What is this

[aaron.steele.9026]

I picked up this fragment of a sharpening stone today and I was wondering if anyone had an idea of what It might be. It's 5/8th square by 3in long but I know that part of it broke off. I've found similar stones before but I was never able to find out what they where.

I've already lapped it into shape and it lapped rather easily on 80 and 120 grit sandpaper (it only took 30 minutes). It feels like my 102 razor hone but it's a lot softer. I'm mostly hoping to find out what it is so that I know whether or not it's a natural stone and if I need to use oil or water as a lubricant.

 

[bucketstove]

Based on size alone Id guess its a "dressing stick" for "dressing and cleaning" abrasive wheels
update: https://en.wikipedia.org/wiki/Grinding_dresser#Types briefly mentions "Dressing sticks"

 

[David Martin]

My guess is a dressing stick as well. I have one made by Norton a India dressing stick which is 1"X 4". It's just not soft material like yours. I've seen dressing sticks made by Empire State that were soft like yours. Made of SiC perhaps around 280 grit of the same color as your top photo. DM

 

[EChoil]

With only pics to go by, and originally looking a little rough, it looks to me exactly like an aged carborundum stone (natural) or piece thereof. I use one a lot in addition to other diamond and ceramic rods and Arkansas stone types. Some would call it old school but it sharpens just fine. Usually they are medium to fine grit but no higher.

I'm not familiar with exactly what they're calling a dressing stick though, so maybe David and them are right.

 

[jpm2]

That might be what we call a comm stone, for dressing the commutators of electric DC motors.

 

[bucketstove]

With only pics to go by, and originally looking a little rough, it looks to me exactly like an aged carborundum stone (natural) or piece thereof. I use one a lot in addition to other diamond and ceramic rods and Arkansas stone types. Some would call it old school but it sharpens just fine. Usually they are medium to fine grit but no higher.

I'm not familiar with exactly what they're calling a dressing stick though, so maybe David and them are right.

Thats just the thing, it could be anything some kind of pocket stone... but if you look at current abrasives catalogs stones that small are sold as dressing sticks
One such catalog says Finer grit and softer grades are used for dressing diamond wheels.

 

[aaron.steele.9026]

Sweet.

 

[Obsessed with Edges]

With only pics to go by, and originally looking a little rough, it looks to me exactly like an aged carborundum stone (natural) or piece thereof. I use one a lot in addition to other diamond and ceramic rods and Arkansas stone types. Some would call it old school but it sharpens just fine. Usually they are medium to fine grit but no higher.

I'm not familiar with exactly what they're calling a dressing stick though, so maybe David and them are right.

Carborundum is otherwise known as silicon carbide (SiC), which is man-made. No such thing as a natural carborundum stone. 'Carborundum' was the trade name given by the discoverer/inventor of it, producing it more or less by accident, in an attempt to make diamond. They have been around a long time and could be called 'old school' (the 'carborundum' description has become almost generic for SiC stones of any brand), but they're not a natural stone. See link below, with relevant part of the history quoted:

(text below quoted from site: http://www.carborundumindustrial.com/CarborundumHistory.aspx )

"It all began with a failed experiment.

It was in 1890. In a small Pennsylvania town, the inventor Edward Goodrich Acheson carried out a series of experiments. He tried to heat carbon so intensely that it would result in diamond.

It didn't work.

So Acheson began mixing clay with carbon and electrically fusing it. The result was a product with shiny specks that were hard enough to scratch glass. This was silicon carbide. Also known as carborundum.

The next year Acheson formed his company in Monongehela, PA and named it Carborundum, and moved the organization to Niagara Falls, NY, USA in 1895."

David

 

[EChoil]

Carborundum is otherwise known as silicon carbide (SiC), which is man-made. No such thing as a natural carborundum stone. .......

You're right of course, in re: the sharpening blocks of today.

No idea why I inserted that for this thread (except that, see below)....especially since natural stones certainly don't come in reversible grit grades out of the quarry. Only been using them off and on for forty years or so. Sheesh....

Just FYI though...CiS "carborundum stone" you mention is a synthesis of naturally occurring CiS, found in Diablo Canyon, Arizona, as well as other parts of the world, including diamond mines/kimberlite areas and the Green River formation in Wyoming. Very rare though....probably used by native Americans long ago.

It was discovered in the late 1800's by a guy named Moissan and first synthesized by a man named Berzilius. As you mention, Acheson resumed synthesizing it later to become the sharpening instruments we know of today.

You can Goog "Moissanite" for further info....