Water Jet

[btyrell@aol.com]

Has anyone heard of using a modified shopbot as a water jet cutter?

[chandler@n-link.com]

I have been studying it for a while, but I am not to sure of the results. I don't think the finish on the cut would be all that good because of the vibration from the steppers. A lot of water jet cutting requires a smooth cut and more accuracy than the SB can provide. I have a 40 HP water jet that I need to get working, so I have been considering giving it a try when I finish the jobs I am working on now. Another problem is the accel-decel around corners. Standard g-code controls have not been particularly successful, even when the g-code was manually enhanced for better feed rates going into and out of a corner.
What did you have in mind for waterjet?

[btyrell@aol.com]

Don,

I have a cabinet & Counter Top Shop. I was thinking of making a machine that I could do sink cut-outs and similar for the granite counter tops that we produce.

It would be beefier than the standard Bot, but it would use the same electronics.

Are there any sources for used or surplus water jet components? Do you have any ideas on the type of bed a machine like this would need?

Bob

[giggalo]

We cut a Marble top awhile back, what we did is use a sheet metal pan with a plug on the side to drain the water, we used a 1/2 diamond bit that the guy brought by for us to try, we used a pump sprayer with handle to spray water on the marble and bit to keep cool, it worked fine but what a mess, we found out that you can lay clear plastic on the table to keep 97% of the water in the pan then on us.....lol, the piece was only 40x28 for a bathroom. you might want to build a heavy duty table to hold the weight?.

Ron

[chandler@n-link.com]

Bob,
The waterjet business is not cheap. There are used systems around, but usually with the cnc machine. Most of the ones I've seen lately in the 4'x8' or 5'x10' range are about $75,000. If you can find a pump, and cutting head it will probably be $25,000. Then you have to have an abrasive feed system, water softener, de-ionized water system, so you have another $10,000. The cutting is done over a water tank about 30" deep. There are steel bars across the top of the tank to lay the work on. These have to be replaced periodically, since they get cut up. The abrasive builds up in the tank and has to be cleaned out (what a job). The tank should built so the water level can be raised and lowered quickly. To keep the noise down (it's noisy), the cutting should be done under water or at least the water should be at the bottom of the part. The other big problem is, keeping the water and abrasive out of the drive mechanisms. Most machines have pressurized bellows to try and keep the track, ballscrews, or rack and pinion clean. They are only partially effective. You will use about .75 - 1 gal/min of water for cutting, but you will use several gal/min for the heat exchangers on the pump. Some places you can run it to the sewer, others you have to capture it and recycle, treat, or ?. In short, there is alot more to it then it appears.

[Chris Freeman]

I am planning to purchase a shopbot for my stone counter top bus. Anyone else tried this machine to cut/polish bowls. It would be nice if it could polish edges with cnc bits. It seems like an inexpensive alternative to large cnc work stations. Any feedback would be appreciated.

[Mayo]

I haven't tried cutting any stone counter top materials yet. I have tried engraving slate tile with a rotozip cement board & plaster lath bit (RZ250) and it seemed to work. I made sure to spray the bit with water while it was engraving.

I also engraved a cement based house siding. I used a rotozip Fiberock bit (FBR250) on this. The siding is about 1/4" thick and made from a mixture of cement, sand, clay and fiber. Everything was going fine until I noticed that the bit was actually glowing red hot. I sprayed water on it and kept doing so until it was done. I looked at the bit afterwards and it had decreased in diameter at the tip by about 1/16th of an inch.

What kind of bits do you normally use when you cut stone? Do you usually cut it with a router?

[chris freeman]

Im sure I would add water feed lines and mud flaps. I know that a straight diamond router bit will cut irregular shapes, sink cut outs. I would probally still use track saw to cut up slabs. Then put the piece in Shop bot to run diamond cnc router bits to profile and polish. It seems like it would do sinks just fine, but Im curious if it will do 1 1/2 full bullnose on the counter edges. This requires alot of torque with low rpm, 5000-8000. Is there a router that will fit, or a motor big enough that bolts on?