Unidentified 3 Jaw chuck with 24mm spigot recess, what will the thread be?

[Ian PParticipant @ianp]

I went to Chester Engineering's open day this morning and one of the bargain items I came away with was small lever scroll chuck. I want to make a 5C arbor for it so that I can easily grip the odd larger objects without having to dismantle the Acrogrip collet system.

The thread looks to be a little smaller than the only thing I have measured so far, and that is the 24mm ID of the register.

Does this sound a standard size for some make of lathe? I have been searching but not found any spindle detail to suite that diameter. I am not sure what the thread pitch is, but its near 1.5mm or 16tpi.

Ian P

[Ian PParticipant @ianp]

[John ReeseParticipant @johnreese12848]

Do you have a thread pitch gauge? Can you use a tap (of any diameter) to check the pitch?

[Ian PParticipant @ianp]

Posted by John Reese on 04/12/2018 01:56:08:

Do you have a thread pitch gauge? Can you use a tap (of any diameter) to check the pitch?

Yes I do have taps and thread gauges of both pitches but the register is quite long and I found it difficult to be certain.

I was hoping someone might know what it was lathe it was for in the slight hope that I could purchase a ready made 5C arbor.

Ian P

[Ady1Participant @ady1]

Piccies would probbly help (A thousand words)

[BazyleParticipant @bazyle]

push a bit of wood like a lolly stick up against the thread, at 1 inch it should be easy to get a finger in to apply pressure, and the oil on the thread will print on it or better the pressure will cut grooves. Then measure.

[not done it yetParticipant @notdoneityet]

Ask Chester?

[LambtonParticipant @lambton]

Ian,

Is the chuck mounted on a back plate or is the thread cut directly into the chuck body?

Eric

[Ian PParticipant @ianp]

Posted by Lambton on 04/12/2018 10:12:45:

Ian,

Is the chuck mounted on a back plate or is the thread cut directly into the chuck body?

Eric

Thread is in the chuck body.

I think its fairly old stock, not in the Chester catalogue and no one I asked knew its history.

Ian P

[Howard LewisParticipant @howardlewis46836]

It might be worth persisting in checking the thread core diameter, and pitch. This should give a better idea, but bear in mind that if it is Imperial, the thread form will be 55 degrees rather than the 60 degrees.of Metric or Unified..

Since it is old stock, you may well find that it is Imperial. 24mm is 0.9449 inch. This is just over 15/16", although this is not Myford 7 Series, or the earlier ML2s and 4s..

Howard

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