Results 1 to 12 of 12

Thread: Having trouble annealing some steel

  1. #1

    Having trouble annealing some steel

    Hi guys, Im getting set up to make a pair of 1/4" hollow/rounds. I needed to make a scratch stock to help shape the soles. (Suggested in two of the books Im using.) I tried to anneal a Garlick scraper so I could shape a scratch stock blade from it - failed miserably and still cant cut it after 2 attempts. Next I tried an old sawzall blade. After 2 attempts I got it softened enough to cut with a bimetal hacksaw blade and filed to shape. She works pretty well. But I cant figured out why I had a hard time with this.

    I used a map gas torch. I let the blade get bright red (to my eyes, it never got orange, but maybe Im wrong). I put it in a can full of lime (insulator) and let it cool. After one pass through this, it couldnt be cut with a hacksaw or filed - both just skated across it the steel. After the second try the sawzall blade was better, but that scraper was still uncuttable.

    Can anyone see what Im doing wrong here? For example, could I be getting it too hot?
    Another odd sign - the stuff Im reading says that when its hot enough the blade will no longer be magnetic. I tried that magnet multiple times during the process - this steel was ALWAYS magnetic.

    Clearly, Im missing something. Can you please give me a hand?

    Many thanks,
    Fred
    Last edited by Frederick Skelly; 03-16-2015 at 6:45 AM. Reason: typo

  2. #2
    Join Date
    Apr 2008
    Location
    East Virginia
    Posts
    830
    If it was still magnetic, my guess would be that you weren't getting it hot enough (to critical temp).

  3. #3
    Join Date
    Feb 2004
    Location
    Perth, Australia
    Posts
    9,469
    Hi Fred

    Firstly, I would not bother softening a scraper to shape it. I would simply cut it to shape with a Dremel, and smooth the edges on a grinder or belt sander. Then I would create the scratch stock shape with chainsaw files.

    If you really want to soften the steel first, heat it to red hot in a darkish room. Often the red you think you are getting is misleading in the daylight.

    Lastly, the sawmill blade/teeth may not be capable enough to cut anyway. I prefer to score and snap blades than saw them.

    Regards from Perth

    Derek

  4. #4
    Join Date
    Jan 2009
    Location
    Williamsburg,Va.
    Posts
    12,402
    It is very difficult to COOL something like a thin sheet of spring steel SLOWLY enough. In the case of the Garlick,you'd have been better off just hacksawing (if possible,or Dremeling it) and filing it to shape as it was originally. Garlick stuff is made of such soft steel as it is anyway. You probably just made it harder than it previously was.

    One time I put some 1/2" wide strips of .042" thick 1095 spring steel in my electric furnace,heated them up to critical temp. turned off the furnace and left them overnight to cool slowly. In the morning they had some scale on them,but were just as hard as before! The furnace must not have been insulated enough. 2" of soft(full of air pockets)fire bricks did not slow down the cooling process fast enough.

    When I want to anneal less stubborn small parts like screws I made from drill rod,I'd play a torch on a tin can full of DRY sand,getting it good and hot. Then,I'd heat the parts orange and thrust them beneath the sand. That worked since the parts were not so thin that they'd cool off too fast.

    If I had to soften it,I'd tie it snugly to a thicker block of steel with iron binding wire (which can stand the heat),and heat the whole thing up in the furnace and let it cool overnight.

    I HAVE put pretty large blocks of hardened steel in the wood stove,well packed with firewood and let it slowly burn down to cool for several hours. The blocks were about 12" x 4" x1". I managed to anneal 3 of them at a time. They got good and red hot in there before the wood slowly got consumed,with the damper just letting in a small amount of air. You could tie the scraper to something like the larger block of steel and try it. Any kind of block will work. You aren't annealing the block. Mild steel is fine.
    Last edited by george wilson; 03-16-2015 at 9:25 AM.

  5. #5
    Join Date
    Dec 2003
    Location
    Hutchinson, MN
    Posts
    600
    Quote Originally Posted by george wilson View Post
    I HAVE put pretty large blocks of hardened steel in the wood stove,well packed with firewood and let it slowly burn down to cool for several hours.
    I had a friend who works in a coal-fired power plant (little one, only 15MW) anneal a bar of 1/4" thick OCLS (old chevy leaf spring, likely 5160) by putting it on the floating bed of the coal burner and letting it cycle through (about 2 hours). He then buried it in the same hot ashes and let it sit for more than 24 hours. The next afternoon, we fished it out and it was still almost too hot to hold but was dead soft. Worked pretty well.

  6. #6
    Quote Originally Posted by Jacob Reverb View Post
    If it was still magnetic, my guess would be that you weren't getting it hot enough (to critical temp).
    Thats what I was thinking when I did it Jacob. Thanks.
    "All that is necessary for the triumph of evil is that good men do nothing."

    “If you want to know what a man's like, take a good look at how he treats his inferiors, not his equals.”

  7. #7
    Derek and George - thank you! I was utterly stumped by what I was seeing. I think I can find a way to get it done now using several of your suggestions.

    Many thanks,
    Fred

  8. #8
    Join Date
    Mar 2012
    Location
    Mid coast Maine
    Posts
    477
    And yet it is so easy to just "blue" a chisel on a grinder and the edge is soft and ruined, go figure.
    Jim
    Ancora Yacht Service

  9. #9
    Join Date
    Jan 2009
    Location
    Williamsburg,Va.
    Posts
    12,402
    The cutting edge of a chisel will only be ruined for a fraction of an inch if you burn it on a grinder. How much will you have to grind off to get back into good steel? Not a lot,usually.

    I just remembered: Back when I was teaching shop,we had no money. But,I got large,6 or 7" wide ruined bandsaw blades from the local saw mill. They were 1/16" thick. I showed the students how to clamp the blades in a machinist's vise,and take a cold chisel to it. The cutting edge of the cold chisel was pointed downwards some,so that the edge was absolutely flush with the top of the vise's jaws. Then,holding the chisel so that one corner of it was in contact with the saw blade,we could crack the blade off flush with the vise,moving the chisel along as we cracked the bandsaw blade.

    These industrial bandsaw blades were at least as hard as your Garlick scrapers could be. The key to success without distorting the scraper steel is to only JUST crack the blade and move the chisel a little bit to the next uncracked place and repeat.
    Hold the chisel so that it is tilted sideways so that one corner is JUST barely presented to the scraper you are cracking. A bit of skill has to be developed.

    The cold chisel had to be re ground a few times in the process,but soon a scraper could be made from the saw blade. It would not have much distortion if the chiseler was careful to JUST crack the blade,and no more as he went along. Some hammering could get the scraper back to flat if needed. Then,the chiseling could be ground away,and a proper scraper edge filed out.

    I must say,the boys were extremely fascinated at how they could draw up big fluffy shavings with them. We had to make our own benches. This is how we finished the tops.

    Sorry I didn't recall this yesterday. Getting old and forgetful,for sure. When you have nearly nothing to work with,a way may still be found if you use your head. Old timers did not have modern sheet metal shear machines. Even if you had one,the strips would come out curled up.
    Last edited by george wilson; 03-17-2015 at 8:13 AM.

  10. #10
    Join Date
    Aug 2003
    Location
    extreme southeast Nebraska
    Posts
    3,113
    If you have a friend or buddy that has a plasma cutter, that'the way ti go.
    Jr.
    Hand tools are very modern- they are all cordless
    NORMAL is just a setting on the washing machine.
    Be who you are and say what you feel... because those that matter... don't mind...and those that mind...don't matter!
    By Hammer and Hand All Arts Do Stand

  11. #11
    Join Date
    Jan 2009
    Location
    Williamsburg,Va.
    Posts
    12,402
    But,Harry,how much width of steel gets the temper burned out of it by the plasma cutter? Wouldn't a water jet be better? I'd rather just do it myself than pay big fees to machine shops anyway.

    Glad you are still well. You don't post often.

  12. #12
    Quote Originally Posted by george wilson View Post
    The cutting edge of a chisel will only be ruined for a fraction of an inch if you burn it on a grinder. How much will you have to grind off to get back into good steel? Not a lot,usually.

    I just remembered: Back when I was teaching shop,we had no money. But,I got large,6 or 7" wide ruined bandsaw blades from the local saw mill. They were 1/16" thick. I showed the students how to clamp the blades in a machinist's vise,and take a cold chisel to it. The cutting edge of the cold chisel was pointed downwards some,so that the edge was absolutely flush with the top of the vise's jaws. Then,holding the chisel so that one corner of it was in contact with the saw blade,we could crack the blade off flush with the vise,moving the chisel along as we cracked the bandsaw blade.

    These industrial bandsaw blades were at least as hard as your Garlick scrapers could be. The key to success without distorting the scraper steel is to only JUST crack the blade and move the chisel a little bit to the next uncracked place and repeat.
    Hold the chisel so that it is tilted sideways so that one corner is JUST barely presented to the scraper you are cracking. A bit of skill has to be developed.
    Thanks George! I'll give this a try too!
    Fred

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •