current & studs brass / steel ?

Today I needed to fix a 35 sq mm cable lug with a 10mm hole to a
brass block. Current is something near the limit for 35mm cable.
(Think car starter motor, it isn't but similar set up). My imediate
thought was to use a brass screw and brass washer so current could
pass through both faces of the lug via the stud. Then I thought that
the torque I can put on a brass 10mm stud is minimal, whereas the
torque I can apply to a 10mm steel stud is considerable before I sheer
it. Steel won in the end as I had no brass 10mm studding or bolts but
it would be interesting to know which way gives the long term lowest
resistance. Any views?
AWEM
Reply to
Andrew Mawson
Loading thread data ...
Use a bigger diameter stud?
Starter terminal studs used to be brass, more recently seem to be generally plated steel, don't think it's zinc plating though. Maybe even silver plated?
Cheers Tim
Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service
Reply to
Tim Leech
The only number out of my head: Brass has 4 times the resistance of copper.
Nick
Reply to
Nick Müller
Any older starters I've worked on have had copper terminals. Modern ones tend to be cadmium plated steel.
Reply to
M Cuthill
I very much doubt that. Cad plating is, AIUI, a real no-no nowadays.
Tim
Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service
Reply to
Tim Leech
Out of curiosity I've just checked a couple of old starters in my 'stores'. One (Lucas) has copper (coloured) studs with steel nuts (plating long gone), the other (CAV), larger and older, has brass studs & brass nuts.
Cheers Tim
Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service
Reply to
Tim Leech
On or around Sat, 28 Oct 2006 18:53:26 +0100, "M Cuthill" enlightened us thusly:
I think a lot of the older ones are copper plated steel. genuine copper terminals are rare and easily fscked-up.
Reply to
Austin Shackles
Wot's wrong in doing it the right way ?
Splay the cable out and clamp on with a big Carver clamp, fits all sizes . -- Regards,
John Stevenson Nottingham, England.
Visit the new Model Engineering adverts page at:-
formatting link
Reply to
John Stevenson
lowest
we're not welding here John ! (but molten metal IS involved )
AWEM
Reply to
Andrew Mawson
I wasn't talking about welding, just making a cable connection. If we are talking high voltage stick a plaggy bag over it for safety. That should give Greg a fit or two [ with a bit of luck one will be a tight one ] -- Regards,
John Stevenson Nottingham, England.
Visit the new Model Engineering adverts page at:-
formatting link
Reply to
John Stevenson
CAV? That must be an old one! Lucas very much used to favour copper terminals (seen several stripped).
Certainly most modern starters appear to be cadmium coated (at least they've got that yellowish colour), but there is the odd one that uses zinc coated terminals.
Reply to
Moray Cuthill
The yellow colour is more than likely a Zinc Passivate coating.
However, the yellow colour comes from hexavalent chromium which is now a prohibited substance under RoHS and also motor industry guidelines, so you won't see this in new manufactured parts, which as from last year will now have a silver-bluish colour, as the hexavalent has been replaced with trivalent chromium. This has a lower corrosion resistance.
Any zinc passivate with the yellow colouring will in all probability be NOS.
Peter
Reply to
Peter Neill
It'll be chromated zinc rather than cadmium. For better or worse, cadmium plating has been effectively banned in the UK since the end of July 1993 :-
formatting link
Mark Rand RTFM
Reply to
Mark Rand
Unless of course you happen to be a goverment owned electroplating shop repairing helicopter parts at Almondbank,Perth.Admiitedly it is well set up with lots of extraction/filters to contain the fumes and sirens/lights for when they don`t. Mark.
Reply to
mark
Yes, I'd noticed that the rules didn't seem to apply to the government/military. How do the government/military/police get away with ignoring the best practice that they force on everyone else? Is it arrogance or stupidity?
Mark Rand RTFM
Reply to
Mark Rand

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.