Thread on bolt and nut on clock mechanisim

[alo]

Problem with thread on hollow bolt, and thread on nut, both on electronic clock mechanism..

I have purchased a replacement Pendulum Clock Movement (see link to pictures). There is a problem with the retaining nut and shaft. It required some considerable force to remove the dial fixing nut, and trying to put it back on the bolt would require the same amount of force, with the chances of ruining the mechanism completely.

I can only get it to go on the first few threads of the shaft.

Anybody know what size tap and die set to get to clean these two items up? I have looked at a 'Rolson 59154 HSS Mini Tap and Die Set - 31 Pieces' but the tap and die are too small to use on these two items.

I have and alternative tap and die set but that is more for car and motorcycle nuts and bolts (they are too big and coarse).

Thanks

[Syd Rumpo]

Well, it /looks/ like a Schrader valve thread as used on car tyres, in which case it's, according ti Wikipedia...-

Metric: 7.7 mm OD, thread root diameter is 6.9 mm × 0.794 mm pitch Imperial: 0.305 in OD, thread root diameter 0.271 in × 32 tpi

You could confirm that by, eg, trying a dust cap.

Cheers

[alo]

Thanks...

I will give that a go and see if a dust cap fits.

[ss]

If that doesnt do it maybe take to a clockmaker/repairer and they may confirm for you or even run it through a die/tap.

[alo]

Yes you are correct the thread on a dust cap is the same as on the nut that should fit on the shaft.. ... the nut fits on the valve of the tyre with no problem, and the valve cap will not fit on the clock shaft. The thread on the clock shaft is defective.

Thanks