[dukegnarley]

I just ordered the motors and electronics necessary to convert my Jet JMD-18 to CNC, and I should have them in a day or two. I've seen a lot of rf-31 conversions where people have just attached the motor to the z axis fine feed wheel.

I've been searching around, but I haven't been able to find how you guys have dealt with the backlash.

The fine feed backlash on my basically new mill drill is about 0.030"

Is there an easy way to tighten this up so i can get acceptable accuracy? The only thing I've found is reversing the return spring on the quill.

[109jb]

On my round column mill I hooked the motor to the fine feed and reversed the quill spring so that it was pushing down instead of up. Worked well. Reason is because normal cutters want to pull themselves into the stock and reversing the spring makes it so the quill spring isn't fighting what the cutter wants to do. I think it was user Arizonavideo that gave me the idea and it worked well. I made some test cuts first milling the top of a piece of stock flat and then milling a pocket into it. The depth of the pocket came out right on what was programmed. I had the motor and timing pulleys set up to provide 0.001" of quill travel for each full motor step.

[109jb]

Here is a link to my build thread.

http://www.cnczone.com/forums/bencht...ill_build.html

[dukegnarley]

Thanks.

If all you had to do was reverse the quill spring, then this should be easy.

I just picked up my motors etc. from the UPS store.

[109jb]

Reversing the quill spring was a pain in the butt. Had to make a little jig to wind it and then held t with a needle nose vise grip to keep it from unwinding while I put it in the spring cup.

[dukegnarley]

I got my spring reversed tonight. They way I did it was to let it completely unwind, and then clamp the outside tab of the spring half way into a vice. To wind it I used a wooden dowel with a screw in one side.

Once the spring was wound up, i was able to just slip the cup over half of the spring since the spring was only half way in the vice.

It was pretty simple, but it required an extra set of hands.

I also have my motors hooked up to my computer and working, so this is going to come together pretty quick. My pulleys and belts should be here on Monday.