"Well, if waterjet works anything like laser (we had a big one at work), then you just barely need to clamp the work. Gravity does its part, and I imagine the cutting force would be aligned with gravity, pushing the work into the table. So the setup really is simple and easy, and you can cut parts off the sheet and let them just drop.
"
Go hit part of something not flat to within a few microns with 75k psi of water and see if it vibrates :)
Also, unless your nozzle alignment is perfectly vertical, there is some sideways motion imparted.
(IE you are kinda right, but you still gotta do something)
Particularly for small pieces, it can be a pain in the ass. On the plus side, yeah, light clamping with c-clamps/etc works most of the time.
Go hit part of something not flat to within a few microns with 75k psi of water and see if it vibrates :)
Also, unless your nozzle alignment is perfectly vertical, there is some sideways motion imparted.
(IE you are kinda right, but you still gotta do something)
Particularly for small pieces, it can be a pain in the ass. On the plus side, yeah, light clamping with c-clamps/etc works most of the time.