Pocket Watch Chrystals

[Txbillyed]

I am very new to pocket watch work and one of the things I am having dificulty with is finding information on how to fit and installal chrystals on pocket watches. Could someone point me in the right directing.

Thanks,

BillyEd

[Jon Hanson]

I am very new to pocket watch work and one of the things I am having dificulty with is finding information on how to fit and installal chrystals on pocket watches. Could someone point me in the right directing.

Thanks,

BillyEd

clean out bezel well

find a fit that snaps in

don;t glue in

develope an inventory of crystals

rotate when inserting

[Kent]

Hi BillyEd:

Crystal Size
Crystal sizes are independent of movement sizes, except that cases of a given movement size will require crystals within a certain range of diameters. Always keep in mind that all cases made for the same size movement do not use the same crystal size. Also, the ranges of crystal diameters that might be needed for successive movement sizes will overlap.

A caliper, reading in thousandths (1/1000's) of an inch, or tenths (1/10's) of a millimeter, is needed to measure a bezel to determine the correctly-sized crystal. Bezels have slightly larger diameters inside the "bottom" of their groove, than inside their upper rim. To find the correct crystal size, one needs to measure that larger inside diameter. This is because the correctly-sized crystal is held in place by the upper rim, such that cement is not needed for a correctly-sized crystal. It simply 'snaps' into place.

Then, depending upon whether the measurement is in inches or millimeters, use the appropriate chart to find the right crystal size. Or, crystal suppliers ought to be able to furnish a correctly-sized crystal directly from your measurement. Depending upon the cost of the crystals, it might be advisable to get one or two sizes immediately larger and smaller than the one indicated by the measurement, especially if expect to continue collecting the same size watches.

Crystal Charts
A crystal size chart, and its explanation, can be viewed at:
www.elginwatches.org/scans/misc_ads/1927/m_index.html
To view, go to the Elgin Watch Collectors Site Home Page at elginwatches.org, then copy and paste the address in your browser's address bar and click on 'Go'.
Thanks to Steve Maddox, we have access to a Crystal Size to Decimal Inch Conversion Chart (http://photos10.flickr.com/16463399_10d80f7055_o.jpg).

Mounting the Crystal
When a glass crystal is sized correctly to the metal bezel that holds it, it is an interference fit. To fit a crystal into the bezel, first clean out any glue or cement that may have been used to previously mount a smaller, incorrectly sized crystal. Then, set the bezel on a flat surface, facing upward, and place the crystal on top. If the crystal is slightly too small, it will drop right into place and be loose within the bezel. A correctly-sized crystal will "almost" fit within the inner rim of the bezel, appearing to extend beyond the rim of the bezel by a tiny amount. If this is a crystal that had previously resided in the bezel, it is correctly sized. If it is a new crystal, be careful that it is not too large for the bezel. The correctly-sized crystal can be "snapped" into place by placing your thumbs on opposite sides of the bezel, overlapping the crystal. As you press down firmly (but not excessively) and roll your thumbs together, the correctly-sized crystal will seat with an audible "snapping" sound.

Cementing the Crystal in Place
If the crystal is slightly too small, and a correctly-sized crystal is not immediately available, it can be held in place by the use of crystal cement. This is viewed as a less-than-ideal situation, but nevertheless, many of us go this route. Crystal cement, available from watch material supply houses - see below, is specially formulated to prevent the release of gases that can leave a residue on the crystal and also to stay slightly pliable. If you don't see crystal cement listed on the below websites, contact them and ask about it. Crystal cement is somewhat removable, more so than many household cements (which shouldn't be used).

Watch Materials are available from:
Brian Cavanaugh, pwpartsetc@pwatch.com
Dashto (http://www.dashto.org/)
Otto Frei (http://www.ofrei.com/)
Uncle Larry's Watch Shop (http://www.execulink.com/%7Elfoord/index/horology.htm)

Good luck,

[Txbillyed]

Hi BillyEd:

Crystal Size
Crystal sizes are independent of movement sizes, except that cases of a given movement size will require crystals within a certain range of diameters. Always keep in mind that all cases made for the same size movement do not use the same crystal size. Also, the ranges of crystal diameters that might be needed for successive movement sizes will overlap.

A caliper, reading in thousandths (1/1000's) of an inch, or tenths (1/10's) of a millimeter, is needed to measure a bezel to determine the correctly-sized crystal. Bezels have slightly larger diameters inside the "bottom" of their groove, than inside their upper rim. To find the correct crystal size, one needs to measure that larger inside diameter. This is because the correctly-sized crystal is held in place by the upper rim, such that cement is not needed for a correctly-sized crystal. It simply 'snaps' into place.

Then, depending upon whether the measurement is in inches or millimeters, use the appropriate chart to find the right crystal size. Or, crystal suppliers ought to be able to furnish a correctly-sized crystal directly from your measurement. Depending upon the cost of the crystals, it might be advisable to get one or two sizes immediately larger and smaller than the one indicated by the measurement, especially if expect to continue collecting the same size watches.

Crystal Charts
A crystal size chart, and its explanation, can be viewed at:
www.elginwatches.org/scans/misc_ads/1927/m_index.html
To view, go to the Elgin Watch Collectors Site Home Page at elginwatches.org, then copy and paste the address in your browser's address bar and click on 'Go'.
Thanks to Steve Maddox, we have access to a Crystal Size to Decimal Inch Conversion Chart (http://photos10.flickr.com/16463399_10d80f7055_o.jpg).

Mounting the Crystal
When a glass crystal is sized correctly to the metal bezel that holds it, it is an interference fit. To fit a crystal into the bezel, first clean out any glue or cement that may have been used to previously mount a smaller, incorrectly sized crystal. Then, set the bezel on a flat surface, facing upward, and place the crystal on top. If the crystal is slightly too small, it will drop right into place and be loose within the bezel. A correctly-sized crystal will "almost" fit within the inner rim of the bezel, appearing to extend beyond the rim of the bezel by a tiny amount. If this is a crystal that had previously resided in the bezel, it is correctly sized. If it is a new crystal, be careful that it is not too large for the bezel. The correctly-sized crystal can be "snapped" into place by placing your thumbs on opposite sides of the bezel, overlapping the crystal. As you press down firmly (but not excessively) and roll your thumbs together, the correctly-sized crystal will seat with an audible "snapping" sound.

Cementing the Crystal in Place
If the crystal is slightly too small, and a correctly-sized crystal is not immediately available, it can be held in place by the use of crystal cement. This is viewed as a less-than-ideal situation, but nevertheless, many of us go this route. Crystal cement, available from watch material supply houses - see below, is specially formulated to prevent the release of gases that can leave a residue on the crystal and also to stay slightly pliable. If you don't see crystal cement listed on the below websites, contact them and ask about it. Crystal cement is somewhat removable, more so than many household cements (which shouldn't be used).

Watch Materials are available from:
Brian Cavanaugh, pwpartsetc@pwatch.com
Dashto (http://www.dashto.org/)
Otto Frei (http://www.ofrei.com/)
Uncle Larry's Watch Shop (http://www.execulink.com/%7Elfoord/index/horology.htm)

Good luck,


Thank you so much for taking the time to write this information down for me and the web addresses. I really appreicate your efforts.

BillyEd

[Tom Huber]

If you don't have crystal cement, a good substitute is Elmer's Glue. The nice thing about Elmers is that it is non-toxic to the crystal and the case. Any residue showing after the crystal is in place can be removed with a damp rag or a toothpick.

Tom

[StanJS]

Since we are discussing crystal manipulation, I could use some help. I bought a wad of crystals (unfortunately, for small pocket down to wrist watches - no 16 or 18 size) and there are some tools which I assume are used for setting and/or removing crystals.

Can anybody instruct me in the proper use of the below items?

Thanks,
Stan

[Cary Hurt]

Stan,

Those look like the plugs and dies that came with one of the old G-S crystal systems that had a foot powered crystal press mounted on the top of the cabinet.

They are for fitting round plastic crystals, basically by setting the crystal onto the recess of a properly sized die, laying the bezel over it, then using the press and the appropriate plug to put pressure in the center of the crystal, causing it to flex inward and thus to reduce the diameter, making it possible for it to fit into the recess in the bezel. When the pressure is released, the crystal goes back to it's original shape, and hopefully is seated snugly into the bezel.

Regards,

Cary

[Jon Hanson]

If glued in use a small hammer and tap out the crystal; I usually use my thumbs and press them out carefully. I recently did one for old timer Whit Joyner of chapter 149 that was glued in so tight that I had to break the crystal and soak the bezel in a solution on order to clean out the groove (gorilla glue?). I used a small pair of special pliers to remove the broken and shattered pieces that remained, glued into the bezel groove. One of the 3 worst of throusands that I have replaced over a 40 yr period.

The problem with crystal assortments is that 60-70% of the sizes you will never use, unless you trim or grind them down on a crystal grinder--some of the "sharpies" are now doing this extensively.

Jon