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Smiths Square Number Impulse Tachometer

Posted: Sun Jan 23, 2022 9:42 pm
by jackPDX
I just picked up an old square number Smiths impulse tachometer. It is missing the nuts for the mounting studs and I'm having a hard time figuring out the correct thread size.

An 8-32 seems like it wants to start but only goes a turn or two. As the studs are not in perfect shape I don't want to force anything.

Anyone know what the correct thread is on these studs? Metric maybe?

jack

Re: Smiths Square Number Impulse Tachometer

Posted: Sun Jan 23, 2022 9:45 pm
by iain1967s
I think it’s the same 3BA as the oil/temp type gauges?
See here: viewtopic.php?p=285413#p285413

Re: Smiths Square Number Impulse Tachometer

Posted: Mon Jan 24, 2022 4:25 pm
by jackPDX
Thank you!

Also the US links in the prior post are much appreciated.

jack