What is it?

[armscor 1]

Given to me 30 years ago by a retired Toolmaker, only markings are Doloro Stollito 1/2 Dia.

[mcostello]

Is the second word Stellite? Might be a hard material drill bit. Google Deloro for more info.

[armscor 1]

The second word is definitely Stollito?????

[neanderman]

Looks like a desktop calculator, to me.

Ducking and running!!!

[Magicniner]

It's a nice, in-focus shot of a calculator and the grain of a wood desk top with something out of focus standing by the calculator.

[Steggy]

Like the others, I see an H-P calculator (one of their annoying-to-use RPN models) and some sort of blurry metal object that could be an instrument used by a proctologist.

[spro]

I agree with mcostello. Stellite is pretty hard stuff and see those black spots? Those could be holes for air or some other pressured coolant.

[pete]

An old school drill for very hard materials. There Triangular shaped so it better resists the very high feed pressures. I read an old post about them on PM a long time ago. And it's almost certainly Stellite tipped.

[spro]

Yep. I hadn't seen one quite like it but it did appear to have a tapered shank for high pressure.

[Wolfgang]

Given to me 30 years ago by a retired Toolmaker, only markings are Doloro Stollito 1/2 Dia.

It is a stellite drill, and the notches in the straight edges are to improve chip evacuation.

This drill is useful for drilling quite accurate holes in HARDENED steel; no need to anneal anything if you forgot a bolt hole prior to hardening.

Try it on and old file. Just grind off most teeth in one location, chuck the drill and run it at about 1000 rpm, and bear down on that file. Clamp down the file and do not use any coolant!

Make sure that there a no combustibles in the vicinity as the chips will come off red/blue hot.

The method of operation is that the drill heats the steel red-hot, thus annealing it locally, and then scoops or pushes the softened steel out of the hole.

Quite an operation to watch. Try it and let us know your observations. w

[armscor 1]

Tried it on a Aussie Nicholson file, ground off serrations and ran drill at approx 1000 rpm, hardly marked the file.
Tried a 1/4"carbide drill and same result.

[spro]

Well dang.