[BuckingFastards]

Hello everybody, i know this is kind of off topic because this is woodworking but a waterjet could cut wood right? Well anyway i was wondering if it was possible to build a diy waterjet with a pressure washer and having it hooked up just lke you would a regular cnc router? So could i use this pressure washer? http://www.northerntool.com/webapp/w...85&R=200317585 And instead of using that kind of nozel i could use a high pressure nozel. Do you think this would work for wood, plastic, and foam or would i need a pressure washer with a higher psi (The one in the link is rated at 1750 psi). So tell me if you think it would work.

[jaako16]

Hi

I assume that you want to cut some material with water, if so I have to disapoint you a little bit. :frown:
Waterjets use some abrasive added to the water, it is the abrasive additive that does the cutting, the water only transports the abrasive media and cleans the cut.

The nozzle ($$$) needed to shape the cutting media is made from any hard material such as industrial diamond, cemented carbide or similar.

I would love to see a homebuilt waterjet cutting machine.

Good luck

jaako

[BuckingFastards]

ok so even if i had some abrasive or whatever and got the nozzle would i be able to cut with that amount of psi?

[chuckknigh]

Whether the abrasive is necessary is a function of the material being cut. "Just water" will cut soft woods, some fabrics, foams, etc.

You obviously know that a high pressure waterjet from one of those things can easily eat into the surface of a wooden deck or even make a slight dent in a cement driveway. I know mine will...but mine is a multi-horsepower gasoline powered one. I don't remember the nozzle pressure...but it's extra high.

Taking it from that stage through to a useful machine, however, is a MASSIVE undertaking. And, the results may not be what you expect -- water, alone, is wear-away at the material, slowly. Ragged edges. Fair warning.

-- Chuck Knight

[Geof]

(The one in the link is rated at 1750 psi).

Just water will cut wood and cut it quite clean but you need to put more than an extra 0 on your pressure. Something like 25,000 psi is needed, maybe more. Working with these pressures is a bit dangerous because flesh and bone is just about as easy to cut as wood. A leak could leave you unable to count up to ten on your fingers or worse.

[unterhaus]

I used to have a link to a diy waterjet site with a forum -- bottom line is that a lot of it is going to be purchased. Even homebuilt waterjets are expensive. Probably better to get into other forms of cutters.

[BuckingFastards]

Ok so you guys think it can be done but it will just cost alot. and i will need at least 25,000 psi to cut stuff and that high pressure is dangerous.

[cbass]

One other difficulty that might not be obvious at first: If you are going to use abrasives in the water, then the innerds of your system (not just the nozzel, but all the tubing and ESPECIALLY the pump) have to be able to withstand abrasion. There's no point in using a system that is designed for water and primarily made of soft plastic if this is going to disintegrate within a few hours of continuous use!

Just my $.02

Carlo

[fyffe555]

The abrasive is usually introduced at the nozzle head. The jewel or carbide nozzle handles the abrasive and water, the pump and the feeds just move water. You do , of course, need a system capable of metering the right amount of abrasive into the high pressure water stream at the nozzle.. clever stuff..

[Geof]

Here is a link that has a very detailed description of water jet cutting both plain water and abrasive.

http://www.flowcorp.com/waterjet-resources.cfm?id=335

[BuckingFastards]

ok well say i just wanted to use plain water no abrasive to cut woods and foam etc? i should be able to do it correct with that amount psi? (1750 psi) I don't want to go out and buy a pressure washer and have no use for it. My budget for a better pressure washer is $500 if i have to buy a pressure washer that costs a lot more well ill forget about it. And also i was wondering if this is possible then could i use some kind of holding tank and a filter to filter the water after the material has been cut so i don't have to waste my own water? Like maybe a 15 gallon tank or something and have it under my cnc table so when the waterjet cuts the material it would go through the filter into the holding tank and be reused and everything thats dirty stays on top of the filter??

[Corvus corax]

Don't bother using the pressure washer. A better way to look at waterjet power is in terms of Horsepower. Even the smaller machines are rated at 25HP and above. Pressure washers simply don't have that kind of power. Its somthing akin to trying to use a marking laser to cut steel. You are off by several orders of magnitude. Waterjets sans abrasive run pressures as high as 300,000 PSI.

[BuckingFastards]

Don't bother using the pressure washer. A better way to look at waterjet power is in terms of Horsepower. Even the smaller machines are rated at 25HP and above. Pressure washers simply don't have that kind of power.

Not saying your wrong or anythin but you said do not look at pressure washer but look at horsepower. So what about this (http://www.northerntool.com/webapp/w...21&R=200317421) I do not have the money for that but still its some where around 25Hp, 7HP less but still. Remember i am not trying to cut aluminum and steel and carbon fiber, i am going to cut stuff like soft woods, foam, and plastic. So if that is rated at 18HP then i can use a pressure washer correct? And as some other people said thier pressure washers puts dents in concreate and stuff.

[Corvus corax]

The problem is that pressure washers and flowjets are two completely different animals. Pressure washers are looking to generate just enough force at the work surface to lightly abrade it, and remove contaminants. A flowjet is punching clean through. Flowjet is high pressure/ low volume; pressure washer is high volume/ (comparatively) low pressure. 100W CO2 laser/ vs. 100W light bulb. Both deliver the same amount of energy, but in completely different ways. Now, you WILL be able to blast your way through things like soft wood, etc. with a powerful enough pressure washer, but to what end? The quality and speed of the result will not justify the cost.

If you are looking to work fairly soft materials, and want speed, your best bet is a high speed spindle. If you want something exotic, look into a good CO2 laser. Thin materials are quickly cut, and the cost of laser systems has been steadily decreasing- you can get a decent turnkey CO2 cutting laser head starting at about $7500 these days. Look at the Synrad 25W system that Torchmate offers. It would probably be sufficient for your application.

[Geof]

Even a 4000 psi pressure washer is not enough to cut something. Pressure washers will erode concrete and wood but it is not cutting it is the water being forced into small defects in the surface and prying it away.

Water jet cutting is dependent on the speed of the jet and it is just not fast enough to cut until you get up into the 25,000 psi region or higher.

Perhaps this analogy might help: You are probably familiar with the nylon filament grass trimmers that "cut" grass. Well they don't really cut it in the sense that a knife cuts it is more a case that the nylon thread hits the blade of grass so fast that it shears a piece of grass out at the point of impact. To do this the filament has to be travelling fast, something like 5000 to 7000 fpm. At lowers speeds the grass bends around the filament and the filament flexes but "cutting" does not take place. There is a critical speed region; below this the filament and grass all tangle up while well above it the filament shears through the grass as if it had a razor edge. Water jet cutting is similar; below the critical pressure region you will get erosion of brittle, defect filled material like concrete or wood which has soft spots and well above the water has enough speed, and kinetic energy, it more or less punches material out of the way. Even the highest psi pressure washer is well below the cutting pressure.

[unterhaus]

Lasers are cheaper and less dangerous. But really, I'm curious why you wouldn't go with a router. It often pays to start with easier projects and work up. You'll be the only person in your neighborhood with one, that's obvious.


They all need a motion system, it's just the cutting mechanism is much easier with the router, much more difficult with the laser, and an orders of magnitude more difficult with the water jet.

[paulC]

I think you will need to do some experimenting to satisfy your curiosity.
With such a low pressure I think you will cut MDF but make it go soggy. Real wood will proberbly deflect the cut to follow the grain.
While you will cut your foam, the cost of building a machine could leave you with something that you are dissapointed with at the end. Remember that with the lower pressure you will get a lot of water splashing about so you will have to ensure everything is waterproof. A high pressure Supersonic jet will not splash, just cut.
Paul

[BuckingFastards]

All right thanks everyone i guess i won't do a diy waterjet. But yeah i am going to do a router though i want at least 4 axis (a rotary table) so i could do a little wood work. I just thought it would be a cool idea of having a cnc waterjet o well. I would get a laser but i thought they were dangerous because without the proper ventelation it causes cancer and i could not have as much axis on a laser or could i?

[erase42]

Im curious as to why you want a waterjet cutter? you mention cutting softer materials, wood, foam, plastic. there are so many easier ways to accomplish this. On your limited budget (not that we all arent) Id start with something like a small dremel powered router and master the whole cnc thing, electronics, software etc. then move on to whatever it is you need to build to accomplish your task. Another thing is, when i was younger i used to use a very powerful pressure washer, maybe 3500 psi and approx 3 gallons per minute WITH a sandblasting attachment, so i had the combination of pretty high pressure and sharp abrasive and even with that i could sort of WEAR a hole in wood or cement. Nothing even close to a useable cut. I wish you well, but hope you dont waste too much money on this idea.

[Verfur]

I agrea I would not suggest a DIY water jet Pump just from the exspearance I have with ours we use well over 40,000 psi to cut parts out. And it will cut would with an abrasive (Garnet) but so slow I could out run it with a hand saw. The wood traps the abrasive in it and the fresh abrasive strikes the trapped abrasive and brakes it down.

I would rather cut metal with the waterjet than wood. But as a note it will cut most anything given enough time.

John