Sorry guys, I can't find the info I need...I need to shorten pull type coil spring from about 23" to 20" and reuse it. The spring is about 2" diam. with 5/16" stock. Any tips for heat treat? All I have found is how to make knifes out of it ...LOL.... 1162 threads on coil spring.....Thanks            Dave

Greetings Dave, 

Sounds like a garage door spring. Just a 41/2 grinder with a cut off disk will work . 

Forge on and make beautiful things

Jim

Thanks Jim, actually it's a lift spring on an old IH rope trip plow. Once I cut to length, I need to bend a loop back on the end to attach to an eye bolt for adjustment. Just so happens there are two different lengths of springs on these plows. I have an extra long one but not the short one...Once I heat to bend the loop in, I'll need to heat treat to maintain the integrity of the original....not to soft, not to hard.....            Thanks               Dave 

Greetings Dave,

The garage door spring company's make a insertable hoop that locks into the spring with an eye bolt that would work. Easy to make.. You would not have to heat treat. 

Jim

 Thanks Jim, I do have a plug that screws into the spring that is used on the hitch spring of these plows. I may go that way if I don't get this worked out....I just ran out and took a couple of pics so you can see what I want to do..... Thanks         Dave     (not sure the 2nd pic loaded or not, tried twice.....we'll see) ds

 

That's an interesting problem Dave, sorry I can't help, I hope the solution will be shared here.

 

Most of those loops are cold formed. Practice on the piece you cut off, but even if you had to warm it up some to bend it it may work fine as is without reheat treating. I would be more concerned with it possibly air hardening and becoming brittle as opposed to being too soft.

Could you not simply relocate the anchor point, either with a replacement or extension?

Looks very much similar to a stake spring or a mudflap spring from a logging truck.  in a pinch we have heated the end up and bent whatever we needed for a loop in .   They do tend to wear faster or depending on load straighten out.  But it does buy time to find the something new.

8 hours ago, BIGGUNDOCTOR said:

Most of those loops are cold formed. Practice on the piece you cut off, but even if you had to warm it up some to bend it it may work fine as is without reheat treating. I would be more concerned with it possibly air hardening and becoming brittle as opposed to being too soft.

I hope that I am not over simplifying this, but the spring in the picture looks like the last coil on the end is just bent outwards 45 degrees and then maybe closed a little. I would second BGD's comment on bending it cold after cutting to length.

if you need to heat it to bend, open the coils up and put a wet rag around the spring to act as a heat sink. or put it in a tube of water with the end out and get after it.

 

 Thanks for the input guys. I do know this spring is to strong 'for me' to bend cold.                      Dave

There's no way to be absolutely certain how to heat treat the spring without having the metal tested to find out what it is.  That said, most of the time, these sorts of springs are made from relatively simple steels such as 1070, 1095 or 5160, hardened and then tempered back to deep blue (550 or 560 degrees, maybe for 20 or 30 minutes). 

If it were me, I'd experiment on the piece you cut off, and start by heating it to just non-magnetic, followed by quenching in oil.  Try not to get it too hot or to let it soak at heat too long, or you'll grow the grain and make it brittle. Once you've quenched, file test to see if it hardened.  You may also want to grind down a bit and then retest to make sure it's hardened all the way through.  If it hasn't hardened satisfactorily, try upping the heat a little, or quenching into a lighter oil or water.  Once you get it hard, clean up the outside (so you can see color when you temper), and draw the temper to a deep blue.  If you have access to a salt pot or heat treating oven, I'd try 550 degrees for 15 or 20 minutes; if not, use a torch and go very slowly and carefully.  You want a nice dark blue color.

One significant problem with an operation like this is that even if you use a torch or induction to selectively heat the spring only where you need to bend it, and even if you use a wet rag to try to keep the rest of the spring cool (both of which are good ideas), it is very likely that you'll end up with at least a small area on the spring that gets hot enough to draw the temper but not hot enough to re-harden in the quench, so that it will be too soft and not springy when you're done.  Depending on how much stress the spring is subject to, this may or may not cause a problem.  The alternative is to re-heat treat the entire spring, but that is a much bigger job, and, since you're likely to be guessing on the heat treat procedure anyway, is also more risky.  Still, you might consider it if you have access to a salt pot or a heat treating oven that will fit the entire spring.  (This is one reason why working the part cold is appealing, if it were possible.)

Hope this is of some help.  Good luck with the fix.

I'm glad I asked this question now....lots of input....Thanks a bunch. Right now I'm thinking to try it cold. I know , I said I couldn't do it cold....But, if I put a piece of angle iron on one jaw of my 6" leg vice, I may be able to squeeze it in like a wedge, between the coils....maybe....How does that sound?                   Dave

Why not just use a wedge and hammer to start with?  if you can get a little separation between the coils then you can probably get hold of it with something and use a pipe cheater to get the extra leverage you need.

Some years back I had a spring on my garage door break when I closed it ( thankfully I was on the outside) it had enough force to put a 1"deep dent in the edge of a metal cabinet and scared the life out of me. Knowing way less then I know now I decided to just bend out a coil to fix and reuse it. Used an OA torch. No quench or HT. just air cooled.  

It did work for a while but again broke and bounced around the garage, and again I was lucky enough to have closed the door from the outside. At that point I had pushed my luck enough and went out and bought a new set. And I was glad to install the wire that would keep them from being rockets if they ever break again. 

I know this is nowhere on the same level so I wouldn't be afraid to give shortening it a try if the the outcome of it breaking in use wouldn't cause catastrophic failure. 

2 hours ago, Daswulf said:

install the wire that would keep them from being rockets if they ever break again

20 yrs ago I was a new car dealer and we had 3 new cars in the shop for the night to melt the snow off them, door closed and bam the spring broke flew around dented the roofs of two of them and through the rear window of a hatchback onto the back seat . Over $8000 later we decided that we might want to  install safety cables in all 12 of our doors, cost $150.   

try bending cold .. if it looks unsatisfactory or wont work, bend it hot with a torch exactly where you want the bend.  if it breaks at some point in the future, bend another loop  install a longer eye bolt, rinse and repeat as needed.  

To keep the rest of the spring cool, submerge it in a bucket of water with just what you want to heat and bend above the waterline, heating will be harder but can be done with a hot enough torch.  and remember soon as you start monkeying around with heating, hardening, and tempering an unknown piece of steel you're asking for more unknowns to happen.

Well, I got it bent. I did it cold in the 6" vice. It was about all I and the vice wanted for sure. After bending, the angle grinder took care of the cut. I got it installed and looks good. No obvious cracks, time will tell. thanks again for all the input.....pics attached, I hope...      Life is Good           Dave

Wow! You even matched the original patina, great job! 

 Yer right on the patina Biggundoctor. Plus, I got to avoid my heat treating phobia......Life is Good          Dave

I see only one problem......what are you going to do with the spare 5 coil spring?

Smoggy, the only thing I know to do with it is to make a sword.........NOT      lol                Dave 

Great thread thanks Dave51B and everyone else.:)

Always a good day when things go surprisingly well.........

Robert Taylor