Mr.Moose Posted July 24, 2005 Share Posted July 24, 2005 Is the force needed to bend a piece of steel directly proportional to it's cross area? Using the same kind of steel of course. So is square 6mm (36mm²) 4 times harder to bend than a square 3 mm (9mm²) piece? Using same length of course. The reason I ask is because I just started bending (last week) and have been practicing on 3/16 which have been VERY easy. So just to test I took two 5,75" pieces and bent them together, took only 20 sec but it was quite hard. Felt great though Bending is great, I'm hooked Claes Quote Link to comment Share on other sites More sharing options...
honk Posted July 24, 2005 Share Posted July 24, 2005 Is the force needed to bend a piece of steel directly proportional to it's cross area?Using the same kind of steel of course. Nope it isn´t that way. If you take bending tension two show how stressed a piece of metal is you can see it quite easyly. S=M*z/I I for cricle: I=TT*r^4/4 bendig tension is biggest on the "outside": S=m*r/I with I=TT*r^4/4 S=4*M/TT*r^3 S: bending tension (y-axis) I: axial angular impulse (y-axis) z: diameter So you can see if you double diameter you piece of steel becomes 9times harder to bend! Quote Link to comment Share on other sites More sharing options...
rolf Posted July 24, 2005 Share Posted July 24, 2005 Maybe this question fits here, it's been lingering in my mind lately... If I bend square steel, why does it bend diagonally? It would seem logical that it would bend perpendicular to one side. Rolle Quote Link to comment Share on other sites More sharing options...
honk Posted July 24, 2005 Share Posted July 24, 2005 Maybe this question fits here, it's been lingering in my mind lately...If I bend square steel, why does it bend diagonally? It would seem logical that it would bend perpendicular to one side. Rolle ← It would make sense to me if it bends not exactly diagonal. I think it bends easier this way. It takes the same strength to bend a piece perpendicular or diagonally. Quote Link to comment Share on other sites More sharing options...
Mr.Moose Posted July 24, 2005 Author Share Posted July 24, 2005 The reason I asked is that I bent two pieces 3/16 together and I wanted to know what that would be equivalent to bending one piece. Maybe someone here with greater mathematical skills than me that can answer? Claes Quote Link to comment Share on other sites More sharing options...
honk Posted July 24, 2005 Share Posted July 24, 2005 I you bend two pieces of steel with the same diameter and want to sustitute them with one piece you must increase the diameter about 18.9%. Sorry to lazy to write calcs down. Quote Link to comment Share on other sites More sharing options...
FrankyBoy Posted July 24, 2005 Share Posted July 24, 2005 or 8 times harder?? So you can see if you double diameter you piece of steel becomes 9times harder to bend! ← Quote Link to comment Share on other sites More sharing options...
honk Posted July 24, 2005 Share Posted July 24, 2005 Of course 8 times harder. I made another mistake you have to increase the diameter about 26%, if you want a piece of steel as strong as two pieces of steel of a given diameter. Quote Link to comment Share on other sites More sharing options...
Mr.Moose Posted July 25, 2005 Author Share Posted July 25, 2005 So I'm not as weak as I thought. Two 3/16 should be the same as one 6 mm. So I basically bent a blue. I didn't because I think this steel is so much softer than what's being used for the IM nails but still nice to know I'm not THAT weak. Thanks everybody for the help. Claes Quote Link to comment Share on other sites More sharing options...
Mr.Moose Posted July 26, 2005 Author Share Posted July 26, 2005 Took two "nails" to the gym today for "testing. A 5,75" 3/16 and a 6" 1/4. Used the Lat's pull down machine to check how much was needed to bend the pieces. I was surprised it took so little The 3/16 bent with 35 Kg =77 lbs. and the 1/4 bent with 70 Kg = 154lbs. That's to bend them to app 25-30°. Saw somewhere that a HRS 6" 1/4 would need 225 lbs to bend, is "my" steel so much softer or do they measure it in a different way? Damn, I AM weak after all Claes Quote Link to comment Share on other sites More sharing options...
supermagnamon Posted July 26, 2005 Share Posted July 26, 2005 Took two "nails" to the gym today for "testing. A 5,75" 3/16 and a 6" 1/4.Used the Lat's pull down machine to check how much was needed to bend the pieces. I was surprised it took so little The 3/16 bent with 35 Kg =77 lbs. and the 1/4 bent with 70 Kg = 154lbs. That's to bend them to app 25-30°. Saw somewhere that a HRS 6" 1/4 would need 225 lbs to bend, is "my" steel so much softer or do they measure it in a different way? Damn, I AM weak after all Claes ← i wish i could see a video on testing out these nails. Quote Link to comment Share on other sites More sharing options...
Mr.Moose Posted July 26, 2005 Author Share Posted July 26, 2005 Took two "nails" to the gym today for "testing. A 5,75" 3/16 and a 6" 1/4.Used the Lat's pull down machine to check how much was needed to bend the pieces. I was surprised it took so little The 3/16 bent with 35 Kg =77 lbs. and the 1/4 bent with 70 Kg = 154lbs. That's to bend them to app 25-30°. Saw somewhere that a HRS 6" 1/4 would need 225 lbs to bend, is "my" steel so much softer or do they measure it in a different way? Damn, I AM weak after all Claes ← i wish i could see a video on testing out these nails. ← Quite simple, I took the bar of from the lat pulldown and centered the nail in the carabiner. I then hooked my fingers around the ends of the nail and pulled down. If the nail didn't bend I increased the weight and did it again, when the nail bends you can see on the weightstack how many kilos was needed to bend the sucker. Quick and simple. Quite funny, the guy who runs the gym asked what I was going to use the nails for. When I said "bending" he tried and said "that's impossible" so I wrapped the 1/4" it in a towel and bent it infront of him. He's a big strong mofo 6'4 and about 280 lbs, Ive seen him bench 400lbs raw for 2 strict reps but the nail was too much for him. Claes Quote Link to comment Share on other sites More sharing options...
burner Posted July 27, 2005 Share Posted July 27, 2005 oh my god my head hurts!! Quote Link to comment Share on other sites More sharing options...
Mr.Moose Posted July 27, 2005 Author Share Posted July 27, 2005 oh my god my head hurts!! ← Please excuse me for any discomfort my post might have caused you. Claes Quote Link to comment Share on other sites More sharing options...
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