Gents,

I've posted in the FAQ section with a design of a grinder which uses a Z axis assembly taken straight from a CNC machine, here it is:



I've read a few threads about z-axis assemblies and quite often the main bit of advice is "use supported rail". Also swap the rail with the linear bearings, so that the rail stiffens the assembly. All great tips to make the machine better, although my gantry will only be doing 10mm of movement and most of the time will be sitting stationary as it's simply a support/adjustment element for the burr in the grinder, more than a moving, active part of a whole CNC machine. Keeping that in mind do you think the above is good enough? It's using 12mm rails, the plate with the linear bearings is 110mm wide and 160mm tall and everything will be made out of 10mm aluminium (12mm MDF for the prototype). As I want to keep the thing rather slim (various reasons), I'm planning to use a standard SS M10 threaded rod through an acetal block (50mm x 20mm x 20mm) and two 10mm Oilite bushings. I'm guessing that the main T plate together with the burr and other bits and bobs, minus the linear bearings, will weigh less than 1.5kg. I will need something to eliminate backlash so might end up with two slimmer 10mm lead screw blocks, one mounted stiff and the other with a bit of play and a spring between them to push them apart and then fix the second lead nut.

So main question: is it good enough or rubbish and needs re-designing?

Regards,
dsc.