Cutting glass

[Hauk]

Using microscope cover slips for glazing material is certainly not a new idea, and I early on decided to use the stuff for my 0 scale engine windows.

But my first efforts to cut the stuff were appalling.

So I have really dreaded cutting the 16 pieces of glazing I need for my two engines under costruction.
But when I sat down to tackle the task the other night, I did a bit of thinking before plunging ahead.

First, I decided to try a much harder cutting surface. My first attempts were made on a self-healing cutting mat, the next on a paper with the cutting lines printed on it. Rejection rates were extremly high, I broke almost every piece I tried to cut.

So this time I used Corian, but any other really flat and hard material should work (a piece of thick glass).

Since all my windows are the same size, I made a simple cutting jig to speed things up.
And, boy, what a difference a little thinking can make! I made the first 8 windows in around 30 minutes, breaking just a couple of slips.

The process in more details:
The width (and height as my windows are square) was carefully drawn with a sharp, hard pencil on the corian.
Then a ruler was placed against one of the lines and taped on the other side to make it "hinged":




Under the ruler a short length of brass L-channel is superglued to the corian flush with the other line:



Now it is possible to place a coverslide up against  the brass channel, lower the ruler and hold the glass in the exact position for cutting:



This way it was possible to make 20 pieces of glass to the exact same size without measuring more than one (the masking-tape hinge is suprisingly precise):



Here is the result, glazing for 16 windows with 4 spare pieces:



If all dreaded jobs could turn out so easy in the end!

-Haavard

[lab-dad]

All great tips!
Glad it (finally) went well!
Thanks for taking the time to share.
-Marty

[finescalerr]

An excellent explanation of a simple solution for a common problem. Thank you. -- Russ

[RoughboyModelworks]

Very nice job Haavard... the simple solutions usually work best. I use a block of aluminum in which I milled a shallow cavity square to two reference edges and the same depth as the thickness of the glass. That way I can use one of the small Starrett squares as a guide for the scriber. Works great, but I learned the very important thing is that the surface below the glass needs to be perfectly clean, no tiny glass particles or other small debris, otherwise the glass will break.

Paul

[Philip Smith]

Awesome tutorial!

What are the window frames made of? they look great!

Philip

[Hauk]

Very nice job Haavard... the simple solutions usually work best. I use a block of aluminum in which I milled a shallow cavity square to two reference edges and the same depth as the thickness of the glass. That way I can use one of the small Starrett squares as a guide for the scriber. Works great, but I learned the very important thing is that the surface below the glass needs to be perfectly clean, no tiny glass particles or other small debris, otherwise the glass will break.

I should have mentioned that I wiped the surface with a damp, clean rag after fiishing a pane of glass. It is my experience also that the slightes of particles can caus the glass to break in the wrong places.

It is also my experince that it works best to press the ruler pretty hard against the glass. With my setup the ruler only touches the glass almost exactly at the cutting line,  so my guess is that pressing the ruler hard against the glass creates tension in just the right places, helping the glass th break along the scribed line.

And I never use the full size way of cutting glass, score and break. The glass is kept in the jig until the cut is done. This can take several passes with the scriber.

Last, I would not really reccomend a material like corian ifyou are making a larg batch of panes. I would gove for something harder, If you have a mill a metal one like Paul descrives would be nice. A thick piece of glass should also work well. Only problem is that it would be hard to draw on.

-Haavard

[Hauk]

Awesome tutorial!

What are the window frames made of? they look great!

Philip

Thanks, Phillip!
The window frames are etched brass. With two-sided etching it is easy to design the frames so the glass do not "stick out" on the backside, but are flush with the frame. The windows are shown backside up in the pictures.

These windows are going to be working sliding ones, so it is essential that the glazing is flush with the back of the frame. (stay tuned, pictures will follow!)

-Haavard

[RoughboyModelworks]

Here are a couple of shots of the glass-cutting fixture I mentioned in the post below. It's machined from a block of 1/2" T. aluminum. The top surface is slightly textured to aid in holding the square in place while in use.



Picture below shows the fixture in use. A piece of cover-glass is placed in the milled recess (milled to same depth as thickness of glass). The square is positioned on the fixture at the desired dimension (set with a pair of vernier calipers referencing from the end of the milled recess) and the glass is scribed with a carbide scriber.



Works very well as long as the recess is kept scrupulously clean so that the piece of glass can sit absolutely flat.

Paul

[eTraxx]

Dang. Going to make me one of those! Thanks.

[marc_reusser]

Havard:
Good tutorial and beatiful work on the windows.


Paul:
That is a sweet jig. A question though; how do you manage to gut all the way to the edge of the glass with the scriber...doesn't the milled edge interfere and thus cause the scriber to stop just at the joint between the glass and metal....thus causing the scriber to slightly "sink in" and cause undue tension and potential corner breakage/chippiing?

M

[RoughboyModelworks]

No, I haven't had that problem Marc. The glass stock is held tight to two edges and the floor of the jig by the square's blade. I've had the occasional piece that floated under the blade. A piece of cigarette paper between the blade & the glass took care of that. I think chipping is more a result of incorrect pressure with the scriber. It does take some practice to develop the right touch.

Paul