Oh My, Doug! Beautiful design and execution as always...The Top of Classy! Been wanting to build one like this for as along as I have had my peanut and wrote my dissertation. I might have considered Acme threads but 5/8-18 is plenty robust and easier to deal with (your threads were Gorgeous!). I've also seen Rack and Pinion types like this too and considered it but with no mill...hard put to do that precision by hand. I am hoping you are adding it to your plans as it Is scale-able as you said, if so...I'm In!! What size wheels does it take??

Thanks so much for sharing your fine work and talents with us!

PJ

P.S. I love that you used double set screws for the wheel pins.