Here is the general concept for the Y axis. I had to make sure that the motor stand offs were recessed deeply enough so that the saddle under the mill table did not hit the motor etc.

Y axis.

Grae-Tech 

I had to make a very strong adaptor to connect the ball nut to the saddle. The old system had incorporated a boss into the brass nut design, but I had to make two separate parts, and bolt them together very tightly.

I made the adaptor from 316 stainless steel. Man, is stainless steel tough! I had to use heaps of coolant, the cutter started to boil off the coolant into steam at one stage, I obviously wasn’t using anything like enough.

I then drilled and tapped M5 holes into the stainless steel ball nut adaptor. I used lots of tapping fluid. After this I used four M5 socket head cap screws to attach the S/S adaptor to the ball nut. 

 

 

To support the “free” of the shaft, I measured carefully and then cut a “Tee” shaped bearing support with a standard car alternator bearing. This was fairly quick and painless to make, but it really took some work to file away the rough casting that the milling machine base had on it.

I used a high tensile M8 socket head cap screw to fix the S/S adaptor to the saddle, and tightened it as much as I could with a short Allen-key and piece of pipe as a lever. If there was going to be any slop in the Y axis, I thought that this is where it would be introduced, so I was very careful.

First CNC cuts with the Z axis and Y axis working together. I realized after I ran the machine that in my excitement and haste I did not have the screws protected from swarf! BAD IDEA! I spent hours picking swarf out of the machine’s screws.

Text Box: Adaptor and ball nut

M8 screw holding it together