hardening fire strikers

[Nobby]

afternoon all,  I've started making fire strikers, for my wife's scout troop, using coil spring. However, i'm having trouble getting them hard enough to produce sparks using flint.

I heated them to the point of non-magnetic then oil quenched but got very few sparks. should i water quench instead or can anyone offer some other advice?

all comments welcome

cheers

Nobby 

[arkie]

Water will give you a harder quench. I like to use old files because the file teeth give you a good grip on the striker.

[Nobby]

Thanks arkie

[Irondragon Forge ClayWorks]

Have you done a spark & break/snap test? I have seen some coil springs that were hard to harden if at all depending on the springs. Do you have any pictures? I've also had some files (HF Chinese junk) that were case hardened and wouldn't get hard enough for strikers.

[Frosty]

I've had my best luck with garage door spring, flint strikers, quenching them in water. I only quench the striker surface, not the handle to prevent brittleness in the handles. 

You don't want the white sizzling sparklers, they don't last long enough, Big red one last but aren't hot enough, I like fat orange sparks, they're hot enough and last till you can get a coal going. I'm way out of practice but discovered it was easier to hold back a little from critical temp than it was tempering them back to fat orange spark hard. 

Frosty The Lucky.

[Nobby]

thanks for all the replies to date. I attempted to harden these again today. took them up to a bright orange in the gas forge then quenched just the striking face in water. NO bloody sparks off of the flint and then bugger snapped as the water quenching had caused a crack in the striking face. So i came to a couple of possible conclusions:

1. I don't really know what I'm doing. However, that's ok as every day is a learning experience.

2. the steel in the coil spring may not be as good as I assumed. However, on the grinder i get a a multitude of orange sparks originating at the grinder disc which appear to fit the descriptions I've found when looking into spark testing ie.

High-carbon steel

High-carbon steel has a bushy spark pattern (lots of forking) that starts at the grinding wheel. The sparks are not as bright as the medium-carbon steel ones.^[5]

3. Am I doing something wrong with the quenching process? Is it possible to do something wrong when quenching? Results with oil and water appear to be no different although I now realise that I should probably have heated the quenching medium somewhat to reduce the thermal shock [like  i said: "every day...." etc]

Conclusion [having recalled Einsteins definition of insanity ie.

 “The definition of insanity is doing the same thing over and over again, but expecting different results.” 

1. try steel from a different coil spring [we have loads]

2. Await further pearls of wisdom from all you kind people out there.

Thanks again

ps. I might try and upload an image or short vid of the steel on the grinder

Nobby

[George N. M.]

I have used garage door springs with a water quench and generally have had good results.  However, there have been a few times when I used a spring that wouldn't harden or spark.  I figure that it was some odd alloy that wouldn't perform for what I wanted.  I suggest that you try a different spring or an OLD file.  Some new files (e.g. HF and similar) do not seem to be good blacksmith stock.

"By Hammer and Hand all arts do stand."

[Nobby]

Hello again,

still attempting to get to the bottom of my issues with attempting to harden coil spring steel so I thought I'd post an image of the spark test under the grinder. Any opinions as to whether this indicates a relatively high carbon content or not would be appreciated.

cheers

 

Nobby

 

 

[Frosty]

That doesn't look high carbon to me, probably has an alloy to make it springy rather than much carbon. 

Spark test with the grinder before spending a bunch of time making strikers next time. The sparks shown aren't branching in general at all. You want a fireworks display of branching sparks. 

Try boot sale Hex wrenches, punches and chisels, they're usually reasonably high carbon but spark test before trying. You'll want to do a test coupon in oil before using water quench to be sure nothing goes wrong in use. If it's hard enough to spark with an oil quench it'll be safer from breaking in use. 

Frosty The Lucky.

[ThomasPowers]

The best way to judge a spark test is to get a number of known samples and compare one to another till you get a pretty good match.

Try a file, piece of automotive coil spring, some A-36, a piece of silver steel, etc.  It's handy to build up a known steel collection and be able to get pretty close to the unknown piece.

[Nobby]

Frosty/Thomas

thanks for the replies. I was finding it difficult comparing the results of the spark test with illustrations. I'll definitely start a trial of different steels. Thanks for the suggestion.

Nobby

[Benona blacksmith]

Here is sparks from some 1095 I had laying around. This is what your looking for.

[Nobby]

Benona

thanks for that. It illustrates the difference quite dramatically. 

Still learning !

[ThomasPowers]

Since the sparks can be a bit different depending on the grinder you are using (speed, medium, pressure, etc) having a set of test pieces that YOU use on the same machine the same way helps. (I'd suggest adding in a piece of cast iron, wrought iron and one of the high alloy steel like H13 or S7 or D2...)  One way to do this economically is to get a group of people together and each one select an alloy to buy a piece of and then cut it in lengths and trade. Helps if you can stamp the alloy in the "holding end".

[Nobby]

On 3/12/2019 at 11:00 AM, ThomasPowers said:

Mod removes waste of bandwidth

Thanks for the idea Thomas

[how do i apply for membership of the curmudgeon club ? ;-)

[ThomasPowers]

Participate here and show a willingness to answer the same questions hundreds of times without becoming any more than "grumpy"?  (Actually I believe we do get more than grumpy; but we try to refrain from posting on those threads...)

Thomas who has the T shirt showing the Curmudgeons club portrait  painted on a cave wall and who was once referred to as "The ancient Smith Wilelm" in a finnish newspaper...

[SLAG]

Curmudgeon club?,

Practice,  more practice.

BUT do not take my advice very far.

My application was rejected!

I think that Mr. Thomas Powers is the registrar.

Not sure though.

SLAG

p.s.  Mr. Powers beat me to the punch, and posted whilst I was crafting my response.

[Rashelle]

Another thing that will effect sparking after hardening on strikers is regrind the face after hardening.

 

[Nobby]

Got my hands on some files now so watch this space.

 

[Nobby]

so, made three strikers from two different files and on from a hex key. all treated at the same temperature in our 0ven [@275C ; @530F if my maths is correct?] and quenched in oil.

The hex key striker gives plenty of sparks off the flint. However, those made from the files - a big fat NOTHING.

Retempered the file strikers in water - Nothing. So, I'm assuming this simply means a different steel - should I temper these at a higher temperature ?

Any advice gratefully received.

cheers 

Nobby

[ThomasPowers]

Ok is that temperature the one you quenched to harden at; or the one you drew temper at?  It doesn't matter what you quench it in when you draw temper.

If it's the quench to harden temperature it's about 1000 degF too cold to do any good; you need to be above the austenitizing temperature to harden. (And what you quench it in does make a big difference!)

If it was the temp you drew temper to it sounds pretty high.

As mentioned quenching after drawing the temper doesn't matter what you use; but oil is messier!

The mixup of jargon/process gives me the feeling you don't understand what you are doing. Did you do a 3 step: Normalize, Harden, Draw Temper on them?  If not what did you do?

[Steve Sells]

28 minutes ago, Nobby said:

Retempered the file strikers in water - Nothing. So, I'm assuming this simply means a different steel - should I temper these at a higher temperature ?

It is not possible to temper in water it wont get hot enough

[ThomasPowers]

Well not without excessive pressures being involved...

[Nobby]

Hi Thomas, you're right I've confused the terms [I tend to exist in a state of confusion].

I'm going to go back and read the stickies again !  but be prepared for more questions .....

thanks for the replies

[ThomasPowers]

Pretty common especially as tempering used to be used to cover all the heat treatments.  Hardening and drawing temper especially as that was often done together using residual heat from the piece to draw the temper.

As it does confuse things we try to split out all the different heat treatments into their own specific terms. (I've had a lot of folks who use Heat Treat  as hardening when annealing is a heat treat and gives you the softest metal.)

It doesn't help when many folks outside of the craft use the terms wrongly---I was looking through a kids book on Historic Tools and Gadgets where they said: smelting was mixing melted metals to form alloys!  I corrected that with my sharpie...it also had that a broad axe was used for chopping and an adze was used to square trees before pit sawing.  I really, really wish they had someone who knew something about historical tools/crafts  edit it before they published it!