuck, then I couldn't move the carriage past the half way point in the bed. If I adjusted it where it was at the tightest point (farthest end of the lathe), then it was really loose at the chuck. This meant that when I tried to get the steps set, the carriage could be off .005 on one move and .015 on the next. It was impossible to get the steps set under these conditions. This was not acceptable for me. Although I was not making space shuttle parts, I felt I could do better.
So....off to ebay I went.
The first item that I found was a set of THK 25 rails that just happened to be the perfect length for the bed. But I needed a way to mount them...
This is where I really did not want to go with the project. Up until I was done with it the first time, the lathe could go back to stock. I still had all the original pieces and planned on putting it back to original if the CNC idea didn't work out. In order to get these THK rails installed, I needed a flat area and unfortunately, I had a V-way in the way.
It had to go.
A friend has a big Bridgeport, so we hauled the bed out to his mill and milled the V-way off on the front side. This way was for the original carriage and since I was building a new carriage, I didn't need the V-way anymore.
Sorry...no pictures on what we did.
I then made 8 brackets (four for each side) to support the new extensions.
The next two pictures show the brackets and the extensions. This is all 6061 aluminum. The brackets are 5/8" think and the extensions are 1/2" (or were). Once they were installed, we took the bed back out to the Bridgeport and milled it perfectly flat with each other. We also milled a "reference edge" on one side for the THK rail to butt against.
Installed one rail against the reference edge and then aligned the second rail off the first one with the use of a jig.
More to follow after the pictures.
Mike