I am helping a bunch of middle/high-school students with a project to make a small computer controlled water jet cutter. A Raspberry Pi (RPi) will be used for control. I can use all the help/advice/wisdom that anyone here can provide: 1) We want to use as many off-the-shelf parts. So, we were thinking of using the C-beam bundle as a starting point. C-Beam Machine Mechanical Bundle We are using this bundle to: a) Provide the mechanical frame for the water jet cutter b) For the motors to drive the screws along x, y and z axes & drive the motors from the RPi. Any comments? We were concerned that this was a little expensive, but felt that the Aluminum cage was strong and offered the movement that we desired. If there is a part set that accomplishes this cheaper, that would be of interest. 2) Is there any issue interfacing with the RPi? Specifically, with driving the x,y,z axes motors in an automated fashion. 3) This is a water jet cutter. So, there will be water splashing. We plan to use a plexiglass enclosure around the cutting area. But are there any other issues? This is our first attempt at this kind of a project. So, if we are completely off, let us know that too. Thanks.
I'd be hesitant to approach this project myself, let alone with students. The pressures involved in water jet cutting are enormous. However, assuming you have a plan to safely try this out, I don't think that the C-Beam machine mechanical bundle is suitable. Waterjet cutting works by dissipating the energy of the water after it goes through the material by having a large (and deep) tub of water underneath where the stock material is held. In a C-Beam mechanical bundle, you have lead screws and motors and a spoilboard there. In order to move the device around, you will need to have a device that moves the gantry entirely on the top so that the bottom can hold your tub of water.
The framing system on this build may be a little more appropriate to where you are going. You really shouldn't need much more than three C-beam actuators plus a few more small parts to bring it all together. As Jonathon noted do be sure you've got a handle on the nozzle pressures. I doubt they'll be an issue but it's always good know for certain up front. Also be sure to check with the shop before you order to see if there are any educational discounts that may apply.
Thanks. I am planning to have the pressure low to cut styrofoam, light wood, or plastic. The project is basically a set of safety features to turn off the jet in case hands get too near, pressure is high etc.
Check this flood-coolant build out, there may be some useful ideas for yours. TACIT RONIN CNC - Flood Coolant Enabled C-Beam
Thanks for the note. I also felt that 3 C-beams should largely be enough. Thanks also for the reference. That build is similar except that I would have preferred the bottom surface to be largely empty so that the water jet can empty down rather onto a platform.
Yes, that design is for a router system. Obviously you won't need the platform or the center supports. You can probably also drop the Y gantry plates to the regular C-beam gantry plates and reduce the number of wheels, saving a bit there. The X axis gantry is also probably a bit over designed for your needs.
The other modification you should strongly consider is adding 'bellows' to both X and Y axes. These are folding accordion covers that stretch and contract on either side as the device moves. This is essential to preventing water/moisture from getting on your rails and components. Most waterjet cutters I've seen do not have a motorized Z-axis. They have relied on a hand crank or some other manual means of moving the nozzle up and down. That might simplify your design as well. -D
Ask Dr. Hashish! Dr. Mohamed Hashish is the inventor of the abrasive waterjet and an expert in high pressure design and tribology. Ask Dr. Hashish - Flow Waterjet
What happens if I stick my finger in there? It will get cut. What stops the waterjet from cutting through the tank to the floor? In most waterjet systems 36 inches of water in the catchers dissipates the energy of the jet.
"It will get cut" is an understatement, high risk of infection, when the jet hits bone it will dissipate causing more damage, i have seen the damage it can do. You maybe be able to run water only with a 0.15mm orifice at low pressure (15000 psi) but parts are going to be expensive. Just be very very careful, a Flow waterjet has a 4ft area all around the machine protected by light barriers.
