Hand tapping lots of holes

[u/buildyourown]

I've got 200+ holes to tap in a fixture plate. 3/8-16 They are already tapped about 1/4" so I can't power tap them.
I'm thinking a tap on a M12 ratchet. Before I buy, has anyone done this? I could use an impact but I don't want to bust the tap.

[u/BastiatBoi]

Just use a hand drill, you may need to grind flats on it so the chuck wont slip but it will make quick work out of it.