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Guidance on slotting a screw


LittleWatchShop
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Here is a screw I am making.  It is a setting-lever screw for a Vulcain 120.  The original one suffered rust that consumed the threads.  Dimensions not shown, but the largest OD is about 1.4mm.

I am getting close to parting off and then cutting a slot.

I have a Nicholson slotting file (my dad had everything) that I think will work.  If not, I will have to buy one of those Vallorbe's I see on the Esslinger site.  Or some other ideas you may have.

The question before me...should I soften the metal first?

This is a brand new area for me.  From what I see on the interweb...I just heat it to cherry red and let it cool naturally.

After cutting the slot, heat it again and quench it in oil (2 parts avacado oil, 3 parts saffron oil, 1 part bacon grease...lol...just kidding).

 

2021-07-17 06_37_27-IMG_7429.JPG ‎- Photos.png

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When making any threaded part I make it from soft steel and harden after turning and threading. As you can see the threads are barely formed there, hopefully the die (or screw plate) didn't suffer too much- steel at this hardness can ruin a die.

 

But, you can certainly file "blue" (hardened and tempered) steel. It's easier to file when soft, but you can do it in the blue state.

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16 minutes ago, nickelsilver said:

When making any threaded part I make it from soft steel and harden after turning and threading. As you can see the threads are barely formed there, hopefully the die (or screw plate) didn't suffer too much- steel at this hardness can ruin a die.

 

But, you can certainly file "blue" (hardened and tempered) steel. It's easier to file when soft, but you can do it in the blue state.

Thanks for that wisdom.  When threading, I did not sense any real stress...I was very careful and slow.

I will heat it up and take a shot at making the slot.

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Just as nicklsilver says the material usually comes “blue”, it’s been hardened and tempered, but just warm it up with a torch until it is faint red (750-800 degrees) and let it cool off in room temperature, the reverse process is called annealing.

Another thing when making the threads, I think what we see in this example is you turned it to a slightly to small diameter too, if making an M0.9 thread you could turn it to a diameter of 1.1mm -1.2mm (0.2mm – 0.3mm thicker) and thread it from there.

If you don’t have a slot cutter to your lathe then one always can use a small saw with a 0.3mm wide blade on it. Make the slot for the screw when you have annealed the steel.

After you made the part, you harden it again you bring the temperature on the material to above 1400 degrees Celsius, it will have a cherry or bright red color. Cool it off to a temperature below 1000 degrees Celsius in less than a second in water or oil. Since it now is hard and brittle you need to temper it to approximately 288 degrees Celsius, you now will have a useable and a part with a dark blue color again.
If you want the blue color gone you always can polish it away.

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Well, the day ended in failure.  I was excited about the early progress, but on the last step I trimmed the screw down too much...too short.

I learned a lot, so I guess the day was not a total bust.

I did lose a watch part in the process.  Complete mystery as to where it went.  Normally, I will find something if I know when I lose it.  This part just showed up missing when I was doing assembly.

Miles to go before I sleep...

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10 minutes ago, LittleWatchShop said:

Well, the day ended in failure.  I was excited about the early progress, but on the last step I trimmed the screw down too much...too short.

I learned a lot, so I guess the day was not a total bust.

I did lose a watch part in the process.  Complete mystery as to where it went.  Normally, I will find something if I know when I lose it.  This part just showed up missing when I was doing assembly.

Miles to go before I sleep...

Don't worry- I've spent a week+ researching remaking a component for a piece and there's probably the same time  maybe +2 till it works, but they (the customer) are ok with that.

 

Always do your best, always ask questions.

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10 hours ago, LittleWatchShop said:

Why not...I am spending money like a drunken sailor.  What is it???  Just a circular blade on a mandrel?

When coming over to the dark side of watchmaking instead of the watch repair with ready made parts it will cost a bit.
I might have been a bit sloppy and lazy in the text above, it’s what happen when you lay in a hammock and drink G&T. I’m on the mandatory Swedish 5-week vacation right now 😉, but what you need to make a perfectly centered slot in your screwhead is a vertical milling attachment in which you have a disc cutter.
You fasten your screw material in the lathe collet next you adjust the height and depth on the cutter with the slides.
When it is perfectly centered you cut the slot. now you will have a perfect, clean and straight slot worthy a vintage watch 😉 .... 

If you decide to use a saw you might consider making a jigg/plate to screw the workpiece into, makes it easier to saw the slot.

MillingAttachement.png.5dbb6513da6abdebd90d1de46d653aae.png

 

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Depending on the tresses but I would not have made the screw with blue steel I would just harden when complete.However I have a old chipped screw head slot file that I picked up in a job lot of tools a few years ago but it still cuts fine. To cut the slot accurately I fit the screw into my lathe collet and use the rest for alignment. The pic below is as new.

 

AF4D69B8-B1B6-4C30-BACB-710824B624D1.jpeg.a280c7b6734ef78e73bda8f0cb257a6e.jpeg

 

 

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1 hour ago, LittleWatchShop said:

What is the recommended bar stock to use for such projects?

In the U.S. O-1 (the letter "o", number 1) steel is commonly used for watch parts. Is cheap and easy to find. Easy to work and easy to harden.

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23 hours ago, LittleWatchShop said:

I did lose a watch part in the process.

Hallelujah!  With extensive searching over a wide are of carpet, I found the missing wheel.  My method involves a very bright light, while wearing 5x magnification and crawling along the floor with my head about 4" from the ground.

I believe what happened was the part fell in my lap.  Then I got up to walk over to the lathe and it fell in the journey.

Since the last nine months, I have completely lost only two parts.  One of this was a click spring (I have many spares) and the other was a date cam wheel that was made of some sort of plastic and broken anyway.

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48 minutes ago, LittleWatchShop said:

 My method involves a very bright light, while wearing 5x magnification and crawling along the floor with my head about 4" from the ground.

How about letting a strong magnet find the wheel for you, demag the part then.

 

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I did some chronograph pusher rods last week and in the end, I slotted with a fret saw. You won’t get as perfectly straight slots as with a slotting file in my experience, but it’s fine for places where you can’t see the screw head in question. 

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Posted (edited)
1 hour ago, Nucejoe said:

How about letting a strong magnet

I did!  But, either 1) I failed to scan the particular area, or 2) it was not ferro.

I suspect #2 because it looked like brass on one side (it was a wheel on the motion works side...an alarm setting wheel with major and minor cogs).

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2 hours ago, LittleWatchShop said:

Hallelujah!  With extensive searching over a wide are of carpet, I found the missing wheel.  My method involves a very bright light, while wearing 5x magnification and crawling along the floor with my head about 4" from the ground.

I believe what happened was the part fell in my lap.  Then I got up to walk over to the lathe and it fell in the journey.

Since the last nine months, I have completely lost only two parts.  One of this was a click spring (I have many spares) and the other was a date cam wheel that was made of some sort of plastic and broken anyway.

weren't we just talking about this and a new work bench in the same conversation?

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17 minutes ago, LittleWatchShop said:

I did!  But, either 1) I failed to scan the particular area, or 2) it was not ferro.

I suspect #2 because it looked like brass on one side (it was a wheel on the motion works side...an alarm setting wheel with major and minor cogs).

btw-I don't have a lathe yet. someday. however I have been known to repair a screw or two. slots being one of them. I use a jewelers saw (piercing saw) to re-shape the slot and get passed the screwdriver slippage gouges, then finish up with a screw slot file #8(.014") that looks like yours. hey the mangle marks are still there some, but it looks much better and works again. Esslinger and everybody else, including folks on the 'Bay sells the files at outrageous prices. the cheapest I've found go to:  

Slotting File 3" Long x 25/64" Wide x .014" Thick | QTE North America, Inc. | QTE North America, Inc. (qtena.com)

if you are able tho, HSL is right on the mark. with the right machinery, correct thickness slitting saw and setup, you'll get the perfect screw slot. 

BWCA is closing more sectors. Canada is burning. im near the twin cities and if the wind blows right we get a whiff now and then and it's hazy here. sunsets are incredible tho. 

 

 

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I ordered some 2mm and 4mm 01 steel rods.  My plan is just to practice practice practice!!  Based on just a short time doing this, there will be enough incidences of needing to make screws, so I need to get good at it.

I think I need a modern screw plate just to be sure that I have good thread cutters.

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Posted (edited)

Following up on this screw.  The first two are FUBAR.  Here is a new attempt.  This time I started with 01 steel rod as recommended by @nickelsilver.

I used the screwplate mentioned above.  I am wondering if it is performing well given how old it is and the amount of use it has gotten.  I know for a fact that I abused it when I was a kid playing around in my Dad's shop--he was patient.

Thoughts on these threads?  They are #12 on my screwplate (a little less than 1mm)

I looked around to see what new die I could buy if I wanted to get serious about screws.  It seems that the Bergeon 30010 is the cat's meow.  However, I am still looking for a place that sells it other than ebay.

2021-07-23 07_00_45-IMG_7440.JPG ‎- Photos.png

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On 7/18/2021 at 3:21 AM, clockboy said:

Depending on the tresses but I would not have made the screw with blue steel I would just harden when complete.However I have a old chipped screw head slot file that I picked up in a job lot of tools a few years ago but it still cuts fine. To cut the slot accurately I fit the screw into my lathe collet and use the rest for alignment. The pic below is as new.

 

AF4D69B8-B1B6-4C30-BACB-710824B624D1.jpeg.a280c7b6734ef78e73bda8f0cb257a6e.jpeg

 

 

Just ordered this from Esslinger...looks like the same as yours.

2021-07-23 07_15_53-Screwhead File with Tang for Making Slotted Screw Heads — Mozilla Firefox.png

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1 hour ago, LittleWatchShop said:

Following up on this screw.  The first two are FUBAR.  Here is a new attempt.  This time I started with 01 steel rod as recommended by @nickelsilver.

I used the screwplate mentioned above.  I am wondering if it is performing well given how old it is and the amount of use it has gotten.  I know for a fact that I abused it when I was a kid playing around in my Dad's shop--he was patient.

Thoughts on these threads?  They are #12 on my screwplate (a little less than 1mm)

I looked around to see what new die I could buy if I wanted to get serious about screws.  It seems that the Bergeon 30010 is the cat's meow.  However, I am still looking for a place that sells it other than ebay.

2021-07-23 07_00_45-IMG_7440.JPG ‎- Photos.png

That thread looks great, especially for a screwplate! Screwplates can be tricky, the older ones both form and cut the thread, so the start diameter can be a matter of trial and error. Good job.

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On 7/18/2021 at 4:52 PM, LittleWatchShop said:

Hallelujah!  With extensive searching over a wide are of carpet, I found the missing wheel.  My method involves a very bright light, while wearing 5x magnification and crawling along the floor with my head about 4" from the ground.

I believe what happened was the part fell in my lap.  Then I got up to walk over to the lathe and it fell in the journey.

Since the last nine months, I have completely lost only two parts.  One of this was a click spring (I have many spares) and the other was a date cam wheel that was made of some sort of plastic and broken anyway.

The members of this forum have helped me with this same issue in so many ways.  I have used the magnet trick before, and the bright light with a magnifying lens.  And started using the trick where you place the movement in a large plastic bag before removing sprung parts that could launch themselves.  And I have also made my own "bench apron", where the bottom edge of the apron is mounted below the edge of my work bench, and the upper part is worn at my neck like any other apron, and this forms a sort of "catch-all" pocket which keeps dropped things from ever hitting the floor.  Altogether, I have to credit the people of this forum for preventing a huge number of potential headaches.

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