Stern tube alterations

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Colin chandler
Lighting the Boiler
Lighting the Boiler
Posts: 39
Joined: Wed Apr 03, 2019 3:58 pm
Boat Name: BUMBLE

Stern tube alterations

Post by Colin chandler » Mon Apr 15, 2019 7:06 pm

Shortening a brass/ bronze stern tube,
Does anyone know what thread is used on stern tubes? Is it a BSP ?
Where can I get my tube re threaded after I've cut it down?
Regards Colin Southend on sea Essex
RGSP
Full Steam Ahead
Full Steam Ahead
Posts: 246
Joined: Mon Dec 14, 2015 2:12 pm
Boat Name: Platypus, Shelduck
Location: Very eastern England

Re: Stern tube alterations

Post by RGSP » Mon Apr 15, 2019 7:59 pm

Colin,
the bad news is that the thread could be any of several things. The good news is that cutting a new thread should be easy enough, whatever it is. You need to make an accurate measurement of the thread outer diameter, and the pitch, and that should be enough to identify a new thread which will fit, even if the thread shoulder angle isn't quite correct. If the tube is out of the boat, putting it in a medium-to-large lathe is the back-up option, though if it is a BSP thread, getting and industrial plumber to do it should be cheaper and easier.

If you get stuck, contact me directly: I'm a few miles north of the Essex-Suffolk border.
Colin chandler
Lighting the Boiler
Lighting the Boiler
Posts: 39
Joined: Wed Apr 03, 2019 3:58 pm
Boat Name: BUMBLE

Re: Stern tube alterations

Post by Colin chandler » Mon Apr 29, 2019 8:13 pm

So far I've discovered it's an inch and five eights , I'm waiting for some pitch gauges to turn up.
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Colin chandler
Lighting the Boiler
Lighting the Boiler
Posts: 39
Joined: Wed Apr 03, 2019 3:58 pm
Boat Name: BUMBLE

Re: Stern tube alterations

Post by Colin chandler » Wed May 01, 2019 7:43 pm

My gauges have arrived and it seams its a 12 G whitworth thread an inch and five eights
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