Vertical moving gantry????

[Ross77]

Thanks guys, I have considered most of those ideas so its good to know im thinking along the right lines.

Kip
did you mean 1mm or 1 m? What are rod less cylinders(probably regret asking that...) are they air driven?

Basically it's just more sliding joints to cause a problem.

If the gantry doesn't need to move during a job then it doesn't need precision rails, it just needs to be adjustable with clamps to secure it in place.

this sounds the most favorable, Think I saw someone on here suggest multiple holes on the Z to gain more bed height, perhaps allow fixings on the end at 50mm increments and then move it when neccessary.

Just a quick thought, instead of moving the gantry up to give you more room why not move the bed down??

Not keen as there will definatly be a rotary table going in for 4th axis

Any one used dual X axis to extend travel?, ie. Moving gantry and moving table.

[rinderpest]

Snap! Mine are 550mm stroke tho. Very nice things; just not yet sure what to do with them. The ones I have are made by SMC.
Shame air is too springy to allow positional accuracy.
What do you plan on using yours for?

Back to the original posters question I would go for a movable bed too.
I saw a very handy post and/or image on cnczone(maybe?) that had a side view of a moving gantry machine with lots of forces drawn on it ie given 50N force on cutter then with n length of Z axis the twisting forces on the gantry will be (x)N.
It was well worked out and made the point you wanted the centre of gravity of the Z axis to be between the two gantry bearing trucks etc.
Saw it once, was impressed, and now I actually need it to help me design a machine I cant find it anywhere.
Anyone know what Im talking about?
Jim

PS Kip, do you live on a boat? That photo looks like it was taken looking to the side of a narrow boat or a broads cruiser.