Blued pivot steel guages ?

[Francis MilsomParticipant @francismilsom24920]

Hi,

I've a lathe (Warco WM240) and a mill (Warco WM14) which I've been using on and off for a couple of years to make small parts for telescopes and some tooling for the machines themselves. However the one thing I really want to start to build is a skeleton clock.

I have John Wildings' A Large Wheel Skeleton Clock bound reprint of the original article and going through the materials list I've come across 'Blued Pivot Steel N° 42 gauge'. I've been searching the web for a size chart for Blued Pivot steel. I can find metric sizes but I have no clue as to how metric sizes relate to the N° 42 gauge size quoted in the article.

My reasoning is because of cost. I simply cannot aford the CZ120 brass at full scale so I'm down sizing to 75% of the original. Still large enough for me to work on and the material resizing brings the price down to a more comfortable level.

Thanks for any help.

[Francis MilsomParticipant @francismilsom24920]

Old – New sizes?

[Michael GilliganParticipant @michaelgilligan61133]

Welcome aboard, Francis

You should find this article useful: **LINK**

https://bhi.co.uk/wp-content/uploads/2023/02/08-HJAugust22-AOTM.pdf

The author is a very well-respected craftsman.

MichaelG.

.

Regarding diameters: The metric ‘system’ of increments is the de facto standard, so I really don’t understand why John Wilding would use ‘Gauge’

Edit: __ Here’s a discussion about the ‘elegant scroll skeleton clock’ … 

https://www.model-engineer.co.uk/forums/postings.asp?th=124747&p=1

…. and a reference to the Clickspring videos about making the ‘large wheel’ clock, here:

https://modelengineeringwebsite.com/Large_wheel_skeleton_clock.html

Note: __ I have no personal experience of either 

Edited By Michael Gilligan on 27/04/2023 09:15:04

[BizibilderParticipant @bizibilder]

Be careful in reducing the scale of the clock – you will have to adjust all the wheel module sizes (sizes of the teeth on the wheels and pinions) as well as the pendulum length and/or a complete redesign of the escapement. By the time you have bought all the cutters required (or made them yourself) you may find that this leads to a far greater overall cost to build than the price of the brass you will need for the original design. If you are careful you can make quite a few components from the left over brass from the great wheel after crossing out the spokes as well as all the offcuts from the frames. If you draw out the parts full size and cut them out as paper templates you can probably work out a reasonable efficient cutting pattern with a minimum of wastage.

 

Edited By Bizibilder on 27/04/2023 09:48:54

[bernard towersParticipant @bernardtowers37738]

MKM advertise No36 pivot steel so possibly at some time in the past it was available in imperial?

[CirclipParticipant @circlip]

Which parts use the CZ 120 that is expensive? Frame plates can be a different material with brass bushes. I have an original Cuckoo clock with the frames from wood and brass bushes.

Regards Ian.

[Francis MilsomParticipant @francismilsom24920]

Many thanks for the replies, they are certainly making me think a little harder about the build.

@Circlip I really want to build the clock in brass with a polished finish. I had considered using aliuminium for the frames but if I'm going to put that amount of effort into the build then (for me) brass is the way to go.

@bernard towers thenks I'll give them a call.

@Bizibilder – Making me rethink…

[BazyleParticipant @bazyle]

You can always make the frames out of aluminium and bush the pivot holes. Probably no escaping the cost of the great wheel but another problem there is making such a big high risk item your very first venture.

I don't mean to be disparaging but there is a lot to be said for starting with the 'beginners clock' (which is the name of a particular design, not just any clock for beginners.) This design also appears to be available as 'the dark lady' clock but as far as I can see is the same one panted black.

[John HaineParticipant @johnhaine32865]

Personally I really dislike a polished brass finish on clock plates, it makes it very hard to see the details of the movement. It has become "traditional" but I prefer a deliberately matt finish, and using a high grade matted aluminium with brass bushes (or better, ball races) provides a better contrast. An example:

**LINK**

I second the points about the complication of scaling down the design.

[SillyOldDufferModerator @sillyoldduffer]

Does anyone have a table of Pivot Gauge sizes converted to inches or millimetres? None of my old engineering books have one.

Dave

[BizibilderParticipant @bizibilder]

If you scroll down to page 18 of this old price list from 2005 you will see blue pivot steel in both metric and Stubbs wire gauge HERE worth downloading and keeping just for this!

[Mike HurleyParticipant @mikehurley60381]

Ian T Cobb's clockmaking supplies site has a detailed table on blued pivot steel if that's any help

Regards Mike

[Francis MilsomParticipant @francismilsom24920]

@John Haine Thanks John. More food for thought.

@Bazyle Thanks for the link to the dark lady clock thread (great build notes and comments).

I'm just not sure I want to build a clock as practice piece to build another clock. Please don't get me wrong, I'm intending to practice gear cutting, depthing and other processes while making further tooling for my clock build before commiting to the actual build.

What started out above as a request for info on blued pivot steel gauge sizes has pretty much turned my thoughts completely around. Gone now are thoughts of downscaling the clock, but thoughts now turning to changing materials for different aspects of the build are calling for a rethink in my whole approach…

[Martin KyteParticipant @martinkyte99762]

I have always bought blued pivot steel in bundles of assorted sizes. Silver steel will do just as well if you want an alternative. As has been already stated rescaling the clock will give you no end of problems so I suggest you really don’t do that. With the Large Wheel clock do stick to the correct thickness for the escape and third wheel which is 18G which off the top of my head is 48 thou. The clock will not run if they are thicker than specified.

As to the arbors if you look on page 33 the drawing of the centre arbor specifies 42 g or 3/32”. Anything close to his will do you provided you can team the collets to size to suit.

It is possible to save a little on brass for the frames by omitting the feet which are drawn integral with the frames which looses an inch from each plate. The ends of the frame can be formed as rounds to take the clock pillars as shown and then the underside drilled and tapped to accept turned bun feet of a similar shape as the old plate feet. Personally I think this looks better but I have to acknowledge the idea as one from the late Chris Sangster.

regards Martin

[Francis MilsomParticipant @francismilsom24920]

@Martin Kyte Thanks martin, I seem to remember from watching the Clickspring videos on the skeleton clock that the feet were replaced for more ornate versions, so your mention of that above has brought that to the fore.

I'm currently reading and re-reading John Wildings' article and making notes not just on his order of building but on the additional tools used along the way to see what I have, what I need, what I can work around and anything I really need to make or buy in.

What I don't have is anything for heating metals for hardening/tempering/bluing components. That's something I will have to start a thread on. For tempering and bluing I wondered if a hot air-paint striper would be okay? I would still need a small burner of sorts to do any hardening with.

[Martin KyteParticipant @martinkyte99762]

Where are you in the country Francis?

regards Martin

[Francis MilsomParticipant @francismilsom24920]

Posted by Martin Kyte on 27/04/2023 18:23:53:

Where are you in the country Francis?

regards Martin

I'm in Kingstone just outside Hereford

[Martin KyteParticipant @martinkyte99762]

Ah that’s quite a way from Cambridgeshire

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