On 2012-05-27, scorched was bm wrote:

"Justin C" wrote in message
...
On 2012-05-24, harry wrote:
On May 24, 5:39 pm, Justin C wrote:
On my boat there are zinc anodes held on by embedded bolts,
one has lost it's nut. How can I identify the nut needed
from only the thread?

I can measure the diameter, and can measure the number of
turns over a set distance. Is there a site I can look up
stuff like this?

Removing the embedded bolt and bedding a new one is well
beyond a job I'm happy to tackle.

Of course, this may all be moot, I may find, when the
boat's lifted, that the bolt has been eaten away because
there was no anode on it (I hope others in the area have
compensated).

Thank you for any advice you can give.

Justin.


The usual method is to buy a thread guage. It has little flat tabs
with various threads cut into it/ You offer them up to the bolt to
identify the pitch of the thread.

http://www.toolfastdirect.co.uk/acat...h_Guages_.html

I've never heard of such a thing, what a marvellous idea.
Thank you for the suggestion.

The boat was built in the UK, around 1980, is it likely
that a commercial builder of the time would still be using
Whitworth, and not metric? I'm just trying to narrow the
gauges I should buy.

Plenty on the bay, dirt cheap.

But are they also nasty - as in: inaccurate? I'd rather try
a reputable source for a quality product.

Justin.