Smooth Holesaw

[k9gl]

What the heck can you cut with this?

The grooves look perfect and not worn at all, but they are smooth. 

[Chillylulu]

Glass, stone, concrete.

It is likely diamond impregnated.  If not, you can run it in a diamon or other abrasive compound to cut materials - mostly non-metal, of course

Chilly

[k9gl]

It is not diamond impregnated.  The end is smooth, and the center drill looks like it is for metal or wood or  ???

I picked this up with a bunch of metal working tools, including other bi-metal holesaws.  At first I thought it was just a regular holesaw that was completely worn down, but the tips look too perfect, and are cut square.

Thanks for looking.   

[Chillylulu]

We buy those new - when retrofitting fire sprinklers into schools here in Denver.

They work well in cutting holes in lathe &  plaster walls that were installed in tye 18th century through the 60's.  They don't spall as much when cutting in (yes, in - not on penetrating through, they have to be cut from both sides)

95% positive they are diamond. Thar is wgat diamond imoregnated tools look like. Just because you can't immediately see it with your eyes doesn't mean that someone else is wrong. They aren't magic, after all.

We get a similar carbide one - but you can tell it has sharpened teeth - for cutting steel.

Google "diamond core drill bits" and learn.