So, the waterjet came standard with a servo controlled X and Y-Axis. Unfortunately, the Z-Axis used was the Amish version 😉 — By which I mean it used a hand-crank.
While having a motorized Z-Axis on a waterjet does not immediately sound very important, as you are normally dealing with flat sheet goods, there are actually very many good reasons to have one:
- The initial pierce is where most things can go wrong. If the nozzle is too close to the material, water will, instead of exiting the nozzle, exit the abrasive feed line. Setting the height too far away causes the beam to deform. Having a motorized Z-Axis lets you perform your pierces elevated and then come back down into the material. This can dramatically increase reliability.
- Small parts fall into the bottom of the tank if tabs aren’t used. Large parts remain by virtue of the sacrificial bed holding them up. It’s possible, however, that medium sized parts may “tip” and not fall into the tank, but remain upright. The nozzle is made of carbide, and if the nozzle were to strike a piece of tilted material, it may potentially shear off the nozzle. The software can anticipate this to some degree, and perform a “Heads-Up Traverse”, where the nozzle is elevated before moving on to the next part.
While the project took a few iterations (Due to selection of a Stepper driver of questionably exaggerated specifications) it ultimately performed beautifully in the final implementation. The 3d printed ABS plastic flange was only intended for “fit testing” before milling out of aluminum, however, the plastic ended up working so well that it continues to perform to this day. We may eventually replace it with Aluminum on a rainy day where there’s time to mill out a new piece.