Welding a bench of half inch plate...tips?

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Hey. I am going to make a bench six and a half foot long by two and a half foot wide. The bench top is going to be half inch steel plate welded to the frame. The frame is going to be some kind of tubing, I was think 2x3 because the person I'm building it for wants the fromt to look "beefy" I am wondering how long of a weld I can make on the plate before it begins to warp. I also would like your opinion on what size of rubin to use as the frame. Thanks
Reply:1/2 thich plate is pretty damn thick, and something that big will be like giant heat sink. I say weld away.
Reply:You gonna land an A380 on that puppy? I was going to do mine out of 3/8", even bought the material, then decided to switch it to 5/16", had my supplier bend down the front and bend up the back for me, came out nice. As mentioned, you will tire out your welder before warping that stuff, super heavy and can dissipate LOTS of heat.
Reply:I have a work table that is 3x8 with a half inch plate top. Started off making a frame of 3/8" 3"x3" angle. Put four braces inside the square frame with the same material. Legs are 8- 3" pipe with cap on one end with a nut welded in the center and a bolt threaded in to level the table. Two of the legs are in the center, spaced out equally. Made a 1/4"2"x2" frame with braces, that is welded to the legs one foot above the floor. Lined that frame with expanded metal. After all was welded together, placed the half inch plate on the top, leveled the table, and skip welded the underside to the angle iron frame.Turned out to be a great HEAVY work table, with small iron storage underneath. Hope this helps you.6"XX P5P8 6G
Reply:Originally Posted by JuddI am wondering how long of a weld I can make on the plate before it begins to warp. I also would like your opinion on what size of rubin to use as the frame. Thanks
Reply:No need for a continuous weld, skip weld, 4 inch bead every foot. Weld the corners and brace the mid-span with adjustable legs to eliminate sagging.
Reply:Originally Posted by transitNo need for a continuous weld, skip weld, 4 inch bead every foot. Weld the corners and brace the mid-span with adjustable legs to eliminate sagging.
Reply:As mentioned above it all depends on how you plan to weld it and how many amps you plan on using. I'm sure I could distort that top no problem using large dia. rods or wire with the amps cranked on the machine. On the other hand, run at low amps you could probably lay your hand on the top shortly after welding the plate to the tube with no issues, especially if you moved around and did short welds in various areas..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Judd, I see a conflict I believe no one has addressed. There is a potential mismatch welding ½” plate to the tubular frame. I don’t know what size tube you plain to use, welding ½” plate is going to take a good deal of heat, so much so that you will have burn through problems with the tubing.Limit the heat as not to burn through the tubing and you have low fusion into the ½” plate. That’s a narrow window.Would pre-heating the plate improve penetration and control distortion at the same time?PS, that plate will weigh about 225 pounds without the frame.
Reply:I would not weld it so much, if it was for me....Any heat, any weld,on any steel, will pull...That's just physics, there's nothing you can do about that except to limit its effects.The only way to do that is to not put so much weld on it....period.1" long welds, about 18" apart, is plenty..it will never come apart...If the customer wants all the seams welded, or at least closed up, see if you can use body putty...its getting painted anyway, so why not?If you weld 100% around the edges, its gonna look like a big, expensive, umbrella
Reply:I could be wrong, but if your going to grind it down smooth anyways, cant you just do the welds in sections? just make sure they meet...
Reply:Why did I think this was a "welding bench"?What TEK said.Last edited by tanglediver; 02-13-2010 at 03:20 AM.City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:i reckon you will get a fair bit of distortion from flame cutting a piece of 1/2 " plate to size, you might be able to use that bend from the oxy cut to your advantage  by putting the bow side down on the bench frame. that will help to counteract the pull of the weld as others have said there is a big difference between the 1/2" plate and the SHS you are welding to, so maybe concentrate your arc on the plate and just try to "wash" some of the puddle onto the SHS frame without burning into it.Last edited by stamp; 02-13-2010 at 05:47 AM.
Reply:Unless this thing is going to fly you really only need about 18 inches of weld total to hold the plate down to the frame.  All you will do is create problems if you weld any more.  Once the top surface of the plate gets spatter and grinding irregularities from five or ten years of use you simply grind out your 18 inches of tack welds, pop the plate off, turn it over and you have another five or ten years of use.  You only need enough weld to hold frame and top together.....  unless you are going to bolt the frame to a six inch thick concrete slab and will be lifting the table top off with a 30 ton crane.
Reply:Weld that thing continuous, as you're proposing, and you WILL warp the he11 out of it.  I don't care how many amps you use.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:With a 200+lb top all you need is enough weld to keep it from sliding on the frame if someone is really beating on it.  I would put a weld about 3" in each corner and call it a day. Completely welding the whole frame to the top is a disaster waiting to happen.If you cannot convince them, confuse them.         Harry S Truman
Reply:Are you planning to build it like this sample I drew up?  With no ledge, welding all around the outside will cause less distortion than trying to keep the top flat with a ledge.  I'm guessing this is what you are planning because it doesn't really make sense to grind down fillet welds under a ledge as they will almost never be seen.  No ledge with the joint ground smooth will also give the impression of a thicker top, 3.5" in this case.  Minimal welding on this inside just to keep it down.  Weld the frame first, and straighten it out if necessary, then add the top to it.  Weld approx 1-12 staggered everywhere, then go back and fill in the outside edges last.  Shouldn't be a big deal to hold it reasonably flat.    No ledge is key...Just noticed the dates on the posts...  ...already put in the effort to make the reply, so I'll go ahead and post it for collective knowledge... Attached Images