[TowerTalk] Tic Ring spur gear

[Sebastian schumann]

Hello OMs

I recently got my hands on a used tic ring, well only the ring without anything else. 
It measures around 48inch inner diameter. 
My plan is to build the holding frame on my own. Should not be a big deal. 

My problem is that I don’t know where to get the small gear that i could put on a slewing gear. 
I measure around 7,2mm from tooth to tooth on the ring. That equals module 2,250 what is hard to find in Germany. 

Could someone please help me finding imperial dimensions, as I think I could get it in UK.  A link would also be vy nice. 
I also don’t know how many teeth it should have. Guess 18 or 20 seems to work out. 

Many thanks 
Hope you guys could help me out. 

73 de Sebastian DG5CST