Difference between crystal polishing, sanding, or buffing

Difference between crystal polishing, sanding, or buffing

RonD.
RonD.

July 7th, 2005, 3:52 am #1

I often hear some of my fellow Timexicans talk about sanding crystals. I wondered if sanding them takes away some of the surface making the thickness of the crystal thinner? Has anyone who sands them noticed the crystals being more fragile?

I have always buffed them with a 4" diameter wheel (1" wide) I have attached to a motor, using red jewelers rouge. It seems to me that the buffing just kind of melts the crystal and smooths out the surface that way. I know that if I am not careful, the heat and buffing I do can sometimes put stress cracks in the plastic.

Ron
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Bill T
Bill T

July 7th, 2005, 4:05 am #2

I start with rubbing compound using a soft cloth and finish with polishing compound. It takes longer but I think it allows for better control and less damage to the crystal.

Bill T
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Joined: May 8th, 2005, 11:38 am

July 7th, 2005, 6:11 am #3

I often hear some of my fellow Timexicans talk about sanding crystals. I wondered if sanding them takes away some of the surface making the thickness of the crystal thinner? Has anyone who sands them noticed the crystals being more fragile?

I have always buffed them with a 4" diameter wheel (1" wide) I have attached to a motor, using red jewelers rouge. It seems to me that the buffing just kind of melts the crystal and smooths out the surface that way. I know that if I am not careful, the heat and buffing I do can sometimes put stress cracks in the plastic.

Ron
All sanding, buffing, and polishing done on a plastic or glass crystal will remove material from it and weaken it. And, unfortunately, the deeper the scratches one is trying to disguise, the more material that must be removed from the crystal and the weaker it will become. Notice that I used the work "disguise" rather than the word "remove" to describe the process. In essence, one is actually wearing down the surrounding surface until it is at the same level as the bottom of the deepest scratch.



Plastic crystals are far more forgiving of this process than glass ones. When a crystal constrictor is used to install a new glass crystal in a bezel, the glass is deformed and under stress at all times and it is its tendency to want to expand back and relieve the stress that holds the crystal in place.



When a glass crystal has been worn down in an effort to hide its previously scratched surface, it can be so weakened that it will not even survive the constrictive forces applied to it when it is being installed in the bezel and may actually crack at that point!



Even plastic crystals that have been highly polished to hide scratches can be so weakened that shortly after installation in the bezel they will develop stress fractures on their "shoulder" because they can not longer resist the constrictive force applied to them by the bezel and must relieve it by forming the fractures.



Whenever possible, I think it is better to install a fresh crystal in a watch because a restored and weakened crystal will be much more prone to shattering the next time the watch suffers a sudden impact.



technoguy
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Joined: May 8th, 2005, 9:00 am

July 7th, 2005, 6:46 am #4

I often hear some of my fellow Timexicans talk about sanding crystals. I wondered if sanding them takes away some of the surface making the thickness of the crystal thinner? Has anyone who sands them noticed the crystals being more fragile?

I have always buffed them with a 4" diameter wheel (1" wide) I have attached to a motor, using red jewelers rouge. It seems to me that the buffing just kind of melts the crystal and smooths out the surface that way. I know that if I am not careful, the heat and buffing I do can sometimes put stress cracks in the plastic.

Ron
I sand with #800 sand paper and then I polish with Brasso. I have had no problems I don't know about glass I have replaced most of my watch crystals with plastic. Sanding takes less time and you don't get the buffing waves or burns.
Ray
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Anthony J. Bonanno
Anthony J. Bonanno

July 7th, 2005, 3:28 pm #5

I often hear some of my fellow Timexicans talk about sanding crystals. I wondered if sanding them takes away some of the surface making the thickness of the crystal thinner? Has anyone who sands them noticed the crystals being more fragile?

I have always buffed them with a 4" diameter wheel (1" wide) I have attached to a motor, using red jewelers rouge. It seems to me that the buffing just kind of melts the crystal and smooths out the surface that way. I know that if I am not careful, the heat and buffing I do can sometimes put stress cracks in the plastic.

Ron
I have had good luck using first a red rouge on a 4 inch buffing wheel and follow up using "Crystal Bright" made by EuroTool. The rouge removes most of the deeper scratches with the Crystal Bright removing all of the lighter scratches along with polishing and making the crystal clear and bright. Use light pressure because if you don't you the heat generated will soften the plastic and leave waves or embed some of the rouge in the soften plastic.

To Ron; You previously answered an inquery of mine and among other things you said that you have collected Elgin pocket watches. Do you know where I can obtaintwo(2) 4th wheels for a Elgin 16s, model 7,grade 291. I have tried Larose, Frei, Uncle Harry and others with no luck. Thanks for any help. Anthony J. Bonanno abona2@msn.com
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doublebarrel
doublebarrel

July 7th, 2005, 8:14 pm #6

All sanding, buffing, and polishing done on a plastic or glass crystal will remove material from it and weaken it. And, unfortunately, the deeper the scratches one is trying to disguise, the more material that must be removed from the crystal and the weaker it will become. Notice that I used the work "disguise" rather than the word "remove" to describe the process. In essence, one is actually wearing down the surrounding surface until it is at the same level as the bottom of the deepest scratch.



Plastic crystals are far more forgiving of this process than glass ones. When a crystal constrictor is used to install a new glass crystal in a bezel, the glass is deformed and under stress at all times and it is its tendency to want to expand back and relieve the stress that holds the crystal in place.



When a glass crystal has been worn down in an effort to hide its previously scratched surface, it can be so weakened that it will not even survive the constrictive forces applied to it when it is being installed in the bezel and may actually crack at that point!



Even plastic crystals that have been highly polished to hide scratches can be so weakened that shortly after installation in the bezel they will develop stress fractures on their "shoulder" because they can not longer resist the constrictive force applied to them by the bezel and must relieve it by forming the fractures.



Whenever possible, I think it is better to install a fresh crystal in a watch because a restored and weakened crystal will be much more prone to shattering the next time the watch suffers a sudden impact.



technoguy
I read from this board and others, from plastic to glass, to sappire, the hardness increases but also the britleness. So the harder they get the easier they shatter. I wonder why Casio uses glass instead of plastic on the G-Shock(also the shock-rated Timex Ironman and so forth). The crystals are so recessed, they got a barrel around them it's almost impossible to scratch the surface. But for a shock-resist watch, I'd imagine they get dropped all the time, banged on the wall, etc. I think plastic makes better sense for this application...
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RonD.
RonD.

July 7th, 2005, 8:35 pm #7

I have had good luck using first a red rouge on a 4 inch buffing wheel and follow up using "Crystal Bright" made by EuroTool. The rouge removes most of the deeper scratches with the Crystal Bright removing all of the lighter scratches along with polishing and making the crystal clear and bright. Use light pressure because if you don't you the heat generated will soften the plastic and leave waves or embed some of the rouge in the soften plastic.

To Ron; You previously answered an inquery of mine and among other things you said that you have collected Elgin pocket watches. Do you know where I can obtaintwo(2) 4th wheels for a Elgin 16s, model 7,grade 291. I have tried Larose, Frei, Uncle Harry and others with no luck. Thanks for any help. Anthony J. Bonanno abona2@msn.com
Anthony,

I did send you an email to your personal address.. I will try again.

Ron
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RonD.
RonD.

July 7th, 2005, 8:41 pm #8

I have had good luck using first a red rouge on a 4 inch buffing wheel and follow up using "Crystal Bright" made by EuroTool. The rouge removes most of the deeper scratches with the Crystal Bright removing all of the lighter scratches along with polishing and making the crystal clear and bright. Use light pressure because if you don't you the heat generated will soften the plastic and leave waves or embed some of the rouge in the soften plastic.

To Ron; You previously answered an inquery of mine and among other things you said that you have collected Elgin pocket watches. Do you know where I can obtaintwo(2) 4th wheels for a Elgin 16s, model 7,grade 291. I have tried Larose, Frei, Uncle Harry and others with no luck. Thanks for any help. Anthony J. Bonanno abona2@msn.com
I will just paste the email here instead:

Hi Anthony,

You might be able to find one at this site:

http://www.dashto.com/sitemap.htm

The guy seems to always have the part I am looking for. I sometimes search for just the part out of his parts list here:

http://www.dashto.com/newlists/selected ... terial.htm
or here:

http://www.dashto.com/newlists/pocketwatchmovement.htm

I sent you the site map but also the individual links because it is sometimes tough to navigate to what you want (I usually find it by accident). For example, I needed to go to "Partial Parts/Movements, then Selected Material, then Elgin Material to find Elgin parts.

The other day I got a NOS balance staff for a Jules Jurgensen watch from him. It was an ETA movement, so I just looked up the number and he had it. He ended up sending me 3 of them, all were balance wheel, complete staff and hairspring (what an easy fix!). He originally told me to send the ones I didn't need back, but when I tried to, he told me to keep them for parts. He is a pretty good guy. Check it out, and if you can't find what you need on his site, email him and ask him if he can look for it.

Ron
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electrichorologist
electrichorologist

July 7th, 2005, 11:41 pm #9

I have had good luck using first a red rouge on a 4 inch buffing wheel and follow up using "Crystal Bright" made by EuroTool. The rouge removes most of the deeper scratches with the Crystal Bright removing all of the lighter scratches along with polishing and making the crystal clear and bright. Use light pressure because if you don't you the heat generated will soften the plastic and leave waves or embed some of the rouge in the soften plastic.

To Ron; You previously answered an inquery of mine and among other things you said that you have collected Elgin pocket watches. Do you know where I can obtaintwo(2) 4th wheels for a Elgin 16s, model 7,grade 291. I have tried Larose, Frei, Uncle Harry and others with no luck. Thanks for any help. Anthony J. Bonanno abona2@msn.com
Hello Anthony,

Repivoting would be another option, if the gear and pinon teeth are fine on these wheels, providing that you do have them to use.

Jay
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