drill old gass

Milady needs me for my shop skills. Don't happen that often.

She has old canning jars. The type with a glass lid and a little wire arrangement to pull the glass lid tight. She wants to put small lights inside and needs a hole drilled. I haven't measured up for sure, but I'm thinking this stuff is 1/8 NPT size.

OK, how do I drill very old glass? I get several points off for every one I break.

Karl

The old way would be to use some copper or brass tube with an OD the size of the hole you want. Make a dam round the hole with plasticene and add some abrasive like valve grinding paste and a bit of water or oil, Hold the tube in a drill press running at a slow speed and repeatadly apply pressure and lift. The abrasive imbeds in the softer tube material like a lap and grinds through the glass.

The new way would be to use a diamond hole saw but still have the dam to retain water to keep the glass cool. You can probably buy them on eBay for a few dollars in the size you want.

Carbide bits are available for under ten bucks and they work extremely well for tile, glass (not tempered), and ceramics. No cooling necessary at all.

Back up the drilling point so the glass doesn't break out the back side. Cold clay works well to provide a solid backing. Use a light touch and immediately stop the drill upon exiting. Quick-stopping cordless drill motors work best for this.

-- You create your opportunities by asking for them. -- Patty Hansen

Cooling may not be required but it does help prevent the glass cracking due to thermally induced stress.

Or a lot of other things either.

David Billington Inscribed thus:

Agreed ! Diamond Drills on Ebay have a good selection that are inexpensive.

I haven't noticed warmth above body temp in drillings I've done with the carbide "spade" style drills I use. I know the powdered diamond style gets hotter and can require coolant.

-- You create your opportunities by asking for them. -- Patty Hansen

That's why I like to buy lots of little things when they show up there.

-- You create your opportunities by asking for them. -- Patty Hansen

Thanks for the advice. I placed an order with an eBay vendor.

Ooo ... they have "Integrated Speed Load system". What??? ... how can a drill bit have an "Integrated Speed Load system"? And what is it, for that matter. Oh, I know ... it's a triumph of marketing over engineering.

Bob

What did you go for in the end?.

BTW never used the spade bits myself but IIRC they've been around for decades or more, at least as long as I can recall but maybe the materials have improved.

I still like the brass tube and abrasive powder method. If you take it slow, stresses are much lower than some pointy hard thing.

Industrial diamond paste sounds like something that might hold promise.

Wes

"Larry Jaques" wrote in message news: snipped-for-privacy@4ax.com...

I haven't drilled that species of old glass but certain of the antique compositions like to fragment around the periphery of hole ends with carbide.

Diamond hole drills would be my option. The tricks are to put them in a pond of water, feed straight, lightly and slowly and back the exit hole up with something for support against rim breakouts.

If you have any waterproof ring (e.g. big gasket, O ring) you can use that as your coolant reservoir after using grease to affix it to the glass.

I use a modified, quick-setting plaster as breakout protection on because it can conform to the glass. It shears off after drilling with a tiny bit of cleanup. Something that didn't involve cleanup would be an improvement.

Regards,

Edward Hennessey

I've bought a cheap and chearful set like that on eBay and it worked very well considering the minimal outlay. Test on some test jars or sheet glass before the SWMBO items but other than that all should go well.

If you do experience cracking it might indicate that the jars were not well annealed and might benefit from a further heat treatment, if that is the case then ask further and I'll try and dig up more info on annealing.

I've found that diamond grinding burrs in a Dremel do the job very well. Submerging the glass under water with the grinding site just beneath the surface catches the dust, keeps everything cool, and damps vibrations in the glass. Art

stresses are

It also costs an arm and a leg and takes a week per hole. Pass. The arrowhead carbides are dynamite, Wes. Try it. You'll like it.

-- You create your opportunities by asking for them. -- Patty Hansen

I used a cordless screwdriver powering a copper or brass tube through a 1/4" square drive U joint and very little pressure. Gerry :-)} London, Canada

Whatever else you do, experiment on coke bottles or mayonnaise jars or whatever new glass things you have sitting around, before you go thumping on SWMBO's nice old antique stuff.

Instead of putting light bulbs in there, wouldn't they look better with canned apple slices, or cherries, or something?