Nuts - Cant find any!

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AlistairC

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Does anyone have a supplier for 3/8" brass nuts, I cant find any!
(From the back of a battery cut out switch - fell into an inaccessable part of the bilge)
 
What thread?
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"Artificial intelligence is no match for natural stupidity"
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Pretty sure RS do brass nuts, both imperial and metric.

Also try looking up fasteners in Yellow Pages, etc. Unless you live in the back-of-beyond (like me!) there's bound to be a fastener centre near you - they stock everything!
 
Aha- This is one bit of knowledge I didnt have when I was in the fixings shop. I've ended up with whitworth but the guy in the shop reckoned that wouldnt be correct.
I had to buy something though - its depressing leaving with nothing!

Anyone know what thread it is on battery posts/isolators?
 
M10 would be more like it. Given the small number of turns and its function, even though it might appear a sloppy fit, there will still be enough pressure to hold terminals in place. It's also possible to use NyLock or similar nuts that stay put.
 
3/8 UNF on mine - try aq scrap yard and "borrow" a couple of nuts of the solonoid of an old mini or the likes.
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"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>
 
And 3/8 UNF is 24 tpi UNC is 16tpi . Whitworth is also 16tpi and BSF is 20 tpi.

All you need now is a thread guage.

3/8" is about 9.5mm so M9 won't help (that has a pitch of 1.25mm which is about 20.3 tpi)
 
M10 has a pitch of 1.5mm, which is more or less 16.93 TPI. A difference of .93 of one pitch for every inch of thread.

Given that here we're talking of 3, maybe 4 turns within the thickness of one nut, the difference would be correspondingly smaller and the difference in diameter would allow the use of an M10 nut on a 3/8 UNC stud before there is interference.

It works if one is pressed for a solution and there is no alternative. One might have no problem with sourcing in england (I don't live there, so I wouldn't know) but non-metric threads are becoming ever more difficult to find elsewhere.
 
[ QUOTE ]
M10 has a pitch of 1.5mm, which is more or less 16.93 TPI

[/ QUOTE ] Yes but it is too large in diameter, These are connections on the battery switch. they have got to be done up tightly to ensure good connections with no risk that they will work loose.

Don't even think about using a steel nut that's not the right size on a brass stud in those circumstances.

The consequences of the lead coming loose when running could be the destruction of the diodes in the alternator.

Last time I found myself in a similar situation over a lost nut I made one. It was a BSF thread and luckily I had a tap the right size!
 
I think that we're saying more or less the same thing: "Don't do it unless it is a real emergency and there is absolutely no better alternative at that time!"

Re the problem of a lead coming off and causing damage to the alternator diodes (I take it you mean a case of running the alternator with no batery attached).

I have my alternator permanently wired to the batteries via a diode splitter, believing that (1) in this case that there will always be a something for the alternator to charge, and (2) that should someone turn off the engine at the switch, this would not jeopardise the safety of the alternator.

I cannot prove it scientifically but I take comfort in that - to me - it appears logical!

Sorry if I misunderstood you and if I have digressed. (TERRIFIC party last night /forums/images/graemlins/wink.gif /forums/images/graemlins/blush.gif /forums/images/graemlins/grin.gif )
 
[ QUOTE ]
I have my alternator permanently wired to the batteries via a diode splitter.............

[/ QUOTE ]

That all sound logical to me as well but it may not (probably does not) apply to AlistarC's installation

He seems certain that it is 3/8" and not metric, he knows its not Whitworth so it is not UNC either as that has the same pitch and would be so close that it could be made to fit. That only leaves UNF as Cliff suggests or BSF which is unlikely or a non standard thread.
 
Is there a manufactures name on the switch or made in as this could give a clue to the type of thread.

Can you take it off and take to a bolt supplier and try various types on until you get the correct nut.

If you cannot get Brass, Stainless will do at a push.
 
I havent actually fitted my splitter yet, but I'm always cautious wiring things in before the switch. There is weighing up the two risks:
1. Turning the switch off accidently whilst the engine is running.
2. Not being able to isolate a circuit in case of fault/fire

As for the nut: I've got a wing nut from a 3/8" battery post which isnt ideal but will keep things going until something turns up!

Cheers
 
[ QUOTE ]
a wing nut from a 3/8" battery post

[/ QUOTE ] If it's the correct thread then I would say you have solved the problem. It'll probably still be there when you sell the boat.

I fully understand your dilemma regarding the wiring uf the diode splitter The diodes do of course isolate the chaging circuit from the battery but relying on them is, I would have thought, unconventional. I suppose you could always put an additional isolation switch in that circuit for emergency use only. I guess the ideal solution is to fit isolation switches that disconnect the field current before the main circuit.

You might find the electrical section of The TB training website interesting
 
Surely it must be wrong that ANY part of the bilge should be THAT inaccessible?

You don't tell us what kind of a boat it is but a loose brass nut in the bilge of an ally boat will soon result in a nut shaped hole in the bottom.
 
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