Adventures in sharpening - long post - questions and one nOObs observations

[agile_1]

Sorry about the wordy post. I put questions at the end so folks don't have to read through all my ramblings...

So, I finally cleared out a spot for the $40 Harbor Freight 1" belt sander that I got about two weeks ago. The main motivation was that I wanted to sharpen my new gen2 ZT0550 on my Gatco sharpening system - also to get it out of the way and into the garage.

I have been using the Gatco for about two months with mixed results. It's the only sharpening equipment I have besides the belt sander. I have had some success with it sharpening relatively inexpensive knives. A couple hair shaving edges but nothing razor edge sharp. Mostly just able to cut paper pretty well.

The original kit came with SiC hones. I got a set of the diamond hones (coarse, med, fine) and the Alumina extra-fine hone. Glad I did. They seem to work a lot faster than the SiC hones. I find that if I use a marker on the edge I can determine what angle to use and it is an excellent way to gauge stock removal. I have even been able to raise a burr fairly consistently with the diamond hones. The Alumina hone seems to load up with metal pretty quickly and has to be wiped down with oil to clean it off.

IMHO the Gatco has some serious design problems. You CAN get a knife sharp, if it fits and does not wobble around a lot. Simply holding the knife securely is a challenge. And using any angle slot below 19 degrees is simply not possible because the hones bang on the clamp or the clamp screw. You can kind of work around this by only sharpening on the side without the screws, but then you have to unclamp and flip the blade every time you want to work the other side but you are still limited to the 19 degree slot. That raises all kinds of questions about how repeatably you can place the blade in the clamp every time you flip it. I took the bottom half of the clamp out to the belt sander and ground it down so the hones have a little more clearance but I still have to repeatedly unclamp and flip some knives.

I was a little hesitant to jump right in and try to sharpen my new ZT0550 this morning so I warmed up a an old SAK. Now I had practiced on this SAK with the SiC hones and got an OK edge. This time I used the diamond hones and it came out sharper even with all the unclamping and flipping and fumbling around getting it held securely. Took it right down to the Alumina hone at 19 degrees. No micro bevel though.

So I put some rubber pads between the 550 blade and the clamp and got started. A little marker on the edge first, then a couple test strokes at 22 degrees. That seemed to be the factory angle so I started right in with the coarse diamond hone. I flipped the clamp and luckily the hone cleared the screw if I stroked at the right angle so I was able to just leave the knife clamped. That saved a ton of time.

Well - I was actually able to get a burr going - and the edge was getting sharp! Huge step in my sharpening ability - getting a burr with the coarse hone in about five minutes. Basically the first time I was able to do this.

So sharpening the 550 S35VN blade proceeded pretty well. Every time I changed hones I marked the edge and stroked till the ink was gone. I have to say - sharpening the 550 was easier and faster than the SAK. Nice and sharp. was able to shave some hair off my arm.

Once I got through the extra fine Alumina hone on the main bevel I went up to 25 degrees to put on a micro bevel. Started with the medium diamond hone, about twenty strokes per side and got a decent micro bevel. Probably a little too much for a micro bevel - it ended up being about half the width of the primary bevel. Still hair shaving sharp.

Anyway - this is a big step in my sharpening ability. First, I a feel like I am able to understand the process better. And secondly, just the success with a large higher end steel blade builds some confidence. And being able to do it with my relatively inexpensive Gatco is a plus.

So if you have read all this bless you - you are a patient person. But now it's question and answer time....

1. The diamond hones seem far superior to the SiC hone for speed. Why would I use the SiC hones? I know there has to be a good reason.
2. Gatco mods - has anyone done anything to mod the clamping system on the Gatco so that the hones clear the screws at the lower angles? Sharpening a kitchen knife or a larger blade on the Gatco seems pretty impossible.
3. Micro bevels - when does it make sense to use one? I decided to put one on the 550 and one other knife, but the SAK is so small that effort was not worth the benefit.
4. The Alumina hone seemed to load up pretty quick. Wiping it down with oil cleaned it right up but I was not sure if that was the right thing to do. What about the diamond hones?
5. Recurves. I have a couple ZT's with recurves that I want to sharpen. Any tips for doing them on the gatco?

Wow. Thanks for reading everybody. And thanks for all the sharpening info and tips you have all provided. You helped one more nOOb make a knife sharper than it was.

 

[9blades]

Alright...take what I say with a grain of salt, I'm no sharpening guru.

1
Diamond stones are good for stock removal and can give you a fine edge, but the silica stones Imo are there to really refine the edge. Don't get me wrong diamond stones can give you a hair shaving edge but the really fine grit diamond stones tend to be on the expensive side.

2
I haven't seen any...

3
I think it makes sense to use them when a steel is extremely soft or hard (lets say AUS8/S90v) where if you dident have a micro bevel on S90V it would be prone to chipping, and with AUS8 it helps because the edge tends to roll if there isn't either a steep angle or a micro bevel

4
Yes it helps silica stones a lot to give them a wipe down with a micro fiber cloth every 10/20 strokes.
And diamond stone need a wipe down to every 30/40 strokes

5
Just make sure to go slow and keep moderate pressure and you should be fine!

Ok got to go, hope it helps!

-niner

 

[agile_1]

Alright...take what I say with a grain of salt, I'm no sharpening guru.

1
Diamond stones are good for stock removal and can give you a fine edge, but the silica stones Imo are there to really refine the edge. Don't get me wrong diamond stones can give you a hair shaving edge but the really fine grit diamond stones tend to be on the expensive side.

2
I haven't seen any...

3
I think it makes sense to use them when a steel is extremely soft or hard (lets say AUS8/S90v) where if you dident have a micro bevel on S90V it would be prone to chipping, and with AUS8 it helps because the edge tends to roll if there isn't either a steep angle or a micro bevel

4
Yes it helps silica stones a lot to give them a wipe down with a micro fiber cloth every 10/20 strokes.
And diamond stone need a wipe down to every 30/40 strokes

5
Just make sure to go slow and keep moderate pressure and you should be fine!

Ok got to go, hope it helps!

-niner

Thanks 9er.

1. Yes diamond is good for stock removal. And I can see using fine SiC for quick touch ups, but other than that why? I have seen lots of posts that say use the diamond for stock removal. I think the main reasons is to save the diamond for blade profiling and fixing nicks and chips.

2. Well this thing (Gatco) needs some help. Out of the box it seems very limited. If you have a knife with a 3-4 inch blade that is 1-2 inches wide with a 22 degree or greater bevel it should work. Otherwise it's pita.

3. Ah - micro bevel on a blade to protect it and compensate for steel weaknesses. I have also heard that it is quicker to touch it up when the bevel is smaller.

4. OK. Oil on a diamond hone is ok then? I have used it on the SiC hones as well as the extra fine Alumina. The Alumina hone is so smooth that when I wipe it down the loaded metal wipes right off.

5. Ah - no real trick to getting in there on the curve. Hope the hones are able to reach in that radius.

 

[BluntCut MetalWorks]

IMO

1. SiC has its advantages -
a. cheaper
b. for low-vanadium-alloy steels, SiC's sharper & highly-friable can be more effective + lower chances of fine grain fracture/crack for extremely-high hrc (per steel type)
c. renewable abrasive surface vs diamond more/less 1 fixed layer
d. waterstone -> use mud (broken down abrasive + binder) for between abrade teeth & surface polish. mud+swarf can also use as strop compound.

2. I don't have a Gatco but it's basically a stroking arm at certain angle, so I can even use a long-nose (or reaching long-nose) locking plier to eliminate the clamp screw altogether...

3. see sticky

4. I usually clean mine diamond plate, whenever it's no longer cutting well or messy with too much swarf. when dry - I use paper towel to brush swarf off. when wet - brush off with my fingers under running water.

5. for recurve - gatco (0.75" wide plate) should works. Generally speaking, use less than 1/5 amt of pressure because most pressure focus on 2 contact points (edges of the plate surface). Envisioning 2 parrallel abrasive rods separate ~ 0.6" gap.

 

[Jason B.]

1. Diamonds are the hardest abrasive, superior to Sic for cutting high wear metals and provide a greater degree of sharpness due to a cleaner apex formation. Sic is a economically friendly abrasive that can be used on high wear steels though typically only found in coarser grits.

2. I'm sure there is and if not I bet you could make some.

3. Depends on your style of sharpening. I personally don't use them because I apply a convex geometry to a edge when I sharpen.

4. Common with aluminum oxide stones. For diamond hones clean with barkeepersfriend when they start to look dirty. Very difficult to clog a diamond hone though.

5. Learn to do them freehand, the clamp will never provide a consistent angle.

6. Try to keep your inclusive edge angle at 40 degrees or less. Going over only makes it harder for the edge to pass through the material regardless of how sharp it is.

 

[Obsessed with Edges]

The 'regular' (non-diamond) brown/tan/grey hones in Gatco's guided kit are definitely NOT SiC (silicon carbide). Much more likely, they are aluminum oxide. A true SiC stone is very aggressive (and much darker in color, almost black), and on anything but the most wear-resistant steels (with very high vanadium content, like S90V or similar), they work very fast. Try one of Norton's Crystolon stones (SiC), to see the difference. I waited too long to pick up one of theirs (a Norton Economy stone in Crystolon), and the difference in performance is glaring, when compared to any other AlOx hone I've tried. I've used it to rebevel knives in simple stainless (420HC/440A/etc., 'mystery steel' kitchen cutlery), as well as D2, VG-10 and S30V on it, and it's surprisingly fast.

Aluminum oxide hones can vary widely in their aggressiveness (& quality), and also seem to be more prone to loading/clogging with swarf. I'm sure this is what you're seeing in your kit stones, at least. Some hones are made with what's called 'corundum', which is naturally-occurring aluminum oxide (as opposed to synthetic). Not to be confused with 'carborundum', which is the trade name originally given to synthetically-produced silicon carbide, by the inventor & original patent-holder.


David

 

[Bill1170]

Like Knifenut said, SiC stones are cheap and cut fast. I prefer them to a coarse diamond plate for big reshaping jobs like on abused/neglected cutlery. Coarse diamonds can tear out of the nickel matrix that holds them to the plate if you grind too aggressively. Another benefit is their wide availability in hardware stores, handy if you are away from home.

A couple of years ago I was visiting friends in Montana. Their kitchen knives were terribly blunt but good knives. I killed several diafolds trying to get an apex. After that I bought a small SiC stone and glued it to a 10" stick to make a rebeveling paddle. It worked better than I expected and I was sold. Now I use it for rounding the backs of bandsaw blades.

 

[Obsessed with Edges]

So if you have read all this bless you - you are a patient person. But now it's question and answer time....

1. The diamond hones seem far superior to the SiC hone for speed. Why would I use the SiC hones? I know there has to be a good reason.
2. Gatco mods - has anyone done anything to mod the clamping system on the Gatco so that the hones clear the screws at the lower angles? Sharpening a kitchen knife or a larger blade on the Gatco seems pretty impossible.
3. Micro bevels - when does it make sense to use one? I decided to put one on the 550 and one other knife, but the SAK is so small that effort was not worth the benefit.
4. The Alumina hone seemed to load up pretty quick. Wiping it down with oil cleaned it right up but I was not sure if that was the right thing to do. What about the diamond hones?
5. Recurves. I have a couple ZT's with recurves that I want to sharpen. Any tips for doing them on the gatco?

Wow. Thanks for reading everybody. And thanks for all the sharpening info and tips you have all provided. You helped one more nOOb make a knife sharper than it was.

• The 1st question, I already commented on in my previous post. Gatco doesn't use SiC for their standard hones, but I wish they did. Performance difference between SiC and the aluminum oxide hones in Gatco/Lansky kits is night & day, if Norton's example of SiC is representative.
  
  
• 2nd, the easiest 'mod' for using lower angle settings on the clamp, is to use shorter screws with low-profile heads. Thread & pitch are common size (10-24), so screws can be easily found at HD or Lowe's or any other hardware store. Might get some in a couple or three lengths (1/2", 3/4", 1") to accommodate thicker or thinner blades. Here's a pic of the screws I used with my Lansky clamp (exact same size works with both Lansky and Gatco). Using brass screws also reduces the wear from the screw ends against the clamp itself (steel screws will dig in & scrub metal off of the aluminum clamps):
  
  
• 3rd, micro bevels. I usually don't bother with them on the guided setup. Easy enough to apply if/when needed, with just a freehand pass or two, at a slightly wider angle, on a Sharpmaker or even on a regular stone. For the most part, I haven't felt a need for them at all, on any blade with a 30° inclusive edge or more.
  
  
• 4th, cleaning the hones. The ceramics will clean up nicely with Comet/Ajax powder & water, scrubbed with a Scotch-Brite pad or rag/sponge. If really, really loaded up, Bar Keepers Friend powder, mixed to a paste with water and scrubbed with a Scotch-Brite, works better than anything. The BKF uses oxalic acid to dissolve the metal swarf, so read & heed the warnings for using it, on the container. Diamond hones clean very easily with liquid dish detergent + water, or the Comet/Ajax + water (DMT recommends this for their diamond hones).
  
  BTW, I've also noticed that some polishing paste, like Flitz/Simichrome, is very handy for quick swarf removal from ceramics. Rub the paste on the hone with a fingertip, and wipe it all away with a paper towel, and perhaps a little Windex. Very effective.
  
  
• 5th, recurves. Go very, very light on pressure, as only the edges/corners of the hones will be in contact. It can get the job done, but you need to be patient and careful.

David

 

[agile_1]

IMO

1. SiC has its advantages -
a. cheaper
b. for low-vanadium-alloy steels, SiC's sharper & highly-friable can be more effective + lower chances of fine grain fracture/crack for extremely-high hrc (per steel type)
c. renewable abrasive surface vs diamond more/less 1 fixed layer
d. waterstone -> use mud (broken down abrasive + binder) for between abrade teeth & surface polish. mud+swarf can also use as strop compound.

4. I usually clean mine diamond plate, whenever it's no longer cutting well or messy with too much swarf. when dry - I use paper towel to brush swarf off. when wet - brush off with my fingers under running water.

5. for recurve - gatco (0.75" wide plate) should works. Generally speaking, use less than 1/5 amt of pressure because most pressure focus on 2 contact points (edges of the plate surface). Envisioning 2 parrallel abrasive rods separate ~ 0.6" gap.

Hey Bluntcut. I am only using the Gatco hones right now. And apparently they are NOT SiC. I thought they were. Obsessed thinks they are an Alumina. Maybe when I get a better feel for sharpening I can try freehand. My diamond hones have not really stop cutting - but I expect at some point they will get loaded with metal. A water rinse is good!

2. I'm sure there is and if not I bet you could make some.

3. Depends on your style of sharpening. I personally don't use them because I apply a convex geometry to a edge when I sharpen.

4. Common with aluminum oxide stones. For diamond hones clean with barkeepersfriend when they start to look dirty. Very difficult to clog a diamond hone though.

5. Learn to do them freehand, the clamp will never provide a consistent angle.

6. Try to keep your inclusive edge angle at 40 degrees or less. Going over only makes it harder for the edge to pass through the material regardless of how sharp it is.

Hi Knifenut. Yeah I did grind down the lower clamp face so I could get 19 degrees with most knives. Obsessed has some good ideas with the lower profile screws too.

barkeepersfriend? That's a new one to me. The hone oil worked like a champ and I had it handy. Hopefully - if I keep the diamond hones from clogging I won't have to run out and buy barkeepersfriend.

Freehand freehand freehand. I have nightmares about it. I am addicted to the angle guide.....

Thanks for the tip on keeping the angle low. That's part of the problem with the Gatco. Impossible to really make use of the lower angles because the design is so effed up.

Like Knifenut said, SiC stones are cheap and cut fast. I prefer them to a coarse diamond plate for big reshaping jobs like on abused/neglected cutlery. Coarse diamonds can tear out of the nickel matrix that holds them to the plate if you grind too aggressively. Another benefit is their wide availability in hardware stores, handy if you are away from home.

A couple of years ago I was visiting friends in Montana. Their kitchen knives were terribly blunt but good knives. I killed several diafolds trying to get an apex. After that I bought a small SiC stone and glued it to a 10" stick to make a rebeveling paddle. It worked better than I expected and I was sold. Now I use it for rounding the backs of bandsaw blades.

Well - I used the diamond on my ZT0550 and it seemed to go well. As it turns out the hones that came with the Gatco kit are not even SiC but some Alumina compound.

The 1st question, I already commented on in my previous post. Gatco doesn't use SiC for their standard hones, but I wish they did. Performance difference between SiC and the aluminum oxide hones in Gatco/Lansky kits is night & day, if Norton's example of SiC is representative.

2nd, the easiest 'mod' for using lower angle settings on the clamp, is to use shorter screws with low-profile heads. Thread & pitch are common size (10-24), so screws can be easily found at HD or Lowe's or any other hardware store. Might get some in a couple or three lengths (1/2", 3/4", 1") to accommodate thicker or thinner blades. Here's a pic of the screws I used with my Lansky clamp (exact same size works with both Lansky and Gatco). Using brass screws also reduces the wear from the screw ends against the clamp itself (steel screws will dig in & scrub metal off of the aluminum clamps):

3rd, micro bevels. I usually don't bother with them on the guided setup. Easy enough to apply if/when needed, with just a freehand pass or two, at a slightly wider angle, on a Sharpmaker or even on a regular stone. For the most part, I haven't felt a need for them at all, on any blade with a 30° inclusive edge or more.

4th, cleaning the hones. The ceramics will clean up nicely with Comet/Ajax powder & water, scrubbed with a Scotch-Brite pad or rag/sponge. If really, really loaded up, Bar Keepers Friend powder, mixed to a paste with water and scrubbed with a Scotch-Brite, works better than anything. The BKF uses oxalic acid to dissolve the metal swarf, so read & heed the warnings for using it, on the container. Diamond hones clean very easily with liquid dish detergent + water, or the Comet/Ajax + water (DMT recommends this for their diamond hones).

BTW, I've also noticed that some polishing paste, like Flitz/Simichrome, is very handy for quick swarf removal from ceramics. Rub the paste on the hone with a fingertip, and wipe it all away with a paper towel, and perhaps a little Windex. Very effective.

5th, recurves. Go very, very light on pressure, as only the edges/corners of the hones will be in contact. It can get the job done, but you need to be patient and careful.


David

Thanks for the great info. I thought those hones were SiC as I am used to seeing white or red Alumina. My extra fine Alumina hone is white. I guess the coarser hones are a less pure Alumina compound?

Great tip for the screws. Will be doing that mod soon. Thanks for the pic - but can you really get the hone onto that edge without hitting the clamp? It looks like there is hardly any clearance.

I did get a pretty decent edge without the micro bevel. Just wanted to put one on as I have read that they help the blade keep its edge longer.

Thanks for the hone cleaning ideas. I know that I will be cleaning them up sooner rather than later.

The ZT recurves got me intimidated. But I was a little worried about taking the gatco to my 550 and that worked out. Maybe once I do the screw mod I will get up the nerve....


Thanks for all the great ideas everyone!

 

[Chris "Anagarika"]

Nothing much I can add with the experts already chiming in .

Freehand is the way to go IMHO. Checkout knifenut video on how he did a ZT, on diamond hone. YT name is mredgy81 IIRC.

Good luck in the adventure!

 

[Obsessed with Edges]

(...) Thanks for the great info. I thought those hones were SiC as I am used to seeing white or red Alumina. My extra fine Alumina hone is white. I guess the coarser hones are a less pure Alumina compound?

Alumina is the raw material that goes into a HUGE array of aluminum oxide hones, both ceramic and not (some 'alumina' products are manufactured with binders & processes that don't qualify as 'ceramics', per se). Chances are, if the hone is man-made, and grey, white, brown, tan, pink, blue, and other colors besides black, it's likely aluminum oxide (there are some dark grey alox hones that almost look like SiC hones). The colors of the binders used to hold the abrasive can also influence the color. There's an equal variation in grit size as well, and some manufacturers actually make 'coarse', 'fine', 'extra-fine' hones using exactly the same grit, but held together by different binders and surface-finished differently, to alter the aggressiveness of each. Spyderco does this very thing with their medium, fine, and uf ceramics. All the same raw grit material at a constant size, but varying the binders and surface-finishing.

BTW, if you do a web search on 'alumina abrasive' or 'aluminum oxide abrasive', you'll quickly get an appreciation for how many variations of it there are. Lots of individual manufacturers, and each of them often have dozens of different formulations/processes, which can alter the grit size, color, hardness, friability (tendency to break down to smaller particles with use) and shape of the particles. All of these variables make big differences in how each performs.

Great tip for the screws. Will be doing that mod soon. Thanks for the pic - but can you really get the hone onto that edge without hitting the clamp? It looks like there is hardly any clearance.

There was just enough clearance there. That particular blade pictured in my clamp was limited by it's narrow width, which I think forced me to use the 2nd-lowest setting on my clamp. With a blade that narrow, the front edge of the clamp starts to get in the way. Still better than if I'd tried it without the low-profile screws, though. Almost all of my knives can be sharpened at the lowest settings on each of my Lansky, Gatco clamps, using the less-obtrusive screws. I think I've figured out, with any blade that has more than about 3/8" clearance from the clamp's front edge, I can use the lowest angle setting.

I did get a pretty decent edge without the micro bevel. Just wanted to put one on as I have read that they help the blade keep its edge longer.

Thanks for the hone cleaning ideas. I know that I will be cleaning them up sooner rather than later.

The ZT recurves got me intimidated. But I was a little worried about taking the gatco to my 550 and that worked out. Maybe once I do the screw mod I will get up the nerve....


Thanks for all the great ideas everyone!

A micro bevel is pretty much a preferential thing. If you think your edge isn't quite lasting as long as you'd expect, it's an easy 'fix' to add a couple degrees to each side with a micro bevel, after which you can decide for yourself if it's making a significant difference. With decent steels used on typical knife tasks (not abuse, in other words), a 30°+ inclusive angle usually does pretty well, and also performs better than a wider angle after the 'shaving sharpness' goes out of the edge's apex.

To get a feel for sharpening the recurve using the clamped guide, in the short-term, you might just use your finest hone to do some very light touch-up on your blade. Go about it very lightly, and take your time. Check the edge after every couple or three passes, just to see how it's affecting your edge, with cutting tests and/or inspection under magnification (use BRIGHT light).


David

 

[agile_1]

Alumina is the raw material that goes into a HUGE array of aluminum oxide hones, both ceramic and not (some 'alumina' products are manufactured with binders & processes that don't qualify as 'ceramics', per se). Chances are, if the hone is man-made, and grey, white, brown, tan, pink, blue, and other colors besides black, it's likely aluminum oxide (there are some dark grey alox hones that almost look like SiC hones). The colors of the binders used to hold the abrasive can also influence the color. There's an equal variation in grit size as well, and some manufacturers actually make 'coarse', 'fine', 'extra-fine' hones using exactly the same grit, but held together by different binders and surface-finished differently, to alter the aggressiveness of each. Spyderco does this very thing with their medium, fine, and uf ceramics. All the same raw grit material at a constant size, but varying the binders and surface-finishing.

BTW, if you do a web search on 'alumina abrasive' or 'aluminum oxide abrasive', you'll quickly get an appreciation for how many variations of it there are. Lots of individual manufacturers, and each of them often have dozens of different formulations/processes, which can alter the grit size, color, hardness, friability (tendency to break down to smaller particles with use) and shape of the particles. All of these variables make big differences in how each performs.

Interesting. I always assumed they screened for grit size and used specific grit sizes for the different grit stones. All my stones are man made and I now suspect have a base of Aluminum Oxide (Alumina). The binders used - ?? who knows.

I am now getting curious about the manufacturing process. My extra fine Alumina stone is white. Probably a very high Aluminum Oxide. The others are brownish and I suspect the color is due to impurities in the Aluminum Oxide itself and the binders. Now I am wondering about the manufacturing process....

To get a feel for sharpening the recurve using the clamped guide, in the short-term, you might just use your finest hone to do some very light touch-up on your blade. Go about it very lightly, and take your time. Check the edge after every couple or three passes, just to see how it's affecting your edge, with cutting tests and/or inspection under magnification (use BRIGHT light).
David

Thanks for the tip. I do need to get better lighting in my sharpening area. I use a loop and magnifier with leds so they kind light things up but a good light source will help a lot.

Since you have both the Lansky and Gatco maybe you can tel me this - can the Lansky stones be used on the Gatco system? If I take the steel rod out of one of my Gatco stone holders will it fit in the Lansky stone holder? I am thinking the thinner stone might make it easier to do the recurves, and I would like to have the option of different stones.

Thanks again.

 

[Obsessed with Edges]

The EF white stone you have is one of the alumina 'ceramics' I alluded to earlier (I have one, in addition to my diamond kit). The brownish/grey stones might not be ceramic, though made with the raw aluminum oxide grit. Different processes to make them, though not necessarily related to any difference in purity. The 'ceramic' process involves heating the materials to much, much higher temperatures, well above 1000° which alters the properties of the abrasive itself (hardness, and perhaps color as well). Other non-ceramics made with aluminum oxide are held together with binder material that's baked at much lower temperatures, for the sake of curing the binder itself, and less-so for the sake of altering the properties of the abrasive.

The Lansky's rods are mounted to the stone-holders differently, with an L-shaped rod. The short arm of the 'L' extends upward through a hole in the end of the stone holder, which allows the working surface of the hone to be adjusted up/down, making it flush and in-plane with the long arm of the guide rod itself. The Gatco's straight rods extend directly from the end of those hones, with no up/down adjustment. If you wanted to, you could use the Lansky hones with their associated rods, in the Gatco's clamp. Due to differences in hone depth and how the rods are attached, you'd have to be sure to use only one type (all Lansky, or all Gatco) to maintain the same consistent angle throughout the sequence. Changing from one type to another in mid-sequence would vary the sharpening angle.


David

 

[agile_1]

The EF white stone you have is one of the alumina 'ceramics' I alluded to earlier (I have one, in addition to my diamond kit). The brownish/grey stones might not be ceramic, though made with the raw aluminum oxide grit. Different processes to make them, though not necessarily related to any difference in purity. The 'ceramic' process involves heating the materials to much, much higher temperatures, well above 1000° which alters the properties of the abrasive itself (hardness, and perhaps color as well). Other non-ceramics made with aluminum oxide are held together with binder material that's baked at much lower temperatures, for the sake of curing the binder itself, and less-so for the sake of altering the properties of the abrasive.

Well - impurities are known to give color to ceramics and glasses. This is how potters control the color of their glazes.

By impurity for Alumina I mean something other than Aluminum and Oxygen in the crystal. Ie - Al2O3 is pure Alumina. For example, you can have red Alumina (ruby) and blue Alumina (classic sapphire - sapphire can take on quite a lot of colors depending on purity) where the color is caused by impurities in the crystal structure. Not a negative connotation.
Sapphire - wikipedia

The baking process (sintering) heats the batch to a temperature below the melting points of the constituent powders. Sometimes high pressures are use (hydrostatic presses) to help form the finished product. In any case, the melting point of pure Alumina itself is quite high (>2000C)- impurities will decrease it somewhat, but at elevated temperatures (>800-1000C) diffusion processes can drive impurities into the Al2O3 structure. When the basic structure changes you begin to alter the properties of the material itself. This is apart from any binders and matrix materials that form in the grain boundary region. The grain boundary region, binders etc. can be a real melting pot.

Bottom line - I would guess that abrasive itself is less important than the binder/matrix that it is contained in. Alumina, SiC, diamond are essentially indestructible in their pure forms when used as abrasives for metals.

Boy - you really got me going on this. It's been years since I had to think about this stuff (degree in ceramic engineering).

The Lansky's rods are mounted to the stone-holders differently, with an L-shaped rod. The short arm of the 'L' extends upward through a hole in the end of the stone holder, which allows the working surface of the hone to be adjusted up/down, making it flush and in-plane with the long arm of the guide rod itself. The Gatco's straight rods extend directly from the end of those hones, with no up/down adjustment. If you wanted to, you could use the Lansky hones with their associated rods, in the Gatco's clamp. Due to differences in hone depth and how the rods are attached, you'd have to be sure to use only one type (all Lansky, or all Gatco) to maintain the same consistent angle throughout the sequence. Changing from one type to another in mid-sequence would vary the sharpening angle.
David

Yes - I would probably get a set of the Lansky stones to try on the gatco and stick with them through the whole process. I have been looking for more info on what the abrasive in the Gatco stones are and have not been able to find anything. Maybe I will contact gatco and see if they can offer any info. In the meantime, I have some mods in mind for my Gatco clamps..... will post some picks if it actually works...

Be well.

 

[Obsessed with Edges]

You're right about some impurities adding color to Al2O3. My earlier comments about 'purity' were less about that, and more about whether the impurity-related color differences affect the quality or performance of the material as an abrasive. With synthetically-produced Al2O3, it's hard to guess which attributes (color, hardness, etc.) are intentional by the manufacturer's specs, and which are just an artifact or by-product of the process. I don't think any assumptions can be made about the quality/performance, based on the color itself. And as I mentioned earlier, the color of the binder materials likely will 'disguise' whatever color the abrasive might be, as evidenced by the different colors of Spyderco's ceramics ('grey' medium, and 'white' F/UF), all using the same raw abrasive base material.

And you're absolutely dead-on right about the impact of the binders on performance. There's been quite a lot of discussion lately on this forum, about how differently some abrasives perform, when used on/in different substrates. Some abrasives might seem inadequate for some uses, if embedded in a weak/soft substrate, while performing much more aggressively in a firmer backing. I've been noticing this lately, in using wet/dry SiC sandpaper on various backing surfaces. With a steel like S30V in particular, sometimes the sandpaper isn't quite aggressive enough on a softer backing (leather, or sometimes wood) to effectively abrade the very hard vanadium carbides in this steel. But, when the sandpaper is used over much-harder glass, I'm suddenly discovering it works much better. And performance improves yet again, if the sandpaper is firmly 'stuck' (glued) to the glass, versus just loosely laid atop it.


David

 

[Razorsharp-Travis]

microbevel should be wel, micro, like 3 strokes per side