56 barley corns
There is no proper scale length, make it whatever feels comfortable.
I went for the lean over with one eye and go 'eeh, that looks alright' .
anything is possible. somewhat depends on how/what you intend to play it. I've built Dbows as short as 12 inch and as long as 30 inch scale lengths. Heavier strings/darker sounds work better in longer scale lengths...think bass guitar. Lighter strings/brighter sounds can handle very short scale lengths...think mandolin. JMHO, hope it helps.