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When does Silver steel not need hardening and Tempering

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Chris TickTock02/11/2019 13:21:39
236 forum posts
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Hi i am currently making a new anvil for an obsolete 0 to 1/2 inch micrometer. I am making the anvil out of silver steel. My thoughts are to harden and temper but then thought is it in this case appropriate as you only want the micrometer jaws lightly on the work piece to be measured so wear will not be great. So just in case i thought i would ask you guys for your opinions.

Chris

Tony Pratt 102/11/2019 13:49:42
934 forum posts
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Silver steel will generally distort when heat treated so you will have to deal with that issue but if the micrometer is only for light usage soft would be ok.

Tony

Jeff Dayman02/11/2019 14:39:43
1661 forum posts
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It might be better to approach this from a different angle. Maybe ask "what job does this part need to do?" consider wear, amount of use, calibration method, how it is retained etc. Then ask "what steel and hardness would be best / adequate for that?"

John Haine02/11/2019 14:50:16
2698 forum posts
138 photos

When originally made they probably anticipated daily use in a busy tool room and not a lot of TLC. For the amount of use an amateur will give it over its remaining life I'm sure unhardened will be just fine. Probably, so would mild steel!

Bob Stevenson02/11/2019 15:00:09
313 forum posts
6 photos

You only need to harden the faces of the anvils......place finished anvil in the corner of the hearth and 'tickle' just the end/face until red hot using small strong flame.......quench just the end,...brighten quickly with wire wool then watch the residual heat colours creep up the piece,..when 'straw' reaches the face quench completely. by this method there will likley be zero distortion and the face will be very hard,..enough to reduce wear significantly.

........This method also works well for clock pivots and is my usual method now.

Speedy Builder502/11/2019 15:21:42
1843 forum posts
128 photos

These are the original specs for the 1961 model 0 -1" micrometer

Measuring face flatness. 0.00005"

Measuring face parallelisme. 0.0001"

Anvil - Tungsten Carbide (or steel)

Spare anvils are available from M&W still, between 4 - 7 pounds

I think that you would struggle to get the original accuracy however that may not be so important depending upon your requirements.

Neil Wyatt02/11/2019 16:10:23
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A better question woudl be 'why use silver steel for a job where it doesn't need hardening?' and the answer would probably be don't waste money. Use PGMS instead if diameter is important, or a medium carbon steel if a degree of toughness/wear resistance is useful (as with your anvil).

Neil

Neil Wyatt02/11/2019 16:11:04
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A better question woudl be 'why use silver steel for a job where it doesn't need hardening?' and the answer would probably be don't waste money. Use PGMS instead if diameter is important, or a medium carbon steel if a degree of toughness/wear resistance is useful (as with your anvil).

Neil

JasonB02/11/2019 16:14:36
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Or just Loctite something hardened onto the end of a softer part which will take the thread better than silver steel.

Chris TickTock02/11/2019 17:48:21
236 forum posts
12 photos

Thanks Guys,

i appreciate the posts and learned quite a bit from them. I lwill upon reading your posts leave them un heat treated silver steel . At least I can use this micrometer now for most purposes as it now has a square face anvil. What it came to me with was a dome shaped anvil like a rivet, it look original but hey I don't know. Yes it is right I would not get the anvil dead on parallel but it matches for accuracy upon testing of my other 2 larger micrometers so it will do for my purposes

Thanks again

Chris

Speedy Builder502/11/2019 18:05:42
1843 forum posts
128 photos

Probably used for measuring tube thickness, hence 0 - 1/2"

SillyOldDuffer02/11/2019 19:40:54
4864 forum posts
1021 photos

Hardening the tip is worth doing because any wear will cause inaccurate measurements but I suggest there's no advantage in tempering as well. Hardening leaves metal brittle. Tempering has the effect of improving toughness by reducing hardness, which is important if the metal is going to be stressed. As a micrometer tip is lightly loaded and needs to be as hard as possible to reduce wear, there's no gain from tempering. Unlike a silver-steel tap or drill which is worth tempering because it needs to be both tough and hard.

Note how difficult a domed end micrometer makes it to accurately measure anything other than a tube. The screw-end and anvil of an ordinary micrometer should be the exact opposite - flat, parallel and sharply square to reduce rocking errors. An interesting question is how flat can a surface be faced by lathe? Imperfectly! As lathes that face convex are a right pain because rods made on them won't stack, most lathes are set to face slightly concave. For this and other reasons micrometers aren't made on lathes at all - instead they are precision ground.

The slight imperfections of a home-made tip may not matter unless the mended micrometer has to be really trustworthy. If accuracy matters buy a new micrometer!

Dave

Mike Poole02/11/2019 21:21:33
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The problem of producing a flat square anvil has crossed my mind before, the situation that got me thinking was producing additional rods for a depth mic. I didn’t come up with a solution but Clicksprings method of making polished screw head faces seemed to have possibilities. If anyone knows how the faces of the anvils of a micrometer are mirror finished and square are produced then it would be interesting to know.

Mike

Neil Wyatt03/11/2019 14:11:12
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Posted by Chris TickTock on 02/11/2019 17:48:21:

What it came to me with was a dome shaped anvil like a rivet, it look original but hey I don't know.

For measuring the wall thickness of tubes.

Neil

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