How do you properly harden small screws like the ones for a Fisher 2 screw grip cap. Not brittle but tougher. Thanks.

quote:

Originally posted by kda55:
How do you properly harden small screws like the ones for a Fisher 2 screw grip cap. Not brittle but tougher. Thanks.

The type and grade of the steel you want to 'harden' must be known as it has direct bearing on whether that steel can be 'hardened', or not.

Purdey did a series of videos a while back and during one showed how they harden small screws. Check their website or Instagram page.

They are mild carbon steel if I recall,I think 1040 or whatever cold roll is. I'll check out the videos.

Kasenite; not being made any more, but it is a powder that you melt on the steel, then quench it in water. Cold Rolled steel is low carbon, 1020 or similar. 1040 would harden itself due to the .4 carbon. I always got it from Dixie Gun Works. Used to harden Frizzens and screws.
Any kind of steel can be hardened with Kasenite. I use it all the time. It's only for small parts lest someone dip a receiver in it.
The Kasenite replacement is called Cherry Red. Also sold by Dixie.

The answer is to make your screws out of drill rod; get them red til they fall off a magnet into oil or water (depending on the type of drill rod); then you have to temper them as they are glass hard .. get them to circa 725 and hold them there. This can be done by heating them in motor oil until the oil flashes and letting it burn out; or by putting them on a piece of tin foil floating on molten lead; or by putting them in a proper oven. They need to stay at that temp for a while, at least 15 mins.

If they are not made of through-hardening alloy, you can sort of harden them by case hardening which is more involved, and it only hardens a thin surface layer.

Russ,
Can you not heat them cherry red, quinch them in water, then polish them and put them in the oven until they turn sky blue. Ive seen this done with small knives, just curious..they sure are pretty.

coffee can.. atf+motor oil . burn it off ... nice nitre blue

It's 2 small screws. I just want them a little tougher than they are. All good ideas, keep them coming. For the gunmakers out there, do you even mess with them or use as is.

for your application i would use them as is, really no need to harden them.

No need to harden them, and heating and quenching plain steel will not harden them; but might turn them blue; better to just polish and heat them and get the blue color. if that is what you like. Quenching does nothing.
Making new screws from drill rod for a grip cap would be overkill for me.
If you just want them tougher than they are now, do what I said above; it is the only way. But totally unnecessary for a grip cap screw.
As craig said so eloquently.

I didn't realize they'd quit making Kasenit! What a shame. Still have a fair amount though.

A similar product called "Cherry Red Case Hardening Compound" appears to still be available.

I like this for hardening small parts. Not sure that you need to harden the screw, but this would work.

Exactly what I said above.

Ray, sky blue is way above the temp that any normal cooking oven can achieve. You would be be lucky to get them to purple in such an oven. Just not hot enough. And wives don't care for metallurgical experiments in their ovens.

You need to temper screws to about the same temper as a spring. Anything less and they can break. Light blue or just beyond that.

The problem with soft screws is the slots get damaged so easily.

Most gun stuff seems to be made from leaded stock..including the screws. You either use as is or full blown case hardening.

I use graded metric screws with a bolt head for my swivel bases. Turn the head round, slot and use as is....plenty tough and will not spread the slot as leaded stock is likely to do when tightened with vigor.

If you really had the mind to do it ..you could do the same thing for replacements

A note on the Cherry Red.
DO NOT HEAT AND QUENCH INDOORS, AND DO NOT INHALE THE FUMES.
The fumes are just nasty on your Sinus system

Do not ask me how I know, but if you do it once you will never do it a second time, trust me.

J Wisner

quote:

Originally posted by J Wisner:
A note on the Cherry Red.
DO NOT HEAT AND QUENCH INDOORS, AND DO NOT ENHALE THE FUMES.
The fumes are just nasty on your Sinus system

Do not ask me how I know, but if you do it once you will never do it a second time, trust me.

J Wisner

Jim.....I assume you meant not to INHALE the fumes???

quote:

plenty tough and will not spread the slot as leaded stock is likely to do when tightened with vigor.

This is the problem and I have twisted heads before due to being very soft. Even with properly lubed threads and a proper diameter hole they can still sometimes go south. Thanks to all who answered.

quote:

Originally posted by kda55:

quote:

plenty tough and will not spread the slot as leaded stock is likely to do when tightened with vigor.

This is the problem and I have twisted heads before due to being very soft. Even with properly lubed threads and a proper diameter hole they can still sometimes go south. Thanks to all who answered.

Pre "tap" the hole with a same thread slave screw and use the correct size hollow ground driver and you shouldn't have a problem.

SOP but good to inform the masses.

Or you could use the correct tap, they are available

quote:

Originally posted by dpcd:
Exactly what I said above.

DPCD, sorry about that.

I have used grade 8 aircraft bolts and turned the heads for the action screws on Stevens Favorite rifles, since the originals are pathetically soft and can be deformed even with 22LR ammo. But you don't need to go to that extent for something that screws into wood.

quote:

Most gun stuff seems to be made from leaded stock.

That would be 12L14 .

Yes, 12L14 would be the common leaded machining alloy. They may or may not be that. The fastener companies I deal with usually use a high manganese 1020 or 1030 and roll the threads in a mill instead of cut them for unhardened fasteners. They rely on cold work to make the hardness spec. Hardened fasteners are made with 1030 that has a touch of nickel, manganese and maybe boron. Sometimes they'll go for a more 4130 style alloy for specific application.

As for hardening, you can case harden with plain old sugar using the same process as Casenit. Heat to cherry, plunge into the sugar to get a coating. Let cool, then heat to cherry once more and quench in water or oil. Oil gives a nicer color. You'll get a couple thousandths thick case. The magnet trick Russ describes is a good method to know you have properly austenitized the steel. I like to wrap in thin wire for control of the part.

Cherry Red will give about a .005" case. 0.007" if you do it twice, but you won't get more than that.

For the record, any steel above .20% carbon (give or take a bit) is heat treatable in thin sections. True Temper uses plain carbon 1030 to make shovels at 0.065" nominal thickness. They heat them in a gas oven and plunge them into a water barrel with continually flowing water, then temper. Final hardness is in the 35 Rc area.

Jeremy