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nickelsilver

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nickelsilver last won the day on July 1

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  1. There's a big difference in making a functional part and making one that's right and looks the part too. I think a good minute jumper, that's indistinguishable from factory would take a skilled watchmaker more than an hour or two. If it is steady pinned and unadjustable, and especially if it's beveled, definitely more. Here's one I did this year for a Longines 30CH. This poor thing had had a jumper from a stopwatch cobbled in, they used one of the steady pin holes for the new screw, so it had been threaded and thus was off location (and the new pins are two different sizes). For this one I used a toolmaker's microscope to locate the steady pin holes and screw hole in relation to where the beak needed to be (hammer down so minute wheel was positioned correctly). Imported an image of an original in cad, scaled it and traced the outline. Cut out the part with cnc, the spring portion oversized, hardened and tempered, thinned the spring down (much easier when heat treated) made and fitted steady pins, fine tuned the beak, polished beak, beveled the foot. That was about a 3 hour job but I'm a prototyper so it's normal work for me, and I have cnc. I left the steady pins visible (with polished ends) as the locations had been changed and this part likely won't fit another 30CH- a little heads-up to a future watchmaker I hope.
  2. I feel that the steady pins are necessary. Especially on jumpers like this that aren't adjustable, once the position is set (you have to adjust the position of the jumper point by filing) then it is set for life. I think he may have left them out to provide a little bit of adjustability, plus it's tricky getting them in the right locations, and you have to make them on a lathe, and press fit, and so on so it's actually a fair bit of work.
  3. I use plug gages, which are in 0.01mm increments, but they are expensive. If you need to measure the hole in the hand and can't measure the pivot (and a micrometer will easily differentiate between 0.25 and 0.27mm, you can easily see a difference of 0.005mm), you can use a small broach. Slide the hand on until it stops, and measure there. There's a little interpolation to do, but you will be very close.
  4. Stainless steel won't blue; I don't know of any watch hands being made of it either. If the supplier doesn't state or know the material check them with a magnet. Hands can be almost any material from gold to plastic but brass and steel are the most common.
  5. What's the diameter? These two look quite similar, the first is 11 1/2"', the second 10 1/2"'.
  6. Standard Seitz jewels are sized in 0.01mm hole increments up to 0.20mm, from there they go in 0.02mm increments. In industry makers would order jewels from specialist makers, to whatever size they wanted. In general the outer diameters would correspond to normal 0.10mm increments but the hole sizes could be anything- one common size I see is a 0.25mm hole, which isn't in the Seitz offering. What are your actual pivot sizes? Thankfully, at 0.20mm and up an extra 0.01mm of wiggle room usually doesn't affect performance. Do any of the suppliers have a 22/120 and 32/160?
  7. That screwplate appears to be metric. So the sizes listed are the thread size, 20 is 2mm, 13 would be 1.3mm. So you would want to start with 1.3mm as your diameter. But- it might (probably) not cut the thread so much as cut and form the thread by displacing metal. I say that because it looks a little dubious in quality. So try a little smaller and see if you get a good thread form. You can turn a taper from say 1.15 to 1.3, and then thread that, and see where along the taper you get a full thread. Make a note of it for the next time you need to thread that size. The old Martin screwplates had a screwy (haha) numbering system. There were two main designations from Martin, L and B; both seem to have the same thread diameters regarding their numbering, the difference is the pitch of the thread. Martin G plates were for left hand threads. Funnily enough, the "backward" numbering system for watch stems and crowns corresponds to the Martin sizing, I guess it was taken up at a time when Martin screwplates were the primary threading tool for watchmakers. 99% of the time I use industrially made metric taps and dies for threading, but sometimes for an old piece I will use a Martin plate. The threads are a little more rounded on their crests. I find that for a given size I need to turn a little undersize, as mentioned above. With new "real" metric stuff I turn to the nominal diameter.
  8. The length of an extended pivot whether to take a hand or a driving wheel really depends on the design, but 1.5-2mm is reasonable. I sometimes add a little Loctite 648 or 638 when friction fitting the new pivot, but I think it's mostly psychological, as there really isn't any room for it if the pivot is correctly sized for a friction fit. If the pivot is loose enough in the drilled hole for the Loctite to have room, then it won't hold anyway, there just isn't enough surface area for it to do its magic. You really have to watch the size of the new pivot- often the wall thickness of the drilled arbor is quite thin, and the interference fit is on the order of a few microns. Too much and you can split the arbor... and of course too little and it doesn't hold.
  9. Broken drills in arbors is a real problem. When repivoting, which generally requires a much shallower depth/diameter ratio (general rule is at least 3 but better 4 or 5 diameters depth), I almost always use a spade drill. These I make up as needed freehand out of tungsten carbide, and make them with noticeable back taper. The advantage is twofold; being hand ground they will almost certainly drill slightly oversize, and being "waisted" they don't stick in the hole in the event of breakage. I just did a LeCoultre escape wheel with one last week- pivot was 0.08mm, was able to do a hole of 0.14mm and have decent wall thickness. Then plug and turn down and burnish- I always figure the ultimate test of the new pivot is if it stands up to the Jacot tool. With handmade drills they are better held in a pinvice and guided by hand as they are rarely perfectly centered on their shank. As long as the center is caught correctly before drilling it's no problem.
  10. As a former teacher and professional of 20+ years, bravo, that's fantastic, especially given how messed up it was and your first go! It won't be a chronometer but I bet it runs.
  11. I had an Omega auto (forget the caliber) I bought and wore for a few months before deciding to check under the hood. It was within about 5 seconds/month, amazing timekeeping. Put it on the Witschi before servicing, had about 200 degrees of amplitude and a timing delta in 6 positions of well over 100 seconds. After service it had healthy amplitude, and a delta under 15. Never kept time as well though! Maybe 30 seconds/month (still fantastic, but it was almost "magic" before).
  12. I think only Bergeon has them, and they give no indication what the actual sizes are. In the pic, the foreground is two commercial one (old, I believe Bergeon but unmarked), you can see what the two ends look like. The other two are shop made and double ended just for turning; I needed an extra small one and a larger one with an extra fine "finger". I don't know what they cost but I'd say just buy the 5 that Bergeon sells, if you just get one or two you'll always need one you don't have.
  13. I've heard that the current ones don't work with smaller canon pinions, which is a shame. I have a couple of the same tool made by K&D which were probably 20 years old when I got them 20 years ago, and work with the smallest canon pinions you can imagine (like LeCoultre 101 small). I would suggest looking for some vintage ones.
  14. That's what's left of the broken tongue end. You will need a new spring, unless you are equipped to rivet a new piece on (or spot weld).
  15. Are you using steel or carbide gravers? Either will work, but both need to be sharpened perfectly. It should be no problem to turn to 0.08mm or smaller. I leave about 0.01mm and finish in the Jacot. Check your gravers and keep practicing. How long is "quite long"?
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