Vertical moving gantry????

[HiltonSteve]

I would say its not impossible but you would have to put some thought into your design.

I used to work on an old Webster and Bennet machine for a while at British Rail (those were the days!) which had a similar configuration to what you are talking about. The only thing was it was a lot bigger and i mean a lot bigger! You could fit 2 railway bogies on the table easily.

That machine had a moving table and the gantry sides were bolted to the floor, the whole gantry moved up and down on the 2 side columns and then you had a moving vertical Z for the spindle, in fact 2 spindles, one at either end of the gantry. the spindles then travelled across the gantry as normal to give you your Y axis. Machine was rock solid but it everything was pretty heavy which worked in its favour.

Hope that makes sense and may give you some food for thought.