Steel Framed Router

[GTJim]

Just an idea and probibly silly, but how would this concept work as a rotating ball nut?



Ball screw fixed at each end, pulley machined to fit ball nut (green) and motor mounted to cross brase of gantry under the table with another pulley and belt.

Jim

[Jonathan]

I'm afraid that wouldn't work. As soon as you put and tension on the timing belt it will bend the ballscrew which is obviously bad. The ballnut needs to be supported with bearings and it's own mount. The best option is a pair of preloaded angular contact bearings with the pulley in between so that both bearings resist the tensioning force of the belt. This is what I used. Angular contact bearings are best as they accept radial and, importantly, axial loads whereas standard deep groove bearings don't take much axial load. Having said that I've seen one on youtube that uses deep groove bearings, but it's only cutting foam...

if I'm reading the drawing right, is the belt the only thing that will transfer the movement to the gantry, for the gantry to move on the x axis?

Yes!!

Here's mine:

http://www.mycncuk.com/forums/showth...t-design-ideas

I've almost finished designing one similar to that for 16mm and 20mm pitch screws with 7207 bearings.