General > General Technical Chat
Logic puzzle.... how many bus bars?
Ian.M:
What's wrong with tin plated busbars? A PITA to make from copper flat bar stock with just hand tools, (as ideally you'd use a drill press to get the holes straight), but you can cut to length with an ordinary hacksaw, and tin them yourself with solder, paste flux, a blowtorch and a cotton moleskin rag (or a wad of cotton wool) smeared with flux to wipe with.
paulca:
The bus bars I ordered turned out to have the wrong sized holes.
Having discovered how tricky it is to ream them with a cheap (yellow painted) dril bit was, I had to order a hand reamer.
Ian.M:
Copper is soft and grabby. Ideally you should stone the front of the cutting edge to a neutral rake to reduce the drill's tendency to self-feed. Use a sharp HSS drill bit, with a bright or TiN surface finish, not black oxide (the chips tend to stick), and keep it wet with a suitable cutting fluid. WD40 will do at a pinch.
If you don't have a drill press, a reamer was probably the best choice.
T3sl4co1l:
Not only that, it's the contrast between relatively hard nickel plating and soft smooshy copper underneath. Maybe the plating isn't enough to do anything once you're through, but it might make it difficult to start.
I'd be fine with plain copper, myself; but I don't know what if any battery standards are, if particular platings are recommended, or required. Some anti-ox grease on the mating face should deal with things well enough, I would think. Unless of course the problem is interfacing to a different metal (the batteries aren't aluminum or something are they?), but even then copper isn't incompatible with too many things I think.
Ah well; definitely enough money in there, it's worth doing right. :-+
Tim
paulca:
Unplated copper is fine, you can scotch bright the hell out of it, get it nice a pink and shining before matting the busbars to the terminals. However. Copper will not stay that way, it will oxidise which at very least means you have to repolish them when you move/rearrange them. There are other issues with copper on aluminium terminals, although I understand? that is only really an issue if they get wet... which is unlikely.
The only drill bits I have are cheap "yellow" pretend titanium coated. The flutes are blunt, hell half the tips calm blunt out of the packet! I'm fairly sure if you did have a drill press, these bits would not cut a chip out of a surface, they would simply skate on it and get hot.
Tring to ream one and the bit self fed... or grabbed and tried to break my wrist. I did persist until the bit spun freely and moved it around like a reemer until it started to smell. (drill + hot metal). There was swarth on the floor and it had worked.
I thought it would be better to clamp all 8 toegher with some mole grips and having put all 8 on the bit already, I clamped them and tried to ream them. Nearly broke my wrist twice and when I did get the bit to spin it only reamed half of them.
The hand reamer ... if it isn't a blunt unfaced peice of shiz should be fairly slow, but more reliable.
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