Poor Man's Tool Post Grinder


I had found a set of outside jaws in a junk box for my three jaw chuck on my old South Bend Lathe. They were really out of spec. I would say about 15 thousand out so I started to search the Internet to learn how to grind chuck jaws. I tried several different ways to do it but failed. I though it was reasonable to put a piece of pipe on the outside of the jaws and run the jaws out to tighten on the inside of the pipe and grind them from that but I would still be out 15 thousand. I finely found an article that indicated that I needed to clamp down on a round object to grind the jaws effectively and they indicated to drill the jaws and put a pin in the center and then clamp down of the piece of pipe. That is the approach that I used. So I used a carbide drill (because the jaws are very hard) and drilled each one of the jaws. Now I could put a pin in each one and then clamp down on the piece of pipe that I had machine on my other lathe.

Now I was ready to find away to grind the jaws. I had a dremel tool that if I had away to clamp it on the tool post I could grind with it. So I thought about using a tube clamp like what I had built for the lights on my bike. Measured the outside diameter of the dremel tool and took a piece of 1/4 inch rolled steel and cut out the circle on the lathe. I then took another piece of metal and braised the round piece on it this will be what clamps on the tool post to hold the grinder. I then braised a shoulder bolt on top of the circle.

After you have finished braising the nuts and whatever on, cut the clamp in half. Using a tap, clean the threads out on one side, and drill out a clearance hole for you bolts on the other. I used cap socket head bolts. They really give the job a finished look. You should file the brackets so that there is a small gap between the cut ends of the nut so that the clamp will be tight enough.

Here are some examples of the tool post holder that you can build. I did have problems trying to center it to the work on chuck. I found using the dremel tool the shaft was not long enough to reach in to the jaws so I thought about it for a while and decided to try my Rotor Zip tool. It was exactly the same size diameter to hold in the clamp and it used a 1/4-inch shaft so I could put longer grinders in it. It is still not centered but I was able to reach the jaws and grind them. This was not an exact science I am still learning but was able to get a couple of things done using this tool post grinder. I have been able to put a point on my Center punches besides grinding small shafts. Hope this project makes you think about some of your needs. I would like to build a small tool post grinder some day like the big ones.

This is the Raw Material

Welding the clamp

This is the finished product