Little experience so advise needed

hi Guys let me first say I have both a Sherline Mill and Lathe. My hobby ney obsession is old clocks. I wish to learn how to machine parts for platform escapements namely the balance staff which is approx 20mm long and are some type of steel, no doubt then hardened. This is micro machining. my initial questions relate to the fact that it is inevitable I will cock up a good few attempts so what material should I use to practice on for starters? I have taken advise on cutters and setup but any other advise including suppliers of Micro-100 carbide bits appreciated.

regards

Chris

Welcome, Chris

Don't waste your energy experimenting with other steels ... Buy some 'Blue Pivot Steel' from one of the reputable supply houses: It is properly heat treated; which, of course, what imparts that lovely blue colour.

... and beware : Some ebay Sellers are listing 'Steel suitable for making blue pivot steel' [or some such nonsense]

MichaelG

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P.S. where are you located ?

The right equipment for the job is a Super Adept lathe

Chris, where in the world are you based ? for practise turning you won't go far wrong with EN1A. Then buy your "Blue Pivot Steel" if you are close to Lichfield I can give you some bits to play around with.

Chris.

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Well that's me told

MichaelG.

Hi Michael I live on the Cambridge area. thanks for the post guys.

Chris

If you're buying it in and you have the choice, EN1APb is even better to machine. The modern ref is 230M07 PB.

The lead stops it sticking to the top of the tool and developing the dreaded built up edge

Chris Evans, and Duncan Webster

Perhaps I was mistaken, but I thought Chris Judd wanted to practice turning things like balance staffs [see his opening post].

I know no-one who could make a useful 20mm long balance staff from EN1A [with or without added lead], so what is the point of him wasting his efforts practicing on that ?

The cutting characteristics of Blue Pivot Steel are surely what he needs become familiar with.

MichaelG.

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I have sent you a PM [personal message] Chris

Please check your Inbox [icon on the top green bar of this page]

MichaelG.

I read it that the OP wanted something easy to start with before attempting pivot steel

As said blue pivot steel is the stuff to use. The problem is that you can't easily harden the staff after making - you burn the pivots. So it has to be made from a good grade of steel hardened to spring temper from the get go.

A read of some of Donald de Carle's books might be an idea. The Web has a pdf. Also getting a pair of pivot files left and right (and they are not cheap if new). To check the size I have made a temporary staff from brass, easy and quick.

Usually hand turning with a lozenge graver is the traditional way but I could never get on with that tool and used engraving tools. Experiment, you will surely end up making a few before you settle on a technique that works for you.

You 'can' polish the pivots in the lathe but it is a bit risky. Some sort of support like a Jacot tool makes it less likely to bust the pivot at the last moment (v annoying).

You can also make a simple turns and do the job between centres. Make a little pulley, some cotton thread and a motor and you are good to go.

Enjoy.

Good here isnt it, I had never heard of Blue Pivot Steel, learn something everyday.

Ron

You don't have to build clocks & watches to use watch-makers materials and tools Ron, they are very useful to model makers too. Don Gordon (a builder of small scale boats) wrote a very good series in ME in the 80's called "Low cost, High Precision" - well worth a read for any small scale modeler. Don used pivot steel to make very small diameter drills when required for instance.

You can get it in various sizes from Cousins UK. I purchased packs of assorted sizes from them some years ago and it can be a useful source of hard, small diameter steel.

Regards,

IanT

Ron,

Not sure if it is mentioned above, but the blue simply refers to the colour to which the material was historically tempered, after hardening. These days, they simply use temperature, rather than the colour, for controlling the tempering process, as it is(or should be) far more precise.