Pickaxe is an "Axe" and located in the axe head secetion
2 ingots heated enables small axe head
3 ingots heated enables large - which houses only the main large axe head type, and pick axe head
Both Large axe head and Pickaxe head require a 2h grip to sell to customers.
Your Personal Pickaxe can utilize 1h grip, though.
Your Personal Hatchet/1h axe can utilize 2h grip as well
Combining either of these this way will not be saleable. It is /only/ your personal ones that can utilize it.
Hammer head also houses Mace/Morning star heads as well. - under the 2 ingot small head.
You can sell any of them as a one hand hammer, Not sure about Personal use.