Direction follower ? Water jet Re: [CAD_CAM_EDM_DRO]

It seems that glass seperation could be much more easily done with a
laser heat/cool/crack mode.

this would be instead of stock removal that would be done with
water. also I am not sure of the cost of the laser, but it would
seem that the operational cost would be much less.

But you did offer one VERY interesting bit of information, and that
is what pressure is needed ? obviously foam and cloth cuts at much
lower pressures than plastic and plastic at lower pressures than
steel and so on. Just where does glass fit on the list ?

assuming a centrifugual load on the pump, a reduction of about 20% of
the pressure would require only about half the motor hp. obviously
lower pressures should have some impact on tool life so it may be
doable in a home environment.

I am not sure if it is shear force (pun intended) or part abrasion,
part supersonic speed of the water that does the cutting. That would
make a huge difference. kind of like lasers are not just bright
lights....

Dave

--- In CAD_CAM_EDM_DRO@y..., "John" <johnhe-uk@s...> wrote:
> > has anyone EVER done a homebrew waterjet cutter? are the
pressures
> involved
> > just too dangerous? as far as i see it, they are just a preasure
> > intensifier, attached to a saphire nozzle, right? over a water
tank?
> > wouldn't it the best way to cut glass? using abrasives in the
water
> (needed
> > to cut glass) you'd even be doing the sanding!---Dave L.
>
> The pressures involved are brutal. There can be no questions asked
there.
> 4000 psi is enough to strip your skin when it's running with grit.
The guys
> I worked with used to take their metal stuff down to be blasted and
they had
> a 4000 psi grit jet which'd actually polish and erode away metal.
40kpsi is
> beyond enough to remove a limb if it hits you close up. I'd be more
worried
> about pressures like that than I would be about running a big
manifold of
> gas cylinders on a flame table.
>
> The pumping system to achieve the pressures is expensive but so is
a lot of
> the machine. Hoses to take that pressure are not easily bought. The
nozzles
> do wear fairly quickly, I think you can buy carbide ones. I read an
article
> by a man who ran these machines but I can't remember where it was
now.
> Please remember that you don't just blast water, you blast water
with
> sapphire grit to cut cleanly. You absolutely must have a recovery
system to
> collect the grit. The piston heads need very snug seals, all the
gaskets
> need checking regularly just in case, they also need changing once
every now
> and again.
>
> If this is for a home sized job, or even small commercial, there is
not
> really anyway to you could justify such an expensive deal. It's
like welding
> your lawn mower with a Syncrowave TIG runner. I would have a bit of
a read
> around on pressures needed. At 40kpsi you are cutting metal and
harder.
> Glass, as I'm sure you'll know, is a lot softer than heat treated
metals
> (Which is one of the reasons for using water jets on such metal,
so's not to
> ruin the treat). I would be guessing but I would think you probably
don't
> need a huge amount of 4000psi to start working on glass.
>
> It's something to have a look into anyway. I can't see glass needing
> anywhere near 30kpsi+. And since you're not trying to chop a foot
deep piece
> of metal in half in under ten seconds you can always run it over a
couple of
> times. I saw one of these machines cutting some sort of soft
volcanic rock
> for a kitchen work top about 3 inches deep. The cutting was as if
it were a
> plasma torch on sheet.
>
> Good luck, and remember, if you build it, you take photos of it!
> John H.
>
> P.S. Check the archives, we had a talk about this last year I think.