Threaded Clock Key

[dnhb]

My neice's no-name clock movement needs a reverse threaded winding key. Would I be right in thinking that it would be best to make one - involving the investment in an appropriately-sized Tap - rather than trying to find one to fit?

Edited August 23, 2024 by dnhb
To add photo

[AndyGSi]

I think it would be easier just to find one.

https://www.ebay.co.uk/itm/175850911870

[dnhb]

Thanks: yes I'd seen these but there didn't seem to be one of the size (I think) it needs & £20+ seemed a lot to shell out in the hope I do get one that's suitable (I know returns are accepted but I don't really want the hassle of that). In addition, buying a tool always seems to me a worthwhile expenditure....

[AndyGSi]

16 minutes ago, dnhb said:

Thanks: yes I'd seen these but there didn't seem to be one of the size (I think) it needs & £20+ seemed a lot to shell out in the hope I do get one that's suitable (I know returns are accepted but I don't really want the hassle of that). In addition, buying a tool always seems to me a worthwhile expenditure....

Do you know what size and pitch reverse tap you'd need and how much one would cost?

[oldhippy]

Can you show me the whole movement?

[dnhb]

54 minutes ago, oldhippy said:

Can you show me the whole movement?

Thanks for your interest. Hope this helps...

[Dell]

Did you find a key because I may have one, is it left hand thread ?

Dell

[oldhippy]

It looks like one of those old 2 inch movements. Have you tried any suppliers? 

[dnhb]

On 9/5/2024 at 9:36 AM, Dell said:

Did you find a key because I may have one, is it left hand thread ?

Dell

Yes it's a left hand thread with an outer diameter of ~3.5mm & an inner (assumed to be equal to that of the top 2.5mm before the thread starts) of ~2.6mm. The thread pitch is ~ 0.75mm. The 2.5mm between the bottom of the thread & the back plate is ~4.5mm diameter. My engineering friend says the pitch looks to him to be relatively coarse & thinks it might be a Whitworth. Thanks for your interest....

On 9/5/2024 at 10:41 AM, oldhippy said:

It looks like one of those old 2 inch movements. Have you tried any suppliers? 

The diameter of the back plate is actually 9cms/2.75" but I can't find any markings anywhere on the movement. I have looked online but without success due to insufficient details in descriptions. Also, I rather fancy using this as a learning opportunity re the selection & use of Taps etc as my engineering knowledge is minimal.

[Dell]

Sorry I can’t shift the key to see what thread but I have soaked in kerosene se if that will loosen it.

[oldhippy]

On 9/6/2024 at 4:24 PM, dnhb said:

Yes it's a left hand thread with an outer diameter of ~3.5mm & an inner (assumed to be equal to that of the top 2.5mm before the thread starts) of ~2.6mm. The thread pitch is ~ 0.75mm. The 2.5mm between the bottom of the thread & the back plate is ~4.5mm diameter. My engineering friend says the pitch looks to him to be relatively coarse & thinks it might be a Whitworth. Thanks for your interest....

The diameter of the back plate is actually 9cms/2.75" but I can't find any markings anywhere on the movement. I have looked online but without success due to insufficient details in descriptions. Also, I rather fancy using this as a learning opportunity re the selection & use of Taps etc as my engineering knowledge is minimal.

Looks as if all you can get these days are those horrid quartz movements 

[rjenkinsgb]

The thread dimensions could be 4BA ?? You can get left hand thread BA taps.

3.6mm outer thread diameter, 2.8mm core diameter, 0.66mm pitch. You could try a 4BA screw & see if the threads fit the side of the winding shaft?

 

Alternatively, M3.5, though I don't think that's all that likely in old items?

3.5mm, 2.85mm, 0.60mm.

 

The dimensions given don't appear to match Whitworth or BSF, in the tabled I've found.

 

[oldhippy]

I think the old movements were made in Germany. 

[dnhb]

On 9/9/2024 at 8:51 PM, rjenkinsgb said:

The thread dimensions could be 4BA ?? You can get left hand thread BA taps.

3.6mm outer thread diameter, 2.8mm core diameter, 0.66mm pitch. You could try a 4BA screw & see if the threads fit the side of the winding shaft?

 

Alternatively, M3.5, though I don't think that's all that likely in old items?

3.5mm, 2.85mm, 0.60mm.

 

The dimensions given don't appear to match Whitworth or BSF, in the tabled I've found.

 

Thanks very much indeed. I'll certainly follow up your helpful suggestions, starting with getting a 4BA screw...