David Harris in "The Art of Calligraphy" shows the drawing of a curved right serif on a vertical, which is part of what I need to do to build the serifs on the verticals in the Bedford Psalter script.

A Bedford Psalter ascender










Drogin has the same information, but Harris shows a nib ladder right next to the vertical, which is what I wanted, so I could see exactly where the curve changed to the vertical line.

I've been practising the L's on graph paper sized to the 1.5 mm nib width, and it seems that I'm curving at the right point.





In real life, these two lines combined are 2.5 cm (1 inch) tall - pretty small.

Having got the curve right, I have another problem.

Because the verticals are spaced one nib width apart (ie one blank column of graph squares between each) - the diamonds hit into each other.
I can't let this happen. The letters will all be joined together at the bottom and be unreadable.
(Not that historically spaced gothic textura quadrata script is very readable anyway, given that it uses this spacing)

I had a closer look at the diamonds on my Bedford Psalter pages, and saw that the diamonds are actually a little tilted.






Having a look at the m or the n - you can see that the diamonds are actually a bit higher on the left than they are on the right hand side. That's how the room is being made.

I figured this out part way through those two lines of L's on the graph paper shown above.
But I'm finding that I'm tilting the diamonds the other way - with the right hand side being higher. I wonder whether this is happening because I'm left handed. It was the way that it seemed 'to work' for me.
I'm going to have a go today at trying to tilt the diamonds up on the left, rather than the right.