Isel ballnuts look like this:
So we need a carrier block for them. The carrier block needs to do two things:
- Hold the ball nut so there is no axial or rotational play
- Provide a means to take advantage of the ballnut's adjustable preload feature
Blocks for these ballnuts are available from Isel, but neither configuration was suitable due to space constraints. I decided to design my own.
As you can see, the block is split with holes for two clamp screws. The larger of the two holes along the side is for a locating screw that mates with a hole on the side of the ball nut to stop axial play, the smaller of the two is a clamp screw that bears on the side of the ball nut and when tightened squeezes the ball nut slightly so that the nut can be preloaded. The other two counterbored holes at the front are simply mounting holes.
Block after milling to size and milling out recess.
Now we flip it over and bore it. The ballnut is 28mm in diameter so I am aiming for 28.00 -0/+0.04. I use WD-40 for cutting aluminium - works the same as kerosene, just dosen't smell as bad.
Drilling the holes for the locating screw and the preload adjust screw
Counterboring the mounting holes.
Just to prove I still use the Taig - here I am adding the chamfer along the sides.
Taig is also used for slitting the block.
All done! Assembled with ballnut.