Need input on my welding table design

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Looking to upgrade from my 3' x 5' welding table to something larger to allow setup of fence sections and longer stock.  I've settle on a 5' x 10' table.  I wanted a 3/4 inch top but for hot rolled plate my local supplier said it would cost me 1100.00 out the door.  1/2 inch was quoted at 750.00.  Does this sound right?   So I have decided on the 1/2 (will be checking prices around).My main question in regards to my design is with a 10' table, using 4" square stock for the legs (1/4 wall), and 4" flat bar (1/2 thick) for the horizontal support, and 1/2 inch plate for the top do I have enough support?  There is an 8' 10" span between the legs.  Do I need another pair of legs in the center?  I would rather keep the span as designed if I can.  Input and thoughts?  Thanks!
Reply:really nice table, sounds expensive for the steel, maybe two pieces would be cheaper? not sure though. really jealous, good luck
Reply:I thought it sounded a little high as well, but to be honest I don't buy a lot of plate steel to know.  I am looking forward to having it done!
Reply:to answer the question about the legs and the span  it is necessary to know the load that will be on the table. should be good for fences unless you are restraining elephants. using 4 x 1/2 flat stock for the "beams" may not be the best choice -might need something stiffer-depending on the answer and your  desire to stay with  4 legs..for the money u are gonna spend i think you need to get it right.
Reply:I have a 2.5 ' x 4.5 ' x 1/2' table top, and it was around $140 - $180 (don't remember the exact amount).The Lord has declared, "This is my work and my glory--to bring to pass the immortality and eternal life of man"  Moses 1:39Link: My name is John, and I am a member of The Church of Jesus Christ of Latter-Day Saints.-- ColdCreekWorks.com --
Reply:Weldbead, thanks for the response.  I wholeheartedly agree that with this investment it's do it right the first time, hence the post. To answer your question about load on the table.  Honestly, I don't know.  Mostly fence and gate setup... So 300-400 pounds spread out over the table?  I know I won't be throwing a big block chevy in the middle of the table, but I don't want to have to baby this thing either.  My desire for the 4 open legs (no lower horizontal supports) is cleanliness.  My 3' x 5' has open legs and it's easier to clean up or roll something under.  Thanks again for the input.
Reply:Originally Posted by jdh239I have a 2.5 ' x 4.5 ' x 1/2' table top, and it was around $140 - $180 (don't remember the exact amount).
Reply:not saying the 4x1/2 will fail, but it would probably be more appropriate to use c channel..in a steel book i dont think you will find flat bar rated in that plane, i could be wrong, but you dont see flat bar used as a beam very often....
Reply:One thing to consider is that your clamp slot pattern is just about cutting the top plate in half. Some stiffness lost there. How about 2 center legs?
Reply:I have a similar built table with 3 1/2" square 1/4 wall tubing. It was built using what I hand. The frame is an old warehouse rack and the top is a 1x1 skeleton with 1/8" plate cover.The top is of mine only adequate. I think 3/8 or 1/2 would be fine though. I added an outlet in the frame but to date have never used it. An extension cord is always pretty handy. As far as the frame it is definitely strong and stable enough. i've gotten pretty medieval with it a few times and it didn't budge. Mine has casters on one end but they are kind of an inside joke beacause it pretty much takes a Kenworth to move the darn thing in my shop which has rough flooring. I have some videos on YouTube showing the bench if you'd care to take a look.AlA man is judged by what's between his legs...always ride a good horseMiller DialArc HFLincoln Classic 300DThermal Arc 181iPowermax 45Scotchman Ironworker(2) BridgeportsOkomota Surface GrinderAutoCAD 2010
Reply:Originally Posted by Sputter FizzleOne thing to consider is that your clamp slot pattern is just about cutting the top plate in half. Some stiffness lost there. How about 2 center legs?
Reply:Originally Posted by weldbeadnot saying the 4x1/2 will fail, but it would probably be more appropriate to use c channel..in a steel book i dont think you will find flat bar rated in that plane, i could be wrong, but you dont see flat bar used as a beam very often....
Reply:Originally Posted by jbyrdLooking to upgrade from my 3' x 5' welding table to something larger to allow setup of fence sections and longer stock.  I've settle on a 5' x 10' table.  I wanted a 3/4 inch top but for hot rolled plate my local supplier said it would cost me 1100.00 out the door.  1/2 inch was quoted at 750.00.  Does this sound right?   So I have decided on the 1/2 (will be checking prices around).
Reply:I'm just a hobbyist, so take this with a grain of salt.  But I would think the main consideration with sag is going to be the weight of the table itself, not so much the load of a fence section.  I'll also throw out the idea that a piece of plate might not be ideal for fence work.  It limits your clamping options.  Why not make the top out of staggered pieces -- like 2" wide strips of plate -- with an inch gap between each one so that clamping is always easy?  You could also make the top out of parallel lengths of 2" square tubing in the same fashion.  But again, it depends on what type of fence patterns you're going to be using, and what you like to do in terms of a jig.It's probably more imortant to have a flat top than a thick one.  Not a lot of pounding involved in most fence work.Jack OlsenMy garage website
Reply:I am new here but not to welding. What I did with my table top was had the place that I bought it from break it 2 times long ways at 90 degrees 1 break up at the rear of the table top and 1 break down at the front of the table top about 3 to 4 inches each break. This not only adds lots of stength to your table it  also saves your cloths and belly  from rubbing on the front of the table on the sharp thin edge. I did mine this way about 15 years ago and it has remained perfectly flat and level without any center supports or frame work. I am thinking it was only 20 dollors extra for the 2 breaks well worth it to have it done at any cost. The break at the rear is also  a great place to hang clamps etc. and you can also clamp to the up or down break for auto 90 degree angle. I hope this may help.                                                                                                                                                                                                                                                                            maxLast edited by max built; 11-16-2010 at 04:07 PM.
Reply:I'd swap the flat bar joists for a channel or better yet a rectangle tube. And I'd also go taller for stiffness sake. A 2x6x.120 rectangle tube is slightly lighter than the 4x.5 flat bar and over three times stiffer. Here is a link to a moment of inertia calculator for rectangle tube:http://www.engineersedge.com/calcula...re_case_10.htmFool around with the numbers to try to get the highest possible MOI, since the MOI is engineer speak for resistance to bending, you can set the inside dimensions to zero to see what solid flat bar will do.here's a chart for channel sections, for MOI look under the "Ixx" column: http://www.engineersedge.com/standar...properties.htmLast edited by fortyonethirty; 11-16-2010 at 05:19 PM.Ian TannerKawasaki KX450 and many other fine tools
Reply:@fortyonethirty:Z, or section modulus, is what you are most interested in, as the MOI is only part of the picture.  So the previous comparison of 2x6 hss and 4 x 1/2 flat bar is only 2 times as stiff, not 3 times.XMT 350 MPA Dynasty 280DXSuitcase 8RC / OptimaSpoolmatic 30AThermco Ar / C02 mixerAssorted O/A gear
Reply:Lots of great information here guys!  Very happy with everyone's input. Drinking it all in and will revise my design accordingly.
Reply:BCRD, I disagree. According to the www.engineersedge.com website the calculation of deflection of a beam does not include the term Z (section modulus). It seems to me that section modulus has more to do with the ultimate load that the beam will support. If the OP plans to put an object on his table that might make a 2x6x.120 steel tube break, then he needs more qualified help than a web forum. Last edited by fortyonethirty; 11-16-2010 at 07:34 PM.Ian TannerKawasaki KX450 and many other fine tools
Reply:I priced a 12'x5'x1/2"  for a table top last week for $565.83 in okc, ok. I saw a post for a table on here, looks like the best table I have seen. Here is the link http://weldingweb.com/vbb/showthread.php?t=26520I have also sent a message to the man who posted it asking if he would change anything now if he had to build it again...but no reply yetTravis
Reply:Last time I bought 1/2 plate it was around $0.50 per pound.  I think 1/2" plate is about 20lbs per square foot.12' x 5' * 20lbs * $0.50 = $600.  So that's right in line with what lik2waterski said.  I'm near Dallas, Tx so probably not too much price difference up in okc.Dynasty200DX w/coolmate1MM210MM VintageESAB miniarc161ltsLincoln AC225Victor O/A, Smith AW1ACutmaster 81IR 2475N7.5FPRage3Jancy USA1019" SBAEAD-200LE
Reply:jbyrd, I think the boys are getting a bit carried away with this. Just have a look at the $ of 2x6 tube and, once someone resuscitates you, you can save the $ and be happy with less. Unless you are building a bulldozer on the thing, 3/8 x 2" is probably plenty of the top frame. You don't need to go nuts welding the top top the top frame either. My top sections are 1" x 9 1/4" x 48" and I just did a 3/4" weld at each end. Enough to hold it in place and not so much to cause a warp. If you do a solid plate top, 4 1" welds will probably be tons. My four table legs are 1/4" x 3.5" x 3.5" angle, no braces, just welded to the top frame. Top frame is 1/4" x 3" x 3" angle. Three lengths, lengthwise and one length at each end. I think I made the top frame 40" x 8'. I got my materials for robbery cheap. They were off the books fook-ups Big outfit messed up the measurements and didn't realize until after my supplier had cut all 40+ of the 1" plates. They paid for them, then reordered the right size and paid again...... must be nice to be dumb and rich......  My supplier just wanted someone to get them out of his way. My top plates were $20/ pc!!! Uh, yes please!!!!!!! Glad to help them out!!!!!200amp Air Liquide MIG, Hypertherm Plasma, Harris torches, Optrel helmet, Makita angle grinders, Pre-China Delta chop saw and belt sander, Miller leathers, shop made jigs etc, North- welders backpack.
Reply:I use my 4'x8' table for building fence but to be honest with you a seperate fence jig is a much more capable set up also your table top will require much less grinding of spatter and tacks. I made a jig with 3" legs, 3" rails and crossbars, then bolted different picket spacers to the top. I evenly spaced bars for where the rails of the fence would land and also the picket jigs. welded stops on one end so that the rails would be evenly spaced every single panel.