Making a 'C' clamp

If one wished to make a 12" 'C' Clamp by bending (say 2"x5/8" strap) in to a 'C', with a threaded cylinder welded to one end, how does one temper it.
Bright Cherry red, and then bury it in a bucket of wood ashes? Then in a kitchen range on 'OVEN CLEAN' for a few hours? No oil tempering? Consider one starting with normal 'mild steel', not auto springs. Thanks
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pintlar wrote:

not even close :.)
mild steel doesn't harden AT ALL so wouldn't make a lot of difference what you do to temper it.
If you were going to use a spring steel (auto springs) then I would heat to red (non-magnetic), quench in water, then temper to a blue colour (around 580 F).
This would make it hard, yet springy
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bigegg wrote:

I'd go with the spring steel also (obviously because I love spring alloys).
You can harden mild steel with super quench, but it's only a temporary solution, it loses its hardness quickly.
Regards Charles
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I would NOT use spring steel and heat treat it. Heat treated steel will snap catastrophically if the C-clamp get overloaded. I would prefer to have the clamp bend when it is overloaded so you can see it before it shatters in your face.
Hope this helps,
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paul snipped-for-privacy@excite.com wrote:

True there is that possibility... if you screw the temper.
5160 can be tempered to a nice spring temper that would do the job nicely. A full spring temper would be recommended.
I don't envisage there would be too much force on the clamp.
So what would you use?
Cast iron, mild steel, or something else?
Regards Charles
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Charles,
I have actually snapped C-Clamps before, so I think that you CAN apply too much force on one. The forces from the "ramp" effect of the screw can apply a lot of force especially when you are trying to get 2 pieces to come togther that just don't want to. Who hasn't done that?
Anyway, I would use mild steel since the high carbon content in cast iron makes it unmalleable as well as brittle. Mild steel will still have a good springyness in it.
Also, WELL SAID about making versus buying one. It's the store bought kind of clamp that I broke. Besides that, it's good to be able to make a clamp to fit a special situation OR in a size that you can't buy. If someone in history hadn't been the type of guy to build his own tools, we never would have gotten to the point where they are mass produced enough to buy them at will.
Paul
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paul snipped-for-privacy@excite.com wrote:

True a blacksmith can pretty much make any tool, and can make better tools in some instances.
I'm just thinking along the lines of how much bending and force Pintlar is going to apply to the clamp, and for what purpose.
With a correct, full spring temper the piece should bend before it breaks. You should also see the bending happening... maybe as a safety a small guide and a painted line could be included on the clamp.
Personally if I were to do this I would make two, and see if I could destroy one. Then I would have an idea if it was going to shatter or not.
Regards Charles
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A vise is made of cast iron and it ain't that way! ;) Because it's been heat treated to form what's called "nodular iron". Just like the store bought C clamps. :)

But "give" isn't the ideal situation here. :) Need a thick hunk [any kind] of steel to make it not open too much. That's the trick. :)
Atom to atom "give" is what you are going to experience with steel. Once you get past its yield point tho, then it'll stay that way.
So the yeild point of a quenched and tempered spring is much higher than mild steel. That's where the idea of a thick hunk of steel is needed. Over time the mild steel will progressively open up where as the heat treated spring steel wouldn't. Automotive parts tend to be made from medium-carbon low-alloy steel. It does all they kind of work we're talking about here with the C-clamp, real nice without breaking.
I have a tire bead breaker. A couple cowboy friends borrowed it and decided to make a couple copies of it. :) They found out real quick that medium-carbon low-alloy steel (4140 in this case) can kick mild steel's butt! LOL :) Different situation they were running into the mild steel's yield point because of the light weight construction of the original.
-------------------
For the OP... Metallurgy Theory and Practice by Dell K. Allen www.amazon.com I guarantee you'll like it, or I'll buy it from you. No kidding. Hadn't had to buy any that way yet. :)
Alvin in AZ
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With all of this blow up in your face possibility - why not just buy one or two. Good grief - They make them - in C and Can't Twist. I use Can't Twist and they are great.
Martin
paul snipped-for-privacy@excite.com wrote:

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Martin H. Eastburn wrote:

Well you've just said what I was thinking, "Why not simply buy one???"
I suppose the answer could be "because I want to make one as a project", which is fine. We made some in an industrial arts class many. many years ago.
We were supplied with a grey iron casting, the "C", and we had to drill and tap a hole and turn a thread. Not rocket science, but challenging enough for a 12 year old.
Regards Charles
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