Tempering Tantrums

[jerrywh]

Wick,
The english navy had thousands of ships that sailed the world. They had to be pretty good.
Good is a relative term i guess. They were on the pacific coast about 200 years before lewis and Clark. gps is better.
I have taken the springs out of French shotgun that was made about 1800. They were made out of crucible steel. you could still see the grain in the metal. They still worked very well. What else could one ask of a spring? I have made crucile spring steel myself.

 

[CoyoteJoe]

There's a wonderful lot of great information here, but to the original question of what went wrong, I think you may have confused spring tempering with frizzen tempering. In other words, you tempered the frizzen too hot. But you now have a good frizzen and you learned from the experience. By posting here you got very good responses from which I also learned, thanks for posting. :thumbsup:

 

[George91946]

Thanks I've learned a lot about tempering and hardening. An update is that I cooked the frizzen at 375 for an hour and it still sparks. Have been shaping the stock with all hardware in place, and have been firing the lock repeatedly. I put in a new flint earlier, and have done over 100 hammer falls. So far, a spark every time, and the flint is still sharp.

Now could I ask a few more questions that your discussions have opened up?

1. What kind of steel would be in an L & R Frizzen?

2. What specific temperature would be recommended for hardening that specific steel?

3. Is automatic transmission fluid the optimal quench for this type of steel? or is a light vegetable oil preferred?

Thanks again.

Lisle George

 

[jerrywh]

The only way to determine what steel L&R is having their frizzens cast in is to ask them.
From having my locks cast I have learned that there are basically four steels used and the process for hardening them is all the same. The steels are 6150, 1095, and 01. The hardening temp is 1550°f. The tempering temp is 350° to 450° depending on one’s preference. I don't know what would be considered the ultimate quenching medium but it is not necessary to have the ultimate. Room temp water or water with a thin film of oil on the top worked for 500 or 600 years.
As with all things it's not so much the guitar that makes the music as it is the guy holding the pick. If you know what you are doing you will have very little trouble. Over the last 55 years I have probably tried every method you can dream up and my conclusion for tempering is the oil burn off method is the least consistent, the lead bath method is the next best and the controlled oven method is the best. However once one has figured out a method that works consistently all of them work pretty well. Sometimes you will find a frizzen made of mild steel. They just won't harden and must be case hardened. I even case harden tool steel just to add carbon to the surface.
PS 6150 doesn't get very hard and doesn't spark very well. It as chrome in it. I case harden them.

 

What it all boils down to is quenching the hot steel at critical temp and cooling it fast enough to get near complete transformation to martensite. Some steels you have 2-4 seconds to quench, others less than a second. If you can cool the steel to below 400 degrees in under a couple of seconds your quench will work with most steels. The trick is not to quench so fast that you cause it to crack. After that you soften the metal slightly with a temper, best to do at least two tempers, as the first causes more martensite to appear and it's untempered.

If you can do that, 90% of the battle is won. You can play with oil temps, cryo tempering, like some sword blades were left in snow drifts, different thermal cycling before harding, multiple quenches, ect, to refine the grain structure, but it all boils down to getting it hard, then softening it to a working hardness so it won't break. Nothing magical about it.

As for the "old ways"? I've talked with old black smiths, some knew there stuff, some didn't have a clue on heat treating. One who sharpened bush hog blades told me you had to have a coal forge, so it'd put carbon in the steel (utter BS), and that to heat treat the blades it would take thousands of dollars of high tech equipment(also utter BS). A lot of them learned through rout, and found a method that worked, not knowing why it worked. Some of the old masters really were masters, some not so much.

As for old steel vs. new steel, a little trace elements can make a difference in heat treating. Will it make a huge difference in making a spring or frizzen? Probably not, but the potential for further refinement is there. Also even today steel varies from one batch to the next. Again, not a big difference, but enough with testing I've seen it.

 

[J.D.]

I do believe that L&R and Chambers use 1095 steel for frizzens. I think Davis does too. All of the European frizzens I have hardened required case hardening or a half sole, which means they are made of a medium to low carbon steel.

As a rule of thumb, if a frizzen isn't made by one of the "name" American lock makers, I case harden or half sole 'em.

As to which is the best quenching medium? Try a few parts in different quenches and find out which works best for you. IMHO, developing your own technique and trying different quench mediums is about the only way you can find out what really works for you.

 

[jerrywh]

Right on. What you say is true about the so called old timers. They werent' much different than we are today. Some were good others never had a clue. Sorting things out can be tough for beginners. Seems like the ones who knew the least were the ones the most prone to argue about it.
The real good bladesmiths to day know a great deal about steels and heat treating but it is a big field now days and almost a profession of itself. As you indicate , this primitive gunlock stuff is basically simple.

 

It maybe basically simple, and a less than perfect heat treat will work,

But the flint lock is elegance personified. Yes, the cap lock could be considered more advanced, but before the cap came along the flintlock was pretty much perfected. Same with the Pennsylvania rifle, in a way they both remind me of the Japanese sword, there are minor differences, but the basic form and function was perfected a long time ago, and form following function both are beautiful. The shear simplicity of the lock does nothing but add to it's beauty.