"Damme, Sir,' said the Major, `there is no use in disguising a fact. Joe is blunt, Sir. That's his nature. If you take old Josh at all, you take him as you find him; and a de-vilish rusty, old rasper, of a close-toothed, J. B. file, you do find him. Dombey,' said the Major, `your wife's mother is on the move, Sir.' "

I wonder if this is a joke about "bastard file". Commuting to Boston by rail from the Cape, used to go by the a building with a sign on it:" J.W.Bastard File Co." College wits used to find it hilarious to call up on the phone, and ask to spead to the Old Bastard. A bastard file is one with a half-round or other special shape, as distinguished from the usual flat or round ones.
Dickens may well have known this, but I wouldn't expect a caricature military retiree to.

A Sears Advertisement:
Craftsman 8 in. Round Bastard File

Craftsman 8 in. round bastard file.


Sears item #00931276000
Mfr. model #31276