bent flat spring, risk?
- Thread starter pomelum
- Start date
You should not be able to permanently change the shape of a flat spring by bending it (without heating it red hot). It should spring right back to its original shape. If it has a line on it now, that sounds like a crack rather than a line. Also heating a spring red hot means that you would have to retemper it
cheers mooncoon
BigUglyMan
CGN Ultra frequent flyer
- Location
- New Scotland
My money is on the spring being hooped.
saskgunowner101
CGN Ultra frequent flyer
- Location
- near Prince Albert
So, are you saying it was rainbow shape for some reason (and not supposed to be), but you tried to make it flat. Now it looks like a pencil line seagull?
Eventually, it can break at the bend. The preferred method would be to heat it and bend it, then go hot enough it loses magnetism and quench. Now, heat it slowly to where it yellows or a little past and quench it one more time.
Your now fragile spring might be served by a heating and a couple whacks with a hammer to deal with the stressed area then going through the harden and temper process. Or, you could find a chunk of flat tempered spring steel and file it to shape.
Your now fragile spring might be served by a heating and a couple whacks with a hammer to deal with the stressed area then going through the harden and temper process. Or, you could find a chunk of flat tempered spring steel and file it to shape.
saskgunowner101
CGN Ultra frequent flyer
- Location
- near Prince Albert
If he was to go through all that trouble to save the spring, wouldn't he be better off to heat to orange, bend, heat, air cool to black, heat, air cool to black, to normalize the steel. Should be in an unstressed state by now. Then heat to non magnetic, quench in 140 degree oil, and then temper at some unknown temperature?
Just heating and cooling likely won't remedy the strain he's put on it at the bend. Needs a thump to get some density back. The oil quench works, but it makes tempering by color too hard. Average garage tinker is not going to have the equipment to do a hot oil quench and a controlled temper.
For all the trouble, grab a larger spring and cut/file to shape.
For all the trouble, grab a larger spring and cut/file to shape.
That is incorrect.
As long as you do not bend the spring past it's yield point, it will return to its shape. If you do bend it past it's yield point, it is going to depend on the original hardness, and upon how much it was bent, to determine whether it will cause any problems.
I would hazard an estimate that better than 90 percent of the springs that folks deal with regularly, are bent cold, from wire or flat stock that is in the spring condition when it arrived in the manufacturing facility. Coil springs get wound cold, flat springs get stamped out of flat stock and shaped in dies, sometimes the same die that cuts it.
Without seeing it, and knowing what it was used for, I would still suspect that it'll be fine, as long as there were no kinks in it, and it was a well made spring to begin with.
Bets are off if it was originally hardened and tempered by guess and by golly by someone with a propane torch and a potato.
Cheers
Trev
I would like to reply to several replies that have been made. Also perhaps worth mentioning that I make 5 to 10 gun lock mainsprings (flat V type) per year and have done so for the last 15 and possibly 20 years (I have lost track)
1. several have commented on tempering springs; after heating red hot and quenching, the spring is now brittle hard. Important to have a uniform heat when drawing the temper. Using the colour scale, I take to just past black and the beginning of grey. I also find it very difficult to do so to a repeatable temperature. When I did use this method, I floated a think piece of steel on top of molten lead, in an electric lead post, and unplugged it when the temperature was correct. For the last several years, I have used a high temperature thermometer to measure the temperature of the lead at draw the temper at 720 to 740 F on my thermometer. That temperature does not work on automotive leave springs (cut up and used for flat springs) I use drill rod exclusively for my springs. Until about 3 or 4 years ago, I drew the temper by putting the spring in a small tray of burning lube oil and letting the lube oil burn away. While it works and never failed, I don't understand why it does and am convinced that it is witchcraft :>) :>)
2. If a flat spring took a permanent set after drawing the temper, I would consider it too soft. Any flat spring that I have made, would accept a remarkable degree of bending and when the elastic limit was reached and passed the spring broke. Worth mentioning that automotive flat springs can be bent cold to a desired shape. Years ago, I watched a local company do so using a large press to do so.
3. the flat V springs used in modern muzzle loaders appear to be cast and you can see the mold line down the center of the spring
4. I guess I misunderstood what was meant by a line across the spring.
5. drawing the temper to yellow as mentioned by one poster, would leave drill rod springs brittle hard. When making D bit reamers, I draw them beyond straw into the brown range. In no way could they be considered springy
cheers mooncoon
1. several have commented on tempering springs; after heating red hot and quenching, the spring is now brittle hard. Important to have a uniform heat when drawing the temper. Using the colour scale, I take to just past black and the beginning of grey. I also find it very difficult to do so to a repeatable temperature. When I did use this method, I floated a think piece of steel on top of molten lead, in an electric lead post, and unplugged it when the temperature was correct. For the last several years, I have used a high temperature thermometer to measure the temperature of the lead at draw the temper at 720 to 740 F on my thermometer. That temperature does not work on automotive leave springs (cut up and used for flat springs) I use drill rod exclusively for my springs. Until about 3 or 4 years ago, I drew the temper by putting the spring in a small tray of burning lube oil and letting the lube oil burn away. While it works and never failed, I don't understand why it does and am convinced that it is witchcraft :>) :>)
2. If a flat spring took a permanent set after drawing the temper, I would consider it too soft. Any flat spring that I have made, would accept a remarkable degree of bending and when the elastic limit was reached and passed the spring broke. Worth mentioning that automotive flat springs can be bent cold to a desired shape. Years ago, I watched a local company do so using a large press to do so.
3. the flat V springs used in modern muzzle loaders appear to be cast and you can see the mold line down the center of the spring
4. I guess I misunderstood what was meant by a line across the spring.
5. drawing the temper to yellow as mentioned by one poster, would leave drill rod springs brittle hard. When making D bit reamers, I draw them beyond straw into the brown range. In no way could they be considered springy
cheers mooncoon
Without a clearer picture of what exact type of spring the OP is dealing with, all this talk of hardening and tempering them is pretty pointless. Other than perhaps, to lead some one that knows no better, into mucking about with things they know even less about, leading to ending up with a worse problem than they started with.
It would help if the OP was a little more forthcoming about what the spring is out of, and which spring it is.
As I took his description, in any case, he is dealing with a simple flat spring that had a curve, which he bent straight, something along the lines of a hammer spring for an old revolver or of that type.
I took the 'line to be a crease, rather than a mold seam. Rarely a good thing.
That's my two bits. A flat vee spring for a lock of one form or another, is a whole different kettle of brew.
Cheers
Trev
It would help if the OP was a little more forthcoming about what the spring is out of, and which spring it is.
As I took his description, in any case, he is dealing with a simple flat spring that had a curve, which he bent straight, something along the lines of a hammer spring for an old revolver or of that type.
I took the 'line to be a crease, rather than a mold seam. Rarely a good thing.
That's my two bits. A flat vee spring for a lock of one form or another, is a whole different kettle of brew.
Cheers
Trev
Can't speak to drill rod. Your temper is going to depend on your carbon content. http://www.anvilfire.com/article.php?bodyName=/FAQs/temper_colors_hardness.htm
Truth be told, I make most of my springs - couple a year, not always for firearms - with tine harrows from the pile of take-offs behind the barn. What's actually in that stuff, I really couldn't say.
That little bump is a kink. And it means that the metal in that kink was pushed past it's spring point. And typically if you could look at the surface in the bumpy area you would see small fracture lines running along the peak of the bump. And that would be the dull looking line you see along the top of the bump. It's all the small micro fractures along the surface which make it look dull.
That dull look suggesting a line of micro fractures also means that you are past being able to heat it up and re-harden then temper the metal. Doing so won't repair the micro fractures.
It is very likely that the spring is ruined. Even if it does not break at the kink it will likely bend more easily at the kink and take up a deformed position the first time you #### the gun and not perform correctly. You can try to put it back in the gun and see if it works. But I would order up a new spring right away for WHEN you need to replace the one you have.
That dull look suggesting a line of micro fractures also means that you are past being able to heat it up and re-harden then temper the metal. Doing so won't repair the micro fractures.
It is very likely that the spring is ruined. Even if it does not break at the kink it will likely bend more easily at the kink and take up a deformed position the first time you #### the gun and not perform correctly. You can try to put it back in the gun and see if it works. But I would order up a new spring right away for WHEN you need to replace the one you have.
