# Cutting glass discs?!



## Mk (Jan 7, 2013)

Does anyone know how to cut a 20mm dia, 1mm thick round glass disc? I've read about cutting it with a copper tube and burnishing compound, but I dont know if it will work  
Any help will be appriciated.


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## Garratt (Sep 15, 2012)

I would do it under a wet slurry so the there is little heat build up that will cause it to break. I used to grind holes in thicker glass under water. 

Andrew


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## Mk (Jan 7, 2013)

Thanx Andrew for the tips, I tried just now to cut it with a small dremel cutting disc and the place where I wnat to cut gets red hot! BTW it is a light bulb with a flat face, really hard glass!


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## Garratt (Sep 15, 2012)

The frictional part gets real hot compared to the rest which cases shattering. If you can set it up so the glass is under the water and the dremel is above the water it should work but don't electrocute yourself. zzz







zzz.

Andrew


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## s-4 (Jan 2, 2008)

Are you actually cutting the light bulb? Or are you making a piece of glass to sit in front of it like a headlamp bezel? I would be cautious about modifying the actual lamp since it may have a mechanical purpose for being the size it is. I would be afraid of the lamp cracking more easily through heat cycling. 

If you're only looking to make a glass disc from a square piece of glass I would suggest using a diamond core drill under water with lubricant. If you have trouble, send me a PM, I can very easily make one for you. 

If you're cutting the actual lamp....really avoid making the glass turn red. This will almost surely cause stress fractures that will likely propagate over time. You can try to avert failure by beveling the edges under water with a softer dremel tool. 

If you have the dremel "snake" attachment, this would probably be a good time to use it so that the dremel motor stays dry. I don't know if your GFCI protection would actually help since most dremels are only 2-prong.


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## Kovacjr (Jan 2, 2008)

Just buy it http://www.toolsgs.com/cart/browse.asp?subcat=252 $1.00 each


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## Totalwrecker (Feb 26, 2009)

Want it quick? Get a watch crystal, there are jewelry repair places at most large malls. You'd be surprise by the quantity of sizes kept on hand. 

John


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## SteveC (Jan 2, 2008)

You might want to keep in mind just where Marinus is located i.e. South Africa.


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## Mk (Jan 7, 2013)

Thank you all for the help  I've already cut the glass by using a engraver and snapping the pieces around the circle of and then sanded it on the belt sander, don't worry I've wet the sanding belt so that no silica dust particles can fly in the air.


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## Greg Elmassian (Jan 3, 2008)

This is for his new pressure gauge... 

Marinus, did you start with a flat face bulb? Have any pictures, or should we look on the pressure gauge thread? 

Greg


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## Mk (Jan 7, 2013)

The bulb was one exactly like this.








First I thouht that the bulb's flat glass had been melted on to it and then I accidentally droped it and the hole glass, except for the flat glass broke so I used the glass. I've added the finished gauge in the other tread, but you won't see the glass because it is soo..... clear


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## Greg Elmassian (Jan 3, 2008)

Great idea! 

I've seen those bulbs many times, never thought of using it as a cover/face plate, etc. 

Yeah, that is high temp glass, and it has to be even more "clear" because of the intense light from the halogen bulb. Any discoloration would cause it to overheat.... 

Thanks for the follow up! 

Greg


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## Garratt (Sep 15, 2012)

Posted By Mk on 25 Mar 2013 12:23 AM 
Thank you all for the help  I've already cut the glass by using a engraver and snapping the pieces around the circle of and then sanded it on the belt sander, don't worry I've wet the sanding belt so that no silica dust particles can fly in the air. Marinus,

An engraver!







The glass would be very hard being for high temperature. A glass cutter would probably have a hard time creating a fissure. I have used a belt sander to round glass before and to give a safe edge. As long as you keep rotating it so it does not get too hot in one spot (until it is too hot to hold). The damp belt will act as a slight lubricant too as there can be minute chipping. 
Definitely use goggles.










Andrew


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## Mk (Jan 7, 2013)

Yep  An electric engraver(punching action not rotating action) and then hitting it on a edge of a wooden plank with a piece of steel.


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## Garratt (Sep 15, 2012)

Marinus, 

Couldn't you try grozzing away the edge with a pair of parallel jawed pliers?

Andrew


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## Greg Elmassian (Jan 3, 2008)

cool term: ( think you have one too many Z's though) 

grozing to bite or wear away the small rough edge and chips of glass along a cut edge using grozing pliers


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## Garratt (Sep 15, 2012)

Greg,

They're some proper ones. I did stained glass work professionally for many years and never bought a pair (or an electric grinder). I used my dad's parallel fencing pliers instead! I still have them from 20 years ago. They do look like they would work much better though with the sharp tip and the flat side to lever near the glass edge.
The glass used for stained glass work is very crumbly so you can gnaw your way through it like a biscuit, where heat resistant glass is very hard and brittle.

Andrew


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