Cutting Thin Mirrors

[trwalters001]

Hi All,
Someone on PL posted about using mirrors from old Polaroid cameras. Good idea, I says. So, I ran on down to the local Goodwill and picked up some. The mirrors are very nice, but are VERY thin. Anybody know a good way to cut these into more usable shapes/sizes (without resorting to the "hammer" method )?
Thanks!
Tim

[buffo]

I've had good luck using a dremel tool with one of the oxide cutting wheels. You have to go very slow! If the glass overheats, it will shatter. Cut a grove along the line you want to break the mirror on. When you've scratched the surface all along the line, go back and work the cut until you're at least 1/6 the way through the depth of the glass along the full length of the cut. Then just snap the mirror off.

Beware! This generates flying glass dust! Wear goggles. Work slowly so you don't overheat the glass. Wear gloves so you don't cut yourself. And try to avoid breathing the dust. (I use a vacuum cleaner to suck it away while I'm running the dremel.)

I've cut mirrors up to 1/4 inch thick using this method. The key is heat control. You have to keep the cutting tool moving, and you might need to stop every few seconds to allow the mirror to cool.

Adam

[DZ]

I've always used one of these little glass cutting tools. Just run it down the back of a mirror and it usually makes a deep enough score to cleanly snap the mirror. Now and then you don't get a clean snap, but most of the time its near perfect.

[trwalters001]

The mirrors that I'm talking about are about 1/32" thick. I think that a roller-type glass cutter would break the mirror as soon as pressure were applied (but I haven't tried it).

I was thinking about the Dremel idea anyway. I was hoping that some of you might have done this in the past and knew a better way.

Tim

[mixedgas]

Tim said,
[done this in the past and knew a better way.


Tungsten Carbide scribe, looks like a pencil, acts like one,available at home despot and lows.

works great, takes a little practice, but less drastic then the dremel solution.

[MechEng3]

A 4 inch diamond lapidary saw makes child's play of those tasks.......with very little loss and no chipped edges!

[Danny]

I have had good luck using clear tape and a sharp carpet knife. Cover the mirror with a layer of thin tape (makes it less prown to shattering) and cut through it. Don't cut all the way through the mirror, just make sort of a deep scratch. Then hold it over a 90degree edge and snap it. Just don't try this on a bad day...

[loopee]

Hi Tim

My recommendation for cutting small thin glass is by the following:

1. Clean the area where you plan to do the cutting, any small bits of grit, silica or glass chips may scratch the mirror.

2. Obtain a diamond tip glass cutter, I wouldn't even dare trying it with a circular wheel type cutter as they are cheap and designed for cutting standard window glass (not fine delicate mirror)
BTW, as for the Dremel, I could probably cut five or six mirrors in the time it would take to cut one with a Dremel, not to mention what damage the heat does to the mirror.

3. Also obtain either light oil or kerosene. Dipping the cutter in the oil before you score the glass creates a smoother score line.

4. Measure and mark where you want to cut the mirror, this makes it easier to align the guide when cutting (there's nothing worse than a crooked cut!)

5. Next, find something that is hard and flat to cut the mirror on, if you try and cut the mirror on something flexible there maybe a chance that you'll just crack the mirror under the pressure when scoring the glass. Also use some paper on top of the surface, this will prevent scratching and provide some grip.

6. You will also need something to guide the cutter when scoring the glass, a steel ruler is best but anything that is straight and won't flex will do. Note, you may want to check how the cutter "rides" along the guide as you want to ensure that the cutter won't jump the guide.

7. Now with the guide aligned to the measurements you made, dip the cutter in the oil and holding the cutter like a pencil, score the glass. When scoring the glass best results will be achieved with a single even score from edge to edge, try not to go back over the score as it may damage the cutter.

This may take some practice to work out how much pressure to apply to get the even score line, so I'd recommend trying it first on some normal glass.

A good tip is that when scoring the glass it should be a smooth silk ripping sound. A gritty sound means that you are pushing too hard or that you did not oil your cutter. The less sound you make, the better your score will be, and remember to try and maintain consistency across the glass.

8. Now that you have a very fine score across the glass, we need to snap the mirror. The way I do this (and have achieved perfect results every time) is to lay the mirror over some small tubing in line with the score and the score facing up (i.e. opposite side of the tubing) With the score on the glass aligned with the tubing, place some plastic strip (or a credit card) on top of the mirror, and then gently apply downward pressure until you hear the mirror snap.

Note: As the mirror only needs to flex slightly, when working with really small mirrors you can pad either side of the tubing with folded tissue to assist in holding the mirror in line with the tubing prior to snapping

9. Once cut you can use a sharpening stone to remove the sharp edges. Not only does sanding reduce the chances of being cut by sharp edges, sanded glass is also less likely to chip along the edges and provides some added strength.


Hope this helps

Troy

[trwalters001]

Hi Troy,

VERY good tutorial!!

The kerosene is a great idea. Thanks much for that!!

This probably needs to be a sticky...

Tim

[steve-o]

I use diag cutters and file the rough spots away... quick and dirty
Just leave the fs film in place until you're done...then peel it off after glued
_edit_ oh no protective film... oh well.. n/m.. maybe protect (if fs mirrs) w/ scotch tape or something)...