shaping and re tempering springs

[yip]

 whats the best way to shape patch box springs (latch and lid springs) and re tempering. i plan on using weed wacker pull springs for this, is this usable? i have new pull springs and plan on cutting and shaping and re tempering for this purpose, good idea?

[LRB]

  Assuming these are the flat recoil type springs, they should do very well. If it was me, I'd cut off a section of a suitable length with a grinder or metal cut off wheel, and go from there. Do all bending and straightening  with a red heat. Heat to a bright red to red-orange, quench in canola oil heated to about 125°. Temper at 700° to 750°, and you'll have a spring again. You might want to buy a "TEMPIL" stick that melts somewhere in that temper range to be able to temper at the correct heat.

[rich pierce]

Not much springiness is needed for these sorts of applications and sometimes it's easy to slip into over-engineering it and the springs end up too strong.  I'd err on the side of "weak".

[Ed Wenger]

I agree with Rich.  I'd experiment by gentle heat and bend.  You might find that no treating is needed, especially with this type of application. 


        Ed

[LRB]

   Bear in mind that what he has is already heat treated, and may be too hard to drill if needed, or bend to what he needs. Chances are a piece of low carbon cold roll would probably work as long as the "spring" does not have to travel very far to pop the lid free.

[Mark Elliott]

You will need to anneal, machine, harden,and temper an exisiting spring.    If you don't have a forge or heat treat oven,   I would suggest that you buy a piece of annealed spring steel from Brownells or Admiral Steel to make your spring.   I will assume that you don't have a forge or heat treat oven; otherwise,  you probably wouldn't be asking this question. 

1/32" thick 1085/1095 will be fine for all patchbox springs (lid and catch)  and you can cut it with aviation snips.   Do file the egdges smooth before hardening.  To harden, you will need a MAPP or hotter torch and a quart can full of 20 wt motor oil.   Heat the finished spring (holding from the edge least likely to bend with needle nose pliers) to bright red/salmon color and then thrust in oil and move it around for several seconds until cool.   A file should now skate off of it.  Next pull out your lead pot and turn up the temp until the lead just melts.   Then, lay the spring on top of the lead for 10-15 minutes.  Remove the spring and let air cool.   You spring is done.   

[PPatch]

This lid spring..........




...started out as a length of hacksaw blade as detailed on Ken G's website: http://tnhogrifle.com/Tutorials_and_Tips.php Which links to an ALR tutorial of his here on ALR at this URL:

http://americanlongrifles.org/forum/index.php?topic=2613.0

Works like a charm and you don't need any fancy equipment, well, you will need a sardine can full of motor oil.  

dave

[LRB]

  With all due respect, two problems with that Mark. Motor oil is about the poorest quench oil there is, plus the nasty vapors it gives off. It is too slow to cool 1095 for good hardness. The other is that lead melts at 625°, give or take a few degrees, depending on purity. Spring tempering under 700° gives a brittle spring with either of those two steels, assuming they achieved full hardness in the quench, which 1084/85 may, but  motor oil will not allow full hardness with 1095 steel. The oil should also be heated to get a better quench and hardness. The file test does not work with 1095. 1095 will lie to you with the file test. If you quench 1095 in something like motor oil, you will end up with a mix of hardened steel, and soft steel. The file will skip off the hard and not be able to reach the soft to tell you the truth of the matter. This results in a weaker finished spring. Weaker in structural  strength, and weaker in power at any given temper heat. I'm sure that method seems to work for you, but sooner or later I would expect failure of some sort down the road. If not, you're very lucky. If you must use 1095, canola oil has proven to be the fastest cooling oil without buying a commercial quench oil, and 1095 demands a fast quench medium. 1095 requires being cooled from around 1475° to under 900°, in from .6 to .8 of one second, in order to achieve full hardness to it's depth limit, which is only a tad over 1/8".  A square bar of 1095, 3/8" x 3/8", cannot be fully  hardened to the center by any oil quench. Maybe if brine quenched, but I don't believe much more depth of hardening even then.

[Mark Elliott]

LRB,

What you say may be true, but I have been successfully making springs for over 40 years.    I use both commercial quench oil and 20 W motor oil.   I have been using the same quart of motor oil for 40 years.   As to the lead,  you can't melt it all and keep it at 625 degrees.   If you measure the temp of lead in a lead pot after all the lead has melted,  it will be around 700 degrees.    I have successfully tempered springs from 650-700 degrees using a heat treat oven.

I have never tried to harden 1095 that was over 1/8" thick except for frizzens (they always worked perfectly when tempered to 350 degrees).   All gun springs are under 1/8" thick and many just 1/32" thick.   The 1/32" springs practically air harden.   If I need to harden something else made of 1095,  then I will consider a brine or agitated water quench.   I have a large aerated quench tank for case hardening.   I assume that would be acceptable for your hypothetical 3/8" or thicker square bar.  

Hopefully Jim Kibler will weigh in on this for a third opinion.   

[LRB]

  I was not recommending a brine quench for 1095, just pointing out that 1095 is a shallow hardening steel, and only brine will cool it to it's potential max hardness and depth. Brine often causes as many problems as not unless used with very thick stock. A good fast oil will get 1095 close enough for most purposes. Motor oil is not a good or fast cooling oil when used as a quench, but if you're happy with your results, then that's good enough for you, but I don't think it should be recommended to others when there are better lab proven methods that give better reliability, and more consistent results with no more extra effort. You have at least two actual metallurgists on this board. I don't believe either would disagree with my comments. Perhaps my poor composing and presentation skills, but not the actual facts. Please believe, I mean no personal argument in this, but only to point out certain indisputable facts involved.

[bob in the woods]

After hardening, I don't "quench" in the motor oil. I put the spring in a tuna can with oil and set the oil alight. When the flame goes out, I have a spring. So far, so good. 

[rich pierce]

Interesting that we have metallurgists who can share best practices and experienced builders who can share what works for them. I wonder how consistent spring steel was in the 1700s and whether large gunshops and smaller ones used the same hardening and tempering practices.

[44-henry]

I like 1095 and use it quite a bit for knives, but it is a tough steel to heat treat correctly if you do not have access to good equipment and still expect optimal results. I think steels like 1075/80 or 5160 would be a better choice as they are all very forgiving as to the heat treat methods used, plus they are so inexpensive that it makes little sense to risk using scrap steel of unknown origins.

[44-henry]

Interesting that we have metallurgists who can share best practices and experienced builders who can share what works for them. I wonder how consistent spring steel was in the 1700s and whether large gunshops and smaller ones used the same hardening and tempering practices.

You might find this thesis interesting, "A metallographic study of 18th century woodworking tools from the Williamsburg collection"

http://preserve.lehigh.edu/cgi/viewcontent.cgi?article=1266&context=etd

[Bob Roller]

I like 1095 and use it quite a bit for knives, but it is a tough steel to heat treat correctly if you do not have access to good equipment and still expect optimal results. I think steels like 1075/80 or 5160 would be a better choice as they are all very forgiving as to the heat treat methods used, plus they are so inexpensive that it makes little sense to risk using scrap steel of unknown origins.

44 Henry,
You are right on with your post. I have used 1075 for years and so far no major problems.I don't know what 5160 is but I have heard 6150 is used for cast springs with good results.

Bob Roller

[LRB]

  Yes. 44-henry is pretty much right on. 1084/85 is also a good choice, and very forgiving in heat treating. 5160 is very similar to 6150, but with a little more carbon. Makes a very good chopping blade, and a decent cutting knife. Very resistant to shock. Would make an excellent sword blade. Once widely used for auto and truck leaf springs. Many bladesmiths years ago used to prefer the 5160 leaf springs from Studebakers for blades made for hard use and chopping.

[yip]

 thanks guys but all this is a little confusing, like numbers of spring metal and such. i'm just wondering about the usage of weed wacker pull spring and how to shape and re tempering it. don't get me wrong i appreciate the input but its a little over my head. thanks again...........yip

[kentucky bucky]

Sounds like there are several ways to skin the same cat.

[Mark Elliott]

  I was not recommending a brine quench for 1095, just pointing out that 1095 is a shallow hardening steel, and only brine will cool it to it's potential max hardness and depth. Brine often causes as many problems as not unless used with very thick stock. A good fast oil will get 1095 close enough for most purposes. Motor oil is not a good or fast cooling oil when used as a quench, but if you're happy with your results, then that's good enough for you, but I don't think it should be recommended to others when there are better lab proven methods that give better reliability, and more consistent results with no more extra effort. You have at least two actual metallurgists on this board. I don't believe either would disagree with my comments. Perhaps my poor composing and presentation skills, but not the actual facts. Please believe, I mean no personal argument in this, but only to point out certain indisputable facts involved.

Ok,  you have convinced me.   I will toss the motor oil and just use the commercial quench oil.   I used the little tin of motor oil mainly for very small spings such as sear and patchbox springs.    Perhaps it didn't make so much difference with those things.   The larger stuff tended to be quenched in my gallon bucket of Brownells Tough Quench.   

No hard feelings.   I learn something new most everyday.

[rich pierce]

Ylp, these discussions serve many purposes, often well beyond the scope of the original question. If you still need more specifics about your plans, ask more. And expect the responses to go every which way :-)

[PPatch]

Yip;

Why not just dive in and give your lawnmower spring stock a try? Follow Ken G's tutorial that I linked to earlier and treat your stock like it was a hacksaw blade and see how it acts.

dave

[Mark Elliott]

Ylp, these discussions serve many purposes, often well beyond the scope of the original question. If you still need more specifics about your plans, ask more. And expect the responses to go every which way :-)

The thing is that the exact answer to the original question would assume the poster has a forge (and all the normal associated equipment) and a sufficient amounts of insulating material in which to place the coil after heating in order to anneal it and unwind it.    The poster never indicated what equipment or experience he had.   We really need to know that in order to make a recommendation.    My assumption, and I believe others, was that he didn't have those things.   If the poster would like to follow up with more information about his situation,  I would be happy to address the exact question.   However, from a pure efficiency point of view,  my original answer would still stand; forget the recycling and spend a few dollars on some 1"x12"x1/32" 1095 from Brownells.     I would consider unwinding a coil spring more trouble that it is worth.   


 

[LRB]

  Considering that he already has the coil spring, and a piece of 1095 + shipping, would not out weigh free, or in the hand, and that the spring he has is likely 1095 anyway, I would suggest he simply cut off a section and try it. No need to anneal the entire coil. Believe it or not, 1095 is faster and easier to anneal than lower carbon steels. A few heats at a very low, just barely reddish, will allow some shaping, and it will drill reasonably easy. That is one of the few good points of 1095.

[flehto]

For Pbox latch springs and Pbox opener springs  I use .015 thick, 1095 spring steel. Heat to bright red and quench in motor oil and they're very hard...can't touch them w/ a file.

Polish all surfaces and the spring is then tempered by laying all surfaces on a 1/4" thick plate heated w/ a Mapp Gas torch  from underneath.  When the surface that's being heated attains a blue/gray color, the spring is dunked in the same motor oil, wiped off and another surface is laid on the plate.  Bends get extra attention by rolling them on the plate.

I use  1/16" dia  music wire to form all bends.....a sharp corner isn't a good idea. 

Used some 1/32" thick 1095 for a lid opener spring for a BC side opening Pbox ala Sapergia  and used the same procedure and it works fine.....Fred
 
 

[yip]

  thanks fellas i'll just dive into what i have and try," live and learn i always say". i thank all for the info.......................................yip