He’s not going to get stuck holding extra’s. I promise you that. Several of us here will up our ante in the long game and there won’t be anything left. By the time that all get’s sorted out and he see’s what is left I’ll know if I can take an extra hundred, or two. Some other’s will do the same thing, problem solved.
If this were tax return time I might be prone to buy a thousand myself. Of course, it’s not, monies are all more tightly controlled right now and we have to start thinking about Christmas soon. (I know, right?)
indeed, if there are some left over I could easily order quite a few more myself. Heck if I have the money I plan to order extras as it is. Just waiting for things to settle down so I can see how much I can afford.
My initial request (20+20) was based on my available hobby funds, but if the price drops from the original estimate or ther are some surplus springs I’d love to get a few more. The prospect of never bypassing another spring is very appealing.
I’m sorry I haven’t read this thread, just post 1.
I wanted to ask if the large spring is going to be 7 mm on the top and 9 mm on the bottom? Typically you would want to get a smaller top so that you have more of a tapered shape. This will allow the spring to partially compress into itself allowing for a shorter compressed height and allowing a wider range of battery lengths to fit. When the spring is shaped more like a cylinder you just don’t get as much compression from it.
If this has already been discussed, just ignore my post above. Thanks
I would just cut off a coil if the cell was too long or if it looked like there would be issues. By cutting off a coil (or two) at the wide base the overall length would be shortened and the cell length wouldn’t be as critical.
Then again, I tend to forget what I’ve found to be optimal and find a new solution every time the problem arises…
This is a good suggestion, the only reason I would see for leaving it larger would be if we made a smaller spring that could fit inside of it for a double high current spring setup.
Honestly I have been to busy to even read BLF, I only found out about this because someone was nice enough to point it out to me in a PM.
We almost need a BLF highlights thread to links to important developments on BLF daily / weekly lol.
Not that I neccessarily recommend it but for sake of the discussion: one reason to want the top wider and the spring compress less by the coils touching is to protect the spring from shortening from over-compression. (It happens with the Fasttech ‘carobronze’ spring: it can fully compress and it does not nearly come back to the original length after that, moreover it gets weaker and weaker over time)
So it all depends on how good the material is mechanically. And you can only really find out about that by testing samples.
Buy some metres of spring wire, various types (this would be the challenge).
Make a fixture to wind them.
Test, evaluate.
The prototype costs and NRE seem ludicrous to me, either the manufacturer knows what they are doing, or doesn’t, or is having a laugh. Winding a conical spring, or any spring, should be trivial. Tooling costs bugger-all.
Making a spring is ultra mature technology, nothing new to be learned, no breakthroughs, no exotic materials science will happen.
That said, a bespoke spring that fits a certain precisely defined requirement that is far out of the ordinary is worth developing. But I don’t think this is one.
@djozz, I had thought about using a 6mm top initially, but as you said, more surface area for contact is better for yield strength and mechanical durability.
Using BeCu C17530 38% IACS should be just a bit worse mechanically than your phosphor bronze springs, and quite a bit better than the C17500 45% IACS Intl Outdoor fat spring.
Edit: We are also at 1511 big springs, and 1032 small springs.
Of course, it’s not, monies are all more tightly controlled right now and we have to start thinking about Christmas soon. (I know, right?)
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