Chain calculation

Any one have a formula for calculating the amount of jump rings needed for a certain length of chain

No Bob, it will vary with the size of links and the style of chain. I have made lots of chains and the way forward is to make five or ten centimetres, if necessary from copper, and work it out from there. Dennis.

Would imagine multiply the largest inner diameter of the link into the length you need would get you close ish ?

Thanks Dennis josef1 the chain will be made from brass (10 x 8 x 2mm)and then chrome plated, so yes I will just make a short length and work it out from there I need about 700mm (350 x 2 )
I have made lots of chain by the guess it method, it will end up curb chain, would it be best to twist it in shorter lengths and join it.

I haven't twisted chain Bob, but I know from twisting wires and watching others, that there is a problem getting it even throughout.
I agree that I would go for short pieces, maybe no longer than 10 cm and then hope that the joining links will obediently follow suit, or have to be twisted first.
I imagine you have already looked here: https://www.google.com/search?client...ing+curb+chain
I only just found it and won't be looking tonight. Dennis.

Yes same here I have not twisted chain, I have watched the videos the likes of Scaffoal make it look really simple but then they have most likely done hundreds of times, looks like I am about to learn
it will end up as a sporran chain, many of the commercially available ones just don't cut it, I used to have one but it seems to have gone to that mysterious place where all lost things go,(probably a good thing, long time since I last used it most likely
needs to be extended these days)

Brass is on it's way I will let you all know how it goes