The other option is, of course, to raise your workpiece up *to* the router.
I agree that a 3 foot (that is what you meant, right?) Z axis travel is a LOT, but an 8 foot Z travel is just bizarre.
Having said that, even just "hanging" a router from a cable from the ceiling, would result in a very accurate Z height control. The problem would be with lateral movement, and that can be minimized by triangulation. Your Z axis might end up being 5 feet across, which means that for a 5 foot Y axis travel, your Y axis would have to be 10 feet wide...but this is not insurmountable, especially if you're building onto the existing ceiling and walls.
Using a truss design would give you "skeletal" support that would reduce the weight...they can be built "Erector Set" style with little trouble, and with pretty good results. Having it travel along a simple set of Y axis rails would seem almost trivial, so long as everything is built good and stiff.
If designed right, it might not be an insurmountable problem.
How's your project budget?
-- Chuck Knight  |