How to cut accurate 6 1/2" squares?

[Deafoldbat]

@SewRuthieSews It has wandered across my mind that if you're desperate to get on, you could place the ruler at right angles to the straight edge and make a mark 6½" in every few inches then line the ruler up lengthways with those marks. (We all seem to be assuming you use a rotary cutter. Once upon a time it was templates, pencil and scissors. Don't miss them a bit.)

[SewRuthieSews]

I am using a rotary cutter, it seems better for the endless squares P&Q requires. I cut out my garments with some fantastic Sheffield steel shears.

I don't need the 6 1/2 " squares yet for the patchwork pattern, so I've been working on my 4 patches (4 x 2 1/2" sqaures), which has mostly worked ok except for a few wrongly cut squares, and one block with an extra layer.....
Good use of the unpicker to sort the few issues out :-)

I should get my new square rulers Wed or Thu so can work out a sensible technique then.

[SewRuthieSews]

I now have my square ruler set, so can presumably cut out all sorts of things....