Hi All

I am arranging my z axis by having 4 * 8 mm shafts placed around the perimeter of the router - one on each corner. The router in turn will have four bushes with 8mm centres connected to the router .... one on each corner. The router will essentially be sliding up and down these four shafts.

I am playing with 8mm mild steel rods at the moment as they are cheap and easy to work with. I realise that they are of poor quality so the bushes are not sliding very tightly on those rods.

What is the best way of manufacturing 4 precision rods 8mm in diameter each of length 200mm with a 8mm*1.25 tapped thread on each end?

I don't have to stick with the bushes I have bought given they only cost $1.00 each. I don't have to stick with metal and am open to plastics but need to bear in mind issues of rigidity.

I have hand tap and dies. I have a bench drill press. I don't have a lathe.

Cheers

Andy

You should use hardened and precision ground shafting. Most of us like to call this "Thomson" shaft (brand name(purchased ready to use)). Ideally you would use linear bearings instead of bushings.
If you make your current shaft retainers as a clamp style you can change out your CRS for Thomson any time in the future.
Also if you use your sloppy bushings and use 8 pcs (4under & 4over) the router you will exponentially stiffen & precision up your Z axis.
Good job - keep truckin

Great Darebee

Thanks very much. Could you expand on the 4 over / 4 under a little more please? I think I know what you mean but I want to be sure.

Very much appreciated.

Cheers

Andy

I mean configured like the tie-rods on a cylinder (or hour glass). Where the bushings are in the tie rod plates and your router is the centre component. This will take more stroke on the Z but will reduce play in the router probably 1000 times.