I have got two mystery milling cutters with a bunch of slitting saws.
They look like a involute gear cutter, but shape is a bit unusual to me and markings don't look familiar. Also tooth flanks look straight - like for rack cutting.
One has markkings:
1 (number "1" alone by slot, one tooth opposite of it has a delibrate nick on the back). Rack?
900 7812 ( could be a material code?)
Schuler (Maker/Brand?)
N12
67x3,3/1,0x22 (67=diameter in mm, 3,3=root thickness in mm, 1,0=what? module? 22=diameter of the hole)
HSSE5Co. (this I know!)
Spanw 8° (Wing span

If everything fails I can still play ninja with it.
Pekka