Hello,
I'm needing to build a water tank to put under my plasma table to catch slag and hopefully reduce smoke etc...

1. How far below the surface of the material should the water be?

2. How deep or how shallow can the water be so that the tank won't be so heavy?

3. Any specific design recomendations or plans/drawings available?

Thanks for any input.

Hi,

As far as i know, plasma cutters are moist sensitive.
I know a simple second solution (I'm not saying yours is bad, it's just a second way ;) ), make a dish out of thin metal sheet with 5-10cm (2-4") high sides and put a couple of buckets of sand in it. When you cut a lot you can spray some water on the sand.

Cheers,
Sveb

I'm not so sure about moister sensitive. Where I buy most my steel they have a 8'x20' plasma cutter that if I recall correctly has a 2" cut capacity. Anyway to keep noise fumes and the light down they cut under water. Have a large tank with a pump on it. Lay the metal down on the finger table then hit the switch. Tank fills with water. It produces a few bubbles and works great. The operaters only problem is you can't see the cut so you don't know if you have a bad tip till your done. I have watched it work a few times. Just bough a buch of plased circles in 3/8" thick for a current project and they look good.

Donny

The Plasma water tables I have come across cut around 1/2" under the water , I don't think the depth under the plate matters, I believe they use the same method that submarines use for quick ballast dumping. i.e. compressed air tanks to refill quickly between jobs.
Al

The moisture sensitivity is with the air being supplied to the plasma cutter from the compressed air system. They're very sensitive to moisture in that respect, but not sensitive to moisture in their surroundings.

Hey,
Maybe I'm mistaken. I was told to put the water tank under the material. In other words, the material sits 3-5" (or whatever) ABOVE the surface of the water at all times. I know some of the big/professional tables cut under water, but I'm talking about cutting above the water. Will this be of any benefit? Maybe I just misunderstood.

Yes, your right, moisture in the gas line, especially if you are using compressed air shortens the life of consumables , and they are not usually cheap!
Al

Having water under the material should help a lot. I know it does on my oxy-fuel burning table. Most commercial plasma tables in the lighter capacities are set up with a draft table to suck away the dust and fumes. Most folks i've seen mention using a setup like this on a home system are trying to do it with too little fan, so it ends up ineffective. There's a definite threshold for perimeter capture velocity for a device like this (similar to a commercial range hood in that respect) and if you're much under that velocity the stuff just goes wherever it wants to even if the fan is running.

I have been running a water table on my plasma cutter for over 10 years now, and I highly recommend it. I built a steel tank about 6" deep, out of 1/8" plate. I took two pieces of 3" angle, the length of the tank, and plasma cut slightly angled slots in them to recieve 1/4" x 3" flat bars the width of the tank, about 2" apart. Slight angle off of straight up and down allows slag to fall off, and makes it easier to drag sheet across. Fill up the tank with water to just about level with the top of the slats. Yes, you can run the metal you are cutting slightly below water level, but I usually try to run it a 1/4" or so above water level. The water catches all the sparks, which are actually gritty slag. And it catches all the red hot drops from interior cuts, which otherwise you would step on, or might catch your floor on fire. It cuts down greatly on smoke.
Make sure you put levelling feet on your water table, especially if you dont have auto torch height, but even if you do. You want the table nice and flat in relationship to your torch. Also make sure you put a hose bib- a faucet, if you will, at the low point underneath the table, so you can hook up a hose and drain the table once or twice a year. With a wire mesh screen over the drain, so it doesnt fill up with mud. The water will be horribly cold when you have to reach in and fish out a piece that you wanted that fell in. And it will fill up with nasty mud like slag stuff, which is one of the dirtiest substances on earth, when you have to clean it out. But all of that nasty stuff would otherwise be on your floor and in the air in your shop, so it is definitely worth building one. Water is heavy- a pint is a pound, the world around. No two ways about it. But a water table will do 75% as well as a 5000 dollar fume extraction system, and only cost a couple of hundred bucks to build.

- a pint is a pound, the world around. .
Only in the US. Most everywhere else its a pound and a quarter (20ozs).
Al
:p

Would the table work as well if it were only 3 " deep and also does it miniumize warping even if you are cutting above the water?

Asking what Txfatboy just did, only different..

Is the need for an auto height torch as great when cutting above a water table?
Is an auto height torch needed at all when cutting below water?

Will your common Hypertherm 600 plasma cutter work under water or is this discussion specific to the industrial machines?

Thanks, I love this discussion, so little info on plasm cnc out there. I'm considering adding plasma to my 4'x4' table. Just need to run a 220v circuit to the garage.

TT

3" deep should work just fine- you just have to clean it out more often, as you have less space for slag and interior drops.

As far as warping goes- when you are cutting below the water, with the material actually underwater, then it should have some affect on cutting down warpage. But the kind of table we are discussing is mostly to catch sparks and hot drops, and cut down on smoke and mess in the shop. It will not affect warpage at all.

I have auto torch height on my machine when I cut just above the water, but Auto torch height is just as handy when cutting below water- 50,000 degrees will still warp steel a little. So unless your sheet is perfectly flat, or say, 2" thick, I think you still want auto torch height. As I have said before, I find it essential for gauge thicknesses up to at least 3/8" plate- it prevents crashes, ruined parts, and interrupted cuts.

My plasma machine uses a Thermal Dynamics Pak 75 with a machine torch- not the cheapest, but certainly not a big industrial machine. I have seen cnc machines which just clamp in the hand torch from a smaller power supply- it works, and all of the things we have been discussing apply equally to an 800 dollar machine as they would to a 30k Hi-def unit.

I have been reading quite a lot recently about high power plasma systems used in ship yards and such lately - The 1000A kind of system.

These systems have a cutting ability of up to 150mm in plate. Cutting with water injection, to define the beam, cool the torch and the work, reduces their capacity to 75mm. Cutting underwater reduces it futher.

Remember, water has a massive energy absorption capacity when it turns from a liquid to a gas.

If there is steam coming off the torch, it's dropping a substantial amount of power into boiling the water that's coming into contact with the plasma and work.

Cooling the work will help prevent warping, but it also turns the work into an excellent heatsink. The torch needs heat to cut the work.

This begins to raise the same questions people have with soldering electronics. It would seem sensible to use a lower wattage soldering iron on SMD components, but in reality, the lower wattage means it takes longer to heat the parts to be joined to the correct temperature - if they ever reach it! :) During this phase, the parts are being saturated with heat; causing extended heat exposure and increasing the risk of damage.

It's much safer to use a higher wattage soldering iron, touch the parts for a second, heat them to the right temperature and solder them. In comparision, you put less heat into the work because the parts that need the heat get it quickly and then the heat can be removed; instead of the heat having enough time to be conducted away almost as fast as it's added.

In a similar way, running the torch at a higher wattage with higher feed rates will likely cause less warping than running it at a lower wattage and lower feed rates. The work only needs to reach a certain tempeature before it melts, but it takes time for the heat to conduct through the work. If you can heat the work to the same temperature quickly and then move on, you give the heat less time to be conducted away from the cut in progress.

Materials handling can be an substantial cause of warping. Steel yards often handle materials in such a way that they sag in their middle during movement.

In ship yards using higher power systems, it was estimated that for every kilogram of material cut away, around 14 grams or more of metal vapour became airborne.

Not a problem if you're cutting some sheets in your workshop. If you're cutting away kilos over a single cycle, that vapour is a serious health concern. With stainless steel containing heavy metal alloying elements like Chromium and Vanadium, the vapour is accumulatively toxic.

Saying that, plasma cutting is still much safer in terms of vapour emission compared to gas cutting using natural gas or other gases like MAPP. Gouging very sharply increases emissions. Carbon arc gouging is the most concerning with well over 40 grams of emission per kilo removed.

The easiest way to clean the vapours from the machine's output is to submerge the work. In fact, I would expect it to become almost mandatory in industrial work places soon. If the work is not submerged, the table will likely require some form of HVAC system equipped with a particle filter on it's output.

A few tens of grams sounds like nothing, but imagine how much damage those grams would do if they were uniformly lining the insides of your lungs.

Aside from that, the water blocks a lot of the UV and sound emission from the torch. From what I've read, a 1000A system produces quite a lot of these. So much so that ear protection is needed.

I think using a subemerged table to lower warping in a home enviroment is perhaps a bit extreme. Experimenting with feed rates and power ratings might be a better place to start.

I think Miller actually publish a graph with at least one of their plasma cutters showing the maximum feed rate they recommend for a given material thickness.

Johnuk, Very informative post! Always wondered how harmfull that airborn vapor was.

This is all good stuff to learn. I have wanted to better control the dust, smoke and fumes from my plasma table for a long time. I did however talk to my welding supply store about underwater plasma cutting and they called Hypertherm and had me talk to one of Hypertherm's tech's. The tech told me to keep my Hypertherm 900 with machine torch as far from water as I could. Sounds to me like he suffers from paranoia if so many actual users are having sucess and not damaging their power sources.

never set a pace that you can't maintain

This is all good stuff to learn. I have wanted to better control the dust, smoke and fumes from my plasma table for a long time. I did however talk to my welding supply store about underwater plasma cutting and they called Hypertherm and had me talk to one of Hypertherm's tech's. The tech told me to keep my Hypertherm 900 with machine torch as far from water as I could. Sounds to me like he suffers from paranoia if so many actual users are having sucess and not damaging their power sources.

never set a pace that you can't maintain

It's probably a case of company talk like you say. If they advised their customers that it was okay to use their gear around water, and a customer then electrocuted themselves, they'd almost certainly be liable for legal action.

There'll be a million and one safety regulations that a piece of high power consumer electronics needs to pass before it can be used around water.

Something I've been thinking about recently was the work suspension method. I know a lot of guys go for slates on a DIY table. Industrially, these can end up getting damaged too quickly, so I've seen them using other ideas.

One was rollers. Essentially, a circle of plate held up vertically through it's centre, allowing it to rotate - like a wheel dressing tool. This way, contact is minimal, and you can just rotate the rollers to get a new contact point.

Another, for underwater cutting, looked kind of strange - almost like a T slotted table made out of green plastic or ceramic. They didn't provide any details on it, unfortunately.

I was thinking, although plasmas are very hot, the way in which they transfer their heat is much more controllable than the way a gas flame would.

For the plasma to conduct energy to the work, it must be electrically referenced to the plasma it's self. If the table is metal, the table them becomes bound and so it will become damaged when the plasma makes contact with it.

However, if the table it's self could be electrically isolated from the work piece, it should last a great deal longer.

I've been spending some time thinking of ways you could practically implement the idea.

One would be by resting the work on stone. You can have stone cut into slab like strips. I figured that was probably a bad idea since the heat might cause the stone to burst.

Another would be to use a castable refractory. Theoretically, you should be able to get a very accurate table with an accurate mold. High aluminium oxide content refractories can last well over a thousand degrees Celsius for prolonged times - which you don't find on plasma tables, the longest being a dwell time of a few seconds perhaps.

If you didn't want to use messy refractories, science labs use rigid heat proof tiles for bunsens and hot equipment. The ones we used in my secondary school a few years were made from a fiberous, crystalline like material. They were also quite strong. I can't recall ever seeing one broken. Which, for a public boys school is a seriously impressive feat!

The tiles could be cut into small sections to act as supports or used as they come - they're about A5 sheet length but square. I doubt they're very expensive if they let kids touch them.

The last idea I had was to use a form of ceramic based paint, glaze or wash on a normal table. I did a bit of quick searching and found a paint made for motor bike exhausts that seems interesting.

http://www.bpmsports.com/hpc/

Although, I'm not sure about what it actually decomposes to when heated, or what it's based on. It may contain metal particles so you'd need to contact BPM.

A ceramic glaze or wash seems like an interesting idea because it should be very easy to do accurately and make it tidy looking. Artists who work with pottery will be able to help you learn more about them. Given the character of most artists, they'll probably help you for free and then colour code the table. :)

A glaze could be as easy as taking the slates off the table, painting them with the glaze and then putting them in a pottery kiln. You could do it a few times to build up a thick layer on them.

The only thing to think about with these ideas is that when the torch cuts a part away it shouldn't be able to fall onto any metal surfaces exposed on the table. Also, if the torch or work damages the table, it should damage it in such a way that the rest of the table can still keep the work off any metal substructure within the table.

I am not fully aware of these ideas being used at the moment, but I know that a plasma transmits many times more of it's energy to metal that is electrically referenced to it.

If you're building a table, or can modify you current table, you might like to give one of them a go.

A quick way of trying the idea out would be to use some of those small easy mosaic effect tiles girls love, the kind that come preattached to a flexible mesh - you can cut them to shape or remove individual tiles. These things -

http://www.mosaicsupply.com/advendrkblue.jpg

Their small size should help reduce the chance of them cracking due to point heating.

Sounds good in theory, but when the rubber meets the road, your ideas are a little impractical. For the plasma cutter to work, the metal must be grounded. All your glazes, ceramics, and refractories dont conduct electricity, which means that you have to clamp your ground lead on the metal every time you cut out a piece.
This is annoying, time consuming, and hard to get little pieces of metal to sit flat. What about after the interior cut piece comes loose, and it is no longer connected to the piece of metal with the ground clamp on it? What about when the weight of the ground clamp wire itself pulls the little piece of scrap right off the table, in the middle of the cut, and ruins the last piece of that material you have, and a full sheet costs $500?
Every commercial table I have ever seen was made of steel- for a reason- it conducts electricity. That way, you can throw a piece of metal down on it anywhere you like, and begin cutting. Much more efficient and effective. The slats on my table last years and years- yes, they get slag on em, but it doesnt affect anything. About every year or two, we pull the slats out, and throw em up in the air and let em fall on the concrete floor, and slag falls in every direction. Cleans em up pretty good. I havent replaced the slats in over 5 years, and even when I have to, its only maybe a hundred bucks worth of material.
Now my waterjet cutting subcontractor that I use- they replace their slats every few months- but they are routinely holding tolerances in the thousandths of an inch, for aerospace and other critical applications. But unless you have a 30 thousand dollar Hidefinition plasma power supply, your plasma cuts are never going to be accurate enough to justify that degree of worrying. I can hold a 1/16", probably 1/32" with my optical trace unit- and everything that comes off the plasma cutter is going to have to have the slag chipped off, and probably be sanded or ground anyway.
Trust me, metal slats made from 3/16" flat bar is the way to go.

Oh, and one more reason why steel slats are where its at- lots of times, you need some special work holding jig, if you are cutting things besides just flat sheet. With a steel table, you just tack weld down your jig, and your piece is held in place securely. When done, you grind it off. I had a job a few years ago where I needed to cut lengthwise slots in 1/2" square tubing- a welded steel jig, and vise grips, enabled me to cut hundreds of lineal feet of it with very little rejects- But without a firm jig, the square tubing would have danced all around, and the slots would have been a joke.
Same thing for mounting a rotary welding postioner on your plasma table, and doing cuts around moving pipe and the like- you need to be able to fasten to the table, for registration, and nothing is easier than just migging the jig down.
The water below still catches 90% of the sparks and slag.

Oh, and one more reason why steel slats are where its at- lots of times, you need some special work holding jig, if you are cutting things besides just flat sheet. With a steel table, you just tack weld down your jig, and your piece is held in place securely. When done, you grind it off. I had a job a few years ago where I needed to cut lengthwise slots in 1/2" square tubing- a welded steel jig, and vise grips, enabled me to cut hundreds of lineal feet of it with very little rejects- But without a firm jig, the square tubing would have danced all around, and the slots would have been a joke.
Same thing for mounting a rotary welding postioner on your plasma table, and doing cuts around moving pipe and the like- you need to be able to fasten to the table, for registration, and nothing is easier than just migging the jig down.
The water below still catches 90% of the sparks and slag.

Sorry Ries, I think I perhaps implied a bit more complexity than I was hoping. Rather, I only really wanted to present a number of different ideas.

As to the table not being conductive, a series of points on it could be made so. For example, patches on the slates could be exposed for conduction. The idea behind my thoughts was that if the majority of the table isn't electrically conductive it's wear should be substantially lower. Usually, the last cycle a code will do is to cut the part free of the plate. So, once the part disconnects from the rest of the conducting sheet, it is finished anyway.

The big heavy clamps that are usually supplied with a welder or plasma torch could be replaced with sacrificial clamps that are designed not to pull the work off the table.

Again, I see what you're saying, I just thought I'd suggest the ideas as a possibility.

It's all kind of 'in theory' stuff for people to think about. I imagine that as the power of the torch begins to rise, the problems get more pronounced, as dwell times and such would begin cutting much deeper into the supports.

I guess I was trying to isolate conductivity from support so that the two don't effect each other.

Do you know what it is about your table that limits it's accuracy? I mean, is it the positioning system, the table, the torch it's self or so on?

I know that the guys who rebuild machine tools or CNC'erise Sherlines can quite often get 0.02mm accuracy, so I'm guessing it's something to do with the torch rather than the positioning system?

Best wishes,
John

I have been running my machine since 1991, and table wear is just not a problem- I have not had to replace my slats very often, and it doesnt cost much when I do.
So I wouldnt worry about expensive and complicated fixes to a problem that doesnt really exist. And I cant imagine any tile or ceramic that wouldnt be a lot more trouble than it was worth.

As far as accuracy goes, you get what you pay for. My machine is plenty accurate for the work I do with it. Two parts cut with it are the same size. But the kerf size of plasma, unless it is hi-def, is pretty large, compared to waterjet or laser. So the smallest radius turn it can make is still pretty big. And 50,000 degrees makes metal move. Plasma cutting has inherent limits in accuracy, and if you need better tolerances, you move up the scale, to more expensive, more precise machines. I know a guy who does edm who routinely holds tolerances of .0005.
But it costs money. As the hot rodders used to say, "speed costs money. How fast do you wanna go?"
Well, precision is the same way.
My machine cuts parts all the time, the parts fit, and people pay me for them.
Works for me.

I have been running my machine since 1991, and table wear is just not a problem- I have not had to replace my slats very often, and it doesnt cost much when I do.
So I wouldnt worry about expensive and complicated fixes to a problem that doesnt really exist. And I cant imagine any tile or ceramic that wouldnt be a lot more trouble than it was worth.

As far as accuracy goes, you get what you pay for. My machine is plenty accurate for the work I do with it. Two parts cut with it are the same size. But the kerf size of plasma, unless it is hi-def, is pretty large, compared to waterjet or laser. So the smallest radius turn it can make is still pretty big. And 50,000 degrees makes metal move. Plasma cutting has inherent limits in accuracy, and if you need better tolerances, you move up the scale, to more expensive, more precise machines. I know a guy who does edm who routinely holds tolerances of .0005.
But it costs money. As the hot rodders used to say, "speed costs money. How fast do you wanna go?"
Well, precision is the same way.
My machine cuts parts all the time, the parts fit, and people pay me for them.
Works for me.

Thanks for your reply.

How easy is it to find work doing plasma cutting?

I realise that it's something not a great deal of people are capable of at home, but at the same time, a lot of metal working places have real big tables or higher production rate machines than you could run at home. Does that not put a stopper on how many customers you can get for the table? Or do you use the table to make your own parts and then sell the parts, not the service, to people?

Best wishes,
John

I am not a job shop- that is, I dont cut parts for other people. I make things which I sell. For many years I made a line of artistic metal furniture and candlesticks- knickknacks and paddywacks, and many of these featured plasma cut sheet parts. Nowadays, I do large sculptures, ornamental iron, and seating, as well as parts of buildings.
But there are people in my area who make a living plasma cutting parts for others. Most do not use little home shop size machines- if you are actually producing parts for money, you need to be able to do most jobs, which means a big machine, as you can always cut small parts on a big machine, but not vise-versa.
Around here, there are a lot of boatbuilders, building commercial and pleasure craft, and many of the fishing boats are built from aluminum. There are a couple of places that specialise in plasma cutting parts for these boatbuilders. It seems that plasma can come in cheaper than waterjet or laser, given the tolerances that boatbuilders require.
I have had parts cut by one of these businesses once, when I needed several hundred large aluminum parts- I chose not to cut them myself, even though my machine could have done it, because of the noxious white smoke that aluminum puts out, and the sheer scale of the job. The company I hired did only plasma cutting- but their machine could take a 10'x40' sheet, and had multiple heads, so it could cut several identical parts at the same time. It used a water table where the metal was held about a half an inch below the surface of the water. It was very fast. A good deal for me, as they cut my parts, which were each about 1' x 8', in about a day, and it would have taken me at least a week.
Market niche in any metalworking business is a tricky thing- I have been doing what I do for 30 years or so, and have a reputation built up so I can get work. Hard to say whether you could make money with a 4'x8' plasma machine- maybe, maybe not.

I've been lurking on this board for a while now and just registered to post. I HAVE to jump in here in regards to the water table. You *CANNOT* run a plasma torch UNDER water unless it is specifically designed by the manufacturer to do so!!!!

Chances are you will not even find a plasma cutter that will do this for under $12,000 (plasma unit & torch only). I run a ShopBot 5X8 machine with a Hypertherm 1250 G3. I made a water table, 8" deep (6" water line) that goes directly under the grid. Hypertherm recommended that the water level be between 6 and 7" below the top of the grid to avoid getting water in the torch...and to minimize the amount that splashes onto the workpiece when a part falls into the drink.

The basic watertable that I made reduced the smoke by about 75%. I originally made a downdraft system...but it did nothing to condense the smoke, so it just bellowed out of my shop with force!

I hope this info helps...I'd hate for someone to get the wrong idea and either get hurt or waste their torch.

On a side note, you can get a water table manual from Hypertherm by calling them if you have a HT torch.

-Brady

I agree with Brady about running a torch under water- the only ones I have seen that do this are designed to do it, and cost over 10 grand.
But I have never had a problem with my machine running just above water level- say 1/2" or so. Yes some water splashes up, but it has never affected my torch adversely. I have a Thermal Dynamics machine torch on this machine, which is a straight cylindrical torch with no trigger- it is designed to be turned on and off remotely, and it comes with an integral rack that fits right into the z axis motorised torch holder on my C &G machine. There are no parts accesible that can be damaged by water, the electrical connections are up behind a screw connection that is sealed with an o ring, and while I would not immerse the torch in water, the occasional spray thrown up by the air pressure has never been a problem. So I would absolutely recommend building a water table. How much you fill it up is up to you- if Hypertherm recommends against torch ever getting wet, maybe you need to be more careful, but it hasnt been a problem with my TD torch.

We have a Thermal Dynamics machine and are cutting alot of 3/16 plate but the smoke is terrible...so I hooked up the water to the secondary supply (as per. manual) and the smoke was completely eliminated. I tried filling the slag bins with water but the water was 6" below the steel (not much difference in smoke) used fans and even an air hog. The problem with water is we have to cut from 130ipm to 86ipm and sometimes the cut is not all the way through. I will now try to combine compressed air and water (mist) through the secondary supply. [B]Note: you can not have water through the primary supply, it will damage the torch head. I don't mind some smoke but hate joined parts.

I'll chip in and allow that my Hypertherm 1650 G3 operates about 0.5" below water level and has no problems.

Level with the water works too, the noise surpression is a big plus.

My table is built out of .125" material and 24" in height.

Imagine a box within a box.... airtight of course, the inside box raised one inch from the bottom. The inside box is sloped for quick water run-off.

Weld two couplings on the upper side. The first is the inlet for compressed air. The second is for the dump valve. a third is a 2" drain on the bottom. Use a gate valve and no PVC ball.... dross and the grit don't mix!

I have a three inch fall on my 10' table. I use 3" slats 3" o.c.

Set the tank on a frame.... leveling screws, proper bracing etc, and you'll have an excellent system. Size your internal bracing for the load your table will carry.

I treat the water with Plasma Quench from Koal Industries. Green in color and it prevents or rather slows tank rust-out. Likewise I have friends who run nothing but water in there system :rolleyes:

Luck,

Tom

Hello,
I am running a Hypertherm Max 100 over a water table. With the water 1/4 to 1/2 inch below the material being cut and if the material is 3/8 or less you can reach in and remove the cut parts off the table bare handed and they will barley be warm to the touch. I have noticed no reduction in cut speeds or consumable life even though quite a bit of water is blown up on the outside of the torch body. Sheet warpage is reduced to maybee 10% of what it is when the cutting with the water level too low. I get no visible smoke running the water level at around 1/4 inch below the material even if I forget to turn on the fan for the hood over the table. If the table is made of iron you will eventually need to provide a separate ground to the material due to rust and crud build up to keep cut quality good.
Arlen

Something I forgot to add that is important if you cut lots of aluminium, cutting aluminium releases hydrogen gas that will collect in large bubbles in the water and go pop with considerable vigor (can be very hard on your nerves and attire) unless you have a air bubbler system to break up the hydrogen bubbles.
Arlen

Gentlemen,

Just an small adder here on the usefulness of water tables. A customer of ours in Oregon was making weathervanes!! He used very thin SS and had a problem with the material warping. The solution was to have the water just barely cover the stainless when it was lying on the cutting table. When the torch started, the airflow out of the torch tip pushed the water away just in the vicinity of the tip. When the cut proceeded, the water carried away all the heat and there was NO WARPING. The water didn't diminish the cut quality in any way.

Regards,
Jack C.

Interesting subject, sorry I've missed most of this thread.

I'm in the process of designing a cnc plasma cutting system based on my Miller Spectrum 375 plasma cutter.

When I built my new workbenches in my garage, I deliberately built a cabinet without a top, which the cutting system will actually *be* the top. The Miller plasma cutter will sit on the workbench right behind it.

http://frederic.midimonkey.com/yard/garage/IM001765.JPG

Anyway, since the Miller 375 at it's maximum setting can make long flame "tails" for lack of a better description, cutting indoors worried me. So, like you, I've considered different methods of containing the "fire" to avoid burning down my garage shop.

What I'm gong to be doing, is building a "sink" that fits inside the the frame of the cabinet, out of 1/4" mild steel plate welded together. On top there will be a 1.5" lip that rests on the top of the cabinet frame, and the depth of this "sink" will be four inches. About 1/2" below the top of the "sink", will be metal slates that go across the width of the cabinet (the short distance in the picture) with about 1/2" between each. Below that will be about 2" deep of water inside the sink. Using some small peices of scrap 1/4" plate I made a 8"x8"x4" bucket, put 2" of water in it, and cut a piece of 18ga steel over that with the plasma cutter, and the fire from the torch seemed well contained and the slag dropped into the water and didn't spray all over the place. Waving the plasma cutter around without material to cut, resulted in water splashing which is something to think about as well. If CNC controlled, one can avoid having the torch flying around off the end of the work for long periods of time either through movement or by turning the flame off via whatever electronics you will be using to control torch on/off function.

I'm just starting to figure out a better X-Y mechanism for a plasma cutting gantry system, as my original design (which I built, and didn't like: http://frederic.midimonkey.com/cnc-gantry.html) worked okay however the machine holds itself together by gravity, and I found if the plasma cutter's hoses twisted or bound up, the sliding dolly's could be pulled off the tracks easily enough and the CNC software would be unaware, and I could become injured, start a fire, and so on.

So I'm going to recycle the software, electronics, steppers and make a much smaller, more manageable system, on the top of that open cabinet in the above picture, with the water "sink" (really a tray) underneath.

Hope that helps you out.

I'm just starting to figure out a better X-Y mechanism for a plasma cutting gantry system, as my original design.
Your original design looked very promising.
Version #2 should be fantastic! Please video it as well.
Tnx. WT :)

Your original design looked very promising.
Version #2 should be fantastic! Please video it as well.
Tnx. WT :)

Thank you!

The link to the second version doesn't work if I post the link directly, so please excuse the following instructions:

My main website: http://frederic.midimonkey.com/_index.html

Click "yard & tools", and the menu replaces itself.
Click "CNC Gantry II" about 1/3 down the menu, and it replaces itself again with the CNC Gantry II project menu, and you can select what you want to see from there.

Note it's a work in progress, and most of the pages don't seem complete yet, because I either haven't finished that part of the project, or I haven't downloaded the pictures out of the camera yet.

Hope it's helpful.

Finally found the pdf I read initially to get some ideas about plasma cutting over, or underwater.

http://frederic.midimonkey.com/temp/PlasmaWaterTable.pdf

Hope that helps.

Anyone have pics of a water setup that they have come up with or seen?

Enjoy watching the progess on your setup Midiguy72, keep up the good work with postings.

You can take a look at my thread "4 x 8 Plasma Table" as I have some photos of the one I am completing for my table. You can use mild steel to build one, I chose to make it last and made it out of stainless. Althought the slats will still be mild steel as they are consumables and will be flipped and eventually replaced.

Anyone have pics of a water setup that they have come up with or seen?

I will in approximately a month.... I'm still building the machine itself.

http://frederic.midimonkey.com/cnc-gantry2.html

Enjoy watching the progess on your setup Midiguy72, keep up the good work with postings.

You can take a look at my thread "4 x 8 Plasma Table" as I have some photos of the one I am completing for my table. You can use mild steel to build one, I chose to make it last and made it out of stainless. Althought the slats will still be mild steel as they are consumables and will be flipped and eventually replaced.

Andrew:

Must be nice having space in your shop :D I struggled to find 2'x3' to embed my little machine.

And thanks for the feedback... that page has gotten more hits in the last few months than every other page on my website combined in the last year. I'm glad it's being hit so much too, as I've gotten a lot of feedback in all directions that has helped me out a ton.

What size steppers did you use BTW?

Wow, that's an impressive setup. Do you guys think that we could just build a platform / frame that is raised to the bottom of our PCNC table then simply make a 5-6" deep tank that sits right under?... Or howabout someone who has done a tank setup with a PCNC macine? The table sits about 3' in the air and don't really want to chop down the legs or anything like that, I like my back just the way it is :)

Dont know if the constant is wright but 8.5 # per gallon of watX16 =136Oz. /8Qt's in a gal. = 17oz. I want to know can tempored glass be cut with a waterjet without it exploding into so many ice cube's wonder about simotanious 3 axis on a water jet to acomadate the arc of most car window glass. Johnuk that's some plasma 150mm= 5.9" must lose a lot my 75amp machine does .75" but is a air hog how many cfm of air to do max might be "cam" cubic acres per min or I think the uk might be hector's heard about a local iragation manf. that tig weld's at 300 amp's with 1/4" tung. on a flanged but weld would make a great tanning booth Great post Kevin

And it will fill up with nasty mud like slag stuff, which is one of the dirtiest substances on earth, when you have to clean it out. But all of that nasty stuff would otherwise be on your floor and in the air in your shop, so it is definitely worth building one.

How do you get rid of this stuff after cleaning the table. Is it toxic or covered by any regulations, will I be able to just fill my regular rubbish bin with it and say nothing to anyone?

This is a great thread. :)

How do you get rid of this stuff after cleaning the table. Is it toxic or covered by any regulations, will I be able to just fill my regular rubbish bin with it and say nothing to anyone?

This is a great thread. :)

I intend to shopvac the contents out, and dump into a rubbermaid container. When it's full, it's getting taken to one of the metal recycling places one town over. It will have more metal than slag, and I hope they like it. lol