Unknown rail

[seber]

This rail shows up in an estate sale ad for tomorrow. Can anyone tell me what this is for? Looks like a milling or grinding clamp but new to me.

 

[laser3kw]

it looks like a machinist vee-block. The top part / horseshoe should be rotated and mounted 90° with the screw positioned above the "V" and the feet in the slots.

 

[BFBOB]

Right you are - I have a very similar setup. I think the beam on yours is rotated 90 degrees axially - it's made to clamp round stock in the v-side of it. The two-slot side (the top side in your picture) is to be fastened to the table via t-slot bolts. Mine is a little different - two short, almost cubical blocks instead of one long one. There should be two clamps, too.
I use mine on the drill press. It makes it much easier to cross-drill a round rod and get the hole centered.

darn laser beat me to the punch.

 

[Kscardsfan]

Vee block, but I’m not near smart enough to tell you what a machinist would use them for. But I know that ammo makers and custom gunsmiths use them for accuracy and press testing in controlled environments.

 

[RTM]

As the others said, Vee blocks. I see a seam in the rail

I’ve never seen the clamp with the off center screw (edit: as seen in this link)

568C V-Blocks and Clamps

Starrett V-Blocks come in a variety of styles to suit the numerous requirements of machinists. They are for general shop use and layout work, as well as for holding stock in place during light-duty milling, drilling, and grinding operations. All clamp screws have a hole to help secure the...

www.starrett.com

 

[TailGunner3000]

As the others said, Vee blocks. I see a seam in the rail

I’ve never seen the clamp with the off center screw.

I think that's just an optical illusion. The screw looks to be centered if you look at the top of the clamp.

 

[ItsNemo]

Vee block, but I’m not near smart enough to tell you what a machinist would use them for. But I know that ammo makers and custom gunsmiths use them for accuracy and press testing in controlled environments.

V Blocks are used for clamping round items typically.

 

[MushCreek]

As others have said, it's a V-block, and the clamp is mounted 90 degrees off for some reason. I have several sets for doing round work. They hold a round piece precisely centered and square. I have tiny ones that mount into a larger V-block for doing really small stuff.