Water pan for CNC plasma question

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So I'm building a CNC plasma and the water tray is 10.5 ft by 5.5 ft, I have 2cross braces running under the middle to support weight. After calculating the volume of 21,870.75 inches cubed, it comes out to a total of aprox 94gal of water. (827.2 pounds) now there are open sections that are aprox 3.5 ft by 5 ft that need to support water weight of roughly 246 pounds. I wnt to go as cheap as posable on the steel that needs to make up the lower pan, but I don't wanna go too thin on the steel and have it sagging. The slats and meterial to be cut will be supported by the main framework, so the sheet only needs to hold water weight. I originally was planning on using 11guage, but do you thin I could support the weight of water (246 pounds) across the open space with 15 or 16 gauge? As I don't want to add any more weight and materials cost if I don't need to. I can get a 5X10 sheet of 11guage for $180 and I'm guessing I can get the 15 or 16 for just under $100 but if the thinner meterial will bow under the weight and put undue stress on the frame I'll go thicker. Let me hear your thoughts thanks a bunch.Offering CNC Plasma cutting and welding projects.Follow me on facebook https://www.facebook.com/nobigdeal.fabSupport those that support WW.
Reply:Mine is 54" x 109" x 5" deep and I went with the 11 gauge.  There was a slight amount of sag in the table so I built a frame out of 2 in channel and welded it to the sides, 1" off the bottom.  That way the slats don't follow the contour of the sag, it sort of just hangs from the sides all the way around.  It seems to have worked well and its dead flat.  I wouldn't go any lighter than the 11 ga, the price is so close that it doesn't matter anyway.  I paid $146 for the 11 ga and the 12 ga. was $127.  Hope that helps.
Reply:Was you table sagging because there was no support under the full span? I have two supports running through the center. My largest span is 38 in by 60in I thought about it and I think I'm going to add in some more supports so the largest span will be 20 by 36.Also my slat holders are 1/2 by 2in bar stock with angle welded to it to form a triangle. That will be above the crossbraceing, so the load will be on the grossbrace not the bottom on the pan.Offering CNC Plasma cutting and welding projects.Follow me on facebook https://www.facebook.com/nobigdeal.fabSupport those that support WW.
Reply:The largest span is about 44" x  47" plus or minus a bit.  The way your setting up the bracing sounds better plus, your slats are much heavier than mine so you might be all set....especially with adding the extra cross members.
Reply:Yeah I just got home from picking up the 16guage. It looks like it will work out just fine. I just wish I had a CNC plasma cutter, or a hand torch as it's about 1/4 inch too wide I thought about having it cut on a sheer, but the steel yard wanted $25 to do it. I'll have to set up a few slats and just cut it be moving my gantry by hand. It will cut close enough that way I already have a 1/16th gap On the 2 5th sides to fill as the sheet was 120 3/8 inch and my frame is 120 1/2 ooh well that's nothing to fill.Offering CNC Plasma cutting and welding projects.Follow me on facebook https://www.facebook.com/nobigdeal.fabSupport those that support WW.
Reply:Well in the past 12 hours I got the slat holders finished, the added supports welded in, went and got the 5X10 sheet, and welded it in. Time to fill it with water and see if I get any leaks.Offering CNC Plasma cutting and welding projects.Follow me on facebook https://www.facebook.com/nobigdeal.fabSupport those that support WW.
Reply:Got 2small leaks. Drained the table. Will weld it up tomorrow. After the pinholes dry well overnight, and most of the day.Offering CNC Plasma cutting and welding projects.Follow me on facebook https://www.facebook.com/nobigdeal.fabSupport those that support WW.
Reply:Take some pics for us visual guys! Jay DavisAWS-CWIC-60 Specialty Welding ContractorLoving husband, and father of two boys (
Reply:Originally Posted by jbyrdTake some pics for us visual guys!
Reply:Dumb questions:Why the water pan with the plasma tables? Why not just blow the debris onto the concrete floor then sweep it up at the end of the day?  (as has been done since the 19th century).Are there recommendations for minimum and maximum distance from table surface to water surface?How about water depth?Is there a benefit to having the steam, generated by hot debris falling into the water, rising up to the bottom of the work piece?-MondoMember, AWSLincoln ProMIG 140Lincoln AC TombstoneCraftsman Lathe 12 x 24 c1935Atlas MFC Horizontal MillCraftsman Commercial Lathe 12 x 36 c1970- - - I'll just keep on keepin' on.
Reply:The water tray eliminates aprox 99% of the dust and smoke. Making everything stay cleaner. The smoke is vaporized metal (not too good on the lungs, especially in a small 2car gerage) there is minamal effect on the cut meterial, As far as dross is concerned. With thinner sheet metal it keeps the steel cool minimizing warping. The deeper the water tray the harder it is to remove drops, but the sooner it fills with junk, so most people say 3-5 inches is about right. All I have read about stainless is it's best to cut it under water (with air plasma cutters) to minimize hardened dross and discoloration. And stainless is going to be a large part of what I do, as my day job involves repairing medical devices, and I plan on catering to the medical industry for replacement parts at a better price than oem replacements.The disadvantage to a water tray is the disposal of the water, as the steel needs to be separated and it can cause surface rust on parts. But since most parts are reworked or coated (powder coated, painted, or stained) this is a minor concern. My reply is not a definitive response, as I'm not up and running yet. This is just baised off of the reading I have done. I'm sure there are more experienced people that could better answer your questions.Offering CNC Plasma cutting and welding projects.Follow me on facebook https://www.facebook.com/nobigdeal.fabSupport those that support WW.