BS mortice lock idea

[Rickthepick]

I have a great idea for a nigh security mortise lock. It needs to meet BS but im struggling with one aspect of it:

This lock requires no curtain wheel (as we know it)

The curtain wheel in a BS mortice lock not only shields the levers but also provides the bolt with the extra 4mm bolt throw. (if you take a look at the back of the curtain wheel you will be able to see what i mean)

I need to design a bolt, thrown entirely by the key alone that achieves the 20mm protrusion.

It doesn't sound difficult but construct a few blueprints in a 2d design programme and youl see that anything above 16mm is nigh on impossible without using a really thick key.

The eurospec locks that use runners to elongate the talon of the bolt are the only locks iv seen that do not use the large curtain wheel idea, but this idea is no good for my lock either.

All ideas welcome

[98AB49DC5A]

why not just shorten the curtain. ie a turnable plate the key goes through at either end of the lock. Hopefully that wouldn't interfere.

[mhole]

Or make it double throw?

[Josh K]

Or put a geared mechanism in there to increase the throw length...