Re: [CAD_CAM_EDM_DRO] Re: water jet

Mark Stacey <pav@...> wrote:


SNIP
Add up the force on the endcap of a cylinder with a 3" dia. piston and
an area of 7.0686" sq/in X 30K/psi (which has been outlined as the
minimum pressure required, 60K is the norm) would equal 212,058 pounds
of force or 106 tons.
Correct
SNIP

However
The calculation of force is correct but with out calculating the
energy behind the force missleading. The water / hydralics is just a
transfer mechanisim. If the presure is being provided to a vessel by a
.25" hand stroked ram even at 1000psi the energy is nothing worth
worrying about, a lot of force there but when a weld lets go, psst
zero presure.

/// With this reasoning it would never cut anything, As soon as the nozzle is opened for a cut it will return to atmospheric pressure? The loss of volume thru the nozzle would need to be overcome by the ability to maintain the pressure = energy to propel projectile.

Which is exactly why I tested a coil boiler and piping
that way.

///Boilers are not tested to 10K/psi and there is a reason for that. I dont think some truly understand how much pressure that is.


So the idea of a home water jet cutter is how to safely apply the
energy to the water. I've been speculating on a large diameter air bag
linked to a smaller diameter hydralic piston. The total energy is that
in the air bag. Having drilled some ugly materials recently a
presurize, jet hole, cnc to the next hole position has my curiousity
aroused.

/// I think what is enticing everyone is the simple concept of water-jetting being confused with a simple application to perform it. I don't see one. Water-jets and lasers are far out of the realm of the homeshop from my inquiries. They will never be safe to experiment with. Explosion/projectile issues with waterjets if even the slightest miscalcualtion is made or detail overlooked. Lasers can permanently blind someone instantly, that means we would have one shot at making it safe. Personally, my eyesight is more important than cutting a piece of steel. Its one thing to create 60K/psi in a pump engineered/thoroughly tested to do so and transfer the medium through engineered piping to a nozzle. And it is a totally different issue to plan on immitating this process with components that were never designed for it in the first place.


Is there any volume of water/abrasive to material removal rates links
avaliable?

/// 10K/psi would cut 16 ga mild steel at 2 ipm according to another post this morning.


Cheers
Mark Stacey
www.cncprototyping.co.nz
PS
All the water jet cutters I've seen worked in air.







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