are we sure it is safe to use this type of metal in a flashlight. Navy divers use this combination of metals in a dive knife but you cannot sharpen it with out a respirator due to dust causing cancer.
It is safe yes in a flashlight yes. I’ve made the research about it, and unless you sharpen the spring or melt down the spring for some reason, there should be nothing to worry about at all. I do get the concern though, but there is no risk of that in a flashlight. And since we don’t use lasers to make springs, that is not a problem too.
Guys, I finally recovered the information I was looking for when talking about which battery spring material to use in terms of elasticity and YIELD STRENGTH!
Elasticity is good, but since all beryllium coppers feature about the same elasticity +/- 2%, I will leave that out.
What really matters is yield strength, which is how much force a material in spring form can sustain before resulting in a plastic deformation, such as the in the Intl Outdoor BeCu 45% IACS spring.
Here is some data about it:
Steel is the strongest at 1700MPa Typical
Phosphor bronze is in the middle at 895Mpa Typical
Beryllium Copper C17530 38% IACS is a bit behind at 820Mpa Typical
Beryllium Copper C17500 45% IACS is quite a lot behind at 620-680Mpa Typical
As you can see, the reason for the BeCU 45% IACS Intl Outdoor spring for failing in djozz’s tests is that it can’t resist as much to a deformation as well as the others, resulting in a quite a bit higher chance of plastic deformation such as the previously mentioned djozz spring test.
Yes, but the cost of $0.26 assumes all are sold. Not fair if Bluesword gets stuck holding unsold springs. If this was a business, that is one of the risks, but since this is a group buy we should consider sharing the cost of unsold stock. Just not sure how to do that fairly.
I agree.
If the sample test works I’ll take 30 large and 30 small. If the test doesn’t look good then I’ll kick in some to help with the sample.
Same here. If the samples are not as expected I would spend a few dollars to get the sample costs covered.
/\ :+1:
I’m in for helping cover the sample cost if the turn out to be crap 
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Same here, let us know.
yes as well.
Please put me down for 30 of each, and if they turn out to be made of old paperclips, I’ll be happy send some money to help cover sample costs as well.
Thank you for setting this up :+1:
Wow.
I never expected such support.
Now, if 5$/spring do not turn out to be the bee’s knees, I will be quite angry.
I do doubt they would risk their reputation however for such a purchase, especially since it is really easy to check if the samples are crap using a multimeter and a power supply.
One last thing before I make the final request and pay for the samples: are there any parts/products you would like to have in a group buy?
Just a question, but seeing the potential of a group buy for us getting things at a much lower cost than initially possible makes me happy.
Well I never modded springs. But I think it would be good to have a few good ones in the part drawer.
I am only willing to pay 15 Euros incl shipping for stuff I don’t see a use now.
Very nice springs. I am sure this has been answered but is there a reason you stuck with 1mm thick?
I would be in for 100 of them myself. Possibly more if I have the funds at that time and depending on what the final test works out to.
Two reasons actually:
1. I could go with 1.1mm or 1.2mm wire. However, the 1.1mm wire is a non standard option, so it will cost more to manufacture. But the 1.2mm wire has the same cost, so no problem there.
2. 1mm wire is already very thick for a battery spring, compared to most springs on the market already. Going with a 1.2mm wire, while better on the current handling side, will make the spring mechanically weaker.
There is a reason: free length between coils. This is for non-plastic deformation to occur at a certain compression force.
If the wire is too thick, what will happen is that under a deformation is that there’s a possibility of coils touching each other. This can end in two things: either the spring collapses at that point, or worse, the spring is stressed in a horizontal way, which will permanently deform the spring.
Either way, a thicker spring at a small size will be mechanically weaker, and since 1mm thick springs are already thicker than most springs on the market and at 38% IACS, its ability to handle current will be very high, probably 14-15A+
Makes sense, 1mm should work for most small lights that don’t see more then 15A
Yeah. I’ll probably do a comparison of all the springs I currently own, which is the Fasttech Carobronze spring, the Kaidomain Phosphor Bronze Spring, and soon enough, the BLF BSM U-Spring.
From my calculations, it should handle 14-15A before it has a voltage drop of 0,100V occurs, but I will have to confirm that once I receive them.
They are looking to be quite promising.
Wikipedia says you shouldn’t grind CuBe without respirator.
I found also regulations for beryllium powder:
http://gestis-en.itrust.de/nxt/gateway.dll/gestis_en/008020.xml?f=templates\$fn=default.htm\$3.0
Capter regulation seems worth a read. The rest I mostly don’t understand.
So do we need a saftey note for the springs, if somebody cut them with a Dremel?
Use wire snips to cut them, why on earth would anyone try to grind a springy spring? 
I don’t have immediate funds for this but in the next couple of weeks I should… if that is ok I’d like to speak up for…
100 large and 50 small please.
If we have leftover’s I’d probably help you (and me) out there and buy more as well, all dependent of course on the testing of the samples.
The CaroBronze springs aggravate me as they don’t take solder well and are so stiff. The heavier Intl-Outdoor spring collapses under heavy loads (high current) and is difficult to bypass because of the thick wire and short height. So yes, I would like to stock my parts box with these more ideal BSL LS springs.
Thanks JoeChina for making me think about this more… 
Maybe we can get up an accompanying Group Buy for those that have real concerns about the safety of these springs or might want to cut them in a manner that would create & cause dust.
I present……… ‘The BLF Respirator’.
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:+1: … … …
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Optional Full Facemask model……
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Or…. be the first on your block to be completely protected from BLF BSM U-Spring dust!
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