You may risk being hurt if the cooldown is higher then max, but you can keep crafting.
max cooldown 1h - You can craft safely
If cooldown 1h 30m - 50% that the crafted item will be deteoriated
If cooldown 2h - 75% that the crafted item will be deteoriated
If cooldown 2h 30m - 50% that the crafted item will be deteoriated, 50% that a random limb will be crippled (including eyes, if working with sharp instruments unsafely).
If cooldown 3h and over - same as 2h 30m, just all % changed to 75.