[grimpirate]

I made a TrueType font called Grim's Hex Paper. It lets you print pages of hexagonal grids for use in RPG gaming. It has one minor flaw in that there's some tiny whitespace between lines when it prints. The metrics are as follows:
Ascent: 10000
X-height: 10000
Cap height: 10000
Descent: 0
Line gap (leading): 0
I'm thinking that's all I need and that those are correct according to this page. However, as I state on my site there's a clearly visible separation which I don't know how to resolve, any ideas what metrics I'm missing or how to solve this problem?