Need Help Machining Thin Glass

fubar62172 · Apr 19, 2016

Hey Guys
I need to machine a profile out if a microscope slide pc of glass?

#1 What is best way to hold it because of how thin it is?
I was thinking double sided tape but what would be best way to remove it afterwards? Or some kind of vacuum set up

#2 Should I cut it in a water bath? Or just with coolant?

#3 I'm machining it on a Bridgeport retrofit and do not have high speeds will that be OK?

#4 I What would be the best tooling to use? I'll need appx a .062 corner rad

Thanks for your help

Mike

mcmachine · Apr 19, 2016

Wax it down.
heat the subplate material and glass on a hot plate then melt a little wax (#9 is best)
let it cool then go...flood with coolant use diamond wheel and go!

Illinoyance · Apr 19, 2016

mcmachine said:
Wax it down.
heat the subplate material and glass on a hot plate then melt a little wax (#9 is best)
let it cool then go...flood with coolant use diamond wheel and go!

Flake shellac also works. Jewelers and watchmakers have used it forever to hold parts. Heat the substrate until the shellac is melted then press your part into it. Heat to remove it or soak in denatured alcohol to dissolve the shellac.

Some people use cyanoacrylate glue to mount the parts and use heat to release them.

fubar62172 · Apr 19, 2016

mcmachine said:
Wax it down.
heat the subplate material and glass on a hot plate then melt a little wax (#9 is best)
let it cool then go...flood with coolant use diamond wheel and go!

Diamond wheel? I'm looking into a diamond cutter sililar to a router bit.....Any certain grit I should look for?
Thanks again

fubar62172 · Apr 19, 2016

Illinoyance said:
Flake shellac also works. Jewelers and watchmakers have used it forever to hold parts. Heat the substrate until the shellac is melted then press your part into it. Heat to remove it or soak in denatured alcohol to dissolve the shellac.

Some people use cyanoacrylate glue to mount the parts and use heat to release them.

would a heat gun work for heating it up?
Thanks for the info

mcmachine · Apr 19, 2016

Finer the better and to reduce chipping.
You can also use another thin piece of glass as a sacrificial cover plate to reduce chipping.
The problem with a router bit will be the runout which will cause chipping.
cyanoacrylate is also good and releases with acetone.
coolant bath and slow feed.
Jon

fubar62172 · Apr 19, 2016

mcmachine said:
Finer the better and to reduce chipping.
You can also use another thin piece of glass as a sacrificial cover plate to reduce chipping.
The problem with a router bit will be the runout which will cause chipping.
cyanoacrylate is also good and releases with acetone.
coolant bath and slow feed.
Jon

Awesome...thanks

fubar62172 · Apr 19, 2016

what type of cutter would you recommend?

Milland · Apr 19, 2016

fubar62172 said:
what type of cutter would you recommend?

If you need an interior 1/16 radius, use a 1/8" or smaller OD diamond grinding pin, like this: 1/8 Inch Diameter, Diamond Grinding Pin 81547333 - MSC [yes, it's MSC, but lots of options out there with a search]. It just mentions that the grit is "course", which I'd guess is around 120. This may chip the edges slightly, but will cut faster than a finer (220-400) grit. You do need to flood the cut to flush the cut dust, make sure it doesn't wash into any of the machine ways. High RPM, very slow feed, test what works. Maybe start at 3000rpm and 0.5ipm.

If you use heat to mount the glass be sure your substrate has the same or close CTE, to avoid cracking during or after the mounting. Be sure about the grade of glass, some have near zero CTE in the ~0 - 100C range. In that case a block of Invar would be a good choice for substrate.

CalG · Apr 19, 2016

IF it were a task posed to me, I would stack up a 1/2 inch thick sandwich of the cover slips using medium hard mounting wax.
Cover slips are brittle. ('could use thin window glass just as well, and might be cheaper if small blanks could be scribe broken.)

If the profile is being done on a numeric controlled machine, set the work up on a glass waster waxed to a block of ALU. Touch off and then submerge the entire set up in mineral oil to do the machining. Generous flood lubricant would work as well, but GENEROUS. Soluble oil mixed stiff would very likely work too.

Doing profile work on manual machines will be trouble in regard to visibility. Cutting dry, even for a moment will result in chipping.
But, I have no clue as to the standard of the results you require.

As for the diamond points. Check with Universal Photonics or others that make for glass. All diamonds are not mounted alike!

magicmaker · Apr 19, 2016

Here are two machines that I might use for the microscope slide job. Chipping and glass dust would be no problems.
Jim

stevet · Apr 20, 2016

Have you thought of grinding it. When I use to do leaded glass work, I would grind the glass with a green wheel spinning slowly, Maybe 500 rpms and keep it wet. You can do the same with a wet belt sander.

Steve t

CalG · Apr 20, 2016

stevet said:
Have you thought of grinding it. When I use to do leaded glass work, I would grind the glass with a green wheel spinning slowly, Maybe 500 rpms and keep it wet. You can do the same with a wet belt sander.

Steve t

This suggestion may not apply as well to microscope cover slips. ;-)

mach2 · Apr 20, 2016

fubar62172 said:
what type of cutter would you recommend?

This might help:

Ultrasonic machining - Wikipedia, the free encyclopedia

Illinoyance · Apr 21, 2016

fubar62172 said:
would a heat gun work for heating it up?
Thanks for the info

Most users of shellac or cyanoacrylate used an alcohol lamp or small torch. I see no reason why a hot air gun would not work.

Illinoyance · Apr 21, 2016

If you decide to use double sided tape it would be best to soak the part and its backing in acetone or lacquer thinner to release the adhesive.

rcoope · Apr 21, 2016

Attaching it to a thicker substrate with shellac and waterjetting it would be nice. You can't really pierce though so it would be a matter of piercing away from the part, coming in and doing the profile. If there were screw mounting holes in the design you can often open these up as slots to the outside edge so they can be made without a pierce.

R

Conrad Hoffman · Apr 21, 2016

They make stuff designed for this sort of bonding and it works far better than the old methods-
Aquabond Technologies > Home

solidworks4u · Apr 21, 2016

The glass is very fragile because of the type of glass it is (as in post #10 states), I would try stacking several between sacrificial ends and abrasive water jet cut them if the tolerance will allow.

Best of luck!

mach2 · Apr 22, 2016

Here is a YouTube drilling glass. I have the head and electronics of one of these ultrasonic millers but know little of how to set it up. Anyone out there with experience or a manual?

https://m.youtube.com/watch?v=nDljw9ZyBZ0

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