5" speedo trip reset retaining screw-er wot size?

1660bob

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Hi All, replacement of said screw is necessary as years of blunt screwdrivers/nail files/ butter knives have destroyed the slotted head.I read that it is 12BA-got some- nope, falls in, too narrow on diameter.Next size available: 10BA-too big won`t go near. I read elsewhwere its metric,....logical: 1.4mm,-got some-screws in but hoplessly loose & wobbly. Hmm, the annoying thing is that the original, knackered screw is a darn good fit in the trip shaft with no play at all, and close examination gives a dia of 0.055" and .30mm pitch-which appears to be as near as dammit 11BA-a size which seems to be unobtainable as suppliers lists go 12BA-10BA,( well they would would`nt they?) Anybody any ideas as to a supplier of 11BA?, or is it another size (1.6mm has a 0.35 pitch-doubtful it will fit....) Ideas appreciated, cheers, Bob.
 

Albervin

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Contact a reputable speedo restorer (see MPH). I am sure they could help for the cost of a couple of stamps.
 

Howard

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Assuming it's steel, how about a blob of weld and a bit of work with the Dremmel?

Failing that 10BA taps and screws seem to be obtainable.

H
 

clevtrev

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1.4 x .3 pitch. Taps and dies available.
Why does anybody think it would be something other than metric. Even the concours article by Ms Bickerstaff is still trying to persuade everybody that the holding bolts are 0BA, all I suggest is that she measures one, not takes an uneducated guess. Otherwise all the specification books out there in engineering land will have to be re-written, saying that BA threads have a 60 degree angle.
 
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John Appleton

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Assuming it's steel, how about a blob of weld and a bit of work with the Dremmel?

H

Sarkey comment!!! "A blob of weld". On a 1.4 mm screw head? I tried it and the screw melted, where did I go wrong?
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John Appleton

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Trevor, I don't think that could have been the problem. I used all the best equipment. Murex number 8 rods and a lincoln bullet welder wound right down to 210 amps, but it still melted.

Baffled of Leiston.
 

Howard

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Sarkey comment!!! "A blob of weld". On a 1.4 mm screw head? I tried it and the screw melted, where did I go wrong?
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Sorry, I'd got my works hat on - we don't use anything smaller than M16. :)

I've just been looking through my box of TINY screws and there's nothing less than 2.4 mm dia, it hadn't registered with me just how small 11 BA (if that's what it is) is.

H

ps If it comes to it I know someone with a laser welder for repairing jewellery (seriously) so I can get a "blob of weld" put on it - way be a gold or platinum blob.
 

bengunnhrd

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I remember reading a story a few years ago that during the latter part of WW2 when Rolls- Royce and Packard were both building the Merlin engine Packard sent over to Derby a drill so many microns thick with a look how clever we are, Rolls Royce sent it back with 3 holes drilled in the shank.
 
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