RE: Water Jet

I know that the in thing with water jet now is the abrasive water jet, but I
remember years ago that water jets were just that with no abrasive added.
Seems like for my use I could live without the abrasive and then the
protection of the machine would be quite simple, just have to worry about
rust and in the Denver climate that is pretty easy to handle. You are right
that a small bit in a high speed spindle would probably get the job done and
for commercial application would make the most sense, but for this hobby
playing it just isn't exciting enough to create much interest. I agree that
a vacuum table makes the most sense for a hold down if I were to use the
'conventional' approach.


Tim
[Denver, CO]

> -----Original Message-----
> From: PTENGIN@... [mailto:PTENGIN@...]
> Sent: Sunday, August 08, 1999 10:56 AM
> To: CAD_CAM_EDM_DRO@onelist.com
> Subject: Re: [CAD_CAM_EDM_DRO] Water Jet
>
>
> From: PTENGIN@...
>
> 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.