here im using the same tried method of laying out your layout.
after laying out my desired size i go back to the mill and start machining all the part
then i pare up a set of blocks to be drilled and tap
then i drill the other half of the block to accommodate the thru hole size of the bolt
then i grab some bolts and pair them up again to be machine
for the bushing that will hold the acme screw.
then mark the center for the hole
then test fit the bushing
then back to the mill to machine the slot for the rail.
now i can head home and install this to rail and also hope fully i can finish the bench.
stay tuned. thanks for stopping by.