Do you know what this little hammer is designed to do?

[Charles Lent]

I think it looks like the ones used by printers of a hundred + years ago to set type, back before the Line-o-type machines when type was set in single characters.

Charley

 

[PeteStaehling]

Looks like a fret hammer used to gently pound fret wire into slots on stringed instruments. Its the right size for this delicate work. Newer quality fret hammers have one brass face and one softer face of Rubber or phenolic. Some old fret hammers had two brass faces or brass and hard wood insert.

Could be. The size and brass faces would work for that. I have never seen one that looked like this one, but still it could be. The screw attachment of the brass faces might have allowed for other possibly softer faces and or a slightly concave one for radiused fret boards.

 

[Pop Golden]

Looks like what Charlie said. It was called a planeing hammer. To level type in the chase.
PS: The Mergenthaler Line-o-type was a news paper machine. Many print shops were still hand setting type long after it's invention. Watching hand type setting is an amazing thing. Type is in a open top wooden box, and the type setter dose'n even look at the box. Sorta like touch typing in the old days when we used typewriters.

Pop

 

[PappiJoe]

Looks like a fret hammer used to gently pound fret wire into slots on stringed instruments. Its the right size for this delicate work. Newer quality fret hammers have one brass face and one softer face of Rubber or phenolic. Some old fret hammers had two brass faces or brass and hard wood insert.

I'll look into that. Thanks @JohnW