Cutting thin tiny glass parts

Not exactly metalworking. I needed to make a replacement glass piece
for a camera because I removed the IR/UV filter and the space needed
filling for proper focusing. I used a 1mm glass slide, the type made
for microscopes. The piece needed to be 8 x 9 mm. I mamaged to get one
and then discovered I had scratched it. So I tried again and was
rewarded with a scratch free piece. I was surprised how hard it was to
cut this glass, for it to break where I wanted it to, and finally
figured out how to score it properly. I hope I never need to do this
again.
Eric
Reply to
etpm
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Years ago I did lapidary work. While most everything was done with stone I used to play with glass sometimes. I was able to cut glass with a diamond s aw, grind to shape using grinding and sanding wheels with water drip to kee p things cool. The glass was mounted to dop sticks using what was called d op wax which was almost like old style sealing wax used with stamps for let ters and such. Maybe you can find someone close by that is into lapidary wo rk for help? A designing jeweler may point you in the right direction. I'd bet that your local glass shop has wet belt sanders with different grit bel ts for finishing glass edges. Maybe they would let you use their belt sande rs for your project?
Reply to
Gerry
Greetings Gerry, I have done lapidary work and even have the stuff still to do it. My stone saw is just not set up to cut stuff so small and the glass is more brittle than the stones I have cut in the past. I did finish off the piece by using one of my diamond wheels on my slow speed carbide grinding/lapping machine. I was actually surprised at how fragile the glass was. I have cut glass tiles in the past year with one of my diamond cutting discs cooled and lubricated with water and had no trouble. But the little pieces I just did were much more prone to chipping and cracking than the tiles and the diamond cutting disc caused too much edge chipping, even when run quite slow. Thanks, Eric
Reply to
etpm
Microscope slides are soda lime glass. If you had some Corning slides, they used to be tempered -- probably, they still are.
Although tempered glass is strong, it gets its strength from being pre-stressed in a way that increases bending strength but also can make it prone to chipping as the stresses are relieved. Generally, the chips are quite large; you've probably seen how tempered car windows shatter into pellets, rather than into sharp little shards.
All of that may be of no help in understanding what you're running into, but be aware that there are different grades and they may break in different ways.
Reply to
Ed Huntress
Oh, yeah, I forgot to mention that there are fused-quartz slides, too. You generally can't tell the difference by looking at them and you'd know it if you bought them in a package. They have very high UV transmittance but I have no idea how they cut.
Reply to
Ed Huntress
The usual scheme, is to rotate a brass or copper cylinder tool, painted with abrasive slurry, and trepan out a disk. A kind of hotmelt glue (jeweler's wax, or dop adhesive) holds the work. It's slow, because the glass will crack if you allow the cut to heat it too much. I've done it with a tinning swab, a few drops of glycerine, and SiC grit.
Reply to
whit3rd
Out of interest why brass or copper? Does the abrasive embed in it?
Reply to
RodK
Ed Huntress prodded the keyboard with:
In all probability the glass needs anealing. Heating up to red and a very slow cooling down. Bottles & such take 8 to 12 hours, but they are much thicker than a microscope slide.
Reply to
Baron
I wish they were quartz because of the toughness and UV transmission. The filter I removed was a two piece affair. At first I wondered why two pieces of glass were cemented together and I thought maybe it was for strength. But I think it is because the clear piece of glass is to filter out UV. This would be good because CCD sensors also see into the UV spectrum a ways and I would like to get some pictures of reflected UV from flowers and such. Tonight I will be installing the glass and doing any adjusting of the sensor location that may need to be done. Tomorrow night I hope it will all be back tohether so I can try it out at a bonfire. Eric
Reply to
etpm
I have done this. I needed a smaller diameter achromat so I used a wax chuck to hold the lens. The saw was a bronze cylinder and the abrasive was diamond. When I was done I had the smaller dia. lens and a ring of glass. Too bad I dropped the ring before I had a chance to show it to anybody. But the lens worked great. But the glass piece I needed for this camera is rectangular, there is a cutout it fits in and a couple gaskets to seal it and the sensor from dust. Eric
Reply to
etpm
Yes, the abrasive does imbed. I make laps for carbide from brass. After the lap is turned to size I press diamond dust into the brass. It really works quite well. For the saw I used to make a smaller achromat I put the abrasive on a piece of hardened steel and pushed (hard) the cutting edge of the saw into the diamond. Eric
Reply to
etpm
Good luck. I never priced the quartz slides before but I just looked them up -- which I should have done before posting. Yipes, they're expensive.
I see that they're also said to be available in borosilicate glass (the stuff old Pyrex was made from -- today, it's tempered soda lime glass), but I didn't look for a supplier. Borosilicate is still another kettle of fish.
Reply to
Ed Huntress
I posted this before, apparently Pyrex is still made with borosilicate in Europe, it seems the US made stuff is tempered soda lime glass, I guess to reduce the price. Certainly all the Pyrex I have here in the UK is clear and doesn't have the green cast often seen in soda lime from iron and when dropped doesn't break like a tempered glass DAMHIK.
Reply to
David Billington
Right. We can get the borosilicate cookware, but my recollection is that it's imported from Europe. The Pyrex cookware usually sold in the US is now tempered soda lime glass.
Iggy had a bad experience with a relatively new Pyrex baking dish. It shattered in the oven. I'm hanging on to my old stuff, some of which dates back to the '60s.
Reply to
Ed Huntress
Yes. The "Pyrex" brand fell into the wrong hands after Corning nearly died when the dot-com bubble burst, and was selling off "non-core" businesses.
The new company is busily destroying the Pyrex brand.
Iggy is not alone. Lots of horror stories on the web now.
There are now people selling borosilicate glassware, by that name,
And I'm hanging onto my old stuff too.
Joe Gwinn
Reply to
Joe Gwinn
[Snip]
Perhaps a source of quarts flats would from quartz crystals used in electronic devices. e.g. RF oscillators, computer clock control and such. I think CCD sensors are more sensitive to IR than UV. In any case UV doesn't transmit well through regular glass lens.
Cheers
Reply to
Gray_Wolf
[ ... ]
The problem with the quartz used in frequency-determining crystals is that they are ground to thickness, and thus have a frosted look, not a nice flat surface to allow it to act as a window/filter for images. The older ones are mounted between two metal plates which make contact only at the corners, with a spring applying pressure to the upper plate.
Later ones have metalized surfaces on each side, with a spring-formed wire soldered to the center of each. There, even if the surface were flat enough for optical image transmission, you would have to dissolve the metal coating with an acid which would attack the metal without attacking the quartz.
And -- the largest that I have ever seen was about 1/2" square, which is not likely to be large enough for the sensor in question. (Well ... I've never opened the two inch long can for a 1 KHz crystal which I have, but it still would not be wide enough, even if it were long enough.
Good Luck, DoN.
Reply to
DoN. Nichols
If you want optical quality windows go to newport.com They sell parallel surface windows made from all known optical materials. There are many other scientific optics sources on the Internet.
Reply to
nobody
May not be large enough but how about the quartz windows on old UV eraseable EPROMs? Have to dig it out of the epoxy, but I'm sure lots of shops and tinkerers have some stuck away in a junk drawer.
----- Regards, Carl Ijames
If you want optical quality windows go to newport.com They sell parallel surface windows made from all known optical materials. There are many other scientific optics sources on the Internet.
Reply to
Carl Ijames
Greetings Carl, I didn't know the windows on EPROMs were quartz but it makes sense. The ones I have though are too small. Fortunately the glass lenses in my camera let through a pretty significant amount of near UV. Just like window glass. Hence the internal two piece filter between the lens and sensor in my camera. This near UV passing through normal camera lenses is also the reason for the UV/Haze camera filters. Eric
Reply to
etpm

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