Homebrew PCBs

hi john

nice to see that, i already thought also of hexagonal stock
(one supplier in vienna has it on his items list)
maybe an option... we will see...

size of the bearings:
why is this critical?
i thought it doesn't change anything?


do you have the main axis driven by one or two threaded rods?


regards
stefan



On Sun, 3 Aug 2003 18:39:04 +1000, John Craddock 
<John.Craddock@...> wrote:

> Stefan,
> I used hexagon bar, like the bar used for making nuts and bolts, for the 
> rails. I have uploaded a pdf into the files area under the folder JLC 
> that shows a cross section of the setup. It uses roller-skate bearings 
> and 3/4" or 19mm hexagon rail. The entire unit can be constructed using 
> only a drill press. My table is 1 metre * 600mm. It can be scaled up or 
> down quite easily. the critical thing is the size of the bearings 
> relative to the hexagon bar. I have used 12mm bar with 12mm bearings and 
> 16mm bar with 17mm bearings also. The feed screws are 10mm * 1.5mm pitch 
> stainless threaded rod with bronze nuts that are split and cross screwed 
> to take up the backlash. These screws turn in 10mmID * 30mmOD deep groove 
> bearings SKF number 6200VVCM. They cost AU$3.2 each; that is about 1.1EU. 
> The roller-skate bearings were really inexpensive.
> Hope this gives you another idea.
> Regards
> John C
>
>