Recent content by John MacArthur

  1. J

    Shape of escapement teeth?

    I would be careful about using Headrick's impulse angles. They deviate from standards developed over centuries. Penman won't lead you wrong. Johnny
  2. J

    Help understanding a depthing tool

    Good spot Graham, but it is just the distortion of the picture. If you look closely the plate appears slightlycurved too. The bushings for the arbors are actually tubes that extend through the fixed end, and are fairly snug. Johnny
  3. J

    Help understanding a depthing tool

    Chris - Here are some pics of my fixture. I have quite a variety of bushings and studs to fit wheel and pallet holes, and various sizes of arbors. I also have pointed scribes which fit into the two holes, so it can be used to scribe arcs for locating pivot holes. Now I just measure the...
  4. J

    Balance staff tooling

    pearl tweezers: Pearl Tweezer Johnny
  5. J

    Watchmaker lathe collet quality and brands

    All of my Rivetts are of a different diameter and thread than WW. I have a relatively complete set for a Rivett lathe, which has a slightly different headstock configuration. Johnny
  6. J

    Help Identifying Gear Cutter Sizes

    Eric - What is the scale of these things? In other words, what is the o.d., and what is the thickness of for example, the 0.3 cutter teeth? I have some old watch gear cutters that look kind of like these, and if that's the case, then the numbers probably don't mean a module. Johnny
  7. J

    Are there standard positions / spec for wheels on a movement?

    Chris - Here is a fairly typical layout for a regulator movement. The great wheel is 144 t, the center wheel 96 t, third wheel 90 t, escape wheel 30 t. All pinions are 12 leaf. This would have a 39" or one second pendulum. Other clocks will be somewhat different, but the center wheel will...
  8. J

    Are there standard positions / spec for wheels on a movement?

    Chris - Yes, the center wheel is the place to start - it is what will tell time, and will usually be near the center of the movement. If you are going to have a second hand on the escape wheel, it will need to be directly (usually) above the center wheel. The intermediate wheel or wheels will...
  9. J

    Rattray of Dundee Scottish Regulator

    I wonder if the tin spacer was a compensating component. How about a pic of that too, and how it fit into the assembly. Was it actually tin? What does "CRC tube" mean? Johnny
  10. J

    Crossing Out / Marking Out Jig

    Dushan - Thank you for that info. Abebooks doesn't seem to be able to locate either of the Jendritski books in any of the editions. I wouldn't ordinarily pay the asking prices from the horological book dealers. I'd add to the list Daniels "Watchmaking" - it's incredibly inspiring. Johnny
  11. J

    Crossing Out / Marking Out Jig

    Dewey - What is the title and subject of the Jendritski book please? thanks, Johnny
  12. J

    Heat treating Invar

    A friend and I have been noticing that an invar pendulum (on a clock he made) doesn't seem to change length/timekeeping in a linear fashion. He doesn't yet have compensation on it for the residual expansion. When the temp rises the clock stays at the same rate until the temp has risen a number...
  13. J

    Cutting clock wheel spokes ...advice needed

    The rule of thumb on which jeweler's saw blade to use is: select one with at least three teeth in the thickness of the plate you are cutting. Use beeswax or Boe-shield wax sticks to lubricate the blade. As far as getting the print-out from your CAD right, just print out 1-1. Johnny
  14. J

    Hand Metallurgy

  15. J

    Questions About a Waltham 9-Tube Chime movement

    From that third photo it looks conceivable that the movement will go into the cutout and the dial will stay on the outside of the partial surround. Cross your fingers.... Johnny
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How to wire a 24 volt secondary for a 12 volt ITR/IBM Master clock system by Toughtool