Homebrew PCBs

hi john

i see the importance of bearing size comes (at least as a big part) from 
using another hexagonal rod
for screwing the bearings onto it.

how have you coupled your 2 screws?
timing belt? (i even saw chain on the web.....)

your second axis (the one riding on the main axis), this uses also two 
rails normally and one screw.
but i wondered if it would be preferable to mount this two rails 
horizontally or vertically...
(lie them flat down on the first axis carriage or put them on a 90 degree 
mounting in relation to the first axis)

regards
stefan

> Hello Stefan,
> I use 2 screws.
> As for the bearing size, If the bearings are too large for the size of 
> the hexagon: -
> the screws and ID will be too large for the hexagon bar carrier;
> the bearings might interfere with each other and will not ride on the 
> rail properly; and
> will set the carrier and the rail too far apart.
> If the bearings are too small there will be no clearance between the rail 
> and the carrier.
> HTH
> Regards
> John C
>