Myford 33t and 34t gears for metric threads

I trained and worked for six years as a scientific instrument maker and I never saw anyone screwcut a BA thread or indeed later in my life of engineering ,thousands of BA threads were cut using split dies and they did not wobble,provided a sliding die holder was used,I can recall ,that in our works some 60 years ago only one job ,a steel 1 BA screw was produced in batches of 2k that used the self opening dieholder. on a Ward 2A capstan, I can never understand why BA was ever thought of though I gather that it was instigated by a commitee and we well know the rubbish committees invent. In the smaller tooth sizes I do not see any problems with running mixed tooth angles together at slow speeds and relative short running time.

I agree. The cost of a rotary table and cutter would likely be less than forking out lots of dosh for a

‘pukka” fymord set of unnecessarily precise gears that may not get used very often. Even better if you already have a mill.

Easy, use one of the 34 tooth 20°PA Delrin gears as an indexing plate.

I may have mentioned them earlier.

Bill

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I think Jason meant 'how accurately' in the sense of 'to what level of accuracy'

[ 'though one of the joys of the English language is it's potential for ambiguity ]

Yes, there will be the right number of teeth ... but

MichaelG.

I note all of the above chatter, if you have a need for a BA threaded item and have a rack full of suitable items, fine.

If not, cut out the fuss and just make what you need, screwcut if necessary, its not difficult.

I know, hence the devil.

Bill

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My apologies then, Bill

I thought you had interpreted Jason's 'how accurately' as 'by what method, accurately ...'

... Which, I suppose, demonstrates my point about ambiguity.

​MichaelG.

I expect you'd need to slightly increase the centre to centre distance of the gears to give clearance, although that wouldn't be a problem to implement on a banjo. The constant velocity advantage of involute gearing would also be lost. So in theory one would cut a wavy thread; although in practice I doubt it would be noticed.

Andrew

On BA, because their only practical application is fixings, the required pitch accuracy is not very high - unless for some strange reason you want to wind studs all the way into really deep holes.

Neil

Another radical suggestion is someone approaching RDG, or Myford, about gettign a batch of 34 tooth change wheels made.

Certainly RDG had some about 6 months ago.

Have just sent RDG an email about the 34 tooth gears. If others contact them as well they may get a batch made. If anyone knows anywhere else that can cut a batch, then please approach them.

An excellent idea Peter, I have just emailed RDG as well and got an almost instantaneous response that the 34t are currently out of stock but are expected back in stock in about 8 weeks.
Clive

The thread form lent itself to instrument making and producing screw threads in thinner sheet (usually brass) material.

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... and was derived from existing Swiss threads

MichaelG.

RDG finally have 34 Tooth gears in stock. They are showing on their websie but not the Ebay store.

I have ordered one and it is currently in transit.

Peter

I see that RDG TOOLS have 33 and 34 tooth change gears back in stock.