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Make a setting lever screw

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oldhippy Distinguished Member

oldhippy

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If you look at the finished screw you can still see blue on the inside of the shoulder and in the thread it is there and can be seen. If you take your time in making any part it should be properly finished. Look at the video at 24 37 and you will see what I mean 

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nickelsilver Distinguished Member

nickelsilver

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1 hour ago, Klassiker said:

Very impressive skills on the lathe, and I want one of those taps!

Those rolling dies are great, but the initial diameter is crucial as they form rather than cut the thread. Made by Habegger, available from www.schurch-asco.com, surprisingly affordable.

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LittleWatchShop Distinguished Member

LittleWatchShop

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This was pure joy to watch.  Several questions though.

1) Is indirect heating better than direct?  Is that holder steel?  What is it called?

2) What is the purpose of bluing?  I thought it was to have a blue result, but evidently not.

3) What is the stuff he is using to blue?

4) I looked at the forming tool at the site given by @nickelsilver.  Seems the options are diameter but not thread pitch.  Thread pitch for watch screws still has my brain wrapped in a knot.  The screws I have made were cut using a screwplate and I have several different versions of the Martin Fills (L and B) that I use when I blindly try to fit the proper size.  So, what are the thread pitches for these.

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nickelsilver Distinguished Member

nickelsilver

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1 hour ago, LittleWatchShop said:

This was pure joy to watch.  Several questions though.

1) Is indirect heating better than direct?  Is that holder steel?  What is it called?

2) What is the purpose of bluing?  I thought it was to have a blue result, but evidently not.

3) What is the stuff he is using to blue?

4) I looked at the forming tool at the site given by @nickelsilver.  Seems the options are diameter but not thread pitch.  Thread pitch for watch screws still has my brain wrapped in a knot.  The screws I have made were cut using a screwplate and I have several different versions of the Martin Fills (L and B) that I use when I blindly try to fit the proper size.  So, what are the thread pitches for these.

When hardening it's good to protect the part from direct flame. This is often done by wrapping in iron wire and coating with pure soap, or sometimes borax, or sometimes a commercial anti-scale powder (a great one is available from gunsmith supplier Brownell's). I have a slightly different technique, using 20mm iron tubes on a handle, in which the part is placed the tube then filled with fine wood charcoal powder. Whatever the technique, even heating and avoidance of oxygen is the goal. The part, when at proper temperature, is then quenched.

 

For blueing his method is very good. I also put the part (which when done with the above anti-scale measures should be a clean grey, otherwise the black scale must be cleaned off to see the color change [and it should be clean of oil]) on brass fillings in a pan, over an alcohol flame. From the quench the steel is at its maximum hardness, and is very brittle. Heating to a lower temperature is called tempering, and blue is pretty much the standard color for watch components. The steel changes color at different temperatures, from a light straw to brown, then purple, dark blue, blue, light blue, then almost grey again. For a cutting tool you would temper to straw. Using the pan with filings helps ensure an even heating, and prolongs the process so that the temperature reaches into the part as well. For parts larger than watch-size you would need to do it in an oven for a specific amount of time for a given cross section.

 

The thread pitches on the Habegger rolling dies are the modern standard pitches according to NIHS. If you look at the Asco Schurch catalog, on the taps pages, they list the pitch for each diameter- as well as the tap drill size for both steel and brass which is great.

 

From memory, the Martin B (Bourgeaux) plates are quite close to the modern norm in pitch for a given diameter. Also from memory, the L or Latard plates are slightly finer pitch. As a bit of trivia- and this is from my observation, not a book, the Martin B holes correspond to the seemingly oddly-backward "tap size" for watch stems.

 

 

IMG_0010 (Large).JPG

Edited by nickelsilver
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