Tuning Cutting Springs

[Steveoo]

For the record, for anyone interested, here is the old English way of cutting and re- tempering mainsprings...carried out for Eons on vintage Webleys and BSAs more than 70 years ago, many of the mainsprings still functioning to this day....The master craftsman way.

You chop the spring coil through on the edge of the grinding wheel....heat the end to orange heat and drop it onto a guide rod or mocked up guide held in the vice, quickly pushing down with a leather gauntlet or flat piece of metal.
The spring exactly follows the square face of the base of the guide and kept perfectly square by the tube part of the guide it is sat over. Perfect square mainspring end.
We can then offer to the side of the grinding wheel to flatten further.

Here's the shocker..
Quenching was actually done into water. ..the way I do it.
This potentially makes the mainspring end quite brittle, but then heating again until a dull blue is achieved (just past purple) and quenching again.
That's the true way old mainsprings were made correctly ...

Another simple way is quenching straight in Parrafin, which offers some level of tempering unlike oil which can be too slow a quench for correctness.

Forget this new contrivence of letting it cool in air...Yes it will avoid brittle issues for the unskilled but the last few coils run the chance of losing potentials.

Polishing ends....well there's no harm doing it is there and brings a sense of job satisfaction.

 

[Mycapt65]

When I make a spring out of music wire which is already hardened and tempered it's bent beyond it's limit to form the spring. Then to stress relieve it I bake it at 350 for an hour. Doesn't take much heat to affect the steel.

You wind your own springs?

 

[KWK]

You wind your own springs?

Not airgun mainsprings, Ron. But small springs can be done easily on a lathe. I can do larger, but still not mainspring size, with a spring winding tool I have but haven't ever used it yet. It's a lathe accessory. Might not be easy on a hobby lathe that doesn't have back gears. Might not go slow enough. Back gears are a set of reduction gears you can engage. Maybe you already knew about them. If I recall correctly I believe you've had some lathe experience.

 

[KWK]

For the record, for anyone interested, here is the old English way of cutting and re- tempering mainsprings...carried out for Eons on vintage Webleys and BSAs more than 70 years ago, many of the mainsprings still functioning to this day....The master craftsman way.

You chop the spring coil through on the edge of the grinding wheel....heat the end to orange heat and drop it onto a guide rod or mocked up guide held in the vice, quickly pushing down with a leather gauntlet or flat piece of metal.
The spring exactly follows the square face of the base of the guide and kept perfectly square by the tube part of the guide it is sat over. Perfect square mainspring end.
We can then offer to the side of the grinding wheel to flatten further.

Here's the shocker..
Quenching was actually done into water. ..the way I do it.
This potentially makes the mainspring end quite brittle, but then heating again until a dull blue is achieved (just past purple) and quenching again.
That's the true way old mainsprings were made correctly ...

Another simple way is quenching straight in Parrafin, which offers some level of tempering unlike oil which can be too slow a quench for correctness.

Forget this new contrivence of letting it cool in air...Yes it will avoid brittle issues for the unskilled but the last few coils run the chance of losing potentials.

Polishing ends....well there's no harm doing it is there and brings a sense of job satisfaction.

We don't call it parrafin here. Guys will think you mean wax. We call it kerosene. And it has many uses in the shop including cutting fluid (usually blended) for certain metals including aluminum (aluminium). It gives the greatest finish. But it stinks! So I usually use something else.
Nothing new about water quench. Brine cools quicker and evenly because it doesn't turn to steam as readily.
As I noted previously, The side of the grinding wheel gives a smoother finish than the face.
I don't nick a spring with the corner of my wheel because it messes the edge of the wheel up. Matters to me because that's where I grind all my lathe and metal shaper tooling. I don't want to keep dressing my wheels away. Everybody uses cut off wheels these days. Practically anybody has them, they're so handy.

 

[Mycapt65]

Not airgun mainsprings, Ron. But small springs can be done easily on a lathe. I can do larger, but still not mainspring size, with a spring winding tool I have but haven't ever used it yet. It's a lathe accessory. Might not be easy on a hobby lathe that doesn't have back gears. Might not go slow enough. Back gears are a set of reduction gears you can engage. Maybe you already knew about them. If I recall correctly I believe you've had some lathe experience.

Thanks. I have very limited experience with lathes. They were either a rough belt driven wood lathe I used for turning cork fishing rod handles or very large lathes at the railroad I worked at that turned train axels or traction motor armatures. So I understand only the basics and welcome any information. Thank you

 

[razor62]

This is a video that I made when I tuned my FWB Sport rifle. There's a segment in the video where I show how I cut and formed the spring. My rifle is currently performing perfectly and produces 14 ft/lbs.

 

[AirShot]

Yeah, sometimes we get too caught up in (details) doing the "perfect job", when just doing a reasonably good one is a 99% cure.
Whether you oil quench, air temper or do whatever likely changes nothing, but we all need to follow our ways.

PS: I do polish my spring-end, but that may not improve performance much -> but it makes me feel better.

Springs do rotate a little when cocking and firing, so...which surface is going to rotate easier...a polished or a rough surface ??

 

[dormitionskete]

This is a video that I made when I tuned my FWB Sport rifle. There's a segment in the video where I show how I cut and formed the spring. My rifle is currently performing perfectly and produces 14 ft/lbs.

Nice video. And you have some more on your channel I want to watch. Thank you!

 

[SpiralGroove]

Springs do rotate a little when cocking and firing, so...which surface is going to rotate easier...a polished or a rough surface ??

Yeah Air,
All the little things do add up to a noticeable improvement; otherwise I wouldn't have continued to do them beyond my first tune .

 

[Steveoo]

We don't call it parrafin here. Guys will think you mean wax. We call it kerosene. And it has many uses in the shop including cutting fluid (usually blended) for certain metals including aluminum (aluminium). It gives the greatest finish. But it stinks! So I usually use something else.
Nothing new about water quench. Brine cools quicker and evenly because it doesn't turn to steam as readily.
As I noted previously, The side of the grinding wheel gives a smoother finish than the face.
I don't nick a spring with the corner of my wheel because it messes the edge of the wheel up. Matters to me because that's where I grind all my lathe and metal shaper tooling. I don't want to keep dressing my wheels away. Everybody uses cut off wheels these days. Practically anybody has them, they're so handy.

Yeah I did say the old English way so I used Parafin in my post....
You are right about the smell though. It's ok in the garage with the door open and keeps a bit of temper left in the spring for the unskilled who do not want the trouble of finding the blue tempering colour. Can be tricky if the shop is not well lit and comes on all of a sudden as the steel shifts past purple....
I hadn't consider the greater finish off the side of the wheel, but didn't think I'd stand any chance off the front due to the radius...
Final step is to buff any burr off it from the grinding. Polishing down on wet and dry optional ...

 

[bucketboy]

This is what I do to my pcp hammer springs,

After heating push end immediately onto flat surface

Edit image 3 should be top