Z Axis

By comparison, the Z Axis is much more straightforward than the X Axis. I purchased a 600mm long 12mm diameter rolled ballscrew from China on Ebay (Img 1). This included bearings as well as a flexible coupling. There was a bit of a drama with one of the bearings the wrong size, but they promised to send me another one, and I dont need it for a few weeks anyway.

I used one of the existing tapped holes to locate the right hand fixed bearing. Other holes will be tapped later.

I used a ground parallel as a spacer and made the gap the same at both ends and then drilled a clearance hole to allow a nut on the other side (Img 2). I made this a little large and nipped it up and tapped the bearing into the exact position. The other holes were then drilled and tapped. All bearings house M6 socket head cap screws onto the lathe bed.

The motor mount was milled to fit the NEMA 24 Stepper Motor .

Due to some work commitments, it took me a couple of months to get to the next stage!

IMG 4 shows the Z axis stepper mounted to the bed, and IMG 5 shows the ball nut mount attached to the carriage.

MOV 6 is a link to a video of first movement of the Z axis with the TB6560 controller!

I set the steps per unit in Mach3 (new Gecko G540 controller) using the Mill screenset as there is a routine under configuration that automatically calculates steps per unit. Then I setup a dial indicator to check movement and backlash. IMG 7 shows where a G0 Z15 goes, spot on!!!. IMG 8 shows where a G0 Z0 goes, no backlash at all!!!

MOV 9 is movement with the Gecko G540, much faster and smoother! This is jogging at 2000mm/minute.

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Last job was the ballscrew cover. This was fabricated from 2 pieces of 25x25mm aluminium angle. One piece had one side milled back to 12mm which formed the lip at the front. Img 10 shows it in place. It is a bit tricky to get this fitted around the coupling to the carriage, so I could not find a way to get it closer to the screw, but it does overlap 5mm, so it will stop chips falling onto the screw.

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