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IndustryArena Forum > CNC Plasma, EDM / Waterjet Machines > Waterjet General Topics > New plasma table with water bed questions ...
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  1. #1
    Join Date
    Aug 2007
    Posts
    47

    New plasma table with water bed questions ...

    I started buiding a plasma table ... no plans, just a lot of passion .... I have a question: How deep the water have to be on the water table? It seems that I can't find that answer anywhere .... Also ... where is the best place where i can buy some linear rails ? Thank you
    Attached Thumbnails Attached Thumbnails DSC02727_table.jpg  

  2. #2
    Join Date
    Aug 2007
    Posts
    47
    I am stuck at this stage ... I cannot continue until I know exactly how to proceed with the water table .... can someone please help ?

  3. #3
    Join Date
    Sep 2006
    Posts
    113
    My water table has about 3 to 3.5 inches of water beneath the sheet being cut. It works very well.

    Here's a picture.

    http://www.cnczone.com/gallery/data/...m/DSC_3566.jpg

  4. #4
    Join Date
    Aug 2007
    Posts
    47
    Thank you .... I can go THE MOST 4 inches. I was just wondering if this was enough. For sure I don;t want to "cut thru" - that will not be funny.
    Did you cut AL with it yet?

  5. #5
    Join Date
    Aug 2007
    Posts
    47
    That is a VERY nice looking table. Where did you buy all the parts for .... did you build the Z axle support or got the whole kit ?

  6. #6
    Join Date
    Nov 2006
    Posts
    473
    Zeoncomp-The table that I am building ranges from 4 to 6 inches for the height of the water. I wish I could tell you how great it works, but I can't. (I am still building it) I purchased the linear rails from Rick Hoback at Superior Bearings. He has done everything that he has said he was going to do and more.If you need a link to superior bearing let me know and I will post it once I get home.Steve

  7. #7
    Join Date
    Aug 2007
    Posts
    47
    Thank you

  8. #8
    Join Date
    Oct 2005
    Posts
    1238

    Arrow Water Table Info.

    Hi zeoncomp & welcome to CNC Zone. :wave:

    Click on this LINK & it will take you to my build log with some pictures, information & a drawing to help you with your water table questions. See posts #161 164 166 & 176.

    The depth of water is 4" maximum & I keep the water anywhere from just touching the underside of the material being cut, to 1/2" below the material.

    Quote Originally Posted by zeoncomp View Post
    How deep the water have to be on the water table? It seems that I can't find that answer anywhere ...

  9. #9
    Join Date
    Sep 2006
    Posts
    113
    zeoncomp,

    4 inches of water depth will be more than enough, assuming your not using a 200 amp plasma machine. The tops of my slat "hangers" are only 1.5 inches below the water surface and show no signs of erosion. I'm using a 60 amp Hypertherm Powermax 1000.

    As for my machine, thanks. The entire machine was built from scratch. I'm planning on doing a post about it's construction sometime this week, as it is a recent build.

    I have yet to cut aluminum on the water table. I'm still pondering it. Hypertherm says it's a no-no due to hydrogen gas build-up. Thermal Dynamics says it O.K. as long as there's some space between the sheet and the water's surface, and you have bubble agitators in your tank.

  10. #10
    Join Date
    Jul 2006
    Posts
    70
    jcar
    nice table i saw the pics in your other posts. whats the bubble agitators that thermal dynamics talked about? my table is similiar in design to yours with the compressed air to raise and lower. fill and empty are opposite corners from each other. i have yet to cut aluminum with the plasma because of the hydrogen build up. my fear was getting it in to the air chamber. hence the reason for a cross flow on the air. i've just been cutting it with a router. i can cut 3/16 single pass with it though, but would like to be able to use the plasma also on alum.
    bear

  11. #11
    Join Date
    Sep 2006
    Posts
    113
    Bearracecars,

    After reading through the PDF files, I've apparently mixed the two companies up. The agitators were in a PDF that I found on Hypertherm's site. Here's a link. https://www.hypertherm.com/library/f...)/800270r1.pdf About 2/3 of the way through the document you'll find a section titled "Aeration Manifold For Cutting Aluminum With Plasma".

    I wish I had thought of installing my input and exhaust air valves on opposite ends of the tank. Smart thinking.

  12. #12
    Join Date
    Aug 2007
    Posts
    47
    Ok ... so I am getting to the point where I have to choose what motors should I use. I think that PlazPak-3 from candcnc.com is very nice .... but maybe I don't need that much. Maybe steppers are just fine. I don;t plan on doing anything with the router in the near future but it can be a posibility. Now I'm thingking - If I'll buy it - might as well but the most complete system - right? Now, are there any differences in the way of building the table if using the servos vs. steppers ?
    Also, is this going to work with a servo : http://www.modularcnc.com/linear_slides ?
    I am still looking for linear slides (need 2x80" and 1x59") and rack and pinion combination for the 3 axis.

    Any sugestion will be appreciated. Thank you

  13. #13
    Join Date
    Feb 2009
    Posts
    227

    Wink Answer

    My table has a 10" deep 4x8 water table with a 200 gal overflow tank and small submersible pump so I can regulate water height.... It can be any depth really... 2" or 3'... If you have a small table 4x4 make it deeper to keep the water cooler (it will get very hot over time especially when you have to grab a small part in the tank) All it is for is to catch the vaporized metal dust( take it out of the air), and keep the material like stainless from warping... fill the water all the way up to the bottom of your cutting material so it touches... seems to work nice.. I would go 6"-8" if I was you

  14. #14
    Join Date
    Feb 2010
    Posts
    3447

    Talking hydrogen oh my!

    Quote Originally Posted by Jcar View Post
    Bearracecars,

    After reading through the PDF files, I've apparently mixed the two companies up. The agitators were in a PDF that I found on Hypertherm's site. Here's a link. https://www.hypertherm.com/library/f...)/800270r1.pdf About 2/3 of the way through the document you'll find a section titled "Aeration Manifold For Cutting Aluminum With Plasma".

    I wish I had thought of installing my input and exhaust air valves on opposite ends of the tank. Smart thinking.
    I will have to check this out. I'm building a plasma JUST to cut aluminum. I'm currently at work so i can't download the PDF. From what i have seen online, people use a waterbed with aluminum just fine. Is the hydrogen gas buildup they speak of superheated water that explodes or what is the deal?

  15. #15
    Join Date
    Jan 2008
    Posts
    2247
    This is a "canned" response from my files.....as questions pertaining to cutting aluminum with plasma over a water table are asked quite frequently"


    Jim

    In regards to cutting aluminum over a water table, there generally is no concern of the possibility of hydrogen production and the ensuing explosion hazard. Aluminum cutting produces a by product of aluminum oxide, which sinks in the water and absorbs oxygen. When oxygen is removed from water (H20) it leaves hydrogen, which you will see rising to the surface (after cutting aluminum) as small bubbles.

    Since the quantity is very small, and hydrogen is lighter than air, the small amount of hydrogen will dissipate in the ambient air.

    Many water tables have a submerged chamber that is used (with compressed air) to rapidly raise and lower the water level in the table for small parts removal, cleaning, etc. If aluminum oxide is allowed to get into a closed chamber, hydrogen could be trapped and over time could form a large pocket, and with the event of a spark and some oxygen there could be an explosion.

    Most of the stories about aluminum and water tables causing explosions have no basis, although there have been a couple of issues over the 32 years I have been working for Hypertherm that involved minor explosions on large industrial machines. The ones that I am aware of were solved with aerators (no pump needed) that simply involved a couple of pipes with holes drilled in them in them...submerged in the water table. Low pressure compressed air was fed into the pipes to aerate the water, diluting the hydrogen.

    Cut all the aluminum you want on small water tables!

    Jim Colt Hypertherm



    Quote Originally Posted by Jcar View Post
    Bearracecars,

    After reading through the PDF files, I've apparently mixed the two companies up. The agitators were in a PDF that I found on Hypertherm's site. Here's a link. https://www.hypertherm.com/library/f...)/800270r1.pdf About 2/3 of the way through the document you'll find a section titled "Aeration Manifold For Cutting Aluminum With Plasma".

    I wish I had thought of installing my input and exhaust air valves on opposite ends of the tank. Smart thinking.

  16. #16
    Join Date
    Feb 2009
    Posts
    227

    Dont Be Afraid!!!

    Two things 1) keep your water table open no chambers to trap gases 2) Dont allow the water to sit up to the bottom of the material over long periods of time. The water could seal under the material and create a small air pocket underneath especially if material is slightly warped domed shaped, first pierce kaboom... Keep water about 1/8" below material and youll be fine.

    My watertable is alum. and I cut alum. all day with no problems... Because I follow rule 1 and 2... lol

  17. #17
    Join Date
    Feb 2010
    Posts
    3447
    Good to know thank you both!

    Quote Originally Posted by jimcolt View Post
    This is a "canned" response from my files.....as questions pertaining to cutting aluminum with plasma over a water table are asked quite frequently"


    Jim

    In regards to cutting aluminum over a water table, there generally is no concern of the possibility of hydrogen production and the ensuing explosion hazard. Aluminum cutting produces a by product of aluminum oxide, which sinks in the water and absorbs oxygen. When oxygen is removed from water (H20) it leaves hydrogen, which you will see rising to the surface (after cutting aluminum) as small bubbles.

    Since the quantity is very small, and hydrogen is lighter than air, the small amount of hydrogen will dissipate in the ambient air.

    Many water tables have a submerged chamber that is used (with compressed air) to rapidly raise and lower the water level in the table for small parts removal, cleaning, etc. If aluminum oxide is allowed to get into a closed chamber, hydrogen could be trapped and over time could form a large pocket, and with the event of a spark and some oxygen there could be an explosion.

    Most of the stories about aluminum and water tables causing explosions have no basis, although there have been a couple of issues over the 32 years I have been working for Hypertherm that involved minor explosions on large industrial machines. The ones that I am aware of were solved with aerators (no pump needed) that simply involved a couple of pipes with holes drilled in them in them...submerged in the water table. Low pressure compressed air was fed into the pipes to aerate the water, diluting the hydrogen.

    Cut all the aluminum you want on small water tables!

    Jim Colt Hypertherm

  18. #18

    Re: New plasma table with water bed questions ...

    [QUOTE=Jcar;336485]zeoncomp,

    4 inches of water depth will be more than enough, assuming your not using a 200 amp plasma machine.


    Hi zeoncomp. What if you have a 200 amp one, what would you recommend?

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