18th century steels for springs?

[Philip A.]

In the late 1700's, what steels did the likes of Manton use for their springs? Did they use available commercial grade blister or shear steel, or did they brew their own?

Seeing how high-grade springs of the time look, my guess is that they did not cut the springs from a bar, but carefully forged them to shape, keeping the finishing touches (filing and polishing) to a minimum, thus achieving unparalleled quality due to the grain flowing with the taper. This would explain why modern springs look clumsy in comparison, even though we have much better steel alloys available.

[rich pierce]

Gunsmith estate inventories I’ve seen include iron and spring steel. No details of course.

[smart dog]

Hi Philip,
By mid 18th century they had crucible steel.  Crucible steel making mills were concentrated around Sheffield.  Benjamin Huntsman's  process allowed good control of carbon content in the steel and removal of impurities.  It was arguably the finest steel in the world at the time and Sheffield dominated steel production in Europe for decades.  However, the molten steel was poured into molds so the raw output was actually a cast product with homogenous structure.  Huntsman was a clock maker who wanted to find better steel for making clock springs.  He achieved his objectives and changed industrial production.  Gunmakers almost certainly used crucible steel for springs when it became available. It was the proximity of Sheffield steel production that was such an advantage to gun making in Birmingham over London. The key bit of information here is that the product later used to forge gun springs was initially cast.  I've made many springs including main, feather, and sear springs.  I almost always use SAE 1075 carbon steel, which is basically just iron and carbon.   

dave

[P.W.Berkuta]

Swords were made in Toledo Spain, Solange in Germany and Sheffield Engling and other countries using spring steel so spring steel was available to the consumer but maybe hard to get in the Americas. Most if not all spring steel was imported.

[Philip A.]

Hi Philip,
By mid 18th century they had crucible steel.  Crucible steel making mills were concentrated around Sheffield.  Benjamin Huntsman's  process allowed good control of carbon content in the steel and removal of impurities.  It was arguably the finest steel in the world at the time and Sheffield dominated steel production in Europe for decades.  However, the molten steel was poured into molds so the raw output was actually a cast product with homogenous structure.  Huntsman was a clock maker who wanted to find better steel for making clock springs.  He achieved his objectives and changed industrial production.  Gunmakers almost certainly used crucible steel for springs when it became available. It was the proximity of Sheffield steel production that was such an advantage to gun making in Birmingham over London. The key bit of information here is that the product later used to forge gun springs was initially cast.  I've made many springs including main, feather, and sear springs.  I almost always use SAE 1075 carbon steel, which is basically just iron and carbon.   

dave

Dave, thanks. So crucible steel was a better process to improve the homogeneity of blister steel than the earlier reforging into shear steel, I didn't know it went back so far. What percentage of carbon did it contain? And did the process unknowingly add small quantities of other elements beneficial to the steel quality?

[smart dog]

Hi Philip,
As I understand the crucible process, Huntsman used coke to melt a mixture of iron and steel.  By fully melting it and keeping it molten for some time he could use fluxes to almost completely remove impurities and control the amount of carbon diffused into the molten iron from the added steel, which was often was blister steel.  He could make steel with various levels of carbon and the slow cooling allowed the mixture to be homogenous.

dave

[Philip A.]

So a modern carbon steel from a good mill should be as good or better than what they had at the time.

What we don't have is the know-how of the top smiths and spring makers, the small details and tricks during forging and shaping, what makes the difference between a good spring and an excellent one. This was taught from master to apprentice, and probably not written in books, just handwritten notes that one would keep as trade secret...

[45dash100]

So a modern carbon steel from a good mill should be as good or better than what they had at the time.

What we don't have is the know-how of the top smiths and spring makers, the small details and tricks during forging and shaping, what makes the difference between a good spring and an excellent one. This was taught from master to apprentice, and probably not written in books, just handwritten notes that one would keep as trade secret...

I don't think forging and shaping has much to do with getting a spring to be a good spring unless you're planning to actually forge one.  You can make a lot more mistakes while forging (too much or not enough heat etc) that can make a bad spring.

As I understand it, all the qualities you want from a good spring come from the heat treating and tempering process.

I think if you're a master at forging, you can probably make a spring as good as a modern machined one, but I'd be really really surprised if you could do better.

[Bob Roller]

So a modern carbon steel from a good mill should be as good or better than what they had at the time.

What we don't have is the know-how of the top smiths and spring makers, the small details and tricks during forging and shaping, what makes the difference between a good spring and an excellent one. This was taught from master to apprentice, and probably not written in books, just handwritten notes that one would keep as trade secret...

I can dispute that and so can others who are still living.The desire to duplicate the English style springs is a stimulant and I think I have come as close as anyone because I wanted to see what can be done  and had/have good quality spring material to work with.The shaping after forging takes time but the end results are worth the effort.I no longer make springs but I haven't forgotten how.
Bob Roller

[Habu]

In the experiments I've done starting with wrought iron (from the bloomery experiments), shear steel will make a fair spring but they often break due to inclusions.  Double-shear steel will work but I'm hesitant to trust it.  (OTOH, a friend has a rifle dated 1775 with a presumably-imported Germanic lock.  The mainspring has a faint stringer of slag visible on the edge, but plenty of power--and it hasn't broken yet.)

My experiments in crucible steel have resulted in steel that will make a decent spring, but the small-scale production of the experiments tends to result in inconsistent results.  The cast steel I've produced has ranged from about .4%-.7% carbon.  On my (very-small scale) production, as long as my welds are good I can get similar results starting with double-shear steel and re-forging it a few times, resulting in some loss of carbon but carbon migration throughout the steel.  Springs made of stock made like this are comparable to what I get from my cast steel. 

I think this is where things came together for Huntsman.  He had good blister steel to start with (it was produced on an industrial scale then), selected the blister steel that was best for his purposes, and processed it in larger quantity: 300-400 pounds per run.  From what I've read and seen, he had good control of the outcomes even if he didn't have lab analyses. 

[Philip A.]

In the experiments I've done starting with wrought iron (from the bloomery experiments), shear steel will make a fair spring but they often break due to inclusions.  Double-shear steel will work but I'm hesitant to trust it.  (OTOH, a friend has a rifle dated 1775 with a presumably-imported Germanic lock.  The mainspring has a faint stringer of slag visible on the edge, but plenty of power--and it hasn't broken yet.)

My experiments in crucible steel have resulted in steel that will make a decent spring, but the small-scale production of the experiments tends to result in inconsistent results.  The cast steel I've produced has ranged from about .4%-.7% carbon.  On my (very-small scale) production, as long as my welds are good I can get similar results starting with double-shear steel and re-forging it a few times, resulting in some loss of carbon but carbon migration throughout the steel.  Springs made of stock made like this are comparable to what I get from my cast steel. 

I think this is where things came together for Huntsman.  He had good blister steel to start with (it was produced on an industrial scale then), selected the blister steel that was best for his purposes, and processed it in larger quantity: 300-400 pounds per run.  From what I've read and seen, he had good control of the outcomes even if he didn't have lab analyses.

Habu, that's very interesting. No better way to understand the ancient techniques than trying and testing them!

I can dispute that and so can others who are still living.The desire to duplicate the English style springs is a stimulant and I think I have come as close as anyone because I wanted to see what can be done  and had/have good quality spring material to work with.The shaping after forging takes time but the end results are worth the effort.I no longer make springs but I haven't forgotten how.
Bob Roller

Bob, you do know a lot, because you spent years studying and trying out various techniques and materials. But how many smiths do, these days? There are thousands and thousands of gunsmiths out there, with various levels of proficiency, but only a tiny percentage of them has a real understanding of the hand skills and deep knowledge required to achieve the level of quality that late 18th century "Best" gunsmiths produced, while in those days all gunsmiths understood what it took - even if they didn't necessarily have the skills and knowledge.

As for the forging, the gunsmiths of the 17th and 18th centuries were drawing on knowledge of precision forging and heat treatment techniques developed over centuries with swordmaking, and culminating in plate armor. When you see how a high quality late medieval armor fits and moves, and realize that this is forged and hardened steel, hundred or more pieces precisely formed, finished, and fitted together, you'll see why I'm persuaded that there was more than just steel, rough forming, heat treatment, and filing involved in top quality springs.

Below, link to an old video showing the amazing flexibility of one of these forging masterpieces.

[Bob Roller]

My knowledge of "Gunsmithing"is small and never claimed to be one.I present myself as a machinist using simple machines and a lock maker/filer.I made what many considered a fine lock and in 1987 I borrowed an original Stanton lock from engraver Lynton McKenzie and was able to copy it so my parts would interchange with the Stanton,all but the screws.I put my bench crafted parts in the Stanton plate by using the screws which were 4x42 according to Lynton.It worked as precisely as the original.Some people did think I was a gunsmith and I got calls asking "Do you fool with guns"? and my answer was and is "That's dangerous" and hang up.I am now retired and no more interest in lock making or any other labor intensive jobs.I  have forgotten nothing but am enjoying NOT working and haunting the antiques district of West 14th Street from time to time.Take a look at the pictures Heinz posted and it will show what can be done with common tools.
Bob Roller

[bpd303]

About ten years ago I forged a frizzen spring out of layered Damascus knife steel that I had a small leftover piece from a knife that I made. It made a good spring but I wouldn't want to do that again. I don't remember what lock it went on and never heard from the owner of the gun if it was still in service.

[Bob Roller]

One thing I forgot to include was/is the fact the spring steels we have now are quality controlled beyond anything that was used in the days when the flintlock was the only firearm made.I used 1075 and bought it sheared to width and could cut a piece from each end of a 12 foot strip and make 2 springs and install them in two different locks and not worry about either of them breaking.No big secrets involved in making these and once a method is established it becomes part of the various parts of the job whicj in this case is a gun lock.
Bob Roller

[Philip A.]

Of course we have much better steels than back then... But we have not yet figured out how real Damascus steel was made, and PhDs in metallurgy are still debating if carbon nanotubes are part of it or not, and how the heck were carbon nanotubes formed in the steel: the blacksmiths of old went to their graves with their secrets.

What I mean is that there were complex skills involved in ancient crafts, taking years to master by someone already gifted, and these would produce superior artefacts. Look at lengedary Katana makers, who have produced unequaled blades centuries ago.

Making a good spring is nothing special, making an exceptional spring with the materials and technology available 250 years ago takes more than basic skills and know-how, and we don't have the books, nor any surviving apprentice-turned-master.

[Bob Roller]

Making a good spring now is nothing special?? It is if you were making locks and trigger for years and sending them to a European market that doesn't mind what the cost is and I speak from experience.I like the idea of not worrying about broken parts of any kind when my work
is scattered far and wide.I was mostly a one man shop and trained a friend to make small screws after he learned to read a micrometer.
He wasn't interested in learning anything beyond that.
Bob Roller

[Philip A.]

Making a good spring now is nothing special?? It is if you were making locks and trigger for years and sending them to a European market that doesn't mind what the cost is and I speak from experience.I like the idea of not worrying about broken parts of any kind when my work
is scattered far and wide.I was mostly a one man shop and trained a friend to make small screws after he learned to read a micrometer.
He wasn't interested in learning anything beyond that.
Bob Roller

I'm not talking about your work... In the 1700's and 1800's thousands of smiths produced hundreds of thousands springs for various muskets and rifles and fowlers, that were good enough to still work on surviving examples 2-300 years later. But to make the finest springs used by the Best English makers took more than that.

[Bob Roller]

I am glad good springs could be made back in the"day" but I prefer using material that I can be 99.9%certain will work and keep on working.I have mentioned a local gunsmith here,George Killen.He made springs form hood and trunk springs that were flat cross section
and he was never sure if the spring he made would work or break the first time it was flexed or compressed by cocking a hammer.I gave him a 6 foot strip of 1075 that was 1/8"thick and 3/4" wide and he tempered it the same way I did by watching the color change and said he never knew such material was available.Most of his work was on turn of the century pistols and single barrel shotguns.He passed away in 1977 at age 89.I am no longer working so springs are no longer on my list and now 88 and done
Bob Roller   

[Dphariss]

In the late 1700's, what steels did the likes of Manton use for their springs? Did they use available commercial grade blister or shear steel, or did they brew their own?

Seeing how high-grade springs of the time look, my guess is that they did not cut the springs from a bar, but carefully forged them to shape, keeping the finishing touches (filing and polishing) to a minimum, thus achieving unparalleled quality due to the grain flowing with the taper. This would explain why modern springs look clumsy in comparison, even though we have much better steel alloys available.

Blister steel. There is a youtube video somewhere on making it. Modern lock springs are generally cast. When I was doing work on Sharps I could obtain Civil War surplus Spencer mainsprings, these lock internals were made by the same company and were identical to the percussion sharps. Great improvement in the lock. Though some were TOO strong and needed to to be lightened a little. Cast springs are just “ok”  but not like forged springs.
Cast springs are invariably too thick and the thickness, from my readings, actually makes the spring sluggish.
The English makers such as Manton did not make their own locks they used “lock filers”, sub contractors,  who made the locks to their specification. Now did some have in shop lock makers. Could be, but I am going by W. Greener’s description in his 1835 “The Gun”. This is a worthwhile read/reference and it can be downloaded once found but his son’s “The Gun and Its Developement” is far more common and comes up first in many searches. Searching “The Gun 1835 W Greener” works best.

[Bob Roller]

One test I used on my locks was to hold the sear up and rock the hammer back and forth and see if the spring has the "oily"feeling Tom Dawson described.This is in springs connected by a link.I wish now that I had archived the calls I used ti get asking me to make new springs for locks that had cast springs break with catastrophic   to the bottom of the lock mortise.I did use cast frizzen springs but they have a very different function in the lock. Sear springs were forged.With a forged spring connected to a link the full strength of the spring should take a bit of effort to move during the cocking cycle and after reaching half cocked it should require little or no effort to get fully cocked.
Bob Roller

[Dphariss]

One test I used on my locks was to hold the sear up and rock the hammer back and forth and see if the spring has the "oily"feeling Tom Dawson described.This is in springs connected by a link.I wish now that I had archived the calls I used ti get asking me to make new springs for locks that had cast springs break with catastrophic   to the bottom of the lock mortise.I did use cast frizzen springs but they have a very different function in the lock. Sear springs were forged.With a forged spring connected to a link the full strength of the spring should take a bit of effort to move during the cocking cycle and after reaching half cocked it should require little or no effort to get fully cocked.
Bob Roller

James Forsythe called it “the heavy first lifting”. Makes for better function in flint or percussion.

[Bob Roller]

I heard of Forsythe but Lynton McKenzie was my "Go to"man and he was more than generous.I asked him if he was in the habit of sending valuable relics to people he never met and he said I was not on any suspect list and he wasn't worried.I still enjoy these discussions and I owe a lot to Lynton McKenzie.I am not the only one that misses this very talented and generous man.
Bob Roller

[45dash100]

Of course we have much better steels than back then... But we have not yet figured out how real Damascus steel was made, and PhDs in metallurgy are still debating if carbon nanotubes are part of it or not, and how the heck were carbon nanotubes formed in the steel: the blacksmiths of old went to their graves with their secrets.

What I mean is that there were complex skills involved in ancient crafts, taking years to master by someone already gifted, and these would produce superior artefacts. Look at lengedary Katana makers, who have produced unequaled blades centuries ago.

Making a good spring is nothing special, making an exceptional spring with the materials and technology available 250 years ago takes more than basic skills and know-how, and we don't have the books, nor any surviving apprentice-turned-master.

Pretty sure we know how the old Damascus steel was made.  Time spent in the crucible, as well as oxygen control was a big component if I remember correctly.  I don't remember the name of the guy who figured it out, but I think a little searching for wootz crucible steel would pull it up.  Think there was a documentary.

Also, while it's extremely impressive that the Japanese were able to make good blades from such poor materials (seriously, the iron sands they had to work with were terrible), their blades were not unequaled.  Not in the past, and certainly not now.

I'll agree that we don't generally have people with much hands on experience working with poor and inconsistent steel left, but that's probably a good thing.  Both for the crafters and the buyers..


ETA:  Here's the wootz steel creation process I mentioned.

[Dphariss]

Hi Philip,
By mid 18th century they had crucible steel.  Crucible steel making mills were concentrated around Sheffield.  Benjamin Huntsman's  process allowed good control of carbon content in the steel and removal of impurities.  It was arguably the finest steel in the world at the time and Sheffield dominated steel production in Europe for decades.  However, the molten steel was poured into molds so the raw output was actually a cast product with homogenous structure.  Huntsman was a clock maker who wanted to find better steel for making clock springs.  He achieved his objectives and changed industrial production.  Gunmakers almost certainly used crucible steel for springs when it became available. It was the proximity of Sheffield steel production that was such an advantage to gun making in Birmingham over London. The key bit of information here is that the product later used to forge gun springs was initially cast.  I've made many springs including main, feather, and sear springs.  I almost always use SAE 1075 carbon steel, which is basically just iron and carbon.   

dave

The steel making in England was state of the art once the crucible process was fully developed. But initially the production was in small batches and this was exported to France initially knives.   Further the crucible steel made in the 18th at least in the early years after 1740, started as steel, blister steel, the crucible process burnt off more impurities and made the cast steel more uniform in carbon content throughout the bar . But the actual steel making was apparently the carbon pack blister process initially.

[Habu]

The steel making in England was state of the art once the crucible process was fully developed. But initially the production was in small batches and this was exported to France initially knives.   Further the crucible steel made in the 18th at least in the early years after 1740, started as steel, blister steel, the crucible process burnt off more impurities and made the cast steel more uniform in carbon content throughout the bar . But the actual steel making was apparently the carbon pack blister process initially.

That was the process for about 100 years.  They had production of blister steel down to a science.  The best wrought iron available--oregrounds iron from Sweden--was converted to blister steel in 10-15 ton lots.  By weight, the blister steel was around 1.5% carbon, but the carbon wasn't homogeneously distributed through the bars. 

By working with the best available materials, and using consistent procedures, Huntsman was able to produce consistent batches of steel that averaged about .78%-.80% carbon (very close to the SAE 1075 that Bob Roller and Smart Dog have been discussing).  His process involved breaking up selected blister steel, mixing in flux, and melting it in crucibles of about 30-35#.  Multiple crucibles were heating in each furnace load.  This resulted in "batches" of 300# or so--you can make a lot of springs with 300# of steel.  Once the spring makers and lock filers got Huntsman's crucible steel, they had a material they could be, as Bob put it, 99% certain would work and keep working.  This let them focus their efforts on perfecting their heat treatment methodology and refining the designs of their springs.