Very well explained, thank you very much.
B.Th.W. i missed the part about patenting it, and i can chime in, good luck with that since there are so many similar designs already patented and in use. I mentioned somewhere I, again 'I' have seen only one LIVE that i could touch and play with ( also walk on the table since it is over 3.5 meters tall
), but i have seen many on the net that use that same principle.
It was one the first ideas that came to mind when i started a bigger cnc a year ago, but i found out that having 40mm lead screws has a nice side effect: you can use two bearings on one side and leave the other end free. To explain it easier here are some pics of what i made using all thread and some NSK industrial assemblies i found at a junk yard.
On the first pic you can see a piece of wood that has chamfered places for bearings on both sides so there are two bearings one on each side folowed by two nuts on each side so i can preload the bearings and fix them in place, but you can not see the other side on the second picture. The third pic shows what is normally a ball nut ( in my case two more nuts adjusted for minimum backlash and the forth pic shows the other end of the all thread. I have this setup working for nearly a year and i have it tuned to about 0.02mm backlash. Luckily i use it rarely and i am aware that is not an 'be all end all' solution but it will take me about 20 minutes to change everything when the backlash goes bigger since inevitably it will when using all thread.
The last picture shows the 40mm NSK ( yes 1.5" ) ball screw and nut as they were fitted on a huge mill ( the X table weighted over a ton ) and i can do 250 rpm with no whip, i did not try anything faster since i don't need it.
Regards,
Tom.