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Cutting new threads on stems, what do you think?


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I cut the following new threads on some stems to test out my new Dies.

I placed each stem in my lathe, cut the existing threads off and trimmed the stem to the end diameter I was aiming for. Then I ran my Die over the shaft while the stem was still in the collet. I think the results are great.

First up is a ETA 6497 1.20 mm stem that was cut down to 0.90 mm, of course you know what this means for PAM owners...

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Then I had to make a Cortbert 616 stem which measures out at 1.50 mm and cut it down to 1.20 mm to fit the crown.

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Thanks for looking.

RG

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Guest carlsbadrolex

I had to thread a 2" diameter pipe last week and couldn't get the threads to look that good. I guess this is what steady hands and good eye sight can do for you!

Very nice work!

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Wow nice work! Very impressive.

I know that when watchmakers make new stems, they cut and finish the stem, then harden it later. That is impressive that you were able to cut the hardened steel!

Off Topic: Isn't making a stem from scratch one of the requirements to receive your WOSTEP certification? If I had 30K and two years of free time, I would love to get a WOSTEP certificate.

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Very nice work. I guess I'll have to buy a watchmakers lathe one day.. just to play..

A question for ubiquitous.. where did the crown tube in your picture come from? Is it genuine? I have a couple of gen crowns but they don't really work with the rep tubes as you end up with doubled up o-rings.

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Ziggy-

Those stems are a work of art. Can't wait to see them on their respective watches. ;)

Logan-

The case tube is from a Jimmy case. It is identical to the case tube on a gen case.

Fxrandy-

Knowing this project was forthcoming and it would allow for the use of the gen automatic crowns on handwinds I did hold back a few crowns for this purpose. The remaining crowns will be offered with stems and possibly case tubes. No worries though as I will make a general announcement when they are ready for prime time.

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Very nice work. I guess I'll have to buy a watchmakers lathe one day.. just to play..

A question for ubiquitous.. where did the crown tube in your picture come from? Is it genuine? I have a couple of gen crowns but they don't really work with the rep tubes as you end up with doubled up o-rings.

Logan,

As kruzer mentioned, this tube is from a Jimmy case (pictured in the background). The gen crown just slides right in and engages with a nice reassuring click.

:)

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I cut the following new threads on some stems to test out my new Dies.

I placed each stem in my lathe, cut the existing threads off and trimmed the stem to the end diameter I was aiming for. Then I ran my Die over the shaft while the stem was still in the collet. I think the results are great.

First up is a ETA 6497 1.20 mm stem that was cut down to 0.90 mm, of course you know what this means for PAM owners...

1.jpg

Actually The Zigmeister - I don't know what that means. Could you tell me? A little out of my league here.

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CSK-

Since I am a layman as well I will take a shot and Ziggy can correct me if I got it wrong. As you probably know each stem has two sides. One side slides into the movement and allows you to wind and set the movement. The other side screws into the crown. The problem has always been that there are some movements which take a larger size stem going into the movement such that the side that screws into the crown is to wide for the crown. So what he is doing is trimming the stem to the right length if necessary and then thinning out the threaded side and rethreading it so it will fit into a smaller hole (the crown).

The real life examples above are:

Cortebert movements often take a 1.5 mm stem. Our usual hand wind crowns take a 1.2 mm stem. So unless you can thin down and rethread the crown side you can't use our normal crowns.

1.2 to 0.9mm - Standard Unitas movements take a 1.2 mm stem. However most of the gen crowns that we bought through our group buy were originally for automatics which have a threaded hole of 0.9mm. Often this can be remedied if using a smaller movement by buying an adapter which screws onto the 1.2mm side and leaves you with a new 0.9 mm threaded end. However in the case of the Unitas movements they are so big that there is no room in the case for an adapter. Ergo you need the revised stem in order to use SS gen crowns that folks bought with handwind movements.

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Kruzer got it right.

The "Dies" which I forgot to take a picture of, are about the size of your pinky finger nail, and they are designed to cut new threads on a shaft.

The big issue is that as stilty mentioned, these stems are already hardened and it's quite a challenge to cut threads that small on a hardened shaft.

Keep in mind that the 0.90mm one is less than 1 millimeter in diameter, were talking really small parts to work with.

At $60 per Die, it's not cheap to get the tooling, I just hope the Dies last a long time or that I don't break them like I did with my rollie crown tube tap...

RG

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