4' x3' x 3/8" steel plate from supplier came with 1/4" bow

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Hi all,Welding noob here.  Just setting myself up with a welder and a space to weld.First order of the day is a small work bench.I just ordered and collected a 4' x3' x 3/8" steel plate from my local supplier.  But when I got it home I noticed it had a 1/4" bow in 2 sides.Here it is in the back of my truck (and yes the bed of my truck is flat!!) I'm disappointed on a couple of levels.. not least is was a 30 mile round trip.  Its too late tonight to call them tonight.  They have all gone home.Anyway my question is this:  Should I be able to expect a flat sheet?  It needs to be flat as this is the top of my work bench!!I don't want to mess around trying to make it flat... Could do with some moral support for my conversation tomorrow.  Seems I stumbled at the first hurdle!Look forward to hearing from you.Thanks.
Reply:I won't say it should be warped, but it doesn't surprise me. I would build a flat frame, and make it flat when you attach it. Typical result from cutting. Unless you specified it flat, and they gave you warped...pretty normal stuff.
Reply:A good supplier should work with you unless it was a deal cause it was bent. I have bought stuff like that when flatness is not necessary. Did they cut it for you read it a drop they had laying aroundMillermatic 252millermatic 175miller 300 Thunderboltlincoln ranger 250smith torcheslots of bfh'sIf it dont fit get a bigger hammer
Reply:I'll add that when you weld, the metal shrinks, which causes distortion. Learning to mitigate the effects is all part of the deal.
Reply:Yeah it was cut specially for me in another branch.  Had to wait 3 days for it.  No special deal.
Reply:Do you mean there are bent spots or a gradual curve? Bent spots is one thing, and a curve may be natural. 3/8" is not necessarily going to be flat anyway. To ensure a flat sheet I'd say 5/8" is minimum, 3/4" and up is really where you might be able to trust it to be pretty flat. But you should not be relying on the sheet to be flat anyway. The frame for your table should be able to hold it down flat. On the other hand, did you tell them that it was intended for a table top and needed to be flat? Did they promise flat? When I built my table i made sure to tell the guys at the yard to pick out a nice one because it was going to be my table.If it will not work, ask the steel yard if they will exchange it for you. Explain your situation and ask nicely. I would guess they will change it out for you, with a return fee.Ian TannerKawasaki KX450 and many other fine tools
Reply:It bows gradually on 2 sides.Yes. I told them it was for a bench top but didn't know I could ask for it to be flat.I would expect some kind of bow but not 1/4" over 4 feet!!  Wooden studs from Homedepot can be straighter than that.... and that's saying something!Edit to say: I'll be mighty ****** if I get charged a return fee!!!!Last edited by 60Hz_Brit; 08-08-2012 at 09:06 PM.
Reply:I don't see anything wrong with this plate.
Reply:Weld up properly squared frame, force it flat with clamps, weld, done.
Reply:OK, thanks for the replies.  I'll man up and quit bitching about it.
Reply:Don't forget to show pics when yer done.-AaronJet 17.5" Drill Press1942 South Bend 16x84 Lathe1980s Miller 320A / BP --- 2013 Power Mig 2562012 Jet 7x12 Horizontal BandsawVictor O/A Setup
Reply:Your supplier has a crappy shear with dull cutters. Their fault, you pay. Welcome to the steel world.Tim Beeker.
Reply:60Hz Brit  -  This is an instance of a noob getting exactly what he asked for.  To the steel salesman you ordered a .375 x 3' x 4' piece of plate.  In steel salesworld, salesman are only concerned with the accuracy of the numbers, and tuneout whatever your project is.  Real steel yards sell to informed clients; a $200.00minimum, and deliver only [no will-call] is not uncommon.  This is keep out thenuisance trade.  Language is important.  Your piece was sheared, not cut.  One of the first realitieslearned in steel fabrication is shear curl.  In heavy fab its the norm, you just dogor clamp it down, because you have the tools to do it.For flat, your piece should have been: laser, plasma, or OA cut.  The price you paid for the plate was a sheared price.  Did sales offer any other "cutting" option?  A really experienced salesman would cue on the "table-top"info, and offer the other cutting options.  You weren't so lucky.You made an honest [uninformed] mistake, and because sales-staff is schooled, not to be part of your design team, you got the cheapest cut option.  Other realities:  The steel yard isn't going to take the piece back, and the extent of their 'working with you' is to accept an order for a new, properly cut piece.Don't attempt to flatten on your table frame.  It can only be flatten by dogging intosomething the is more ridged than the top itself.    Opus
Reply:If I needed a "flat" table and was forced to use the material in the photo........ I'd build my frame out of stout enough material to where I could pull the bow out of the plate.Just what tolerances are you working to with your table top?Thanks,HoboLincoln SA200's... at least 15 - 20. They come and go. Growing partial to the "Short Hoods" in my old age. Last count on Short Hoods was 13 in possession.
Reply:Thats what you get when its been cut on a shear. I just did a job that used 72 pcs of  3/8"  plate60" X 18"- had them cut on the high def plasma so we wouldnt have to fight the curl.
Reply:OpusFerro & HoboHilton.  Great input, and even better questions! Thanks for your time.OpusFerro: To be honest, a $200 minimum and no will call policy would have suited me so muuuuuch better.  These modest bench materials came to a shade under $500.  Would have saved me a couple of hours as well to have it delivered! But when I got there and after the willcall was done with, I couldn't believe the Aladdins cave of stuff they had in the front.  Various steel components, tabs of different shapes & sizes. Wheels, hinges. remnants. Tools, magnets. I was like a kid in a toy shop!Copy that. Language, Check.  I wasn't offered different methods of cutting.  I was (I thought) bantering away with the sales guy. I had everything worked out prior to the call and was honest from the get go:"Oh, hey. This is my first order so I need a little bit of slack. No, I don't have an account. What? No, I'm not from a company. I'm an individual.  I need this, this,this & this for a work bench... you'll look after me, right? Awesome.  See you in 3 days."I love learning new skills.  I wasn't quite prepared for the steepness of this learning curve!  It's all good.  But wow, there's more to it that I imagined!Trouble is I don't have anything flat and sturdy yet.  That's what I'm trying to achieve with this first step!HoboHilton:  Tolerances? Well, I was at least aiming for "looks good enough by eye using a straight edge".  Not aerospace quality.I'm taking my prompts from the Millerwelds website. They have a pdf you can download for a Weld table. I'm taking prompts but have basically halved the size of it for my space. They suggest 2" x 2" x 1/8" square tubing.  You reckon this will be strong enough to pull 1/4" out of a 4' x3' x 3/8" steel plate?Eric:  Ok. Lesson learned.  This is a great website for that. I did sooo much reading before I took the plunge. Just not quite enough it seems!!Last edited by 60Hz_Brit; 08-09-2012 at 02:13 AM.Reason: use of english
Reply:2x2x.120 will get some of the curl out, but not all. I'd suggest something like 2x4x.120. Also, the table frame should be built before the top is put on, the 3/8 top sheet should not be a structural piece, because, as you have noticed, you can't trust it to be flat. Once you've got the frame welded up, clamp the top on with the curl side up like a happy face. Once you've got it clamped where you want it, weld it to the table using small stitch welds, to avoid warping, starting in the center of the table and working out towards the edges.Last edited by fortyonethirty; 08-09-2012 at 11:52 AM.Ian TannerKawasaki KX450 and many other fine tools
Reply:So I got completely stone walled this morning.There are no options for other methods of cutting.  It is by shearing only and I can't specify "flat". Apparently.I was told: According to ASTM A36 it is in spec.  Later, I looked up A36.  I can't see how it relates to a cut sheet being bowed on a shear.Basically if I can prove it does not conform to A36 I might be able to change it out.He finished the phone call by saying "if there's anything else I can help with let me know".Class act.I was expecting not to be able to change it per the conversations above... but the guy was a complete *** hole.  There was no need for that.  Leaves a bad taste, you know?Last edited by 60Hz_Brit; 08-09-2012 at 11:53 AM.
Reply:here is a pic of the under side of one of the 3/8 table I have in my shop. 1/2 bolt pulls it down pretty easy. this top was sheared and the frame is 3x3x1/4 angle. Attached Images
Reply:The spec A36 has nothing to do with the shape, just the chemistry. 1/4" bow over four feet is not a big deal. In fact, for this application a slight curl can be helpful because it will hold the sheet down tight against the frame of your table while you weld it.Ian TannerKawasaki KX450 and many other fine tools
Reply:Originally Posted by Eric Chere is a pic of the under side of one of the 3/8 table I have in my shop. 1/2 bolt pulls it down pretty easy. this top was sheared and the frame is 3x3x1/4 angle.
Reply:Originally Posted by fortyonethirtyThe spec A36 has nothing to do with the shape, just the chemistry. 1/4" bow over four feet is not a big deal. In fact, for this application a slight curl can be helpful because it will hold the sheet down tight against the frame of your table while you weld it.
Reply:I like Eric's solution. You could also flame straighten it if you have access to a torch.
Reply:Yes. I like this solution as well.
Reply:60Hz Brit  -  Unfortunately your plate is within A-36 sheared spec.  On a platethis size, maximum Permissible Variation is 9/16".  If shearing is the only cutting option your supplier offers; you need to find anew supplier.  Every real steel yard at least has a track-torch.  OA is old-school,but a good operator can still produce a near laser quality cut.  The Intermountain West is relatively nowhere, but we have had a choice between, hi-def plasma, laser, or water jet for 10 to 15 years.For price and service comparison, I can have your plate hi-def plasma cut anddelivered tomorrow for $188.00.  If this were an emergency, I could have it today.I recommend that you talk to as many older welder-type craftsmen in your neighborhood as you can ferret out so you don't get burned again.    OpusOpus.  Thanks.  That's good to know.  I'm in Southern California.  $188 delivered is good value.  I paid $154.60 plus tax for this sheet. $166.58 total.I live near the ocean so there are loads of welding places around.  Some large, some small.  I might go for a walk one day and put some feelers out.
Reply:Originally Posted by 60Hz_BritYes. I like this solution as well.
Reply:Originally Posted by forhireAnother option would be to run a tube down the middle. Put the plate on the table bow down. Clamp one outer edge down, then clamp the other outer edge down. You'll need a bunch of clamps. Now the plate should be flat. Tack weld the center which will relieve some of the stress. Tack down the outer edges. Done.
Reply:60Hz Brit  -  When building a table the surface is the tool feature,and often the most ignored.Metal fabrication isn't welding, it's metal joinery.  Anything that aids fit-up is a big plus; it all starts with your table's surface.  Think of it, not just as a work place, but as your biggest tool.  If you are building a steel fab table from all new materials in this dayand age, the surface should be nothing less than: Cut, all 4 sides, by: Hi-Def plasma, laser, or water jet.  The life long reward is: a flat plane, square corners, straight and parallel edges.  These features make your table a tool.You can only have these life-long benefits if you build them in fromthe beginning.Don't turn the fabrication of your dream table into a marathon, serial repair nightmare.  Put your sheared plate in 'inventory' for futureprojects, and order a new proper-beginning.    Opus
Reply:I completely agree... and I'm kind of pissed at myself for falling for this one.  I wanted to take my time making a nice little bench for myself.  Not wrestling a sheet flat.I'm going to sleep on it and then maybe PM you tomorrow about your offer.  Thanks.
Reply:Good plan, while youre at it consider going with at least 1/2 inch materialMiller diversion 165Miller mig 211Hypertherm pm 30Milwaukee 6230 14 inch chop sawMd 45 mag drill (RIP; fell on its head)New MD 45! Thanks to the esposa!Finally got an O/A setup
Reply:Holy cow. Dude. It's a quarter inch on 4 feet. BFD.If it bothers you that damn much, get your stick welder and weld at high amperage a big "x" in the middle of the convex side, then take a garden hose with cold water and quench the opposite side.  If you do it right, the shrinkage of the welding will "pull" the plate back into a plane.Google "flame bending" for a better explanation.Keep checking flatness with a straight edge and lather/rinse/repeat until it's flat.Then grind off your beads to make the tabletop fair/smooth.Then attach your tabletop to your table ... and watch it pretzel up into a taco again due to shrinkage!
Reply:Originally Posted by KelvinBFD
Reply:BFD - big Effin dealSo, I might be crude and ignorant thinking this, but after reading the options I'd run it over with the truck.  Would that be useful in any way?Lincoln AC225 and CartLincoln WeldPak HD and CartOne hand
Reply:60Hz_Brit,build your table frame, using advice posted previously.  Place your 3/8" plate on the frame, so the edges are floating, and the plate is resting on the frame in the center. Set 2 Clamps in the center and tackweld near the clamps.  Then set 2 clamps on either side of your center tack welds.   4 clamps is the minimum I'd use, but if you have more set them in pairs every 6" outward from the center. Tack near each clamp.  Move clamps and tack as necessary. you should be able to pull the sheet flat.  Use screw=type c clamps; not vise grips or woodworkers sliding jaw clamps.  C clamps generally generate more clamping pressure, unless they're low quality crap.Once you're tack welded down, you could declare victory.  If you intend to use the top as a clamping surface to pull other objects flat, then you need to take one more step.  Carefully roll or flip your table upsidedown.  Make 4 fillet welds, 2 each long side, each about 1/3 along the length of the frame.  2" of fillet weld, a single pass, about 1/4"  wide will strongly attach the top to the frame.  You should see minimal distortion with just 4 welds.    Roll your table back upright, move to it's permanent home, and shim the 4 legs so it sits level and doesn't wobble.Declare victory and have a beer if that suits you...Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Originally Posted by MonicaBFD - big Effin dealSo, I might be crude and ignorant thinking this, but after reading the options I'd run it over with the truck.  Would that be useful in any way?
Reply:Originally Posted by MonicaBFD - big Effin dealSo, I might be crude and ignorant thinking this, but after reading the options I'd run it over with the truck.  Would that be useful in any way?
Reply:To be successful you need to bridge it. Non controlled will probably make things worseMillermatic 252millermatic 175miller 300 Thunderboltlincoln ranger 250smith torcheslots of bfh'sIf it dont fit get a bigger hammer
Reply:Originally Posted by farmshopTo be successful you need to bridge it. Non controlled will probably make things worse
Reply:A_DAB, I can *just about* move it by wedging myself between the sheet in the back of the truck and the top of may garage door frame (using all my strength).  I tried just to see how much it would move.  I might wedge it and have the Mrs. drive over it to see what happens in the name of science.Your advice is great... Thank you, but I'm also looking at getting another top cut properly on all 4 sides, possibly 1/2 inch as some one else here suggested.So, I might just practice on this sheet.  I just started out so I'm a bit green to say the least.I was thinking though.  I was going to go for 3 inch clearance all round for clamping.  It's going to be on wheels to pull out for various projects.Pretty much everything in my workshop is on wheels so I can re configure for what ever I'm doing.Is 3 inches too much?  2 inches perhaps?I see some people drill and tap all over their work top.  This appeals to me.  What does everyone think?  Pro's & cons?I was going to drill & tap for the vice bolts.  No reason why I shouldn't, right?Also I have been thinking about the wheels and maybe having bolts that I can wind down to level and take the wheels off the ground for when I'm working.Thoughts?
Reply:Originally Posted by 60Hz_BritYeah it was cut specially for me in another branch.  Had to wait 3 days for it.  No special deal.
Reply:Hi all, if you put the 3/8" plate on the floor and put two pieces of wood under the ends, then stood on the middle, assuming you weighed 80Kg, you would bend the plate back the other way......doesn't take too much force over 4 feet to bend a piece of plate, even 3/8" thick, but it'll spring back when you get off it, but it can be "persuaded" to lie flat and stay flat with a bit of clamping to a strong frame etc.So, make the table frame with a substantial sub frame round the edge, we used 100mm X 50mm 3mm wall square tubing, mitred corners and just welded the top to the frame with short welds and clamping it to keep it straight......never moved, and as flat as is "good enough".....you won't get it dead flat unless you have it machined and that is going from the sublime to the ridiculous for a welding table.BTW, you can warp the table by having it sit on an uneven floor, so have screw adjusters on the bottom of the legs and you can "dial" it flat by screwing the adjusters out to suit the floor, or just use packers under the legs tacked in place.....the table should not be moved anyway or you will get uneven top features from the floor levels if the sub-frame is not all that rigid.I would also add two cross spacers across the front and back to keep the sub frame as rigid as possible and this will keep the top relatively flat even if you move the table and it needs the legs adjusting to keep it from rocking.....if it rocks when moved it's rigid, if it doesn't it's flexing.Incidently, if you haven't got a decent straight edge....one can be made.......you are working in the dark and can't judge the flatness or truth of ANY work you do.If you can find out what a Camel back straight edge is and make one, then you'll have a method to guarantee 100% to anyone what flatness is all about, but you'll need to make three of them (and certify them) to make one true one.....you end up with two extras you can sell for profit.Without a straight edge of known quality, anything "flat" is anyone's guess.If you can move the table and it "adjusts" itself to the uneven floor (flexes) then you'll never have a level top without going to the trouble of packing the bottom of the legs each time you move it etc, and sometimes you want to move the table to the middle of the shop to suit the bigger jobs and allow you to move around it. Ian.
Reply:60Hz Brit  -  As suggested by E@y, 1/2" would be better  -  Opus