Any knife makers on here? Steel question

[GraemeVW]

I have a very nice antique pocket knife.
Unfortunately, it's broken. Well, 2 of the back springs are.
It's been sat in a drawer for a year as no one thinks they can fix it. Took it to some professional folding knife makers and although they loved it, they didn't want to risk trying to fix it.
It's quite rare, desirable, and valuable and I think that scares them.

This all sounds a little defeatist to me, so I guess I'll try and do it myself.

The hard part, or so I'm told, will be removing a couple of the rivets, and putting new ones back, without breaking the scales.

But before I get to that, I need to make new springs. They are an odd thickness if i remember right, dont think they were made to a size, were probably just ground till they fit.

I can cut the shape, I can grind to the right thickness, but what steel?

I've tried to find out but don't really know what I'm looking for. Will need hardening and tempering I assume, so something that can be heat treated at home too. Needs to then act as a spring.

Any thoughts?

 

[magnet]

Ive made a number of folding knives. For mine i've used en9 carbon steel mainly because i can get plenty of scrap from work. The back spring is the hardest part to get right but can be done with pretty basic tools.
You might want to get Knife repair by Adrian A Harris its an inexpensive book and pretty good.
If you want any en9 steel just pm me be happy to send you some.

 

[GraemeVW]

Ive made a number of folding knives. For mine i've used en9 carbon steel mainly because i can get plenty of scrap from work. The back spring is the hardest part to get right but can be done with pretty basic tools.
You might want to get Knife repair by Adrian A Harris its an inexpensive book and pretty good.
If you want any en9 steel just pm me be happy to send you some.

You say the back spring is the hardest part to get right, is that when making from scratch?
I can imaging knowing where to place the pivots, how to judge how much spring it needs etc, would all make designing it a real pain.
But, all i have to do is copy what was made originally.
Or am I missing something and This is going to be alot harder than I think?

I will look for the book, thanks.

En9 you say? Internet tells me heat to around 830°, quench in oil, then temper. Do you know what temperature I'd need to temper it to in order to create a decent back spring?

Thanks.

 

[Barking Mat]

Could you not adapt something which is commercially available ?

Just a thought.

 

[GraemeVW]

Could you not adapt something which is commercially available ?

Just a thought.

I wouldn't have thought so. It's a hand made 100 year old knife.

 

[magnet]

You say the back spring is the hardest part to get right, is that when making from scratch?
I can imaging knowing where to place the pivots, how to judge how much spring it needs etc, would all make designing it a real pain.
But, all i have to do is copy what was made originally.
Or am I missing something and This is going to be alot harder than I think?

I will look for the book, thanks.

En9 you say? Internet tells me heat to around 830°, quench in oil, then temper. Do you know what temperature I'd need to temper it to in order to create a decent back spring?

Thanks.

When i've tempered the springs i heat to cherry red and until non magnetic. Quench in oil, polish back to bright then heat gently from the thickest section until a uniform blue runs the full length then quench again. As for exact temperature i have no idea.
I've had my share of failures with back springs but with perseverance ive ironed out most of the difficulties. If that is a rare and valuable knife it may not be the thing to cut your teeth on (pun intended).
Why not make a few springs and see how you go. The way i see it however if its broken and no one can be found to fix it what have you got to lose.

 

[Screwdriver]

I second that. Blue is typically referred to as "spring temper".

As for the repair. First thing I'd do is measure carefully and maybe scan for "perfect" dimensions. Vectorise or make a line drawing/CAD and send it out for laser cutting. I image it would be very cost effective. Would be fun to hand craft but if you can get the right material at the correct thickness, laser/wazer (or even wire EDM @awemawson) would be the way to go.

 

[GraemeVW]

When i've tempered the springs i heat to cherry red and until non magnetic. Quench in oil, polish back to bright then heat gently from the thickest section until a uniform blue runs the full length then quench again. As for exact temperature i have no idea.
I've had my share of failures with back springs but with perseverance ive ironed out most of the difficulties. If that is a rare and valuable knife it may not be the thing to cut your teeth on (pun intended).
Why not make a few springs and see how you go. The way i see it however if its broken and no one can be found to fix it what have you got to lose.

Blue is a good enough for me. I can work with that.
It's a Joseph Rodgers knife from the late 1890s, but as you say, it's broken now so I may as well try.
Luckily I can try making the springs before I even need to touch the knife. If I think I've managed to make suitable springs, I'll remove a rivet or two.

 

[GraemeVW]

I second that. Blue is typically referred to as "spring temper".

As for the repair. First thing I'd do is measure carefully and maybe scan for "perfect" dimensions. Vectorise or make a line drawing/CAD and send it out for laser cutting. I image it would be very cost effective. Would be fun to hand craft but if you can get the right material at the correct thickness, laser/wazer (or even wire EDM @awemawson) would be the way to go.

It would be easier and quicker for me, with the skills I have and the skills I don't, to just hand make them rather than create a cad file.
I have done some 2d cad before, but it's really not my happy place.

 

[pedrobedro]

I made a new back spring for mine out of O1 tool steel or precision ground flat stock from Cromwell. It's easy to temper to spring hardness just using a bean can of oil and a blow lamp.

 

[GraemeVW]

I made a new back spring for mine out of O1 tool steel or precision ground flat stock from Cromwell. It's easy to temper to spring hardness just using a bean can of oil and a blow lamp.

I was looking at 01 last night. I can pick it up cheaply and locally too.
I need some 1/8" flat and it seems i can only get that in mild steel, or 01 ground. So I'll probably use that.
Good to know you used it successfully .

 

[tom2207]

how about wire cut it from a spring ,,, no heat to play with at all ,,, just install it and your laughing

 

[GraemeVW]

how about wire cut it from a spring ,,, no heat to play with at all ,,, just install it and your laughing

Can't do that in my workshop though.

Other thing I guess is this is an opportunity to try something new (spring tempering)

 

[tom2207]

Can't do that in my workshop though.

Other thing I guess is this is an opportunity to try something new (spring tempering)

yep ,,, but theres a man who can ,, he may show up here but it was just a thought , a way to get the job done and be sure of the results , if you want to play with heat treat start with a few flat screwdrivers then move onto a simple knife , and if they dont quite work as well as you would like you dont have to start knocking out pins again in your knife ,,,,

 

[GraemeVW]

yep ,,, but theres a man who can ,, he may show up here but it was just a thought , a way to get the job done and be sure of the results , if you want to play with heat treat start with a few flat screwdrivers then move onto a simple knife , and if they dont quite work as well as you would like you dont have to start knocking out pins again in your knife ,,,,

I will.
I'll probably cut the new springs, then practice heat treating, and even when everything gone well I probably won't pein the new pin in until it's been thoroughly tested.