Re: Water Jet

In a message dated 8/8/99 5:35:55 AM Hawaiian Standard Time,
timg@... writes:

<< My idea is much like Mario in that I want to cut things like balsa upto
3/16" and maybe carbon laminates up to .020".

>>

Tim,
Water jet is not supposed to be as dangerous as a laser but the thrust of
the jet is quite strong. All the water jet machines I have seen have rather
large components to handle the thrust. I don't think they need large motors
as there is no side cutting forces. Most of the commercial units use approx
50,000 PSI. They use ruby or other synthetic nozzles. Garnet or other
abrasives is usually added into the stream after the water exits the high
pressure nozzle. Most machines use a water tank system and shoot the stream
into 6" plus deep water. Similar to many plazma systems.
I doubt you want to get into this as just the guarding of all the machine
parts from water and grit makes for an expensive machine. They all have
bellows, accordian tubes or telescopic way covers.

My vote for cutting balsa and carbon fiber would be a 1/32" or slightly
bigger 2 flute carbide endmill spinning at about 40 to 50,000 RPM. This would
be held down by a vacuum table. Sorry it's so conservative... No fun huh?

Peter
PT Engineering

FYI, Our Thermwood CNC router at my day job has a 40 hp motor to drive a
large vacuum pump. This draws air through a 5 foot by 10 foot particle board
table. It is so effective that the machine can take 3/4" dia. router bits
through 1.5" thick MDF at over 200" a minute. The spindle is 18000 rpm 10 hp.
I have not seen the wood move except when the piece is real small. You should
be able to make a vacuum table for routing balsa on a much smaller scale.