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pressbrake1
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Yes the beginning of flex is similar as dictated by Young’s modulus but better materials then hold on . A good example would be a mild steel pry bar compared to carbon steel
Screwdriver
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Yes but in this specific example where you are using it as a vice handle, the difference is only a few percent. Like I have said (and @brightspark) once you exceed the elastic limit, all bets are off because you are exceeding your design parameter for the vice.
It would be hilarious to use a spring steel handle on a vice though I'd probably want to have my dentist on speed dial before I tried it!
In my mind the matter has been answered concerning a vice handle using 303 stainless steel. As pressbrake1 mentions regarding the choice of steel material for a pry bar. What is your view on the use of mild steel for this tool when it has been suggested "every type and grade of steel will have identical behaviour under bending stress"?Yes but in this specific example where you are using it as a vice handle, the difference is only a few percent. Like I have said (and @brightspark) once you exceed the elastic limit, all bets are off because you are exceeding your design parameter for the vice.
It would be hilarious to use a spring steel handle on a vice though I'd probably want to have my dentist on speed dial before I tried it!
Misterg
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It isn't a few percent - it's several hundred percent, no matter what the application.
How much weight do you think it's sensible to put on a vice handle?
50kg on a 300mm long, 17mm diameter handle gives a maximum stress of about 310MPa
Cold drawn mild steel has a yield stress of about 350 MPa = job's a good 'un.
Hot rolled mild steel has a yield stress of 200 - 250 MPa = bent handle.
303 stainless has a yield stress of >400 MPa*, so should be OK.
(*Presumably 'as drawn' but not stated - many stainless grades have very low yield stresses (~~200 MPa ) in the annealed condition)
Heat treatable steels, when quenched and tempered can easily exceed 1500MPa yield stress - 580% higher than hot rolled mild. (But don't get me started on toughness.)
Below about 200MPa, I agree that the different grades / types will have almost indistinguishable stiffness (deflection for a given load) which I think was the gist of the original comment.
To be sure of ending up with a vice handle (or pry bar) that doesn't bend, however, one needs to check that the yield stress isn't exceeded in a 'reasonable' usage scenario - pretty much any steel that isn't hot formed or annealed would survive the vice handle case above.
Screwdriver
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I would expect them to behave identically right up until the moment they exceed the elastic limit which would be lower for mild steel.
I am way out of my depth here though as soon as we get away from vice handles! All I would say is that 1. It would be very difficult in practice to place 50kg on the extreme tip of a vice handle (without a cheater bar) and 2. in the real world with the width of your hands etc. reducing your leverage you actively want the handle to cry "enough"and be the first point of failure. 3. If you're using a cheater bar on your vice, well, that's cheating!
MattF
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It isn't a few percent - it's several hundred percent, no matter what the application.
How much weight do you think it's sensible to put on a vice handle?
50kg on a 300mm long, 17mm diameter handle gives a maximum stress of about 310MPa
Cold drawn mild steel has a yield stress of about 350 MPa = job's a good 'un.
Hot rolled mild steel has a yield stress of 200 - 250 MPa = bent handle.
303 stainless has a yield stress of >400 MPa*, so should be OK.
(*Presumably 'as drawn' but not stated - many stainless grades have very low yield stresses (~~200 MPa ) in the annealed condition)
Heat treatable steels, when quenched and tempered can easily exceed 1500MPa yield stress - 580% higher than hot rolled mild. (But don't get me started on toughness.)
Below about 200MPa, I agree that the different grades / types will have almost indistinguishable stiffness (deflection for a given load) which I think was the gist of the original comment.
To be sure of ending up with a vice handle (or pry bar) that doesn't bend, however, one needs to check that the yield stress isn't exceeded in a 'reasonable' usage scenario - pretty much any steel that isn't hot formed or annealed would survive the vice handle case above.
FFS. I hope you know how drawn out this thread is about to become after that post.
Misterg
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FFS. I hope you know how drawn out this thread is about to become after that post.
Sorry ! - That's why I didn't respond to the original last night...
The comments included in connection with this issue are essentially to counter and try to explain inaccurate and perhaps misleading comments made related to Young's Modulus definition particularly the inclusions of bending stress when this does not apply. It is sad that the term "FFS" needs to be provided by a contributor.
Gareth J
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Fascinating. I mean, technically, I am relevantly qualified to comment (MEng mechanical) but I can't recall enough to be confident.
To be clear though, in the context of a vice handle, I couldn't give two hoots about what happens up to the elastic limit. Properties I'm interested in would be yield stress, failure modes and fatigue resistance.
Could, say, a MS bar, straight out of a cheese factory in China really permanently deform under the same bending force that it'd take to deform, say, a nice bit of silver steel?
To be clear though, in the context of a vice handle, I couldn't give two hoots about what happens up to the elastic limit. Properties I'm interested in would be yield stress, failure modes and fatigue resistance.
Could, say, a MS bar, straight out of a cheese factory in China really permanently deform under the same bending force that it'd take to deform, say, a nice bit of silver steel?
MattF
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See if you're still saying that a few pages from now.
brightspark
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ive pressed a few bearings out and in with my 6 inch vice and pulled as hard as i can without bending the bar . all i can say is theres some animals out there that arnt fit to be using tools of any description 
MetalMonkey
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Don't take it the wrong way. MattF is just gently ribbing.
The tendency is for threads about a simple topic to end up drifting off on a tangent for several dozen pages and end up about something else entirely.
It's all good fun and the banter is not to be taken too seriously.
MattF
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ive pressed a few bearings out and in with my 6 inch vice and pulled as hard as i can without bending the bar . all i can say is theres some animals out there that arnt fit to be using tools of any description
Yup. They'd rather bodge & risk damaging something, than use the proper gear, else gear properly.
That's why I fitted a brass rod/handle on mine. I want the bugger to bend before risking the vice. It's my early warning system.
Mattf: please confirm if this some sort of threat? Site Moderator please intervene and let me have your views.
MattF
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Are you serious?
anto44
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I've used normal 14mm mild steel rod as a handle on one of my vices, I probably could bend it if I wanted to but I wouldn't put my vice under that kind of pressure. I'd also be afraid of what would happen to me if something broke while swinging out of it that hard.
It seems a simple question I have asked. Please reply.
