Carborundum Stones Questions, Uses, Tips, Comments

Hi All,

Probably like many of you, from the time I was a kid and later, the local hardware stores and lumber yards had carborundum stones as the only sharpening stones in stock.

So, we bought and used them. I still have a big stone I bought as a young man, inherited another from dad, and got a really large carborundum stone in an assortment of oil stones I recently bought.

I bet a lot of the rest of you still have a large carborundum stone or two as well. Some in the assortment of oil stones I bought are dished out, and need flattening. Most I mine have a coarse and a smooth side, but in reality the sides should be called coarse and extremely coarse.

The questions I have are:

1. Should they be used with oil like an oil stone? (The boxes say they can be used dry or with oil.)

2. What is a way to flatten them, other than diamond stones, as I am NOT going to try to flatten one with one of my diamond stones. They won't get anywhere near one of my diamond stones, it isn't going to happen!

3. Are there applications where they are fairly useful?

I use mine for sharpening my wife's kitchen knives, and for initial rough work like the first stage of sharpening nickers, etc.

I ask because I have several, including two big ones.

I have thought about trying to flatten the dished out ones with coarse wet or dry sand paper on a left over piece of granite from a kitchen counter.

I have thought that once dead flat they might be OK for a coarse stone in a set of oil stones for a carpenters travel tool set when doing carpentry away from home. I want oil stones for that sort of tool chest because I don't want water stones in the box with tools because of potential rust formation due to a wet stone, and I don't want to take diamond stones because they are so heavy.

My current sharpening, once the iron or chisel is rough ground to roughly the correct angle, leaving a small flat on the end of the iron, is with coarse followed by fine diamond stones, then going to 1200 and 6000 water stones. Lastly I finish up by stropping. So oil stones don't play much of a factor, but for a travel tool chest they might be the preferred sharpening set up.

However, again, when on the road and having to carry the stones in a tool chest, I am thinking coarse carborundum followed by fine carborundum, followed by medium oil stone, followed by a fine oil stone and ending with stropping.

What do you think?

Thanks and regards,

Stew

I see the coarse carborundum stuff as a memento of earlier work done on site ,when hand tool use was more routine for
home repair. Compact grinders requiring niether electric power or exhausting peddling. Can still be useful, especially for small tools that can quickly "melt away" in inexpert hands using electric grinder. And still useful on the road.

Do you live somewhere with a concrete sidewalk out front? Or do you have an extra concrete block around in the yard? Water and one of the two will get the stone(s) flat again.

Quote:

---

Originally Posted by Stew Denton

Hi All,

Probably like many of you, from the time I was a kid and later, the local hardware stores and lumber yards had carborundum stones as the only sharpening stones in stock.

So, we bought and used them. I still have a big stone I bought as a young man, inherited another from dad, and got a really large carborundum stone in an assortment of oil stones I recently bought.

I bet a lot of the rest of you still have a large carborundum stone or two as well. Some in the assortment of oil stones I bought are dished out, and need flattening. Most I mine have a coarse and a smooth side, but in reality the sides should be called coarse and extremely coarse.

The questions I have are:

1. Should they be used with oil like an oil stone? (The boxes say they can be used dry or with oil.)

2. What is a way to flatten them, other than diamond stones, as I am NOT going to try to flatten one with one of my diamond stones. They won't get anywhere near one of my diamond stones, it isn't going to happen!

3. Are there applications where they are fairly useful?

Stew

---

My opinion in the order of your questions;

Q1: Should they be used with oil like an oil stone?
A1: Given a choice, water is better than oil, since oil tends to glaze much faster than water, and it is a lubricant placed on a surface where the desired effect is NOT lubrication but friction, and therefore counter-productive. But once a stone has been soaked with oil or kerosene, they usually won't work well with water.

Q2: What is a way to flatten them, other than diamond stones.
A2: Two ways. Rub one carborundum stone against another, checking flatness frequently. Second way is to find a flat piece of sloping concrete, like a driveway. Don't use a high-traffic area because the concrete may become slick when wet after you do this. It need not be smooth, but it does need to be reasonably flat. Dribble water from a garden hose and rub the stone hard. Assuming the stone is dished, even pressure should work, but if it is scooped out on an end or side, you will need to vary focus of pressure. Check frequently. Reverse end for end frequently.

Q3: Are there applications where they are fairly useful?
A3: Sure. Wasting metal. For instance, removing the chip from a blade, changing a bevel angle. Any work where speed is more important than precision.

Stan

Quote:

---

Second way is to find a flat piece of sloping concrete, like a driveway.

---

A Carborundum Oil Stone. The best of luck with the concrete.

Quote:

---

Originally Posted by Stewie Simpson

A Carborundum Oil Stone. The best of luck with the concrete.

---

Not pretty, but it will work.

My own personal preference is to use loose sic powder over a glass surface.

http://i1009.photobucket.com/albums/...ps8azt6ihy.jpg

http://i1009.photobucket.com/albums/...psta8qgzjw.jpg

Quote:

---

Originally Posted by Stewie Simpson

My own personal preference is to use loose sic powder over a glass surface.

http://i1009.photobucket.com/albums/...ps8azt6ihy.jpg

http://i1009.photobucket.com/albums/...psta8qgzjw.jpg

---

You do realize the subject of this post is carborundum stones?

Stan; that fact hasn't escaped me.

I have used Carborundum stones for over fifty years; I have worn through three one inch stones. Carborundum can be used to manufacture either oil stones or water stones. The difference is in the bond that holds the abrasive together. Water stones need a soft bond so that the surface wears away easily. Oil stones have a harder bond and depend on the oil to suspend the iron particles and keep the stone free from loading with iron. The oil needs a certain viscosity to perform well. If you use a thin oil like kerosene or WD40 you might as well use water because the suspension will not be very good.

I like a water stone for initial (coarse) sharpening for a plane iron or a chisel, but a coarse or medium oil stone like Carborundum or India is nice for a narrow tool or a gouge because the stone does not get out of shape so fast. You don't want to be constantly flattening a water stone.

I use silicon carbide grit with kerosene on glass to flatten Carborundum stones.

Stewie and Warren,

I may end up going the Silicon Carbide on glass route for flattening after I get the dished out middle sections on the problem stones to go away on the concrete. If that is the route I use, where is the silicone carbide available, what grit sizes are good, and what are the commercial names of the material, so I know what to get?

Is it pretty commonly available? Come to think of it, I may have seen some on that auction site when the use on a ceramic tile came up a couple of years ago.

Thanks and regards,

Stew

Quote:

---

Originally Posted by Stew Denton

Hi All,

Probably like many of you, from the time I was a kid and later, the local hardware stores and lumber yards had carborundum stones as the only sharpening stones in stock.

So, we bought and used them. I still have a big stone I bought as a young man, inherited another from dad, and got a really large carborundum stone in an assortment of oil stones I recently bought.

I bet a lot of the rest of you still have a large carborundum stone or two as well. Some in the assortment of oil stones I bought are dished out, and need flattening. Most I mine have a coarse and a smooth side, but in reality the sides should be called coarse and extremely coarse.

The questions I have are:

1. Should they be used with oil like an oil stone? (The boxes say they can be used dry or with oil.)

---

I use them with mineral oil. Carborundum is SiC, which is pretty friable, so IMO you want something to carry the muck away.

Quote:

---

Originally Posted by Stew Denton

2. What is a way to flatten them, other than diamond stones, as I am NOT going to try to flatten one with one of my diamond stones. They won't get anywhere near one of my diamond stones, it isn't going to happen!

---

Lap them with loose SiC powder on glass, ideally with a sacrificial laminating sheet in between. Caborundum stones are infamous for stripping diamond stones, so you're right to keep those separate. Carborundum isn't hard enough to attack diamonds directly, but it can do a number on the metal that binds them to the plate.

Quote:

---

Originally Posted by Stew Denton

3. Are there applications where they are fairly useful?

I use mine for sharpening my wife's kitchen knives, and for initial rough work like the first stage of sharpening nickers, etc.

---

SiC is harder than the other common abrasives (SiO2, Al-Oxide) so it does better with difficult steels like HSS. It's also more friable, though, so the stones will wear down faster.

Had two such stones. New in Box. Instructions on the box says to "clean in Kerosene" I gave the smaller one away. So far, the longer one has stayed flat.
Attachment 368761
I use this one between the grinder/beltsander, and the 600 Medium India stone. Usually give it a dribble, squiggle of 3in1 oil. No signs of any "dishing out" yet.
YMMV

To flatin my carborandum stone I use a chunk of concrete that has a decent flatness to it. To give it a smoother finish i rub it on my older Norton stones. I use mine for jointing joiner knives. That's why I need it smooth.
So I use the method Stanley mentions.