Purchasing a z-axis?

[Tonyel]

Hi Dave

I'm interested to see how you're getting on. I'm also in the process of designing (and hopefully, later, building) a CNC gantry style router.

I was wondering about how much Z travel to allow; seems on the face of it that 250 mm is a good compromise between rigidity and travel. I haven't done any calcs, but just by 'seat of the pants' engineering it looks to me that much more than that and it just looks a bit too far. Most of the time I imagine it will be operating at the far end of its Z travel too, unless I put a riser on the table.

Does your Z axis screw have a 'zero backlash' nut? How much are you looking to get for it?

I attach a pic of my design so far, for what it's worth. Criticism and suggestions are most welcome :D!