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What's the technique to anneal thin carbon steel consistently ?


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I recently bought three Movado watches, and all three had broken setting lever springs (is this common to Movado?). As parts are hard to find, and very expensive if available, I've started making the parts using feeler gauge steel. 

For the first one,  it took me several goes to get the steel soft enough to work.

I've started on a second one, but I've tried three times to anneal the steel without success. Heating to red how with a torch, then slowly moving the steel up the flame over several minutes.

From what I've read, the ideal annealing should be a temperature drop of 70°F/h. Which would take 14 hours to anneal 🥴

Is there a "tried and trusted" method to anneal thin parts ?

Maybe putting the thin steel on a thicker block and heating that too ?

 

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42 minutes ago, HectorLooi said:

Feeler gauge steel already has the correct temper for a setting lever. Why do you want to anneal it?

If you soften the steel, you will need to reharden and then temper it again.

Because it's too hard to drill, saw or file. It's easy to work once annealed, and it's easy to harden and temper once shaped.

Edited by mikepilk
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I use diamond wheels and burs for this kind of work. So that saves me doing heat treatment.

If I want to soften hardened steel, I heat it with a spirit lamp till dull red for around 20 to 30 seconds then allow it to cool slowly in the air.

Getting it back to spring temper is tough. How do you do it?

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1 hour ago, mikepilk said:

I recently bought three Movado watches, and all three had broken setting lever springs (is this common to Movado?). As parts are hard to find, and very expensive if available, I've started making the parts using feeler gauge steel. 

For the first one,  it took me several goes to get the steel soft enough to work.

I've started on a second one, but I've tried three times to anneal the steel without success. Heating to red how with a torch, then slowly moving the steel up the flame over several minutes.

From what I've read, the ideal annealing should be a temperature drop of 70°F/h. Which would take 14 hours to anneal 🥴

Is there a "tried and trusted" method to anneal thin parts ?

Maybe putting the thin steel on a thicker block and heating that too ?

 

To increase the cooling time you can try quenching immediately in hot sand or oil heated in a wax burner, leave it for half an hour before taking heat away completely to let it finish cooling.   Hot  wax may even work but then you'd have to dig out the part. 

Edited by Neverenoughwatches
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41 minutes ago, Neverenoughwatches said:

To increase the cooling time you can try quenching immediately in hot sand or oil heated in a wax burner, leave it for half an hour before taking heat away completely to let it finish cooling.   Hot  wax may even work but then you'd have to dig out the part. 

 No master metalurgist here, I have seen a proceedure done which seem to yield good results.

Light up some charcoil, spread  on it a 5cm cake of ash, place the piece on top of the ash, cover it all with 5cm  more ash.

The ash;

1-Regulates the amount of oxygen fed to the charcoil, 

2-Spreads heat rising evenly.

3-Takes the charcoil to completely  burn 10 to 15 hours, as the flow of oxygen to it is regulated by the ash.

After twelve hours, the piece is cold and need not quenching in liquid. 

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14 minutes ago, Nucejoe said:

 No master metalurgist here, I have seen a proceedure done which seem to yield good results.

Light up some charcoil, spread  on it a 5cm cake of ash, place the piece on top of the ash, cover it all with 5cm  more ash.

The ash;

1-Regulates the amount of oxygen fed to the charcoil, 

2-Spreads heat rising evenly.

3-Takes the charcoil to completely  burn 10 to 15 hours, as the flow of oxygen to it is regulated by the ash.

After twelve hours, the piece is cold and need not quenching in liquid. 

👍same way i used to keep my wood burner ticking overnight by shutting the oxygen down, shame a don't still have it.  You could make a little steel firebox.

17 minutes ago, Nucejoe said:

 No master metalurgist here, I have seen a proceedure done which seem to yield good results.

Light up some charcoil, spread  on it a 5cm cake of ash, place the piece on top of the ash, cover it all with 5cm  more ash.

The ash;

1-Regulates the amount of oxygen fed to the charcoil, 

2-Spreads heat rising evenly.

3-Takes the charcoil to completely  burn 10 to 15 hours, as the flow of oxygen to it is regulated by the ash.

After twelve hours, the piece is cold and need not quenching in liquid. 

I think the trick is to get the part into something hot very quickly after heating to cherry, if its thin it will cool rapidly in the air rehardening it .

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1 hour ago, HectorLooi said:

I use diamond wheels and burs for this kind of work. So that saves me doing heat treatment.

If I want to soften hardened steel, I heat it with a spirit lamp till dull red for around 20 to 30 seconds then allow it to cool slowly in the air.

Getting it back to spring temper is tough. How do you do it?

It's much easier working with saws and files on a soft material, and the hardening and tempering is so easy and simple. I temper to light blue.

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Along the lines of what Joe said, for annealing small pieces I put them in a tube with powdered charcoal, heat the whole thing up to red, and let cool. Works great. For larger things like the end of a clock mainspring that needs a new hole, I do the flame in the air thing, letting it cool as slowly as possible. It doesn't get fully annealed but enough to drill with HSS drills, and file easily.

 

Bergeon and others used to supply carbon steel sheet in 0.10mm increments, but not for some time. I've been trying to find a supplier of it in thicknesses that correspond to watch parts without a whole lot of luck. McMaster in the U.S. has 1070 steel in interesting thicknesses, in the annealed state (but they don't ship to Switzerland). I saw these guys in the U.K. who say they will sell in small quantities to hobbiests, and seem to have a decent selection in both hardened and annealed state. CS70 is equivalent to 1070 and fine for watch parts, CS95 (1095) is probably a little better. Both easily hardened with a torch and oil quench. It's definitely easiest to start with the material in the annealed state.

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1 hour ago, Nucejoe said:

 No master metalurgist here, I have seen a proceedure done which seem to yield good results.

Light up some charcoil, spread  on it a 5cm cake of ash, place the piece on top of the ash, cover it all with 5cm  more ash.

The ash;

1-Regulates the amount of oxygen fed to the charcoil, 

2-Spreads heat rising evenly.

3-Takes the charcoil to completely  burn 10 to 15 hours, as the flow of oxygen to it is regulated by the ash.

After twelve hours, the piece is cold and need not quenching in liquid. 

Sounds good, but November in England is not the time for barbeques 🤣

I'll try @nickelsilver 's idea, get some charcoal in a tube. Something I can do in the kitchen (when SWMBO isn't around 😯)

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What sort of feeler gauges are you using that are hardened? Go to whatever FLAPS you like over there (Friendly Local Auto Parts Store, since this isn't that kind of forum) and grab a cheapie. I've used them to make all sorts of things in the past, and never had any trouble. Definitely never needed hardening, tempering, or annealing. 

That said, my hardening/tempering/annealing experiences have all been with oil or water cooled tool steels of a much larger magnitude (old **BLEEP** mill files and the like for stock mostly). Harden with heat and whatever the alloy wants to be cooled with (feeler gauges aren't intended to be hardened exactly, so anything will do as much as it's going to), anneal with a torch, to whatever color you're after, and temper with anything with a lot of thermal mass and some insulation that will keep it hot and cool it down nice and slow. Don't forget, this is pretty much iron age technology, not rocket surgery.

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1 hour ago, spectre6000 said:

What sort of feeler gauges are you using that are hardened?

All the feeler gauges I've bought are hardened. They wouldn't be much good otherwise. I bought some cheapies for this purpose, and cannot drill, file or cut them without annealing.

I've no problem with hardening or tempering. For tempering, I put a handle on an old watch case filled with brass shavings. Held over a spirit lamp, it's easy to get the correct colour.

I've ordered some powdered charcoal, going to use an old box spanner as my cylinder, and hope a hand held gas (propane/butane) torch will provide enough heat.

 

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19 minutes ago, mikepilk said:

All the feeler gauges I've bought are hardened. They wouldn't be much good otherwise. I bought some cheapies for this purpose, and cannot drill, file or cut them without annealing.

I've no problem with hardening or tempering. For tempering, I put a handle on an old watch case filled with brass shavings. Held over a spirit lamp, it's easy to get the correct colour.

I've ordered some powdered charcoal, going to use an old box spanner as my cylinder, and hope a hand held gas (propane/butane) torch will provide enough heat.

 

How about a used aerosol tin for your,  tube. Thinner walls quicker heat transfer, dunk the lot in the ashes of your chimnea while you toast marshmellows 😛

31 minutes ago, mikepilk said:

All the feeler gauges I've bought are hardened. They wouldn't be much good otherwise. I bought some cheapies for this purpose, and cannot drill, file or cut them without annealing.

I've no problem with hardening or tempering. For tempering, I put a handle on an old watch case filled with brass shavings. Held over a spirit lamp, it's easy to get the correct colour.

I've ordered some powdered charcoal, going to use an old box spanner as my cylinder, and hope a hand held gas (propane/butane) torch will provide enough heat.

 

Once you've figured out the softening how are you marking up the part ?, i remember something somewhere about acid etching the shape using the old broken bits.

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35 minutes ago, Neverenoughwatches said:

Once you've figured out the softening how are you marking up the part ?, i remember something somewhere about acid etching the shape using the old broken bits.

I superglue the old part on to the metal, then jewellers saw and fine files until close to the edges. Remove the old part, then finish by eye. 

My biggest problem is drilling holes. My Dremel type tool is too fast. A very thin drill in a cordless drill usually results in a snapped drill. Last time I fixed the cordless drill to the desk, and held the metal piece on a bit of wood, the right height to drill the hole. Working under the microscope it's still very tricky. There must be an easier way?  (Yes I know, get a lathe)

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2 hours ago, mikepilk said:

I superglue the old part on to the metal, then jewellers saw and fine files until close to the edges. Remove the old part, then finish by eye. 

My biggest problem is drilling holes. My Dremel type tool is too fast. A very thin drill in a cordless drill usually results in a snapped drill. Last time I fixed the cordless drill to the desk, and held the metal piece on a bit of wood, the right height to drill the hole. Working under the microscope it's still very tricky. There must be an easier way?  (Yes I know, get a lathe)

Lidl had a cheap variable speed bench grinder that included a more manageable flexi shaft for drilling.  For shaping the part you could try a miniature diy spindle moulder or sanding plate made from a dremel and micro sanding drums, burrs and grinding stones and disks. It wont cut fine details but would remove the bulk of the shape.

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35 minutes ago, Neverenoughwatches said:

Lidl had a cheap variable speed bench grinder that included a more manageable flexi shaft for drilling.  For shaping the part you could try a miniature diy spindle moulder or sanding plate made from a dremel and micro sanding drums, burrs and grinding stones and disks. It wont cut fine details but would remove the bulk of the shape.

For shaping a jewellers saw and file will do the job nicely. I can't imagine using grinding tools on such a small part 

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  • 2 weeks later...

How are you getting on with making a setting lever @mikepilk, i need to make one for a Kasper 700.  This has 3 pins and a tapped hole, so 4 holes in total to drill. Any luck with the annealing, I've found it possible to rough out the shape in its hardened state using a 20mm grinding wheel. But for shaping the fine details it will need to be soft to be able to use files and drill the holes.

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1 hour ago, RichardHarris123 said:

I don't know about the tempering but the  holes could be drilled by hand with an Archemedes drill. 

The steel I'm using is from a feeler gauge, last week i tried to drill steel from a hand saw blade, a feeler gauge and also some set bridges using hss bits, pivot drills and even cheap carbide drills, nothing doing. I going to need some decent dormer or carbide bits to drill hardened steel and at nearly 5 quid a pop for small sizes a few of those broken can soon add up. I need to soften the steel really, rough shaping out is the easy bit with a grinding and diamond cut off wheel. 20231120_193923.thumb.jpg.5ff7d44e6b3371b63940d251000d779a.jpg

20231120_192030.jpg

This is basic roughing out set up 2.5x magnifier and a 5x loupe gets you close enough to see to remove the bulk of the waste safely with a 20mm grinding wheel and then some detail with the cutting edge of a diamond cut off wheel. Dremel type drill has to be on the lowest speed for any details , its surprising how quickly what you want off at the end is removed. You also need to be mindful of your approach angle, keep the piece square on to the wheel at all times its extremely easy to undercut the piece you are working on. Lastly dont try to be too clever leave the last bits for some steady filling, you only want to make one of these 🤣20231120_203635.jpg

20231120_203717.jpg

Does anyone know how to safely decompress one of these to make use as a tempering tube, unless i go round my neighbours field popping a few bunnies off with lead slugs🤷‍♂️

17005140082512759106846517887406.jpg

Edited by Neverenoughwatches
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4 hours ago, Neverenoughwatches said:

How are you getting on with making a setting lever @mikepilk, i need to make one for a Kasper 700.  This has 3 pins and a tapped hole, so 4 holes in total to drill. Any luck with the annealing, I've found it possible to rough out the shape in its hardened state using a 20mm grinding wheel. But for shaping the fine details it will need to be soft to be able to use files and drill the holes.

I managed to find a setting lever so gave up trying to make one.

The first one I made, using a feeler gauge, took me two attempts to anneal, but it somehow worked, and was so and easy to saw and file.

The second time, using the same set of feeler gauges, I just didn't manage to get it soft enough to work. 

I now have some powdered charcoal, and a cut down box spanner to use as a cylinder, for the next time I try annealing.  I hope to get it all red hot with a hand held butane torch, and it cools slowly enough.

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  • 2 weeks later...
On 11/20/2023 at 11:19 PM, mikepilk said:

I managed to find a setting lever so gave up trying to make one.

The first one I made, using a feeler gauge, took me two attempts to anneal, but it somehow worked, and was so and easy to saw and file.

The second time, using the same set of feeler gauges, I just didn't manage to get it soft enough to work. 

I now have some powdered charcoal, and a cut down box spanner to use as a cylinder, for the next time I try annealing.  I hope to get it all red hot with a hand held butane torch, and it cools slowly enough.

Finally got around to annealing my homemade setting lever. First attempt was half of the old part wrapped in copper strand from flex, that didn't work the copper melted like hair on my head. Second attempt heated the same part just held in the air for 10 mins with a small butane torch gradually reducing the flame and moving it further away. After chipping away the  outer carbon layer that had formed i was able to drill with a 0.4 pivot drill part way a hole behind one of the pins so i could remove it. Very slow going and had to sharpen the drill 4 times, gave up that idea and decided to stop fannying around. Final attempt involved the use of a compressed air pistol cartridge for the annealing cylinder a couple of spoonfuls of ground charcoal scavenged from my chiminea and 20 minutes of the old faithful Rothenberger torch. Yeah, no don't try this in your upstairs converted bedroom its not a particularly safe practicebut i am a professional and did have contingency plans in place if things started to go pear-shaped,  and its fricking freezing outside. Results to follow. 20231202_134220.thumb.jpg.d7ce07a939037f62cd571339aa615bf9.jpg20231202_161036.thumb.jpg.a1324e54a90b96d47d56182a03a362ce.jpg20231202_161507.thumb.jpg.130282028107ea31b4518bc1313ec042.jpg

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3 minutes ago, Neverenoughwatches said:

Final attempt involved the use of a compressed air pistol cartridge for the annealing cylinder a couple of spoonfuls of ground charcoal scavenged from my chiminea and 20 minutes of the old faithful Rothenberger torch. 

"To anneal steel, heat it up about 100 degrees F above its critical temperature, soak it at that temp for 1 hour per inch of thickness, and let it cool at a maximum rate of 70 F per hour"

So, for the thicknesses we are working with, say <0.5mm, the time held above critical temperature would only need to be 1-2 minutes.  The problem is knowing how hot your metal is in the centre of the charcoal, and how long the cooling process needs to be.

I eagerly await your results.

10 minutes ago, Neverenoughwatches said:

 Yeah, no don't try this in your upstairs converted bedroom its not a particularly safe practice but i am a professional and did have contingency plans in place if things started to go pear-shaped,  and its fricking freezing outside. Results to follow. 

I have bottles of IPA, naphtha, meths, acetone next to my desk in my small room 😯 so only use a spirit lamp there. Serious heating I do in the kitchen, or outside. 

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43 minutes ago, mikepilk said:

"To anneal steel, heat it up about 100 degrees F above its critical temperature, soak it at that temp for 1 hour per inch of thickness, and let it cool at a maximum rate of 70 F per hour"

So, for the thicknesses we are working with, say <0.5mm, the time held above critical temperature would only need to be 1-2 minutes.  The problem is knowing how hot your metal is in the centre of the charcoal, and how long the cooling process needs to be.

I eagerly await your results.

I have bottles of IPA, naphtha, meths, acetone next to my desk in my small room 😯 so only use a spirit lamp there. Serious heating I do in the kitchen, or outside. 

The cylinder and its contents were cool within the hour. The difference in drilling is night and day. The first photo was probably around an hour trying different drills, cheap carbide ( absolutely rubbish and chip when you give them an angry look )and  resharpening a 0.4 pivot drill 4 times, i barely managed to make a start, just a very shallow shiny dent. The second photo the hole is through the piece up to the pin on the other side i just need to widen the hole so i can pull out the pin. This took just 5 mins hand drilling with a pin vice and just one initial sharpening of the drill, not easy to sharpen  a .4 pivot drill, the angle is awkward to get as the clearance on one side affects the cutting edge of the opposite side more than it does with a dormer hss bit, the angle has to just so.

20231202_172534.jpg

20231202_181349.jpg

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