Version 1.12.2, forge-184.108.40.20660/fml, java 1.8.0_51
Computercraft mining turtles are not craftable, nothing happens when an unused diamond pickaxe and a turtle are put into a crafting grid. Other turtle variants (digging turtle, felling turtle, etc.) work but nothing happens with mining turtles. Is there a conflicting recipe or a setting that needs to be changed?
UPDATE: I made a new pickaxe (I repaired the first one before trying to craft a turtle) and it took it but the output of the crafting grid was a regular turtle, not a mining turtle. I ended up having to place the turtle and use the lua prompt to equip it.