Bottoming taps for watch case pendants

kingleo59

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I am trying to purchase a set of taps for pocket watch cases typically size 16 and size 18. I want to be able to chase out the threads in certain instances or possibly re-tap the pendant so it will fit the sleeves that I already have. Does anyone know where I can purchase the various taps that will allow me to tap out the pendants on antique pocket watch cases? I have a lot of size 16 and size 18 cases and the sleeve has been rusted in there and I destroy it getting it out. I need to be able to tap that hole. They are extremely fine threads and I would definitely need a bottoming tap to do it correctly. The picture I am including shows one with the stem and sleeve frozen in the pendant. I would really like a book that explains all of the different styles of sleeves and stems and crowns that are used in hunter cases and old size 18 cases and mainliner cases that have a cap on them. Please help I think I have found a niche in the market if I can learn to work on just antique pocket watch cases especially railroad grade. Again, please help

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DeweyC

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I am trying to purchase a set of taps for pocket watch cases typically size 16 and size 18. I want to be able to chase out the threads in certain instances or possibly re-tap the pendant so it will fit the sleeves that I already have. Does anyone know where I can purchase the various taps that will allow me to tap out the pendants on antique pocket watch cases? I have a lot of size 16 and size 18 cases and the sleeve has been rusted in there and I destroy it getting it out. I need to be able to tap that hole. They are extremely fine threads and I would definitely need a bottoming tap to do it correctly. The picture I am including shows one with the stem and sleeve frozen in the pendant. I would really like a book that explains all of the different styles of sleeves and stems and crowns that are used in hunter cases and old size 18 cases and mainliner cases that have a cap on them. Please help I think I have found a niche in the market if I can learn to work on just antique pocket watch cases especially railroad grade. Again, please help

View attachment 640234 View attachment 640235

There are two different aspects to your post.

First: references. The only halfway complete reference on PW cases I encountered was in AWI HT articles by Archie Perkins (not the ones that were ultimately collated into his books on restoration). As for the taps, mechanics are not above modifying a tap to a bottoming tap.

As for a "niche", most people use established care repair services such as Bill Eicholz at Pocket Watch Case Repair. I do not even bother with lid repairs and went so far as to send him all my case springs and case tools to avoid temptation.
 

Jerry Kieffer

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I am trying to purchase a set of taps for pocket watch cases typically size 16 and size 18. I want to be able to chase out the threads in certain instances or possibly re-tap the pendant so it will fit the sleeves that I already have. Does anyone know where I can purchase the various taps that will allow me to tap out the pendants on antique pocket watch cases? I have a lot of size 16 and size 18 cases and the sleeve has been rusted in there and I destroy it getting it out. I need to be able to tap that hole. They are extremely fine threads and I would definitely need a bottoming tap to do it correctly. The picture I am including shows one with the stem and sleeve frozen in the pendant. I would really like a book that explains all of the different styles of sleeves and stems and crowns that are used in hunter cases and old size 18 cases and mainliner cases that have a cap on them. Please help I think I have found a niche in the market if I can learn to work on just antique pocket watch cases especially railroad grade. Again, please help

View attachment 640234 View attachment 640235

Unfortunately, I know of no taps that are available for tapping a pendent that will match typical sleeves. In addition, retapping a pendent would require a larger full depth thread and in many cases you are unlikely to have enough wall thickness to support a larger thread. A better solution may be to rethread a very close sleeve with a die. More on that later.

Again the issue of finding Taps and dies. I measured a sample 18s and it was a .201" x 60 TPI that would be extremely unlikely to find even on your luckiest day. But even if you were to find one, it may not be what you are looking for just to chase and clean a thread, since it is likely to remove metal. For oddball threads that need to be cleaned and reformed slightly without removing metal, I make a special tap as follows.

(1) The tap is machined from Drill rod per the first attached photo.

(2) The nose (red arrow) is rounded allowing the thread to start. The body (white Arrow) will be threaded. The relieved area (green Arrow) will supply spring tension.

(3) A slot is machined to supply both a cutting/cleaning tooth edge and spring tension on the thread when hardened/tempered. the slot should be ever so slightly expanded on the end to provide thread tension after threading but before hardening/tempering.

(4) The second photo shows single point cutting whatever thread is desired or required. A drill bit shank was inserted in the slot to support the two half`s while threading. Threading should only be done after the slot is cut to provide sharp edges on the thread teeth.

A die can also be machined once you have machined a standard Tap.

I have covered machining, hardening and tempering micro taps and dies in detail, in a article published in the 2008 Jan.- Feb. of the " Home Shop machinist". For anyone interested, they will send a reprint of the article by phone call. 800-447-7367
Its more than is practical to cover here.

While a little time consuming in the beginning, you eventual accumulate what you need as well as a very useful skill.

Jerry Kieffer

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Last edited:

oic55

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Aug 21, 2009
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Pendant taps were available in the past, have seen some sets on ebay, but are like hen's teeth.

Here is a table on pendant taps sizes from : Louis & Samuel Levin, Practical Benchwork for Horologists, Eighth Edition, Louis Levin & Son, Los Angeles 1950 .

1614381420564.jpeg

Here is a photo from an ebay auction showing the tap set, thought it might be helpful to show geometry. Also matches the thread sizes called out in the table.

1614381803844.png
1614381865192.png

Hope this helps

Don
 
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Jerry Kieffer

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Pendant taps were available in the past, have seen some sets on ebay, but are like hen's teeth.

Here is a table on pendant taps sizes from : Louis & Samuel Levin, Practical Benchwork for Horologists, Eighth Edition, Louis Levin & Son, Los Angeles 1950 .

View attachment 640447

Here is a photo from an ebay auction showing the tap set, thought it might be helpful to show geometry. Also matches the thread sizes called out in the table.

View attachment 640455
View attachment 640456

Hope this helps

Don
Don

Thanks for the chart.

It turns out that I actually have a .128" X 80 TPI and a .176 X 66 TPI, but never realized what they were used for.

Unfortunately, now days it takes less time to make what I need, than to find what I have.

This is especially true of Taps and Dies that are not available or perceived not to be available as in this case. In addition, special pitch micro taps and dies of usable quality as required in Horology, are rapidly becoming hard to come by at reasonable prices even if available. At this point, if you do not have a lifetime supply, your only option is to make what is needed and has become a popular topic when covered in Lathe class. The good news is that if properly equipped, it is really not an issue.

The attached photo shows an example display that I use in class and show displays when covering the construction of taps and dies. The .100 X 80 TPI was actually used to duplicate an existing stem thread in a new crown not found in my standard taps for crowns.

The smallest Tap and Die shown (.27mm or about .011" ) is slightly smaller than typically found in Horology, but smaller yet is sometimes required in model engineering and industry as was the case for these.

Jerry Kieffer

fullsizeoutput_7fd.jpeg
 
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