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CNC Plasma guys! water table question for ya....

3K views 13 replies 10 participants last post by  jetboy 
#1 ·
I folded up a water table pan last night and got it installed. Started thinking about rusting. What coating to use to limit rusting? gotta handle scraping the crap out of the bottom and potential hot droppings.

Or am I just being a worrywart dumbass. Is this even an issue, ie it will rust slowly and when it does start pinholeing, just make a new one?
 
#3 ·
Unless you are cutting under water, I wouldn't worry about it. I think no matter what you do, it will at some point give out. The tubs I have seen are .250 thick. I am guessing you used 16ga or lighter. Maybe a marine paint, I am just throwing darts.
 
#4 ·
5150Creations said:
wait school me on this pan. so you just made a sheet metal pan that holds probally like 2" deep water that goes right under where you are cutting to catch all the hot sparks??

damn you guys are smart. learn something new everyday
yeah, basically catches the hot stuff and most of the dust and smoke. Cuts down on the mess and hazardous air. Still hafta put a drain and valve on it to empty the water when it needs cleaning. Just trying to think ahead to save effort later. Didn't know if spending time trying to seal up the box from rust would even help at all or just waste time and money. Just looking for what others have done.
 
#6 ·
I made one last year out of 14g and about 5 or 6 inches tall (filled an inch or so from the top). I didnt coat mine and there is no rust really yet but it will fill up with scrap and debris quickly. Mine has actually burned up all the water and I will not be using it any more once I move into my new shop. It really only helped with the sparks. Thats it. The smoke is just as bad and now its a pain in the ass to get the small parts out of the water. I am very disappointed with it. I'm going to build a vaccum encloser around it and push the air/smoke/fumes outside through ducting. Basically just box in the bottom around the legs and use a exhaust fan or squirle (sp) cage fan to pull/push it out. If you get a good enough one (cfm) it will vaccum it all out and the sparks are still contained within the skirting. I'll place a piece of mesh under the grate to catch parts and the skirting will be easily removable. Even with a full sheet on the table there is enough space around it to pull in fresh air creating the vaccum. Hopefully this works better. I'll post back when I get it done.
 
#7 · (Edited)
My father built one that has a 18" basin for water and a grate that consists of a bunch of lengths of 1/8"x2" flat bar that sit on end in slots with about 3" spacing. they all run parallel. they are removeable and replaceable as needed and it's easy because they all just slide into slots. this big grate is then set up with four cyliders on a hydrolic system so it can be raised or lowered withing the water to compensate for cleaning as well as the thickness of the material and the current depth of the water. The material is then set on the grate, and cut while sitting partialy submerged. this way there is almost no smoke. nice set up. the table is about 9' x 12' so it can accomidate three 4x8 sheets or up to 8x12 sheet. it can also be raised out of the water for cutting with gas (his plas will only cut about 1" without deflection) I don't have a pic, but I could get him to send me one or make a diagram if anyone is interested.

I know this didn't exactly answer the ? but the idea works well, i'm sure there are others like it. The depth of the water will cool anything before it hits the bottom so the paint won't melt, but it's just painted with some red primer and a coat of cheap industrial paint. the walls are .250 so I don't think it will rust through in my lifetime.

Good luck
 
#8 ·
I wouldn't do one. I thought about it, but just use a grate and sweep the debris. All it does is arrest the spark anyway. If I ever build / buy a cnc (never) I will do a hood. the suspended metal dust/smoke is the real issue imho.

j
 
#9 ·
Yes, the smoke/dust IS the problem. My garage is COVERED in a fine, black plasma dust. It sucks. The hood works too but you have to have some real, real good suction because a lot of it escapes out around the sides before it gets caught in the vaccum. I know a guy who built one just to re-do it and put it on the bottom. The smoke blows down (due to the compressed air through the cutter) and then it billows down and outward. Thats why I feel the bottom or downdraft method works better.
 
#10 · (Edited)
Bruce T said:
Yes, the smoke/dust IS the problem. My garage is COVERED in a fine, black plasma dust. It sucks. The hood works too but you have to have some real, real good suction because a lot of it escapes out around the sides before it gets caught in the vaccum. I know a guy who built one just to re-do it and put it on the bottom. The smoke blows down (due to the compressed air through the cutter) and then it billows down and outward. Thats why I feel the bottom or downdraft method works better.
we run a down draft table for our cnc...and it sucks bad..we will be converting over to a water table in the next few months...not only will it cut back on the dust (if built correctly) it will cut on energy costs so we dont have to have a 50hp motor running all day for the dust collector..the biggest thing about a water table...need to make it so you can adjust the water level...when cutting the steel should be just touching or slightly under the water....
 
#11 ·
I used to work for a large HVAC company. All of their duct fittings were cut out on a CNC plasma table about 5'x10' equipped with a down draft exhaust. There was NEVER any smoke or dust that escaped the table. The key to making this work well is to make sure that the entire table is covered. If there are large gaps around the edges of the piece you are cutting on, the air will be sucked in through them rather than the smaller are left by your cuts.
 
#12 ·
I wouldnt bother painting it. if your using it alot, anything under the cutting will need replaceing before it will rust. just make it simple and easy to replace. work has a downdraft table that works really good. its baffled into three sections, with switches on the rails and air-actuated valves. allows the fan can be much smaller than it would otherwise. If you not nesting full sheets, or if you tweek the cut order you could probably do manual valves.

Ben
 
#13 ·
Chaz- your right, if the material could be touching the water it would help a lot. BUT on a Plasmacam that isnt possible. The main framework is made out of about 4x4 angle and the grating (about another 4" ) sits on top of that (the flat part, not the upright side) so the closest you can get to the water is about 5 or 6 inches away. Maybe that is why it doesnt work for me and others that have tried a watertable under a Plasmcam. In my new shop I will go with a downdraft from below and with all the sides closed in and that part of the shop will also be closed off with retractable welding curtain (think giant shower curtain) to minimize what does get out. The shop I'm in now is just too small to do it now. Also the motor for the suction will be fairly small (no 50hp!) and onlt turned on when I'm cutting so I dont think electricity will be a problem.
 
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