workbench overkill?

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So my first big project is going to be a large workbench.The top will be 96” x 28” x 4” solid maple. Additionally the top will have two 2” x ¼” angle sections (red) recessed and lag bolted into it. The legs (blue) will be 2 ½” x ¼” square tubes. The cross bracing (blue & yellow) will be 2” x ¼” angle. The diagonals (green) will be 1” x 1/8” flat.The cross bracing and diagonals along the back of the bench will be bolt-on so if I move the bench can be disassembledI have been flipping through the MSC catalog and it lists several benches made of 14 gauge steel with load capacities of 3500 to 4000 pounds. They are shorter than my design, but not nearly as thick, and have no diagonal bracing.http://www1.mscdirect.com/CGI/NNPDFF...2311&PMCTLG=00So lets say I want a load capacity of 2000 pounds do I really need to use ¼” thick steel?
Reply:I really like your design.. No you don't need to use 1/4 " material.. 1/8" should be sufficient...
Reply:Originally Posted by dan sSo my first big project is going to be a large workbench.The top will be 96” x 28” x 4” solid maple. Additionally the top will have two 2” x ¼” angle sections (red) recessed and lag bolted into it. The legs (blue) will be 2 ½” x ¼” square tubes. The cross bracing (blue & yellow) will be 2” x ¼” angle. The diagonals (green) will be 1” x 1/8” flat.
Reply:Here is what I did.I manage a lumber yard, and once in a while we get left over beams.We had a 3 1/8" x 24" Glu Lam beam that was 16' long.  It had set in the yard for almost 2 years.Well, somehow, it got cut into a 7' and 9' piece, and loaded in my truck.  Still havn't figured that one out.The 7' got mounted on a cabinet against the wall of my tool room, and the 9' piece is mounted on a rolling frame with 1" threaded landing gear to stabilize it.I have since put a shelf under it with 3/4" expanded to hold tools and such.On the far end you can see a 20" long chunk of rail road track that I use as one of my anvils.
Reply:looks good!   One more piece in the center at the bottom would help a lot in strength, two and you can have a shelf to load crap onto. Me!
Reply:as far as if you NEED it or not, the answer would be a NO. however, would it hurt much? once again, the answer is NO. as long as you can afford it, get it. at cost, a 2x2x1/4" angle stock length (20' long) is only about $30-$35. i'm sure your 2x2x1/8" is less. as far as the over-all design goes, it looks good and stable. in order to cut down on costs, you can eliminate the red angle pieces since your 4" thick top will be able to support those legs just as well, if not better than those angles. also, you can cut down the number of cross-bracing by half if you would like. as long as there is at least one diagonal running in each of the "holes" that you are showing (each side and in back), you should be fine. they won't really do much anyway unless you have a lateral stress on the shelf. with the 2x2 square legs and the 4" thick top, the cross bracing will be the weakest point on the table during a side-impact. i would not use much less than 1.5x1/4" flat stock tho. anything thinner would probably bend/warp pretty easily under stress. about the only thing that could break the table would be something about the size of a riding lawn mower or larger, in which case, if it were me, i would want the table to break before the mower, tiller, or truck got a dent in it, or worse. keep the lower cross-beams tho (blue and yellow). they will help keep the bottoms of the legs where you want them when you go to move the table (intentionally). without them, you run the risk of bending the legs out if they get caught on anything during transport across the shop. without sitting down and running the numbers, i would be willing to bet that you could fairly easily meet your 1-ton capacity goal with a fairly good safety factor. if you wanted to be extra safe, you may want to throw in one extra leg in the middle of the back. i would also reccomend dropping in an extra leg in the front, to keep everything symetrical and even. the front center leg would not really need the cross-beams or bracing as it would only be subjected to vertical loads. after all is said and done, it seems like a good work bench. may i suggest you try to incorporate some sort of leveling device? between human error during the floor construction, building code requiring some sort of drainage plan, and the simple fact that it would give you a little more play-room when cutting the length of the legs (so they don't have to be EXACTLY the same length), there is a very good chance that you will need some way of keeping this table from wobbling, and after putting this much time and effort into it, i doubt you would want to shim it every time you needed to move it somewhere.good luck and keep us posted!Later,Andy
Reply:Originally Posted by wizard691.I doubt you will need the two recessed red angle irons.   The problem is that they won't match the expansion rate of the table and the environmental reactions of the wood.
Reply:Originally Posted by aczeller1.5x1/4" flat stock tho. anything thinner would probably bend/warp pretty easily under stress.
Reply:Originally Posted by dan sThe Bench will have a metal lathe on it and the large mass of wood will provide excellent vibration dampening. The only things that would be better would be lead, concrete or marble.
Reply:A lot of time frittered away on this topic---and nobody's bothered to consider the loading that's apparently intended by the designer. It's now revealed that the loading will be asymmetrical.......Okay, now--where do you guesstimate the loading to be placed on the length?1- approx. location of headstock centered weight?2-approx. location of the end of the tailstock?3-what is the total weight and o/a length of the lathe?4-Can it be presumed (for some common sense reasons) that you wish the steel topped table to remain F-L-A-T....during its use?5-Are the tube legs resting on the floor? or casters? or leveling pads?I have been flipping through the MSC catalog and it lists several benches made of 14 gauge steel with load capacities of 3500 to 4000 pounds. They are shorter than my design, but not nearly as thick, and have no diagonal bracing.      Any and all table mfr's. love to give and impressively wrong and high, theoretical value of an exactly uniform load, very carefully placed on a theoretically perfect, assembled table. Use MSC's stated values--above with a ton of salt. Those jive MSC #'s are not any indication of values to use in your table's engineering--or anybody else's!So lets say I want a load capacity of 2000 pounds do I really need to use ¼” thick steel?     .....16 ga., 1/8", 1/4', or 3/8" plate top over that wood is not going to stop deflection in the vertical direction....IOW----SAGGING--aggravated by your wish not to have a center or two center support legs.      Again a question for a structural engineer and an issue of what you expect life span wise. One thing I will say right away is that sheet metal leg assemblies don't take the abuse the way structural steel does. Since it isn't that much of an expense I'd stay with the structural steel.    The stout tubular legs with angle horizontals is okay. Don't mess with sheet metal for something as heavy and offset loaded as this. Additionally, there will be some dynamic loading on the entire assembly, during lathe operation.    Using 1/8 x 1 diagonal bolted bracing on the rear side--does not provide for multi-directional stiffness this assembly requires. Much stouter angle or bolted tube needed. These can bolt to 1/4" welded flat or angle tabs on your 2.5 x 2.5 legs. I can't say what the load limit would be but maybe somebody with an engineering back ground could chime in.      **chime**    Provide the answers to 1-5 above....and then---we look at beam loading chart to see what options you have.    Some size angle will need to be bolted to both leg sets, spanning under the wood deck, to support the wood deck and prevent excessive deflection....or worse! (Obviously, you can then bolt the wood deck to the horizontal angle beams of yet--unknown sizing.)   (this topic's a great case study in why 'design by committee', 'design by consensus', and 'shoot from the hip-design'..... just doesn't hack it.)Blackbird
Reply:I think it looks good.  1/4" is prob. a little overkill, but will be fine.  You could maybe try 3/16" if you can find it.  The angle iron for attaching the table top is fine, but I would put oval slots in the angle so the wood can float over the angle.  The wood will still move even if encapsulated.  Maple likes to move around.  Just put the slots running width wise with to the top and allow a 3/8" to 1/2" either way.  If it were me I would epoxy fine thread nuts into the underside of the tabletop so that I could use bolts to attach the top and not just lags.  Lags might strip out over time if you removed the top too many times.