On Fri, 19 Jun 2020 19:59:48 +0100, newshound wrote:

Thinner glass can be scored and lifted and gently tapped with the
cutter underneath the score line, the weight of the glass and the
impact causing the crack to grow.

The other useful technique is, after making the score, to gently tap
along the line of it with something like the ball of a ball pein hammer.
Done correctly, it will cause the surface defect to propagate through
the thickness of the glass.

Wasn't sure if that would work well with 4.5 mm thick glass, I guess
it should and might be a bit more controlled that applied pressure.
The thickest glass I've cut would be 3 mm the lift and underside tap
worked well.

--
Cheers
Dave.