Hi RJSutton

I have been thinking on your project and considering a timing belt driven linear motion instead of a ball screw drive, this will simplify construction, be more compact and be cleaner.

Ballscrews need to be lubricated externally require bulky end support bearings and very accurate alignment between the ball nut attached to the moving member and the screw itself. Ball screws are not always self locking due to the low friction coefficient.

A timing belt drive is run dry, It can work successfully with some misalignment and can use simple off the peg sealed bearing units bolted on to or using flanged or circlip bearings clamped into laser cut frame members. For a project like this laser cut sheet parts should be a primary objective, remember they can be press brake folded after cutting.

You will be surprised at the load carrying capacity of a timing belt, the backing contains multiple strands of fine steel or kevlar.
Timing belt drives are extensively used in industrial robotic applications.
For reciprocating drives the belt can be purchased by cut to length, The two ends are attached to the moving member. Using a timing belt you would use a higher ratio worm reducer to achieve the same output speed.
Beyond a certain ratio worm reducers are self locking an important consideration for a lift drive subjected to gravity.

Below is a link to Gates among the world leaders in this field. Have a browse around the website you will find a lot of useful information..

https://www.gates.com/us/en/resource...x-pro-software

Regards
John