Tool steel question

[44man]

I needed to make a little piece out of .050" oil hardening steel and make it spring temper.
Problem is there is a tight, right angle bend on one end. The first try cracked. I found with another try that I can't soften the metal by heating red hot and letting it cool slow, got so hard a file squeeks.
I made another and could find no cracks but as soon as I applied heat to harden it, it split.
The part is small and I have no way to keep it red hot to bend.
How do you fellas bend tool steel?

[NoZombies]

What kind of steel are you using?

I heat to bright red, and bend to my hearts content. Then harden and temper.

[Bullshop]

+1 yes bend while red.

[John Taylor]

You should be using 1075 to 1095 steel for a spring. Some tool steels are not right for springs and will break.

[44man]

+1 yes bend while red.
That is a problem, the end is only 1/2" long, 3/16" high each direction from the bend. the bend has to be precise, in the right spot.
I could just machine it from thicker steel instead of trying a bend.
There are no numbers on my steel, I have Starret, Warplis and PK, 0-1.
No worry about breaking, it only has to flex 1/64" or so at the end of a long piece. I have made muzzle loader mainsprings and frizzen springs from this stuff and they are still going after 40 years.
It is only the tight 90* bend that gives me trouble with such a small piece. I take the torch off and it gets cold FAST!

[bohica2xo]

I am having trouble visualizing the part.

Does it have two bends on one end? Back to back bends?

What I get from your description is a 1/2" long part with two legs 3/16" high - miniature angle iron.

When you work thin sections hot, it is best to work them in the flame. Stand your propane torch up, and use two pair of pliers.

When a bend is where the critical dimensions are located from, start with oversized stock and put the bend in first. Heat treat, draw - then finish machine the part & polish the machined surfaces. A second draw to the same temperature is a good idea after all machine work when using O1 for springs.

[NoZombies]

If my shop was set up I'd offer to make the bend for you, sadly it isn't. What are you using to make the bend? Pliers? if it was me, from what I can understand of the problem, I'd probably put it in the vise. The point of the bend should be a little above the jaws of the vise. and then get it hot with a torch and tap it over with a hammer. The rule I use for such things is that the bend point should be the material thickness +10% above the jaws when the outside dimension of the bend is important. start with a piece a little bit long, and then you can cut, file or machine to fit after forming the bend.

Remember not to have machine or file marks on the outside radius of the bend, and as few as possible on the inside radius.

[44man]

I am having trouble visualizing the part.

Does it have two bends on one end? Back to back bends?

What I get from your description is a 1/2" long part with two legs 3/16" high - miniature angle iron.

When you work thin sections hot, it is best to work them in the flame. Stand your propane torch up, and use two pair of pliers.

When a bend is where the critical dimensions are located from, start with oversized stock and put the bend in first. Heat treat, draw - then finish machine the part & polish the machined surfaces. A second draw to the same temperature is a good idea after all machine work when using O1 for springs.
Your right about shape and I made one with an over size piece, works fine, Thanks.

[JIMinPHX]

Different tool steels handle differently. Some bend readily when red, some when orange, some when yellow hot. The tempering temperatures & methods vary by alloy. The temperature & method are also different for a spring temper than for a simple hardness temper. You should choose a tool steel than is recommended for spring use. You must use the proper tempering data for the particular tool steel that you use.

If the steel is cooling too quickly once you remove the torch, then you may not be heating a large enough area.

The color that the metal turns when heated is a very accurate indication of temperature. A lot of the old school heat treat guys judge their soak temperature by eyeballing the color rather than relying on a thermometer. The Rockwell test at the end of the day tells the story if they got it right or not. A lot of those old timers get remarkably consistent results.

Bent pieces & pieces that are unusual shapes have more of a tendency to move & change shape when heat treated. Sometimes people fixture parts to be heat treated. Other times they allow extra material to compensate for expected movement & finish grind after heat treat.

If you could post a picture of what you are trying to make, it might help the rest of us to come up with some more creative ideas on how you might form that particular shape & get it heat treated.

[BABore]

O-1 is not an type of steel that you want to make a spring out of. Even if you manage to get is bent like you want, it will fracture is use. Look to Brownells. They carry stock for making springs.

[Bulldogger]

It's mostly about winding coil springs, but the tempering information holds.
http://home.earthlink.net/~bazillion/intro.html

I've read that one may use one's oven or a toaster oven to temper. I've read (but not tried yet) that if you put it in the oven at 500deg for an hour and then quench it'll turn out fine.

+1 on annealing, I did it making a flat firing pin for a .22lr pistol. Using a piece I hacksawed out with much sweating. I then heated it red hot over my gas range and let it air cool. It was hard then, but much easier to file and saw. Once it was done I heated it light red and let it cool to a straw color and quenched in water. I'm happy to report it's doing fine as a firing pin.

Spring tempering is different, one must reach a certain temp and hold it. But the site above will get you started. Once you get rolling, it's not that hard, at least not so far!