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jdrichard

Best Stock for Making Balance Staff

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When i figure all this out, i will make a youtube video on exactly what to buy and if or not tempering is needed and how. I think Blue Steel can be cut and nothing else has to be done, correct.

 

blue steel isn't a different kind of steel, it is just tool steel that has been tempered to blue after hardening - and you buy it that way in a package saving some steps.   it will machine but is a lot less machinable than annealed, as Marc noted above.   "Hardening, Tempering and Heat Treatment" is the book for the amateur/home shop type if wanted to learn about it - its a small paperback. 

imo hardening and tempering is an important home shop skill applicable to horology as in addition to parts, its how you make your own cutting tools - something used quite a bit if read horology texts etc.  Non-horology wise its saved me numerous times over the years, gear cutters, broaches, specialty taps etc

Edited by measuretwice

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The reason for the different types of steel has to do with their application. End mill cutters, drills and reamers produce heat under normal use and the "O" type steels hold up better. The "W" types are used for low heat usage applications and are typically used for knives and scissors. As I mentioned before, the "A" type steels exhibit almost no deformation after heat treatment and are used for stamping dies. There are many other types of steel that have uses in many applications such as shock resistance ("S7"), "P" series steels (for injection molds) and so on, but the "O", "W" and "A"  are the most common types for drill rod.

david

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JD Richard,

If the steel was so hard that you had to cut it with a carbide graver then you will probably have problems trying to thread it. Pivots and staffs are not threaded and milled which allows the machining to be done with a prehardened piece of steel. For a winding stem, which needs to be milled and threaded after turning, I prefer to use unhardened steel (drill rod) to begin with. If prehardened steel is your only option, it would be a good idea to anneal it before beginning to machine it.

david

Edited by david

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JD Richard,
If the steel was so hard that you had to cut it with a carbide graver then you will probably have problems trying to thread it. Pivots and staffs are not threaded and milled which allows the machining to be done with a prehardened piece of steel. For a winding stem, which needs to be milled and threaded after turning, I prefer to use unhardened steel (drill rod) to begin with. If prehardened steel is your only option, it would be a good idea to anneal it before beginning to machine it.
david

So i should simply heat up the thread end?


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24 minutes ago, jdrichard said:


So i still need to cut the gap and thread it. It is tempered blue steel so what is the simplest way of softening the tread end before taping/dyeing the stem.
 

Looks like lots of progress is being made with the lathe work.   You need to thread that with a die (a tap is what is used to thread holes) which is in the good luck department unless you anneal it imo.  Annealing requires a slow cool.  Soak at red wrapped in say binding wire or in a recess of a bigger piece of steel to give it some thermal mass then put in a box of ashes (makes a good insulator). 

You be better imo to start with a piece of annealed O1 and forget about heat treating it

 

Edited by measuretwice

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10 hours ago, david said:

JD Richard,

After doing the machine work the part should be hardened and then tempered. Watch this video, it should answer a lot of your questions.

https://youtu.be/mkGygB7BMsQ

...Who's on first :)

To be clear, he's currently asking about making a stem, (or at least I assume so as it followed photos of a stem being worked on),  when I responded I would use O1 and wouldn't heat treat it.  If he's back to staffs,  then yes of course, harden and temper afterward.  Your video link was of a staff being made.

I wouldn't have thought you would harden and temper a stem, based on machining and tool making experience but with admittedly little watch experienced....so I could be wrong.  Not saying hardening threads is never done, but you can have problems with hardened threads, so is less than ideal unless some other design objective overrules.

Edited by measuretwice

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...Who's on first
To be clear, he's currently asking about making a stem, (or at least I assume so as it followed photos of a stem being worked on),  when I responded I would use O1 and wouldn't heat treat it.  If he's back to staffs,  then yes of course, harden and temper afterward.  Your video link was of a staff being made.
I wouldn't have thought you would harden and temper a stem, based on machining and tool making experience but with admittedly little watch experienced....so I could be wrong.  Not saying hardening threads is never done, but you can have problems with hardened threads, so is less than ideal unless some other design objective overrules.

I think i need to do a lot of reading followed be trial and error. Initial question was stems and i kind of get the answers. Mark gave me the complete answer fir staffs (blue steel) and no treating needed nut need to use carbide graver.


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On 9/26/2017 at 5:10 PM, Marc said:

Take your pick.....

https://www.cousinsuk.com/category/pivot-steel

https://www.hswalsh.com/product/blue-pivot-steel-wire

http://www.m-p.co.uk/muk/parts/chap10/pivot-steel-0.61mm.-10pcs-no.72-0618007215.htm

https://www.esslinger.com/staff-and-pivot-watch-and-clock-wire-rod-assortment-blue-steel-55-1-93mm-12-pieces/

http://timesavers.com/i-24049935-30-pack-3-00mm-3-95mm-blue-wire-assortment.html

https://www.amazon.com/Assorted-Tempered-Pivots-repair-pinions/dp/B01N1SOLDF

http://redroosteruk.com/11-assorted-tempered-blue-steel-wire-pivots-clock-repair-pivot-pinions-staffs/

https://perrinwatchparts.com/collections/metals/products/pivot_wire_43_2115?variant=37875445135

Google "blue pivot steel" and you will find more.

This has been the basic stock for watch and clock pivots and staffs forever. It is a carbon steel that has been hardened and then tempered back to a dark blue so that it can be cut on a lathe. It is still quite hard, try and cut it with snips and it will resist, eventually giving suddenly and breaking rather than cutting. In the lathe though it cuts easily with either a tungsten carbide or HSS graver, although a HSS graver will need frequent touching up to keep it cutting with a good clean finish. Keep a hard Arkansas slip by the lathe for this. Let it get too dull and it will chatter, resulting in a poorer finish, and it will also cause you to apply more pressure to get it to cut. If you're not careful you will break off the work piece by pushing too hard. Don't try to cut it too quickly either, and don't expect long curls of swarf. Take your time and make dust. You will get a better finish and the HSS graver will keep its edge longer, whilst the tungsten carbide will be less likely to chip.It also burnishes well so don't try to cut the pivots to size in the lathe, leave them over size and finish in the Jacot tool.

This doesn't need any further heat treating when you're done, it already has the right balance of hardness and strength for pivots and staffs, especially if you burnish the pivots in the Jacot as this locally work hardens the surface giving the correct hardness to resist wear whilst the rest of the staff retains enough strength to cope with a degree of mechanical shock without shattering.

Practise and enjoy.

I got some stuff from Esslinger and have had a hard time working with it.  It's almost impossible to cut into pieces.  Tried using a jewelers saw, no luck.  Graver won't part it--at least not in any reasonable length of time.  Doesn't want to be cut into pieces with snips either.  Definitely not getting curls of sworf and, yes, I am making dust.  Takes forever to make any progress.  Tried to anneal it but still application of my graver still yields a kind of brittle powder.  Didn't think about finishing down to size with the Jacot tool.  Thanks!

Edited by DouglasSkinner

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Blue steel can't be cut with a jeweler's saw but can be filed. That used to be how they checked the repivoting exam for clocks back in the day- saw bites, fail, file doesn't bite, fail.

The commercially available blue steel bars watch and clockmakers typically use is very hit or miss. The nomial size is often way off (not such a big problem), and the heat treatment can vary between too soft, uneven, or sometimes actually ok.

I have some and use it for pins and such.

For staffs, stems, pinions- anything from steel- I use oil hardening steel in its annealed state. The standard in Switzerland is Sandvik 20AP, probably not so easy to find in small quantities elsewhere. In the U.S. O1 would be the closest thing (and is a fine steel for watch parts). Parts get hardened and tempered after machining, with generally the last 0.01mm or removed in finishing for bearing surfaces.

For a staff I cut everything right to size except the pivots which are a good 0.10mm oversized, and I leave the taper for the roller table straight and oversized. After heat treatment, holding on the now straight roller diameter the top pivot is brought to 0.01mm over final size, the surfaces polished, rivet formed. Flip around and do lower pivot, roller taper, polish. Finally finish pivots in jacot.

Heat treatment is a little different than most books or schools teach. I use an iron tube welded to a long thin bar. These are actually CO2 or N2O cartridges from selzer or whipped cream bottles with the neck cut off (about the size of the first two digits of an index finger). This gets filled about 1/3 with fine wood charcoal powder, parts go in, filled the rest of the way. The whole thing is torch heated until glowing orange, then the contents dumped in oil. The parts fished out with a magnet, and they are a nice grey color and very clean. After cleaning off the oil they are blued in a pan of fine brass filings over an alcohol lamp.

With the above method there is rarely any deformation of even long thin parts, and no pitting.

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On 4/13/2019 at 4:17 AM, nickelsilver said:

Blue steel can't be cut with a jeweler's saw but can be filed. That used to be how they checked the repivoting exam for clocks back in the day- saw bites, fail, file doesn't bite, fail.

The commercially available blue steel bars watch and clockmakers typically use is very hit or miss. The nomial size is often way off (not such a big problem), and the heat treatment can vary between too soft, uneven, or sometimes actually ok.

I have some and use it for pins and such.

For staffs, stems, pinions- anything from steel- I use oil hardening steel in its annealed state. The standard in Switzerland is Sandvik 20AP, probably not so easy to find in small quantities elsewhere. In the U.S. O1 would be the closest thing (and is a fine steel for watch parts). Parts get hardened and tempered after machining, with generally the last 0.01mm or removed in finishing for bearing surfaces.

For a staff I cut everything right to size except the pivots which are a good 0.10mm oversized, and I leave the taper for the roller table straight and oversized. After heat treatment, holding on the now straight roller diameter the top pivot is brought to 0.01mm over final size, the surfaces polished, rivet formed. Flip around and do lower pivot, roller taper, polish. Finally finish pivots in jacot.

Heat treatment is a little different than most books or schools teach. I use an iron tube welded to a long thin bar. These are actually CO2 or N2O cartridges from selzer or whipped cream bottles with the neck cut off (about the size of the first two digits of an index finger). This gets filled about 1/3 with fine wood charcoal powder, parts go in, filled the rest of the way. The whole thing is torch heated until glowing orange, then the contents dumped in oil. The parts fished out with a magnet, and they are a nice grey color and very clean. After cleaning off the oil they are blued in a pan of fine brass filings over an alcohol lamp.

With the above method there is rarely any deformation of even long thin parts, and no pitting.

Thanks for the help, especially the tips about making the staff.  I can see if I can get some CO2 cartridges.  Didn't know N2O cartridges.  Not sure you can get them here in the US.

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Thanks for the help, especially the tips about making the staff.  I can see if I can get some CO2 cartridges.  Didn't know N2O cartridges.  Not sure you can get them here in the US.
You can get both for sure, definitely in a good kitchen supply like Williams Sonoma or something. Sometimes the N2O has to be asked for as it's a favorite among teenagers for huffing (it's laughing gas).

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On 4/13/2019 at 4:17 AM, nickelsilver said:

Heat treatment is a little different than most books or schools teach. I use an iron tube welded to a long thin bar. These are actually CO2 or N2O cartridges from selzer or whipped cream bottles with the neck cut off (about the size of the first two digits of an index finger). This gets filled about 1/3 with fine wood charcoal powder, parts go in, filled the rest of the way. The whole thing is torch heated until glowing orange, then the contents dumped in oil. The parts fished out with a magnet, and they are a nice grey color and very clean. After cleaning off the oil they are blued in a pan of fine brass filings over an alcohol lamp.
 

I  agree about machining annealed material.  I've made lots of tools and cutters over the years and would never imagine heat treating first.  No doubt intended to be a convenience for watchmakers, but imo heat treating is so easy, and turning hardened material such a pita, that its not.  And that a $3 length of small dia O1 drill rod available from any industrial supply will probably last a lifetime of amateur balance staff turning, makes it an easy call.

The charcoal I assume is to get rid of oxygen, i.e. to prevent scaling?   You don't like the cover in soap trick?

Edited by measuretwice

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The charcoal I assume is to get rid of oxygen, i.e. to prevent scaling?   You don't like the cover in soap trick?


Yes, it really works great. I've tried various soaps, borax, Brownell's proprietary concoction- this is definitely the best I've seen. It's kind of messy, and you need wood charcoal and a good espresso grinder, but worth it. I harden something probably once a day on average.

I guess the alimentary charcoal powder you can get in health food stores would be ok for occasional use.

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