By: Jeff Davis
This is a picture from the bottom of the base. It is the Y-axis screw. You can see that the far end is unsupported. The nut is in the center of the shaft. See the slit in the nut? This is for taking up backlash when the nut starts to wear.------------->

This picture is at the other end of the Y-axis screw. You can see that they make the screw hole very large for a good reason. Things don't always line up. Notice the bolt holes. The pattern is symmetrical to the axis screw, although I found out that the bearing plate can be rotated around the axis screw to any position, and then drilled and pinned. I wanted to use the existing holes in the casting, so it was a small problem to measure the holes and pins for every bearing plate.


Here you can see how the bolt pattern looks from the outside. If you ignore the large hole then the bolt holes look close on center. When I drew some horizontal and vertical lines on the casting with a pencil I could see that the bolt pattern was rotated counterclockwise. The assembly procedure must just line up the bearing plate with the axis screw, get the plate looking level. Then drill the mounting holes and bolt it in place.------------------------------>
Here are the bearing blocks. The X-axis block is below and the Y-axis block is above. You can see the locating pins on the Y-axis block. I needed to measure the location of the bolt holes and pins in relation to the center of the axis holes. The best way that I had for this was to take them to my work. I used a probe scanner called Reneshaw. I created a drawing to document the position of the pins and holes here.
The only modification that I did to the Drill/Mill was to enlarge this hole under the head casting. I needed to get this big enough to hold the Z-axis screw and servo motor. I used a die grinder. It only took about 1-1/2 hours to do this. Later when I get the Z-axis plate designed I will drill and tap holes to bolt it over this hole.

You have to dismantle the mill a bit to measure all the parts. I have included some CAD pictures that you can look at to see my ballscrew design. Click on the links below.

Full Assembly

X-axis Section

Y-axis Motor Mount

I have designed the timing belt system to be 2-1 ratio in all three axis. The belt was very small for the Z axis. (Not much room).

Notes about the drawings: The X-axis has two angular contact bearing on the right side. The left side is floating. The Y-axis is the same with the exception of no bearing on the far side. (away from you) The Z-axis uses two angular contact bearings, one on each side of the pulley. The ballscrew is fixed to the quill clamp. Everything else turns around the ballscrew, this is what makes it move up and down.