Need to duplicate an old flat spring

I need to duplicate an old flat spring but need to match the hardness or flex. The "spring" is just a small flat piece, 3/16" wide, 1-1/2" long
and .005" thick.
It goes to a 1900's vintage device so the original would not have been anything exotic.
All I know is it really hard (brittle) -it will snap if you try to bend it in half.
I tried an old clock spring I had of the same thickness but that would bend, not snap so I need something harder.
Does anyone know if blue spring shim stock will bend or break? If it bends can I temper it more to get the hardness (flex) that I need?
MikeB
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wrote:

Just one point: The hardness has nothing to do with the spring rate (the "flex") It only has to do with how far you can bend it before it either bends or breaks (the first if too soft; the latter if too hard).
There is a widespread misconception that hardness affects spring rates. It doesn't.
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Ed Huntress

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On 8/4/2013 8:33 PM, Ed Huntress wrote:

So it would be possible to find a spring with the same rate that would not break as easily?
MikeB
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wrote:

Sure. Is this a spring that has to be sprung (flexed) a lot? Often?
The less your spring bends, the softer it can be without taking a permanent set. But if it bends at a high frequency, that will reduce the degree to which it can be bent.
Is this an important spring for you? If so, let's identify the correct terms so you won't be confused when looking something up.
The spring rate for any given material is called the Young's modulus of the material. It's the same for nearly all types of steel, except for stainless, which has a slightly lower rate. It's also true for all degrees of hardness.
The degree to which it can be bent before taking a permanent bend is called its yield strength. For steel, harder steel has higher yield strength. But beyond a moderate point, it also can be more brittle. It will also *appear* to be more brittle, because it might break before it takes a permant bend.
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On 8/4/2013 9:12 PM, Ed Huntress wrote:

Yes, this spring is one used in pairs as a speed regulator for an early telegraph device that I am fixing/restoring.
The flat spring strip is attached on both ends with a small weight in the middle. They fly out & raise a brass disk against a brake to regulate the speed, so it must be the same as the original to maintain the proper speed. (similar to a flyball governor on a hit & miss engine)
I can measure the deflection of the one unbroken spring under a given weight I guess, then experiment with different tempering temps to get as close as I can.
MikeB
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Telegraph?
Please describe... do you mean a "teletype" device?
Lloyd
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On 8/4/2013 9:41 PM, Lloyd E. Sponenburgh wrote:

It is an Omnigraph, the springs are in the top left of this image, though partially obscured by the winding key.
This is not the one I am working on, but similar:
http://uv201.com/Misc_Pages/Misc_Images/omnigraph_10_large.jpg
I am a ham & love CW & all contraptions thereof.
MikeB
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de WA4ZEG (inactive)
I once had a code recorder that scribed the results on a very narrow paper tape, similar to ticker tape, but it didn't decode to alpha.
That was back in the '60s, and I really don't remember much about it, except that you still had to read code to use it.
Lloyd
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On Sun, 04 Aug 2013 21:37:51 -0400, BQ340 wrote:

My understanding is that the modulus of most steels is very similar -- it's just the yield strength that changes.
So just about any degree of hardness or temper will give you the same flexibility.
Pick the size for the springiness, harden for the hardness, don't confuse the two.
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Tim Wescott
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wrote:

given

get as

That won't do what you think it will.
All steel bends the same, as long as it's not pushed so hard it takes a permanent bend. If one pound bends it one one-hundredth it will do the same nomatter what the temper ( or composition). This is a simplification, or course, there are minor differences, but on the order of a few percent.
To match what you have get exactly the same size. To find out how much it must take before bending you must bend the remaning one, so don't. Instead, make three new pieces exactly the same size, and try them. If they bend make three more, harder. Repeat as required.
How accurate does the speed regulation have to be?
Is there an adjustment mechanism?
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It looks to be a call-sign sender, maybe for portable hamfesting, or maybe a 'code' sender for a crypto pack, with canned messages. Kind of like our old 'Cack wheels' in 'Nam. You have a "sheet of the day" indicating a response numbers cross-reference. When you get a particular message that requires a particular response number, you look up the cross-referenced number of the day, which you then select on the stack of codes, and send back multiple times without any human errors.
The one he showed (not exactly like his)does appear to have a speed adjustment, by moving the friction disk up and down on the bottom sleeve of the centrifugal weights part. But it looks to be a very critical and difficult adjustment... no vernier is apparent.
Since automatic receiving equipment for certain CW codes was prevalent by the 1930s (ticker tape machines), it makes sense that the rate adjustment is pretty critical. The KSR and ASR teletypes followed shortly, and were in common use through the late 1970s.
Lloyd
Lloyd
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On Monday, August 5, 2013 7:01:58 AM UTC-5, Lloyd E. Sponenburgh wrote:

It looks like it?s a Morse Code practice device like the one shown in ope ration here:
http://www.youtube.com/watch?v=byEDYuRIH5E
Maybe made before W1AW broadcast its practice sessions.
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On 8/5/2013 6:55 AM, DD wrote:

So I must find out what the original is made of & get that same type steel?
The speed it adjustable over a small range, but not much room to play with.
MikeB
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AND tricky to adjust, probably.
But then, it's only a "music box" with a leaf contact in place of a reed. Unless you're transmitting the code to a compatible receiver, the exact speed doesn't matter very much.
Lloyd
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wrote:

Greetings Mike, I'm pretty sure the springs, in normal use, don't get very close to the yield point. Based on this assumption most any steel hardened to a spring temper will work. You do not need the same exact steel. Differences in thickness will have a much greater affect on deflection that differences in width. Twice as wide will be twice as stiff. Twice as thick will be 8 times as stiff. So get some spring steel the same thickness but a little wider and trim until it acts the way you want. Someone here mentioned the use of feeler gauges. That's good advice. And Ed mentioned using a nail to anneal spots for drilling. More good advice. So buy a set of feeler gauges, trim to size with a Dremel tool and grinding points and/or parting discs, anneal the three spots you need, and trim the sides until it works the way you want. Eric
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On 8/5/2013 6:43 PM, snipped-for-privacy@whidbey.com wrote:

Hi, Eric
Regular feeler gauges are not nearly as stiff as I need, but I see some blue spring steel shim stock is available.
I will get some of that & from all the replies it sounds like that should work but I may need to tweak the width to get the results I need.
MikeB
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Again, I think you've missed the point. If the gauge is as thick, and as wide as the spring you've got, then it will be exactly as "stiff".
That is, it will be if the remaining spring is steel, and not (say) beryllium bronze.
Lloyd
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On 8/5/2013 8:10 PM, Lloyd E. Sponenburgh wrote:

I understand what you are saying, I'm probably not using the proper engineering terminology, but regular feeler gauges won't work.
Here is a video someone made of a different model but it has the same springs & speed regulator assembly in action:

http://www.youtube.com/watch?v5TtoYYJkfY

Regular feeler gauge stock would distort under the forces, the brass weights are fairly heavy at the rpm's it operates at.
http://www.mcmaster.com/#9503k14/=nxsdcj looks like what I will try.
I hope those links work!
MikeB
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I don't know what you mean by "regular feeler gauge stock". It comes in all thicknesses, all the way up to "you can't bend it with your fingers", and down to "feels like metal paper". Feeler gauges have many thicknesses in one 'kit'.
Lloyd
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On 8/5/2013 8:52 PM, Lloyd E. Sponenburgh wrote:

The .005 one from my 1970's craftsman set is what I am comparing against. I have no idea of the type of shim stock they stamp them out of.
MikeB
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