If 'lines' in Springs cause them to break ... then WHY do these work?

[Flint62Smoothie]

Look at the highly decorated 'V'-springs on this hand made lock by Bolek M. from Poland. The lock works like a charm! But with all the filed decorations across the thickness of the springs, never mind on the edges ... then why don't they break?

 

[Sooty Scot]

I'm no expert but it looks to me as if those "grooves" were cast in-not cut in. It seems that they would not create a weak point for stresses in the metal because those stresses would have been set in the casting, and are essentially round-bottomed.

In working wood, sharp edged grooves or scratches weaken the fibers more than a round- edged equivalent. I suspect hard spring metal would behave similarly.

Just my speculation, mind you.

 

[HSmithTX]

No sharp edges to create a stress riser. Rounded or radiused is fine.

 

[SOLANCO]

I'm no expert but it looks to me as if those "grooves" were cast in-not cut in. It seems that they would not create a weak point for stresses in the metal because those stresses would have been set in the casting, and are essentially round-bottomed.

In working wood, sharp edged grooves or scratches weaken the fibers more than a round- edged equivalent. I suspect hard spring metal would behave similarly.

Just my speculation, mind you.

I do not believe springs are castings. I do not believe you can cast a flexible item.

 

[Pete G]

I do not believe springs are castings. I do not believe you can cast a flexible item.

There are several commercial manufacturers who would disagree

 

[Flint62Smoothie]

All parts were hand forged ...

 

[ZUG]

It's MAGIC ---

 

[HSmithTX]

You can in fact cast springs, it's done all day every day. The metal and process used and the heat treat most importantly determines if you have a 1/2 cycle spring or a good quality long lasting spring. I would very much prefer a bar or sheet stock spring forged and heat treated over cast for lock parts but where the application is right a cast spring can be just fine.

 

[Nav]

I would say the composition of the steel is everything.

 

[HSmithTX]

You can make a decent spring with half decent material and a great heat treat, but you can't make a spring worth a squirt using the best material possible and a poor heat treat. The material and the heat treat go hand-in-hand really, both need to be good to get a good spring. The better both are the better the spring.

 

[James Kibler]

To answer the question, notches such as these will tend to act as a stress riser, but I suspect the amount of concentrated stress isn't significant enough to make a difference.

The same thing goes with file marks across a spring. This has been way overblown in the past. Just look at original work and you can see that they knew it didn't really matter much.

And yes, springs can be cast. Very common in the muzzleloading world.

Jim

 

[dave_person]

Hi,
As Jim wrote, in theory the transverse scratches could cause stress but the reality is the concern is way over blown. Just look at original springs used for centuries with all kinds of transverse scratches. I forge quite a few springs and on a Brown Bess spring I just made, I filed in notches in the side used as production marks on all original Bess springs.

dave

 

[Flint62Smoothie]

Thank you all!

 

[Old-Duckman]

Don’t know the answer but that is some beautiful workmanship!

 

[Nav]

Witchcraft!

 

[rich pierce]

They are at the edge not across the leaf.

 

[LRB]

They are at the edge not across the leaf.

I agree. I think that fact is the most significant reason they are of little concern if any at all.

 

[Eutycus]

A form of knurling , maybe?

 

[shorthair]

Plus they may have been done prior to heat treating, not sure as I have little knowledge in this area.

 

[TobJohn]

This is a much more simple example, but the spring of this wheellock has some light engraving, but the wide part of the spring has the diagonal file marks that are usually recommended for making springs (from what I’ve read. Never tried myself). It could be proof that wheellock smiths understood the weakness of perpendicular or parallel file marks, even if they decorated the springs.