# I Guess I Need To Make Room For A Cnc Water Jet



## intjonmiller (Sep 13, 2016)

Benchtop/desktop cnc water jet that runs on 110v household power. Yes please!!


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## intjonmiller (Sep 13, 2016)

Hopefully their next move is an intermediate size unit for small shops.

Sent from my SM-J700T using Tapatalk


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## JimDawson (Sep 13, 2016)

OK, I need (want) one 

https://www.kickstarter.com/projects/1294137530/the-first-desktop-waterjet-cutter


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## intjonmiller (Sep 13, 2016)

Of course anyone with knowledge of CNCs and hydraulic systems could theoretically build one for less. Of course that would be a lot easier if you already had one to cut out your parts...


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## JimDawson (Sep 13, 2016)

I didn't realize you could do this with less than 60,000 PSI or so. Pressure washer pump in this one maybe?  
Hmmmmm????


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## intjonmiller (Sep 13, 2016)

PRECISELY what I thought as I watched it. I was first exposed to water jet cutting in the mid 1990s, through my father's work in rapid prototype development. (He managed a branch of one of the only companies at the time with a stereolithography machine, now known as a laser 3D printer, but had dealings with other industry processes.) In 1999, right after graduating high school, I got a will-train job in screen printing. One of the steps in that process is washing and reclaiming the screens between jobs with an industrial pressure washer. I was pretty good at it already when I had a small accident wherein I inadvertently squeezed the trigger with my right hand just as I grabbed the tip to rotate the spray pattern. It sliced right through the side of my left index finger between the first and second knuckles. Cleanest cut I've ever received. I had a moment to stare through the gap, marveling at the physics of what had just happened as only engineering types can appreciate, before the blood started to flow. It wasn't a new concept, as I mentioned, but it took on a much less abstract significance at that moment. 

Anyway, probably due to that experience, as soon as I saw the thing in the video, before they even fired it up, I thought about how to adapt a pressure washer to do the job. 

Coincidentally at the dealership where I work the three small pressure washers used by lot and wash techs are being upgraded to a centralized system today. I wonder what they're going to do with the old diesel units?  

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## hman (Sep 13, 2016)

I just did a quick-and-dirty cut cost calculation, based on the cost of the abrasive.  The power and water consumption should be negligible in comparison.  Cutting speed varies widely, depending on material and thickness.  I arbitrarily chose 1 IPM as an average figure.  Abrasive consumption is ⅓ Lb/minute.  Abrasive cost varies from $.30 to $.60/Lb for bulk purchases, and Wazer will sell small quantities for between $.60 and $1.10/Lb.  I arbitrarily chose $.50/lb as a rough average.

Abrasive cost per inch (or minute) of cut = 1 min/inch * 0.33Lb/min * $.50/Lb = $0.165/inch -or- $0.165/minute
An object requiring 10 inches of cut or 10 minutes would cost $1.65 for abrasive; 100" or 100 minutes would cost you about $16.50

The website gives several examples of finished objects and lists the cutting times for each:
Custom knife 118 minutes = $19.47
Penny necklace 60 minutes = $9.90
Baker's rack 95 minutes = $15.68
Belt drive bicycle 168 min = $27.72
Glass art 34 min = $5.61

I have no idea how this would compare with the cost of having parts cut commercially, but that would be the obvious trade-off.


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## JimDawson (Sep 13, 2016)

Time to do some experimenting.   I just happen to have a 2000 PSI pressure washer pump here, and a CNC plasma setup


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## JimDawson (Sep 13, 2016)

hman said:


> Abrasive cost per inch of cut = 1 min/inch * 0.33Lb/min * $.50/Lb = $0.165/inch
> An object requiring 10 inches of cut would cost $1.65 for abrasive; 100" would cost you about $16.50



I wonder if the abrasive is reuseable.  And how do you get it to flow into the head, venturi effect?.

All I need is another project


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## hman (Sep 13, 2016)

JimDawson said:


> I wonder if the abrasive is reuseable.  And how do you get it to flow into the head, venturi effect?.
> 
> All I need is another project


The FAQs at the bottom of the website recommend against reusing the abrasive, as it could cause clogs.  I guess that makes sense, as the used abrasive will include swarf particles and chunks.


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## intjonmiller (Sep 13, 2016)

If the only concern is swarf, and the abrasive hasn't somehow bonded to it, that would be easy enough to separate, at least when cutting ferrous material. Options for others, but the cost-benefit analysis would surely show diminishing returns fairly early on.


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## TOOLMASTER (Sep 13, 2016)

i was at an auction years ago where their water cutter went for a 100 bucks..no one wanted to move it...something like 30x50 ft..huge rig


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## intjonmiller (Sep 13, 2016)

I finally got back to my desk where it's easier to look stuff up. Sure enough, there are industrial abrasive recycling systems for water jets. The reasoning, beyond the sheer cost of the abrasive, is obvious once you think about it: most of the abrasive never touches the workpiece. Assuming your feed rate is appropriate, only the leading half of the effective cylinder of pressurized abrasive does any cutting. And the abrasive is typically usefully friable (not as much as engineered materials, but enough to still be useful). Only the abrasive that was completely pulverized is not reusable, and it can be screened out.


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## pegg (Nov 21, 2016)

intjonmiller said:


> Hopefully their next move is an intermediate size unit for small shops.
> 
> Sent from my SM-J700T using Tapatalk



Not sure what you mean by "intermediate size" - WARDJet makes an industrial waterjet KIT - - of course this is a huge jump in price from the Wazer but way less than a turn key system (all made in the USA)
https://wardjet.com/products/waterjets/wardkit


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## Billh50 (Nov 21, 2016)

Last place I worked at had a waterjet machine that had a 2' x 4' bed. Whole machine was only about 4' x 6'. They didn't use it because it needed a new control board. Don't know what it went for at the auction when they closed.

I threw out a pressure washer last year when the motor quit and I had another one anyway. Should have kept that pump.


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