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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. 
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#1




resistance to bending angle or tube which is more resistance
Want to build a gravel screen to sort out over size rocks from sand.
The gravel and rocks would be dumped on grizzly bars on a 40 degree incline and the gravel and rocks would slide down the slope rocks sliding off the top of the grizzly bars, and sand falling between the grizzly bars under the grizzly bars to be picked up and moved to usage area. the rocks moved to waste area. Spacing between bars would be 3 inches. Question which would bend the least when the gravel and rocks are dumped on the grizzly bars? Rocks would be up to 18 inches round so about 150 pounds each. Dropped about 18 inches on to the bars. Size of wheel loader bucket is 1.75 cubic yards so total weight to be slowly dumped on the grizzly bars would be 1.75 x 2800 lbs in yard = 4,900 pounds. Data grizzly bars angle 2 inch x 2 inch and 3/8 inch thick. grizzly bars angle 2.5 inch x 2.5 inch and 1/2 inch thick grizzly bars 3 inch x 3 inch x 1/8 inch thick square tube grizzly bars 3 inch x 3 inch x 1/4 inch thick square tube all 36,000 pound strength steel thank you for replying it is much appreciated. 
#2




resistance to bending angle or tube which is more resistance
On Friday, February 10, 2017 at 6:13:43 PM UTC5, lakeside bob wrote:
Want to build a gravel screen to sort out over size rocks from sand. The gravel and rocks would be dumped on grizzly bars on a 40 degree incline and the gravel and rocks would slide down the slope rocks sliding off the top of the grizzly bars, and sand falling between the grizzly bars under the grizzly bars to be picked up and moved to usage area. the rocks moved to waste area. Spacing between bars would be 3 inches. Question which would bend the least when the gravel and rocks are dumped on the grizzly bars? Rocks would be up to 18 inches round so about 150 pounds each. Dropped about 18 inches on to the bars. Size of wheel loader bucket is 1.75 cubic yards so total weight to be slowly dumped on the grizzly bars would be 1.75 x 2800 lbs in yard = 4,900 pounds. Data grizzly bars angle 2 inch x 2 inch and 3/8 inch thick. grizzly bars angle 2.5 inch x 2.5 inch and 1/2 inch thick grizzly bars 3 inch x 3 inch x 1/8 inch thick square tube grizzly bars 3 inch x 3 inch x 1/4 inch thick square tube all 36,000 pound strength steel thank you for replying it is much appreciated. The last one will bend the least, by far. The stiffness of the angles will depend on how they're oriented, but neither one is even close to the tubes, no matter how you arrange them.  Ed Huntress 
#3




resistance to bending angle or tube which is more resistance
On Friday, February 10, 2017 at 6:13:43 PM UTC5, lakeside bob wrote:
Want to build a gravel screen to sort out over size rocks from sand. The gravel and rocks would be dumped on grizzly bars on a 40 degree incline and the gravel and rocks would slide down the slope rocks sliding off the top of the grizzly bars, and sand falling between the grizzly bars under the grizzly bars to be picked up and moved to usage area. the rocks moved to waste area. Spacing between bars would be 3 inches. Question which would bend the least when the gravel and rocks are dumped on the grizzly bars? Rocks would be up to 18 inches round so about 150 pounds each. Dropped about 18 inches on to the bars. Size of wheel loader bucket is 1.75 cubic yards so total weight to be slowly dumped on the grizzly bars would be 1.75 x 2800 lbs in yard = 4,900 pounds. Data grizzly bars angle 2 inch x 2 inch and 3/8 inch thick. grizzly bars angle 2.5 inch x 2.5 inch and 1/2 inch thick grizzly bars 3 inch x 3 inch x 1/8 inch thick square tube grizzly bars 3 inch x 3 inch x 1/4 inch thick square tube all 36,000 pound strength steel thank you for replying it is much appreciated. You provided a lot of information, but not quite enough. How long are the bars? Are there any supports other than at the ends? When you dump a load on to the bars how many bars got the load. How are the bars supported at the ends. Welded or sitting on top of a r? Why 36,000 steel. Low alloy would probably be cheaper for equal strength. Dan 
#4




resistance to bending angle or tube which is more resistance
On Friday, February 10, 2017 at 8:14:34 PM UTC5, wrote:
On Friday, February 10, 2017 at 6:13:43 PM UTC5, lakeside bob wrote: Want to build a gravel screen to sort out over size rocks from sand. The gravel and rocks would be dumped on grizzly bars on a 40 degree incline and the gravel and rocks would slide down the slope rocks sliding off the top of the grizzly bars, and sand falling between the grizzly bars under the grizzly bars to be picked up and moved to usage area. the rocks moved to waste area. Spacing between bars would be 3 inches. Question which would bend the least when the gravel and rocks are dumped on the grizzly bars? Rocks would be up to 18 inches round so about 150 pounds each. Dropped about 18 inches on to the bars. Size of wheel loader bucket is 1.75 cubic yards so total weight to be slowly dumped on the grizzly bars would be 1.75 x 2800 lbs in yard = 4,900 pounds. Data grizzly bars angle 2 inch x 2 inch and 3/8 inch thick. grizzly bars angle 2.5 inch x 2.5 inch and 1/2 inch thick grizzly bars 3 inch x 3 inch x 1/8 inch thick square tube grizzly bars 3 inch x 3 inch x 1/4 inch thick square tube all 36,000 pound strength steel thank you for replying it is much appreciated. You provided a lot of information, but not quite enough. How long are the bars? Are there any supports other than at the ends? When you dump a load on to the bars how many bars got the load. How are the bars supported at the ends. Welded or sitting on top of a r? Why 36,000 steel. Low alloy would probably be cheaper for equal strength. Dan If by "bending" he's referring to stiffness (resistance to springing, not resistance to permanent bending), then the alloy makes no difference at all. 36,000 psi tensilestrength steel us just as stiff as 200,000 psi hgh strength alloy. If he's referring to permanent bending, then a little deeper section of lowstrength steel is still 'way less expensive than a lesser depth of highstrength steel.  Ed Huntress 
#5




resistance to bending angle or tube which is more resistance
On Friday, February 10, 2017 at 5:13:43 PM UTC6, lakeside bob wrote:
Want to build a gravel screen to sort out over size rocks from sand. The gravel and rocks would be dumped on grizzly bars on a 40 degree incline and the gravel and rocks would slide down the slope rocks sliding off the top of the grizzly bars, and sand falling between the grizzly bars under the grizzly bars to be picked up and moved to usage area. the rocks moved to waste area. Spacing between bars would be 3 inches. Question which would bend the least when the gravel and rocks are dumped on the grizzly bars? Rocks would be up to 18 inches round so about 150 pounds each. Dropped about 18 inches on to the bars. Size of wheel loader bucket is 1.75 cubic yards so total weight to be slowly dumped on the grizzly bars would be 1.75 x 2800 lbs in yard = 4,900 pounds. Data grizzly bars angle 2 inch x 2 inch and 3/8 inch thick. grizzly bars angle 2.5 inch x 2.5 inch and 1/2 inch thick grizzly bars 3 inch x 3 inch x 1/8 inch thick square tube grizzly bars 3 inch x 3 inch x 1/4 inch thick square tube all 36,000 pound strength steel thank you for replying it is much appreciated. OK some more information. Bars will be 8 feet long with a support under each one three feet down from the top of the sloping deck. The bars will be welded to cross tubes of 3 x 3 x 1/4 inch steel at the top of the frame and bottom along with one at 3 ft down from the top of frame. the 36,000 pound steel is what the local shop sells. the wheel loader bucket is 8 feet long or wide, so with the cap between bars at 3 inches and each bar being say 3 inches wide the gravel will be dumped on 16 or 17 bars. 
#6




resistance to bending angle or tube which is more resistance

#8




resistance to bending angle or tube which is more resistance
Want to build a gravel screen to sort out over size rocks from sand.
The gravel and rocks would be dumped on grizzly bars on a 40 degree incline and the gravel and rocks would slide down the slope rocks sliding off the top of the grizzly bars, and sand falling between the grizzly bars under the grizzly bars to be picked up and moved to usage area. the rocks moved to waste area. Spacing between bars would be 3 inches. Question which would bend the least when the gravel and rocks are dumped on the grizzly bars? Rocks would be up to 18 inches round so about 150 pounds each. Dropped about 18 inches on to the bars. Size of wheel loader bucket is 1.75 cubic yards so total weight to be slowly dumped on the grizzly bars would be 1.75 x 2800 lbs. in yard = 4,900 pounds. Data grizzly bars angle 2 inch x 2 inch and 3/8 inch thick. grizzly bars angle 2.5 inch x 2.5 inch and 1/2 inch thick grizzly bars 3 inch x 3 inch x 1/8 inch thick square tube grizzly bars 3 inch x 3 inch x 1/4 inch thick square tube all 36,000 pound strength steel thank you for replying it is much appreciated. Just to get you started, the spec that determines how stiff a beam will be is the moment of inertia, and you can look it up in tables for standard structural beams. Assuming the angle is oriented with one flange horizontal and one vertical, and the load is in the vertical plane: 2x2x3/8 angle 0.473 in^4 2.5x2.5x1/2 angle 1.219 3x3x1/8 tube 1.851 3x3x1/4 tube 2.888 So, the 3x3x1/4 wall tube is 2.888/0.473=6.1 times stiffer than the 2x2x3/8 angle. In another post you say that each beam will be 8' long and supported 5' from one end,m and I'm going to guess the grate will be 3' wide so with 3" bars and 3" gaps that's 7 bars so 4900 lbs./7=700 lbs. per bar. I'm not an ME but I like to use a program called engineering power tools for stuff like this (http://www.pwrtools.com/). According to it, a 5' beam of 3x3x.25 tube simply supported at each end (I'm assuming the end beam can twist a bit) with a load of 700 lbs. uniformly distributed will flex 0.023" and the maximum stress will be 2700 psi. That stress is about 1/13 of the tensile strength which looks good, but in reality if you dump the load on all at once the peak load will be at least 3 times the static load, and you don't know if the load will really be exactly uniformly distributed, so your real safety margin is more like 4x which still should be good. The deflection and the peak stress are inversely proportional to the moment of inertia, so if the beam is twice as stiff the deflection and peak stress will be half. Going to 3x3x1/8" wall square tubing raises the deflection to 0.036", the peak stress to 4210 psi, and the safety margin drops to about 2.8. I wouldn't go less than that even if no people will be on or under the grate without a much more careful analysis, and if I just wanted to be sure I was only going to build it once I'd go with the 3x3x1/4 tube at the least. Going to a stronger alloy won't change the deflection (which is so small it shouldn't be an issue anyway) but will raise the tensile strength so you could go with smaller tubes to support the weight, but you won't save money so why bother. The real problem you will eventually have is wear as the rock and sand grind away your tubes. If that's a real issue you could weld on flat tops of armor plate as needed, but again, it might just be cheaper to buy more mild steel tube. The more you buy the cheaper per pound, so build it once and see how long it lasts, then buy enough tubing for 25 more :). Remember, I'm not an ME and this is just for fun and probably worth what you are paying for it :).  Regards, Carl Ijames 
#9




resistance to bending angle or tube which is more resistance
On Saturday, February 11, 2017 at 10:44:00 AM UTC6, wrote:
On Friday, February 10, 2017 at 5:13:43 PM UTC6, lakeside bob wrote: Want to build a gravel screen to sort out over size rocks from sand. The gravel and rocks would be dumped on grizzly bars on a 40 degree incline and the gravel and rocks would slide down the slope rocks sliding off the top of the grizzly bars, and sand falling between the grizzly bars under the grizzly bars to be picked up and moved to usage area. the rocks moved to waste area. Spacing between bars would be 3 inches. Question which would bend the least when the gravel and rocks are dumped on the grizzly bars? Rocks would be up to 18 inches round so about 150 pounds each. Dropped about 18 inches on to the bars. Size of wheel loader bucket is 1.75 cubic yards so total weight to be slowly dumped on the grizzly bars would be 1.75 x 2800 lbs in yard = 4,900 pounds. Data grizzly bars angle 2 inch x 2 inch and 3/8 inch thick. grizzly bars angle 2.5 inch x 2.5 inch and 1/2 inch thick grizzly bars 3 inch x 3 inch x 1/8 inch thick square tube grizzly bars 3 inch x 3 inch x 1/4 inch thick square tube all 36,000 pound strength steel thank you for replying it is much appreciated. OK some more information. Bars will be 8 feet long with a support under each one three feet down from the top of the sloping deck. The bars will be welded to cross tubes of 3 x 3 x 1/4 inch steel at the top of the frame and bottom along with one at 3 ft down from the top of frame. the 36,000 pound steel is what the local shop sells. the wheel loader bucket is 8 feet long or wide, so with the cap between bars at 3 inches and each bar being say 3 inches wide the gravel will be dumped on 16 or 17 bars. OK some more information, the width of the grizzly box is 10 feet wide that the 8 foot wide wheel loader bucket will be dropping the gravel onto. 
#10




resistance to bending angle or tube which is more resistance

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