Need to duplicate an old flat spring

BQ340 fired this volley in news:52004b7b$0$49327 $ snipped-for-privacy@ngroups.net:

The set consists of several different thicknesses. Are you telling us that the spring in your device is only 0.005" thick, yet FAR stronger than a steel feeler gauge of the same 0.005" thick?

Llyod

Mike, how thick is the original spring? What the guys are saying is you need the same thickness feeler guage. Half as thick is 1/8 as "stiff", so .005" is 1/8 as strong as .010 - and i suspect your spring as closer to .020 or 025"

Blue spring stock (not shim stock, which I have not tried, but the coils of spring stock) will bend as long as you don't want too small a bend radius.

Tempering it would make it softer. You would need to harden it (and how hard you can get it is a function of the alloy). And to treat something like that (you have to get it up to at least red hot) you would be exposing it to serious oxidation -- unless you have an oven which you can pump argon into before getting it hot. Then it has to come out quickly and go into the quench before it cools any. (Probably better to have a stack of them together, so the center ones at least would not cool too much before the quench.) And if you want it that hard, quench in brine (very strong solution of salt in water), which will probably get it as hard as you can manage for whatever alloy you have. (This would work with your clock spring as well.)

If you heat it in air, the oxygen will burn out the carbon in the alloy.

To find your target hardness, you will want to do a Rockwell hardness measurement -- with the "superficial" scale, because the spring is not thick enough to be done with the Rockwell C scale -- that needs more depth under the surface.

Once you know the hardness of the originals, you can then try the heat and quench with new spring stock and see what that does straight out of the quench. If it is too hard, then you get into tempering (heat to a given temperature for a given time to reduce the hardness a known amount.

Good Luck, DoN.

Shit...call around to your local machine shops and find one with a good hardness tester and have the thing tested. Once you find out how freaking hard the survivor actually is...make the new ones just as freaking hard. Its not rocket science for cripes sake.

Bring em a dozen donuts and it wont cost you anything other than the donuts

Gunner Asch fired this volley in news: snipped-for-privacy@4ax.com:

yeah... I get the feeling this guy is going 'tangent' on us. You'd have figured he'd have 'gotten it' by now, but it sounds like we're all walking around in a circle...

Oooops! Here comes the FIRST question, again!

LLoyd

Of course it will distort - that's how it works - by flexing. Unless by "distort" do you mean "yield", with a permanent distortion. If so, I don't think so - feeler guages are pretty hard & the video doesn't show that much deflection in the springs. Try bending a feeler guage by hand

- about the same radius as the Omnigraph spring while running. Does it yield? If not, keep trying smaller radii until it does yield. I'll bet that the radius that it does yield at is much smaller than will ever happen in the Omnigraph. In which case, you're set to go.

Bob

It looks like it?s a Morse Code practice device like the one shown in ope ration here:

Yes, it kinks permanently, I am bad with my terminology!

The problem seems to be that it doesn't bend evenly along it's length in use, the 3 attaching screws have square plates under the heads to clamp the spring & weights -they must focus the force and leave a slight crease in the shim stock after a couple test runs. It almost works but I'm not happy with the results.

I am trying to keep this original as possible, not just hack it up with any old spring that will "work".

MikeB

BQ340 fired this volley in news:52016b19$0$9076 $ snipped-for-privacy@ngroups.net:

So... you use a spring of equal hardness to the original, and equal thickness, and equal width.

Just because the feeler gauge stock isn't hard enough is not a limitation. Harden and temper it.

Lloyd

If he hasn't done that before, trying to get it right with such a thin piece is not likely to be successful.

Quenching a thin blade evenly isn't usually accomlished by dunking it in water or oil. You'll preferentially quench one side, resulting in a weak and, probably, a curved piece. Swishing it around does NOT accomplish it, if we're talking about something thinner than 0.030" or so.

I have a nozzle made as a coil of bendable copper tubing, with many spray holes pointing inward, that screws to my laundry-tub faucet. I made that after a lot of wrecked pieces.

Ed Huntress fired this volley in news: snipped-for-privacy@4ax.com:

Not if you PLUNGE it vertically. Besides, he can layer material to equalize the quenching.

C'mon... this isn't rocket science, it's craftsmanship. Artisans have been doing it successfully by hand for three centuries.

Lloyd

Good luck. I haven't been successful doing that, except once or twice by pure luck, and I've heard from experienced heat-treating people, and knife people, who also say not to do it.

Maybe your eye/hand coordination is a lot better than mine d8-)

This is a very thin blade. They're very hard to quench right. My experience is mostly with hacksaw bladers, carbon steel, which I use for a lot of things.