I've seen the MIT videos and they scratch them with a ruler and scribe, then snap them on the bench. But that looks kind of messy to me. The lines end up wonky, they might not snap properly (which is expensive), I'm used to snapping things like this but still think it risks wonky lines or cutting myself and it means grubby'ing up the surfaces on the bench or gloves.
I was thinking of buying a cheap tile cutter, then gluing some tiles to the bed. I was going to use two, have a very small gap between them and use the concaving, rounded edges along the break point to avoid scratching the plate.
Then I could get an accurate score and, I'm hoping, a clean snap.
Has anyone tried something like this or have an idea if it'll work or not? Please only reply if you're used to scratching and snapping TLCs, as I need some first hand advice.
All the best from sunny England! [edit: aww.... it's dusk time now]
That jiggy thing is a tile cutter, used to scratch the glaze and snap it along a line. Same trick for glass. And bricks actually, with a different tool (although, I tried that with high purity alumina / zinc oxide refractory rated for molten iron contact and it doesn't work so well).
The reason I thought of a tile cutter is that they essentially do exactly the same thing as the ruler / scribe / snap method, but the scribe is fixed to a linear rail, so it'll produce a perfectly straight, controllable score. The way they snap tiles, by placing a little break point on the scribe line, also tends to encourage a clean snap.
And, as I say, if I lined the support area of it with glazed, smooth tiles, I could ensure the plates where cut spotlessly clean and, I'd like to think, dead on straight and repeatable.
I should have tried this with a bit of glass when the plumber left his cutter here.
I was going to say, I'm surprised they still do the big plates. But I guess they'd be handy for developing a ton of spots on one for direct comparison. Perhaps it's fairer to say I'm surprised by the lack of prescored done slips. Unless the ones I'm looking at are being surplus'ed out of service for that reason.