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Austinsevenfriends
Rist Horn Threads - Printable Version

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Rist Horn Threads - Chris KC - 23-05-2018

Anyone know what thread the terminal posts on a 6V Rist horn are? 3BA perhaps?

They are a shade bigger than the 4BA screws which hold the unit together.

RE: Rist Horn Threads - Stuart Joseph - 24-05-2018

(23-05-2018, 07:57 PM)Chris KC Wrote: Anyone know what thread the terminal posts on a 6V Rist horn are? 3BA perhaps?

They are a shade bigger than the 4BA screws which hold the unit together.
Good morning Chris, I've just tried two horns and the thread on them is 2BA.

Regards from the creative county - Staffordshire

Stuart

RE: Rist Horn Threads - Ian Williams - 24-05-2018

Are you sure, I thought they were coarser 5/32 whit from memory??

RE: Rist Horn Threads - Chris KC - 24-05-2018

(24-05-2018, 08:45 AM)Ian Williams Wrote: Are you sure, I thought they were coarser 5/32 whit from memory??

Not sure at all Ian, wild guess based on approx dia over threads ~4mm; so 5/32BSW sounds plausible. 

They are a bit manky so I want to clean them up, would be good to do it with the right die...

RE: Rist Horn Threads - Stuart Joseph - 24-05-2018

(24-05-2018, 08:45 AM)Ian Williams Wrote: Are you sure, I thought they were coarser 5/32 whit from memory??

Hello Ian, I too thought they were courser than BA but a 2BA nut fitted both horns perfectly.

Stuart

RE: Rist Horn Threads - Chris KC - 24-05-2018

Sorry Stuart (& thanks) - somehow I missed your reply earlier.

I wonder if more than one size was used? I'm pretty sure I offered up 2BA last night but it looked way too big; and that would be 4.5mm across the threads (might be more worn than I thought). I'll have to check again tonight, stuck in the office right now!

RE: Rist Horn Threads - Ian Williams - 24-05-2018

Interesting Stuart, I have two genuine Rist horn's here and both are not 2BA, in fact a 2BA nut goes straight over the studs 5/32 BSW is correct for mine so perhaps there was a variation.

RE: Rist Horn Threads - Geoff Halstead - 24-05-2018

5/32x32tpi on mine.

Geoff - Compressed air cooler completed.

RE: Rist Horn Threads - David.H - 24-05-2018

(24-05-2018, 12:55 PM)Geoff Halstead Wrote: 5/32x32tpi on mine.

Geoff - Compressed air cooler completed.
This may help (or confuse....)  
Across flats a 2BA nut should be 0.324". 1/8BSW 0.338" . (M5 nut  is 8mm ...0.315")
I think a No 6 UNC/F is 0.313 (5/16"A/Flats)

RE: Rist Horn Threads - Stuart Joseph - 24-05-2018

(24-05-2018, 10:55 AM)Ian Williams Wrote: Interesting Stuart, I have two genuine Rist horn's here and both are not 2BA, in fact a 2BA nut goes straight over the studs 5/32 BSW is correct for mine so perhaps there was a variation.

Hi Ian, just tried a third Rist's horn and it is as you suggest 5/32x32tpi BSW, so there is (was) variation.

5/32 Whit is of course the same size as the original Meccano thread.

Regards

Stuart