Home Build Water Jet - Pressure Washer

[1ctoolfool]

Hi,

I'm looking to modify an electric or gas pressure washer to cut 1/2" drywall.
Has anyone tried anything like this or can direct me to a website maybe someone else has experimented with this?

Can anyone say for sure it's not possible or point to some engineering data about pressure, flow, orifice diameter, depth of cut, etc.

Any help is appreciated, thanks

Jv

[ViperTX]

problem.....the paper on the drywall will absorb moisture and you'll have nice mold & mildrew growth...so score & snap won't work for you??

[yellow73bb]

Probably not a lot worse than the water in the mud. Sounds like an interesting idea.

[1ctoolfool]

Regardless if it's a good idea or not I need to know if it will work and if anyone has tried it.

I've done some research on this and a lot of people are telling me it won't work but no-one has any evidence or proof that it won't work.

I do know that industrial water jet cutting leaves no water absorption in the cut material. It's a perfectly dry cut, and it is used by the fabric industry to cut highly absorbant materials. There is a critical velocity required also and I don't know what that velocity is or how to calculate the pressure/orifice required to get it. The other "black art" is the orifice design. Can't find info on that either (yet)

I am talking about pure water cutting. There is abrasive water jet and plain water (hydrojet). I am not interested in the complicate abrasive aspect, dont' want to go there.

I just want to know if anyone has built a "water pic from hell".
As a side note I did learn that watter jetting injuries are particularly dangerous so I've pretty much decided to stay away from higher pressures (over 5000psi). If someone can offer proof that it can't work at 5000 psi I'll drop it.
Thanks.

Joe V.

[Torchhead]

even 3000 to 5000 pressure is enough to slice skin and even penetrate. If it was concentrated enough to cut 1/2" drywall it would slice double or triple that into "meat"!. All that asside: My (limited) understanding is that the extremely high pressure used by waterjet cutting is to force the water and cutting agent through a tiny oriface. Much like concentrating a laser beam the waterjet works on the principle of force applied to a small area. 5000 psi spread across 1" remove dirt and debris. 5000 psi base pressure across .001 cuts stone and steel. I doubt the pump for a pressure washer could develop 5000 Psi head pressure with a tiny tip.

I used to hang out on the waterjet list but based on reading a lot of posts I came to the conclusion that DIY home waterjet stuff is not very feasible. I have yet to see a post on any list where someone has actually built and used a low pressure waterjet for cutting. Lots of verbal engineering presented but all theories and ideas that are unproven.

Tom Caudle
www.CandCNC.com

[Geof]

What do you consider proof? I do not know of any water jet cutters that operate below 25,000 psi or around there, I also don't know of any that only have single stage pressure generation. The lowest pressure I have ever read about being tried for water jet cutting, about thirty years ago, was 12,000 psi and this was experimental work cutting softwood lumber.

[ViperTX]

http://fab.cba.mit.edu/classes/961.0...i/proposal.doc

Here one doc....but they propose using a pump and nozzle from OMAX.

Here's one on the design of the nozzle:
http://engr.smu.edu/rcam/research/waterjet/par9.html

Paint Removal using a water jet...note the 36000 psi pump.
http://www.lakehurst.navy.mil/p2/ser...rvlet?wDID=103

[Switcher]

Originally Posted by 1ctoolfool Hi, I'm looking to modify an electric or gas pressure washer to cut 1/2" drywall. Has anyone tried anything like this or can direct me to a website maybe someone else has experimented with this? Can anyone say for sure it's not possible or point to some engineering data about pressure, flow, orifice diameter, depth of cut, etc. Any help is appreciated, thanks Jv

It will work.

You might not be able to use the drywall after you soak it with water. I'm thinking the end result would = a lot of mud.









.

[1ctoolfool]

I appreciate the input. If nothing else I have learned a lot about the technology.

I am comming to the same conclusion.
The engineering and money involved looks beyond the scope of home shop work. But I would like to look at the homemade waterjet list if someone can point to it. Is it still around?

Pressures required for functional machines seem to start around 20KSI and pressure washers stop around 5KSI. Big gap to make up the difference.
I have no doubt that a .005" orifice mounted on my pressure washer would do some cutting, and I still may try it just to see what it will do.

The thing that scares me is the potentially fatal nature of high pressure jetting injuries. Microscopic contaminants and organizms get propelled deep into your tissue. No exit wound means your tissue absorbs all the hydroshock energy. Jetting injuries on extremeties typically call for amputation of finger/hand/arm. Abdominal jet punctures (even tiny jet streams) typically fatal, slow horrific septic death. Plus very few medical facilities and/or personnel are familiar with how to treat these unusual medical emergencies.

Makes me not really excited about experimenting with a home made 20KSI water pump.

Thanks for the input.
Joe V.

[Geof]

Originally Posted by 1ctoolfool ....I have no doubt that a .005" orifice mounted on my pressure washer would do some cutting, and I still may try it just to see what it will do. The thing that scares me is the potentially fatal nature of high pressure jetting injuries. Microscopic contaminants and organizms get propelled deep into your tissue. No exit wound means your tissue absorbs all the hydroshock energy. Jetting injuries on extremeties typically call for amputation of finger/hand/arm. Abdominal jet punctures (even tiny jet streams) typically fatal, slow horrific septic death. Plus very few medical facilities and/or personnel are familiar with how to treat these unusual medical emergencies. Makes me not really excited about experimenting with a home made 20KSI water pump. Thanks for the input. Joe V.

There was a thread about hydroforming metals a while back where the topic of safety regarding high pressure liquids and gases was discussed; the dangers are not trivial. You have to be careful with pressures as low as 500 psi, maybe lower, if you have cuts or abrasions that provide a weak area on your skin. I did some reading and found that 'water jet cutters' working at 300 to 400 psi are used in surgery for separating tissues and debrading wounds. Apparently with the correct nozzle you can peel tissue from bone at this low pressure! Makes me wince when I think about what I could have done with the 2000 psi water pistol I made when I was young and stupid.

[WayneHill]

What happens to the drywall dust after it is cut? The filter will clog very fast.

[tyler774]

Hey Toolfool

You are definatly right about the hazards of high presure fluid injuries. I remember now about the medical alert cards that Graco includes with there industrial airless sprayers. They operate at around 3000 PSI if I remember corectly. The medical alert card is for painters to keep in there wallet, it instructs hospital staff to start cutting and not to dick around. Says nasty infections will set in if paint contaminated flesh is not removed/amputated.

Grim stuff, glad I don't paint anymore.

Tyler