KA-BAR USMC, Short; Came dull, cannot get Sharp

[Obsessed with Edges]

I actually wouldn't be surprised if the HD 'Norton Economy' stone is aluminum oxide. Most cheaper synthetic stones are made of it. And AlOx can be found in a variety of colors, some of which will look a lot like the black/grey SiC stones.

Looking at a .pdf copy of Norton's catalog (link below), the 'Economy Tool & Knife Bench Stone' in either 6" or 8" sizes, are both listed as aluminum oxide. These are Norton part #87933 (6") and #87934 (8"). Norton also lists a 'High Quality Tool & Knife Bench Stone' in similar packaging (shrink-wrapped card), part #87935, which is listed as a Crystolon (SiC). I'm assuming 'High Quality' also implies it's a little more expensive than the 'Economy' stone. Searching the web for the SiC stone, Norton part #87935, shows pricing in the $20-$25 range, in most places (compared to ~ $6 for the #87933 AlOx economy stone).

http://www.nortonindustrial.com/upl...talog_PDFs/NortonCatalog-SharpeningStones.pdf

All of these stones are listed in the 'Retail Packaged Sharpening Products' section of the catalog, which is the very last page in the .pdf file. The pic below is a snip from that page, showing (from left to right) the 8" economy AlOx, 6" economy AlOx, and 6" SiC 'High Quality' stones, in their retail packaging (you can see how the SiC stone appears 'blacker' than the AlOx stones, which look more 'grey'):

And, looking at HD's site listing of the stone they sell, it's listed as MFG Part #87933, which jibes with the above-mentioned 6" economy stone in aluminum oxide. The corresponding HD store SKU# is 823691, for this stone (pic below, linked from HD's site description).

David

 

[BluntCut MetalWorks]

I actually wouldn't be surprised if the HD 'Norton Economy' stone is aluminum oxide. Most cheaper synthetic stones are made of it. And AlOx can be found in a variety of colors, some of which will look a lot like the black/grey SiC stones.

Looking at a .pdf copy of Norton's catalog (link below), the 'Economy Tool & Knife Bench Stone' in either 6" or 8" sizes, are both listed as aluminum oxide. These are Norton part #87933 (6") and #87934 (8"). Norton also lists a 'High Quality Tool & Knife Bench Stone' in similar packaging (shrink-wrapped card), part #87935, which is listed as a Crystolon (SiC). I'm assuming 'High Quality' also implies it's a little more expensive than the 'Economy' stone. Searching the web for the SiC stone, Norton part #87935, shows pricing in the $20-$25 range, in most places (compared to ~ $6 for the #87933 AlOx economy stone).

http://www.nortonindustrial.com/upl...talog_PDFs/NortonCatalog-SharpeningStones.pdf

All of these stones are listed in the 'Retail Packaged Sharpening Products' section of the catalog, which is the very last page in the .pdf file. The pic below is a snip from that page, showing (from left to right) the 8" economy AlOx, 6" economy AlOx, and 6" SiC 'High Quality' stones, in their retail packaging (you can see how the SiC stone appears 'blacker' than the AlOx stones, which look more 'grey'):

And, looking at HD's site listing of the stone they sell, it's listed as MFG Part #87933, which jibes with the above-mentioned 6" economy stone in aluminum oxide. The corresponding HD store SKU# is 823691, for this stone (pic below, linked from HD's site description).

David

Thanks for the crossed-reference to confirmed Norton Econ stone is AlOx. I was fooled by its color; reflection; hardness so similar to SiC w&d sandpaper.

Oh well

 

[Obsessed with Edges]

Thanks for the crossed-reference to confirmed Norton Econ stone is AlOx. I was fooled by its color; reflection; hardness so similar to SiC w&d sandpaper.

Oh well

I've been tripped up by that too. I'm quick to assume 'silicon carbide', everytime I see a 'black' synthetic stone or other 'black' abrasive. I recently got fooled by some black Ryobi compound that I'd been tinkering with. Just assumed it to be SiC, but a closer examination of the labelling revealed it was corundum (natural aluminum oxide). It was right in front of me on the label, and I ignored it. Live & learn...


David

 

[BluntCut MetalWorks]

While at OSH, I picked up a $16 Norton 87935 2x6x0.75" SiC stone. Pic of its coarse side

.

 

[HeavyHanded]

I have the 87933 stone - made in Brazil, am reasonably certain it is silicon carbide, at least the fine side certainly is. If the conversation is still going on Wednesday I'll get some side-by-side pics. The only real difference is that it doesn't come loaded with oil, that and it doesn't come flat. Color wise it is essentially the same as a Crystalon, perhaps a shade lighter as it isn't pre oiled. With a 30x loupe they appear identical.

 

[stalag2]

I vote for wet or dry sandpaper, thats my favorite method for stubborn big blades, put sharpie on the edge every few strokes until you get confidence and muscle memory. Edge trailing strokes are advised but i find myself going back and forth gently when doing the rough work then i go trailing for the final strokes though.

 

[Obsessed with Edges]

I have the 87933 stone - made in Brazil, am reasonably certain it is silicon carbide, at least the fine side certainly is. If the conversation is still going on Wednesday I'll get some side-by-side pics. The only real difference is that it doesn't come loaded with oil, that and it doesn't come flat. Color wise it is essentially the same as a Crystalon, perhaps a shade lighter as it isn't pre oiled. With a 30x loupe they appear identical.

If it's actually the 87933, Norton says it's AlOx on both sides (might even be corundum, a.k.a. 'emery' or 'naturally occurring' AlOx, which sometimes is also black like SiC, and is about ~9 on Moh's hardness scale). The Crystolon stone (87935) looks very similar, and is packaged the same, but is a bit darker in color. Here's a snip from the product catalog I linked earlier (see the last 5 digits of their product part no., at the right):


David

 

[fervens]

So i stopped by home depot on my way back home today and picked up a new economy stone. i took pictures of it before and after opening. The one on the right is one i bought from the same store years ago. My old stone is bluer then what is shown. I only had my phone to take the pictures. I still think they are silicon carbide stones, They don't work the same as the AlO stones i have at all. Also, after rubbing the two stones together, the new one is softer then the new one.

https://plus.google.com/photos/103299096945919349437/albums/5827837352580942657

 

[HeavyHanded]

If it's actually the 87933, Norton says it's AlOx on both sides (might even be corundum, a.k.a. 'emery' or 'naturally occurring' AlOx, which sometimes is also black like SiC). The Crystolon stone (87935) looks very similar, and is packaged the same, but is a bit darker in color. Here's a snip from the product catalog I linked earlier (see the last 5 digits of their product part no., at the right):

David

I know what the catalog says, but if anything can be discerned visually, the stone is SiC. Graded AlumOx is more expensive to produce than SIC as well, so why the econo stone would be AlumOx is a mystery to me. Also, the stones cut exactly the same as my Crystalon, so maybe they're sourced from different suppliers...

 

[Obsessed with Edges]

So i stopped by home depot on my way back home today and picked up a new economy stone. i took pictures of it before and after opening. The one on the right is one i bought from the same store years ago. My old stone is bluer then what is shown. I only had my phone to take the pictures. I still think they are silicon carbide stones, They don't work the same as the AlO stones i have at all. Also, after rubbing the two stones together, the new one is softer then the new one.

https://plus.google.com/photos/103299096945919349437/albums/5827837352580942657

Aluminum oxide comes in a huge range of physical attributes (hardness, color, shape of particles, etc). This applies to both natural and synthetic varieties of it. The 'corundum' type of natural AlOx is very hard (Moh's scale ~9) and an aggressive cutter (used in 'emery' cloth/paper).

If the manufacturer says it's AlOx, I don't have any doubts that it is.


David

 

[Obsessed with Edges]

I know what the catalog says, but if anything can be discerned visually, the stone is SiC. Graded AlumOx is more expensive to produce than SIC as well, so why the econo stone would be AlumOx is a mystery to me. Also, the stones cut exactly the same as my Crystalon, so maybe they're sourced from different suppliers...

Actually, this is why I think it might be the 'corundum' (natural AlOx), which presumably wouldn't need the same level of production (no synthetic processes, aside from making the binders), if it's naturally occurring. That would go a long way toward explaining the reduced cost of the stone.


David

 

[HeavyHanded]

Aluminum oxide comes in a huge range of physical attributes (hardness, color, shape of particles, etc). This applies to both natural and synthetic varieties of it. The 'corundum' type of natural AlOx is very hard (Moh's scale ~9) and an aggressive cutter (used in 'emery' cloth/paper).

If the manufacturer says it's AlOx, I don't have any doubts that it is.


David

I'm more along the lines of the mfg isn't really on top of the supply line or current listed specs, as this is an economy stone. Was just at HD and took a look at the packaging - "Made in Mexico" on the package, but said "Brazil" on the stone. Maybe the Mexican made ones were AlumOx and the Brazil ones are SIC? Printing was different from the one I bought last year. I'll take a closer look on Wed when I can get a better view. From how it grinds, reacts to oil and abrasion, the edges it produces, I still believe mine is SIC. It looks just like my other SiC stones and nothing like an India stone or the other cheap ALumOx (grey) stone I have - at least at 30x. My cheap alumox stone grinds like an India stone, just a bit slower. All the ones that look like SIC grind like SIC.

I've been wrong before...

 

[David Martin]

Thank you guys for looking in to these stones and digging up what they are made of. I've wondered...
Fervens, "the new one is softer than the new one" ? DM

 

[Obsessed with Edges]

Thank you guys for looking in to these stones and digging up what they are made of. I've wondered...
Fervens, "the new one is softer than the new one" ? DM

This has all piqued my curiosity. So, just to confirm (hopefully), I sent off an email to Saint-Gobain Abrasives (apparently the current owner of the Norton Abrasives brand) to ask them about it. If they actually respond, I'll post it here.

I haven't used one of these economy stones, but now I'm all the more interested. If it seems to perform so much like a SiC stone, even if it may be AlOx, that seems like a great deal for $6 spent.


David

 

[BluntCut MetalWorks]

My Norton Economy stone also made in Brazil. It's very dense & hard. Economy & Premium stones shared many sharpening characteristics, which mean why not opt for the less expensive (Econony) one. I just flatten both stones (using 140 grit diamond plate and also test lapped with a DMT X). The Premium was already flat got flatter - surface abrasives stay sharp just like pre-lap. The Enonomy flattened fine side is much smoother, i.e. loss about 2/3 cut rate. Economy flattened coarse side became exceedingly smooth, ~90% loss in abrasion <= I had to rub it against the sidewalk to restore its cutting surface.

Abrasives in the Premium SiC stone are definitely more friable than abrasives in the Enonomy stone when sharpening a hatchet using edge-lead. For normal sharpening, it's hard to tell the difference between the 2 stones. Premium stone worked 2x faster on S30V than the Economy stone (solved: use more pressure & speed).

OP: The Economy stone offers great value and performs almost like SiC stone. Go for it!

 

[HeavyHanded]

This has all piqued my curiosity. So, just to confirm (hopefully), I sent off an email to Saint-Gobain Abrasives (apparently the current owner of the Norton Abrasives brand) to ask them about it. If they actually respond, I'll post it here.

I haven't used one of these economy stones, but now I'm all the more interested. If it seems to perform so much like a SiC stone, even if it may be AlOx, that seems like a great deal for $6 spent.


David

I'll be interested in the response too, but for a corp as large as StGobain/Norton is wouldn't surprise me if they just looked it up in the catalog and gave the stock reply - they must sell tens of thousands of products, most of which carry higher price tags and margins than ANY of their sharpening stones. Having the 8" Crystalon and the 7 buck econo stone, I can say they work about the same. Under magnification the econo stone may have a greater variance in particle size, and has many more voids in its structure - this is visible without magnification. From what I can tell they grind at the same speed give or take, which is only a bit faster, but noticeably so, than the India stone - which is one tough, hard cookie. My other verified AlumOx stone is a touch slower yet. I guess either way the econo stone is a very good bargain, be ready to lap it flat and it should tackle just about any chore you need tackling. I WILL be a monkey's uncle for thinking it a SIC stone though if it isn't. Aside from some very slight color variance it appears the same.

Here I am approaching my New Year's vacation and almost wishing I had to go in to work so I could take a look at some inexpensive grinding stones under a microscope - I AM a sharpening geek!

Happy New Years all!
HH

 

[fervens]

To justify spending the $7 I don't have, I decided I needed a lapping stone for my old "SiC" stone. So after I took the pictures, I got to work rounding the corners and flattening the old stone. The old didn't change much, but the new one was loosing grit all over. It may be because it's a new stone though and the top layer wasn't bound as well. I'll see if I can get picture to show this after work.

P.s. the 60/80grit SiC stone I have didn't do anything to the old stone either and vice verse if that makes a difference.
-Enjoy your fun times tonight!

 

[HeavyHanded]

Without looking into the matter any further I'm going to proactively invoke my second favorite smiley

:foot:


Bluntcuts observations re the economy stone glazing over/loosing abrasive action, and my own recollection of a similar condition when using my econo stone to generate abrasive slurry for a pseudo waterstone experiment, have pretty much convinced me the econo stone 87933 is AlumOx in a very loose binder. SiC stones might load up, but I have never gotten one to glaze like an AlumOx will do if lapped too fine or lapped with a soild abrasive and too little water.

I also am considering the relative length of time it took to grind the Sandvik blade in the video I made - in retrospect it should have done that job in less time, especially the burr removal if it really is SiC.

Was fooled not by the color, but by the relative looseness of the binder and how it generates a mud very much like a silicon carbide stone when used with oil. I'll still take a look with the microscope as time allows, but for now I have to agree with the majority.

Hmmm, this also means I have to recommend the ACE hardware stones over the economy Norton for overall utility (or just get a Crystalon stone), as the latest crop of ACE stones say right on the pkg that they're silicon carbide (and made in USA). And of course the regular India stone is always on the short list too...

 

[Obsessed with Edges]

Blunt & HH, just want to say 'Thanks!' :thumbup: for your observations on this.

As I mentioned, I hadn't tried one of these economy stones, so I didn't have any frame of reference on which to base a personal opinion. The observation about alox stones losing aggressiveness after lapping does seem to ring true to me, if any of my alox ceramics are an indication (I've lapped three of those; all became much, much smoother), and the friability of SiC is a good point too. The thing I've liked about SiC (at least as used in sandpaper) is it continues to be aggressive, even as it breaks down and becomes finer in grit (goes from aggressive material removal, to 'aggressive' polishing, if that makes any sense). But it never stops working entirely, it seems.

I still think I might look into picking up one of the economy stones sometime. I really am curious about them now.

Still waiting for the response (if any) from the source. Being the holidays, it might take a few days I'd bet. And on that note, I'll also wish everybody a GREAT new year, however that may manifest itself.


David

 

[recon1s14]

I had problems with the new tech Kabar, the steel is hard, and seems to take an obtuse edge better than an acute, the finer I got the edge the less it would cut, and it wasn't because of a burr or wire edge I took care of that with 3m sandpaper, I completely ruined one of my whet stones trying to re-bevel the sucker XD I found the easiest and best way was to just stick with sandpaper and get a wood chopping edge on it, it will never shave, keep in mind I have sharpened many many knives and do know what I'm doing, putting a convex edge on a knife is a simple process for me, from my experience with that Kabar I donot think I will be buying another.