I want a 6 1/2 foot circles of metal. My options are stainless steel, steel, or aluminum.
What would the weights of these circles be for 1/8 and 1/4inch thicknesses?
If these are individually laid flat and only supported at 6 points evenly distributed around the outside edge(within an inch underneath) would they deflect under their own weight? No corrugation or other support methods could be used.
What size sheets do metal fabrication shops generally have available to them? Is 6.5 foot stock within the realm of possibility? Would it be more practical to seek out say 4 foot stock and weld it to get the needed 6.5?
That’s 33.2 square feet of metal.
1/4 thick steel weighs 10.21 lbs/sq foot, so it will weigh 340 lbs.
1/8 (if you can find it) will weigh half as much.
1/4” aluminum weighs about 3.7 lbs/sq. foot, so it will weigh 123 lbs.
You’ll have to go to a steel yard to find sheets wider than 4’, but they are available.
The standard thicknesses are just about everything. I can recommendMid-City Steelhere in New England. They can cut the circles for you. They have used steel for sale also at a lower cost, except you have to buy whole pieces. 1/8" steel is pretty strong, and heavy, and it will deform a little under it’s own weight in the situation you describe, but it won’t fold up or anything. You would be better off with aluminum weight-wise, but it will cost more (although aluminum prices have gone down lately, but it’s almost a day by day thing).
Yes, for all metals and all thicknesses, the unsupported center of your disk will sag out of plane, and the only question is how much.
The thinner your metal plate, the more it will sag; it weighs less than a thicker disk, but because it’s thinner it’s also less resistant to the sagging.
Aluminum is about 1/3 the density of steel, but also exhibits about 1/3 of the material rigidity of steel or stainless steel, so you would expect aluminum, steel, and stainless steel disks of the same thickness to sag about equally under the influence of gravity (they will of course respond differently to externally applied loads).
Someone running a finite-element simulation could predict fairly accurately how much sag you should expect for the various material/thickness combinations. A SWAG would be maybe 1.5-2 inches of sag (at center) for the 1/8" thickess disks, and maybe a third of that for the 1/4" thickness disks.
The amount of sag can be calculated from formulas such as those appearing here. The 6-point support is probably close enough to continuous to be considered a simply supported edge.
Thanks everyone for the info so far it’s certainly saved me some time.
My recommendation was an angle iron x on either side but that was shot down. They want it unobstructed area.
A few inches of sag in the middle is acceptable.
Due to weight my original recommendation was 1/8 inch steel or 1/4 aluminum. Being reasonably movable by two people is the ideal. beowulff’s math confirmed that for me.
A person involved in the project doesn’t like aluminum, as a concept not any reasonable engineering concern. I’d have preferred 1/4 Aluminum because 1/8th inch is a pretty sharp edge to deal with.
I think the material of choice is going to be stainless steel, that is until I source it and they realize how much money that is going to be, then steel might seem more reasonable.
How about a sandwiched, honey comb, aluminum sheet? I know there is a name for it but I can’t recall it. The top and bottom will be a solid sheet of aluminum but within is a honeycomb structure to both reduce weight and increase rigidity. Probably have to go for 1/4" thickness though.
You could also go with 1/8" aluminum or steel, place it on the supports, and then deflect/bend it ever so slightly. Then flip it back over and see if the deflection will compensate for the sag.
stainless steel all the way I used to operate a very large cnc plasma table. SS steel is more rigid espeically after its heated and then cooled then it gets extremelly rigid.
It’s just called aluminum honeycomb. Super rigid and light weight. We used it in all the interior cabinets in the Gulfstream jets.
It would work, but it’s really expensive. I think you’re looking at something like $1200 for a 12’X4’ sheet. I dont’ know if you can get it in 6’ widths either.
By the way, boytyperanma, how much do henchmen get paid these days? Are you getting bonus pay for working on a doomsday device? Oh, and please tell us you don’t have to wear one of the red uniforms!
A possible design consideration … If this thing is installed horizontally it will sag, at least a smidgen, and as other have said above, maybe more like a couple inches. That wll form a large shallow bowl. If this is installed outside it will be able to hold a few gallons of water.
That much rain water or snow (depending on location) probably won’t weigh enough to break the supports or buckle the disk. Unless you’re in Buffalo where 5’ of lake effect snow would weight about a ton.
But a snow or water load may interfere with whatever function you are using the disc for. At a minimum after a good rain it may stay wet for a few days & become a mosquito breeding reactor.
Everything deflects under it’s own weight. You need to quantify how much deflection you are willing to accept for your application. For some applications you can quantify the deflection and compensate for it.
Agreed. Here’s a calculator that will do the math for you. It requires only radius, thickness, Young’s modulus, Poisson’s ratio, and loading (which is really, in this case, weight per square meter).
No bonus pay what so ever, no real pay to begin with, just sorta potential for future work. I can wear whatever I want.
I think I’d just be considered a subcontractor for this dooms day device. My contact works for essentially an eccentric millionaire so it could well be a evil plot to take over the world. I’m not well informed as to what the hell they are doing.
They have open air tanks, They are sorta like small above ground pools. So the six points refer to the corner posts of the pools. The covers will actually sit on the top which is a continuous edge. The covers are to prevent animals from getting inside. I’d have thought plastic or plywood would have been fine but this seems as much an art protect as anything else.
As far as I knew the tanks are just holding tanks for irrigation. They had wood covers before that have lasted 20 years. Now if they want to buy 1500 dollar stainless steel covers, I’ll just keep my mouth shut and nod my head. When they need new pumping equipment to supply the needed water I’ll be happy to sell it.
The tanks seem kinda small for raising sharks with lasers on their freaking heads, maybe the lasers can’t cut metal? I only put so much thought into speculating what the evil plot may be.
