Silicon Carbide Stones - Anyone Actually Use Them?

[D_W]

This is a curiosity question as I've had a bunch of these things, but I am a natural stone hound more than manufactured, and on the manufactured side, I think india stones have everything except heavy grinding covered.

My curiosity is that these stones (specifically carborundum labeled stones from the early to mid 1900s) sold in droves, and they cost as much as a washita, but they're often little used. Carborundum corp made some razor hones, too, but they get less love than the woodworking stones - silicon carbide is practically toxic to razors unless it is really tiny, it's too aggressive and their bevels are too thin to tolerate anything aggressive.

Not talking about medium and coarse grinding stones, those were used heavily, and are (at least when new and somewhat friable) better than any other grinding stone that I've used.

Anyone use the fine ones?

 

[D_W]

Looks like no!

I got a block of used stones for $1 each on ebay early this week, and ordered a fresh new carborundum 118 yesterday for $4. I'm curious as to how well they'll work followed by something simple like autosol on a strop. I'm guessing well (but based on the ones I've had before, I can understand why someone would've rather used a washita as a first and last stop).

 

[bugbear]

Looks like no!

Either that, or sensible people are suffering from sharpening thread venom fatigue. :roll:

bugBear

 

[Jacob]

No idea what mine are made of.

 

[D_W]

Looks like no!

Either that, or sensible people are suffering from sharpening thread venom fatigue. :roll:

bugBear

Well, hopefully this thread will be filled only with garter snakes and drone bees. No venom.

As an aside, I did get a view in a trade used toolbox that a friend of mine had (belonged to his dad in England - somewhere well north of London). This friend of mine is a true engineer, ends his sharpening routine with a shapton 0.5 micron stone. His father worked as a carpenter and jointer for a living (until about 40 years ago), had three planes in his tool box, a silicon carbide stone and an arkansas stone. All well used, none flat. The arkansas stone was of the washita variety and not something overly fine.

Other than that, the silicon carbide stones and the various low-priced barber hones made of graded grit can be found at flea markets around here because they persist on dealers' tables. Often little used.

Sharpening can be done with anything, though. if someone wanted to use 400 grit sandpaper and wheel polish, it wouldn't make much difference. I'm just curious as to why some stones come up so well used (like washita stones) so often, and others, like the carborundum stones, are often used a tiny bit and then cast aside. My guess being that the final edge they offer is not something that's very good, even after a strop - too bad for the guy who bought one back in the day to replace a washita and paid half a day's wage for it).

 

[essexalan]

Might have at one time in the form of a double sided stone, probably in the reject box in the shed. I do use higher grit SiC stones made by Sigma and they cut well if probably overkill for most steels.

 

[D_W]

Might have at one time in the form of a double sided stone, probably in the reject box in the shed. I do use higher grit SiC stones made by Sigma and they cut well if probably overkill for most steels.

I have had those (well, just one of them), but you are right, they are more or less the same thing as the old stones except that the sintered bond is more friable. They are a lot like a japanese blue aoto, but they do cut much faster.

 

[essexalan]

If you are talking about the Sigma SiC stones then they probably act much the same as a new Crystolon. Always meant to dig them out, boil all the oil out and use them with water I reckon that might help with the clogging effect. Flattening an oil loaded stone would drive me nuts! All the other coarse SiC stones I use with copious amounts of water which keeps them cutting fast but they do wear down fast as well, letting them dry a little clogs the stones quickly. Never even seen a Japanese natural stone let alone a blue aoto.

 

[D_W]

I'm assuming you're talking about the sigma power II stones that are sintered silicon carbide and that go up to 10k grit. I know they also make a crystolon style stone that has trouble clogging, but that's just because no 120 grit SiC stone works well with anything thinner than mineral oil.

The crystolon stones are slightly friable, but not remotely to the degree that the SP II stones are. I think that softness is fine in finer stones (I had a 3k stone that I used in place of a blue aoto - the blue aoto are just natural soft stones about 2-3k grit, but a pain to use - I think they are abundant in US woodworking catalogs because they are cheap (the blue aoto). They certainly aren't good. Sometimes they're referred to as tanba aoto).

Crystolon stones may not be as cheap over there, but I see looking around that there are a fair number of european made silicon carbide stones that are about 12 quid for an 8x2 stone. I've scratched my itch by getting one lot of SiC old stones and a stone that's unused, and I'll probably let it stop there. A stone that I have on hand in an oil bath (one of those norton tri stones) is the norton medium crystolon, and new enough that it's still friable. It's fantastic, but what makes it great would make for a not-so-great finishing stone in the grits that a lot of the carborundum stones are made, which is many times more coarse than the SP II stones.

 

[essexalan]

No problems with my 120 grit as long as it is well soaked and flushed frequently, occasional refresh with 60 grit powder keeps it flat and cutting. Perhaps a refresh with SiC grit on Crystolons would be a good idea. Possibly a fine Crystolon would make a good finisher when you consider how quickly the abrasive breaks down. Will have to dig mine out of the shed and have a play and I know I have some Ark stones in there as well....somewhere!

 

[D_W]

I got my $8 box of stones (well, just over double of that with shipping), and in it are a couple of fine stones as well as the typical india/crystolon combo.

The one that is probably coarse fine actually isn't too bad, but it can't make a finished edge that anyone would tolerate. Same could be said about a 1k waterstone.

In the box are also a couple of scythe stones, which I thought I'd have no use for, but I pulled up my hallway carpet last night, and am refinishing the floor under it and test scraped a spot with a stanley 82 to see how it would fare removing the finish and the spot seen is how much the scraper will cover before being restoned.

So I will probably get my dollar (or two with shipping) out of that stone. when I get back to building cabinets, I will use the black silicon carbide stone and follow it with a piece of jasper with loose diamonds on the surface.

 

[essexalan]

Think you are going to need a bigger scraper! Have you worked out just how many sharpenings it will need to complete the job? Seem to remember that type of stone was what the fish market guys were using to touch up their knives, oval in shape but flat on each side, quite fine and only lube used was water. I did strip a staircase once by hand and settled on hand scrapers and abrasive paper, vowed never to do it again!

 

[D_W]

I've got an array of things, including a 4x24 PC belt sander and a dual mode bosch sander (orbital). I don't generally sand, but I do keep a couple of large sanders for house projects.

i haven't hooked up the belt sander yet, but the dual mode sander works OK and then fairly quickly gets gummed up. To do 150 square feet, you could easily go through 25 discs or more, which is a shame because it works a treat until the discs load.

I did a room before with the PC belt sander and it works fine as long as you order 24 or 36 grit belts to start. I have 40 grit discs for the dual mode sander.

What I've found that actually works best is to knock most of the finish off quickly with the scraper running it on the diagonal and then finishing with the sander. It keeps the disc from loading and it works faster than sanding or scraping itself. I'm doing this next to open rooms with carpet, so I haven't resorted to the belt sander yet - the dust collection is a bit lacking on it.

At any rate, that scraper works quite well, but the blade is too hard for modern files (just barely). It only takes about a minute to stone the edge and re-roll the burr and then you can use it for a couple of minutes and you're ready for another minute break - trust me. I wouldn't want it any bigger for removing finish, and luckily, the last person who had used it was smart enough to sharpen it with a fair bit of camber, so I didn't have to do much other than freshen the edge and take off a little light rust to use it.

 

[swagman]

DW; leave that job to the pro's with their industrial floor sanders. https://www.youtube.com/watch?annotatio ... FxjkS91hhU

Stewie;

 

[ED65]

This is probably going to sound like a daft question but how can you be sure a stone is made from silicon carbide? The standard combinations stones are obviously and I assumed that darker grey would equal SiC, but looking at some pics online of stones with their original packaging that doesn't seem to be the case.

Do you have to have a new, or thoroughly cleaned, stone to be sure?

 

[essexalan]

This is probably going to sound like a daft question but how can you be sure a stone is made from silicon carbide? The standard combinations stones are obviously and I assumed that darker grey would equal SiC, but looking at some pics online of stones with their original packaging that doesn't seem to be the case.

Do you have to have a new, or thoroughly cleaned, stone to be sure?

Colour alone is not a good indicator as the Japanese can produce stones in just about any colour using dyes. My experience shows that the SiC stones I have which are the cheaper end of the market are either darkish grey or grey/blue. The dark grey ones are harder and slower cutting than the blue ones which are very friable, fast cutting and wear fast, very fast. SiC particles break down, fracture, in to smaller particles hence you can clog a stone up pretty quickly. Corundum or Aluminium Oxide does not do this, at least not to the same extent if at all. Hence the reason I use water on SiC stones is to continually wash away these particles to keep the stone cutting, I think oil helps clog the stones faster but that is just my opinion and observation.

So buying a used stone is a minefield and I definitely would not buy an oil impregnated SiC stone.

 

[D_W]

DW; leave that job to the pro's with their industrial floor sanders. https://www.youtube.com/watch?annotatio ... FxjkS91hhU

Stewie;

Not this time, Stewie. The area is too small for me to pay someone to do it. I've finished it already and am only waiting for the wife and kids to go on holiday so that I can stain and polyurethane it.

Bigger sanders are easier for larger areas, but there are a number of factors why I did it myself:
1) cost
2) dust level (wife is hard core about the level of clean)
3) cost
4) I have the tools to do it
5) cost
6) maybe most importantly, the floors have been sanded before and I want a minimum of material taken off of them. The commercial sanders are set to take a large amount off of the floor to speed up the process.

 

[D_W]

This is probably going to sound like a daft question but how can you be sure a stone is made from silicon carbide? The standard combinations stones are obviously and I assumed that darker grey would equal SiC, but looking at some pics online of stones with their original packaging that doesn't seem to be the case.

Do you have to have a new, or thoroughly cleaned, stone to be sure?

I have a couple of norton products that are known SiC, one of them is a new (er) crystolon stone.

Silicon carbide stones wear different than aluminum oxide stones, and you can tell it when you're using them. Unfortunately, the broken particles do become loose and can cause a problem if grit contamination is an issue. Not a big fan of that.

But it's still possible that I may guess wrong, even given those things.

 

[D_W]

After 60 grit sanding, scraping the rest of the way:

https://www.youtube.com/watch?v=LjLATlAIrqw

I don't get to anything until about 3:00, but made a video because I literally couldn't find anyone using a Stanley 82 or preparing one (no big deal to prep one, of course, except as a kid when we used scrapers, I always remember filing them and this blade cannot be filed without ruining files).

I started with the scythe stone but I had a better time sharpening with a stone laying flat on the floor or bench (the IM 313 setup worked like magic, but having it full of oil on an unfinished floor wasn't a risk I was willing to take).

Like many, I could use the exercise and scraped all of the entry and hall that goes from the entry to the far end of the house. The next time I take carpet out of a bedroom, I will scrape that, too.