Pivot Steel

[Robert HodgkinsParticipant @roberthodgkins92224]

[Robert HodgkinsParticipant @roberthodgkins92224]

Hi Guys

I'm pretty new to clock building. I have just started building JW Eight Day Wall clock. I'm not really ready to make the pivots yet but i was making an order for materials and I thought I would order some blue pivot steel. JW's book says 3/32" but I see that is not readily available now. What size should I go for 2.5mm?

Thanks

Bob

[BizibilderParticipant @bizibilder]

Yes – Just use the closest metric size. If in doubt go up rather than down in size if you have to.

3/32 is 94 thou and 2.5mm 98 thou – so just about spot on. With clocks you hand fit the pivots etc so the exact size doesn't matter.

To get a 2.5mm hole in a wheel collet grind or file a piece of the pivot steel you intend using at about 30° and use that as a reamer to size the holes you need for that size of pivot steel

This gives you the idea: Here But he uses three facets on his reamer – I prefer to just have one – the choice is yours.

[John HaineParticipant @johnhaine32865]

Only .12mm larger so better than 2 mm which is .38 smaller, or 3 which is .62.

[Dick HParticipant @dickh]

Just use silver steel and harden the ends afterwards, blue pivot steel can be a pig to work.

Which version of the JW 8 Day Wall Clock are you working from?

[roy entwistleParticipant @royentwistle24699]

Bob If you can get 3/32" silver steel, use that

I see Dick types faster than me

Edited By roy entwistle on 06/11/2020 21:56:35

[Michael GilliganParticipant @michaelgilligan61133]

I admit that I was surprised by the mention of 3/32” blue pivot steel, for I have only ever purchased this material in Metric sizes … So I went back to John Widing’s series, which commenced March 1972 in the Horological Journal.

Sure enough : He mentions using either blue pivot steel, or silver steel, for the arbors … and, perhaps more significantly, makes a point of explaining that he has dimensioned the project in ‘English sizes’ for convenience of obtaining materials.

I’m not sure if the introductory note made it into the book, so I am repeating it here:

 

Like other contributors; I would use blue pivot steel in Metric sizes, and adjust to suit.

 

MichaelG.

.

Edit: just noticed that the last two posters prefer silver steel 

Edited By Michael Gilligan on 06/11/2020 22:35:49

[Robert HodgkinsParticipant @roberthodgkins92224]

Hi Guys

Ok I am working to the "How to make A Weight Driven 8-day Wall Clock (updated)" book from Ian Cobb.

I have made the Frames, Pillars and Barrel. I have just plunged into cutting the ratchet teeth. I really should hve read the script before posting. Sadly I just looked at the diagram and just saw 3/32" and assumed I needed that size blue pivot steel. I have now read in a bit more detail and I can whats required. I was just trying to put a materials order together for what was coming up.

I am currently working on the main wheel but have run into a snag. I made a Aluminium arbor which I turned up on my Cowells Lathe. I stuck the blank to it with super glue and turned it all to size drilled and reamed 5/16". I have to cut my gears on my Warbeco milling machine. I have a divisionmaster with a 4 jaw centering chuck. When I transferred the arbor to the mill I loose concentricty. Its only a few thou but I'm not sure what my tolerences are as I have never made gears before. I think I am going to buy a 14mm rotary table adapter so I can just move my cowells 3 jaw with the Ally arbor in it to see if it improves things.

The black art of clock making Lol. But I am enjoying the challenge atm.

Bob

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