What chuck for Arundel j4 junior m24x2.5 spindle?

[John Brown]

It's a leftie. But I have a face plate for it already.

 

[Deckerwoodworking]

I have some original Arundel literature where a J4 MK11 is illustrated. This lathe has bronze bush bearings and is listed as having spindle threads of 7/8”x14 RH and 5/8”x14 LH .These were made in the mid 1980 s.

 

[Fergie 307]

That sounds more likely than a one off, but badly worn if it started out at 7/8, which is 22.2 mm.

 

[John Brown]

I raided my plumbing box. Will check sometime soon.
Grandchildren priority mode right now!

 

[Deckerwoodworking]

As I said in my last message that Arundel lathe is listed as 7/8”-14tpi right hand .

 

[J-G]

That sounds more likely than a one off, but badly worn if it started out at 7/8, which is 22.2 mm.

Although I agree that 7/8 x 14 makes more sense, there is no way that the thread presented could possibly be that spec..

The root dia. of a 7/8 x 14 Whit form would be 0.783" (19.9mm) and with an OD of 20.7mm that would make the depth of thread 0.4mm (0.016") whereas the enlarged photo shows that the (trunacted) DoT is 0.033" (0.85mm) so if the OD had been reduced to 20.7mm the truncation shown would be very much greater.

I've rounded these figures for clarity.

'Wear' would not affect the root dia. - well it might, but imperceptably - it might affect the thread form, ie. making it thinner, and that is not evident from the photographs supplied. This does suppose that @John Brown's assertion that the OD is correctly measured at 20.7mm but that is evidenced again in the photo's.

 

[John Brown]

As I said in my last message that Arundel lathe is listed as 7/8”-14tpi right hand .

Understood. But maybe that's just approximating to the nearest 1/8", as it does correspond more closely with 1/2" BSP.

 

[John Brown]

I have male and female 1/2" BSP fittings to test, but won't be able to do so until I can sneak away for 5 minutes..

 

[okeydokey]

Start sneaking
Some things stay stuck in the mind until you've scratched the itch

 

[Fergie 307]

Although I agree that 7/8 x 14 makes more sense, there is no way that the thread presented could possibly be that spec..

The root dia. of a 7/8 x 14 Whit form would be 0.783" (19.9mm) and with an OD of 20.7mm that would make the depth of thread 0.4mm (0.016") whereas the enlarged photo shows that the (trunacted) DoT is 0.033" (0.85mm) so if the OD had been reduced to 20.7mm the truncation shown would be very much greater.

I've rounded these figures for clarity.

'Wear' would not affect the root dia. - well it might, but imperceptably - it might affect the thread form, ie. making it thinner, and that is not evident from the photographs supplied. This does suppose that @John Brown's assertion that the OD is correctly measured at 20.7mm but that is evidenced again in the photo's.

Yes, that was a careless remark. If it was that badly worn the threads would look very different. Like you I have a feeling his BSP nut is going to fit.
Oh the suspense

 

[John Brown]

Yes, that was a careless remark. If it was that badly worn the threads would look very different. Like you I have a feeling his BSP nut is going to fit.
Oh the suspense

Fits like a glove!