Thanks for the welcome.

I'm not underestimating the challenges of getting enough rigidity to allow 300mm of usable Z travel, I hope!

What will probably help is that I don't need heavy-duty cutting capability for making tall foam parts, which should ease the problem a bit. I think that one way to make the gantry stiffer is to opt for moving the table in the Y direction, rather than the gantry.

I may opt to make a lower level, removable, stiffening brace to allow heavier work that needs less Z clearance, to be done, as I might like to do some cabinet work with it at a later date.

I'm in a bit of a quandary about the small machine at the moment, as, although I have acquired a pair of very nice Velmex Unislides, I am getting increasingly tempted by the Sable machine advertised on eBay. See here (for those that have not spotted it yet): http://tinyurl.com/5ad6du.

I have a small benchtop milling machine already (a kit-built Dore Westbury) but this isn't really suitable (IMHO) for a CNC conversion, as the only way to provide Z travel is to drive the quill. Apart from only having limited travel, the quill drive has a fairly high degree of inherent backlash, as it's rather similar to the rack and pinion drive on a pillar drill. I have toyed with the idea of getting a small Sieg and then fitting a CNC conversion to it, but the slow spindle speed would be a problem for milling and drilling PCBs.

If the small eBay machine turns out to be as stiff as it seems, then it may well be up to doing light alloy machining (with small cuts). If this turns out to be the case (I'm awaiting a further report from a CNCZone member who has just purchased one) then my best compromise might be to keep the Dore Westbury as a manual machine for heavy work, get the Sable for light work and PCBs and use a combination of both to make the large machine for making big mould formers.

I've already purchased all the electrical bits, so I can crack on with building a multi purpose driver/interface box. Hopefully this will work with whatever machine(s) I finally end up with!

Jeremy