Widening the light fitting hole of a glass shade?

[gizmo1990]

Bit of an odd question so thought this would be the best place for it!

I have an old glass globe light shade which unfortunately has a split/crack. I've managed to find a replacement which is a reasonable size match, except for the hole for the light fitting. It's a little too small at dia 4cm when it needs to be 5cm.

Can anyone give me any advice on methods for making the hole wider? I was thinking of creating a kind of large cone which I could wrap grit paper around to gradually make the hole bigger. However I've no idea where I could find a cone big enough?

Currently I'm thinking 'carefully' grinding the hole bigger using a dremel would be the easiest route? I've not attempted grinding glass though. Does anyone have any experience of this? Is it even possible?

Any advice greatly appreciated.

 

[cdbe]

Hard to picture, but I'd have thought you'd have more luck modifying the light fitting to fit the new shade rather than vice-versa.

 

[SpecialK]

Go on ebay and buy a glass hole saw at 50mm
Normally you can get them started by going at an angle. If not drill through some plastic and use it as a guide to make your hole bigger...

 

[lostinthelight]

.

 

[foxhole]

Doomed

 

[lostinthelight]

Doomed

Yep, most Ive seen have a thickened flatter area around the hole which gives strength/bearing for the fixing and maybe contain any stress so cutting into could, be disaster?

 

[gizmo1990]

Thanks for the replies everyone. @cdbe I've never even heard of a glass hole saw/bit! Thanks for that! I'm certainly up for giving it a go.

 

[lostinthelight]

A picture before and after would be good, whatever the outcome

 

[gizmo1990]

Haha, sure! Whatever happens, finding out about the existence of glass hole saws, would of made it worth it.

 

[SpecialK]

Go steady! Use some water. Set your drill to the lowest screwdriver torque setting so if it bites it wont break the glass.

 

[foxhole]

Hole saw is intended for use on flat plain glass not curved heat treated lamp shade.

 

[SpecialK]

I have drilled curved bottles etc without a problem. If its heat treated / tempered glass it will just shatter, not sure if light shades are?

 

[lostinthelight]

It would be better to shatter as its being cut than shattering on someone's head after its installed especially if its ground floor with kids causing vibrations from above?