Water cutter

Hi,

Okay, - several has come with input to this subject, and I am
just going to say something about it.

From Dan: - you could probably cut basla wood with 2000-3000psi
All others came with valuable comments and info, - some of it I
have not check out yet. My idea is to use the "impulse" effect,
and the way I think of it, is like a what happens in an inductor.

The describing equation for an inductor, is

U= L di/dt, and the power is E=1/2 Li^2

Fluid inertia is,

P=I dQ/dt, and the power is E=1/2 I Q^2

( P= pressure, I = fluid inertance, Q is volume flow )

( If anyone think I have any math skills, - I don't :-)

The principle is *very old* , they used this in old monostries to
have a fountain, and the locations were often on high places with no
water. They used this system, and the river that supplied the water,
could be a 100 meters below.

As in my "STIR CRAZY" note - where I had to many drinks, I
suggested to test Xfig in Linux, to pass ideas. I made a simple
drawing of what I had in mind, and put it in the drop box, at
http://www.metalworking.com The drawing is: pr_fig.gif

Take a look at it, and come with comments !

If we could just double the pressure, - we would be able to cut
balsa, styrofoam, and stuff.

Here is some of the named parts:

1 - inlet pressure from pressure washer
2 - valve
3 - exhaust ports
4 - plunger
5 - spring
6 - nozzle.

The inlet pressure will press water into the pressure chamber, but
the face of the plunger is designed so that it will push the whole
plunger in. After it has moved a bit, the exhaust ports will be
open. This is importent, as you want the pressure washer to supply
a constant volume of water, and not open the "over" pressure valve
on the pump. ( The exhaust water, can be collected in such a way,
that it will not make a lot of water spill at the cutting head. )

Because the area is smaller in the high pressure side, - you will
have an increase in pressure, but at a smaller flow rate. The unit
will genereate pulses, but there is many ways to make it more like a
steady flow. You also may need an "air chamber" - but I am not
sure.

Here is place for a lot of improvements. You could make a unit as a
push-pull design, add more stages, or put them in paralell. Here I
just wanted to show a very simple design, - and hear your comments.

The idea, is that this should oscillate, and in principle, it would
be like your ignition coil in your car, bringing the 12V up to
20.000volt. ( I know about the secondary winding, - but you get
1000V or so on the primary - and that is exactly the same principle
)

I don't have the tools to make this, - yet. So if anyone wants to
experiment - do so !

But, I would suggest to just use some simple pipes/parts, use air
as the fluid, - or tap water. The idea is to just work with low
pressure, and just make the thing crude and simple. If it turns out
that you can get a pressure increase, - then we are on to
something. Made simple enough, it would have a lot of applications.

Is there any proffesional people that could help out ? Univerity ?

In closing: Test out Xfig, or whatever, and let us see if we could
pass drawings and ideas. If this list takes html, then the drawings
could be inserted in the text.

By the way, it is one of my first usages of xfig, - but it didn't
take long before I figured out how to do some simple work with it.

//ARNE