Re: CNC waterjet cutter....pump and nozzles available???

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mike Mueller"
<mueller914@y...> wrote:

> I have a friend that wants to a 48"x48" or so working area abrasive
> waterjet cutter. Has anyone built thier own? If so, what was done

for

> the pump and the nozzle?
>
> The use would be for sheetmetal up to ~3/8" thick max, would we be
> better off building a plasma cutter table? Accuracy in the .005
> to .010 would be nice...is that asking too much??
>
> thanks,
>
> Mike

The problem with AWJ is that you have to have multistage high
pressure pumps capable of 30 to 60 THOUSAND PSI. That takes some big
motors and ususally a source of lots-o-3phase power! The accuracy
you want is easy to do. There is a waterjets group on yahoo that can
make for some interesting reading. This subject comes up often on
the CNC lists and a lot of members jump in with ideas for using
eveything from pressure washers to small pumps. I haven't heard of
anybody actually BUILDING something like that, so I have to believe
is not as simple as our "engineer" minds tend to conceive!

In addition waterjets are:

^Expensive to run (electricity, consummables, abrasive garret)

^Requires a lot of maintenance (tips, clogged stuff)

^Messy. (You have to get rid of the abrasive stuff) While 4GPM
doesn't sound like much that's about 1600 gallons a day of sludge you
have to deal with. Most cities frown on just dumping it down the
drain

^Slower than other methods

They are a good choice if you need to cut metal over 1" thick,
hardened tool steel over 1/2" thick, non-metallic stuff (wood,
plastic, cork, rubber, etc) or you need small fine detail. The sides
of the cuts are smooth and straight. Big AWJ's can cut 4 to 6" thick
steel with no problem.

My suggestion for cutting metal up to 3/4" is plasma. Thicker metal
is more problematic and the sides of the cuts are not as smooth or as
vertical as a waterjet or laser. You can cut 3/8" steel, aluminum,
stainless, etc with a plasma at about 35IPM or more (depending on the
plasma unit you are using). I cut 1/8" at 55 IPM and 1/4" at 35IPM
with an old Miller 55A unit.

If you do elect to go with plasma, plan on building a full 3 axis
machine (Z moves up and down) and investigate using a Torch Height
Control (THC) to keep the arc constant.