Spyderco Benchstone

Glad it is working out well for you. Now all you need is that Shapton 16k glass stone and some 0.3 micron microfinishing film and you'll be making razor blades. ^0^
 
I am always chasing that next level fo sharpness Yuzuha. I may have to save for awhile but that Shapton sure looks good.:D
 
Quite by accident I found a very good "nagura" stone. Basically I bought a Belgian razor hone from e-bay very cheap because the light brown side was almost used up. The back side was the belgian blue waterstone. They appeared to be glued together and soon the brown side disintegrated.

The belgian blue waterstone makes a great nagura. It is only about 2" X 3" so is not large enough to make a good sharpener on its own.

Got me to thinking that any of the small, cheap razor hones that you find on e-bay, especially the slightly coarser ones would make excellent nagura stones, with the bonus that you can use them as sharpening stones on their own.

Don Clark
 
While there are certainly more exotic stones, I've never yet found one that leaves a better and sharper finish on my razors and knives. I have other stones that should to a better job (such as Norton 4/8 and Belgian Coticules), but for whatever reason (probably my faulty technique), the Spyderco Extra Fine does the best. As an aside, I can also get tree top sharpness with just the Fine stone, the extra fine takes it to another level...
 
sodak said:
While there are certainly more exotic stones, I've never yet found one that leaves a better and sharper finish on my razors and knives. I have other stones that should to a better job (such as Norton 4/8 and Belgian Coticules), but for whatever reason (probably my faulty technique), the Spyderco Extra Fine does the best. As an aside, I can also get tree top sharpness with just the Fine stone, the extra fine takes it to another level...
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I agree. I have the Norton 4/8 also. I use it then finish on the Spyderco ultra fine benchstone. Yuzuha says it burnishes the edge. All I know is that it makes the knife sharper.
 
Yes, it sort of acts like a steel. On a microscopic level, steel acts a lot like modelling clay. It will gouge, flow, tear and squish together.

Waterstones have sharp loose grit so they are like smoothing clay with a stack of fine combs. Each tooth cuts a fine shaving off any high spots, leaving lots of tiny parallel scratches (generally less than half the grit diameter deep and less than the diameter wide). The Spyderco is more like dragging a wavy but smooth stick (or maybe a stick with a bunch of small, irregular but smooth stones glued to it). They sort of glide over the surface while the high spots play bulldozer and push along little rolls of cold worked metal smearing it into the low spots leaving a sort of scalloped surface with wide, shallow furrows that have smaller striations corresponding to the roughness of the surface of the grit. Sometimes the little balls of steel that are being bulldozed along, break loose and sort of roll along getting caught, flattened and smeared along the surface as they leave a deep rough gouge (you'll see this in clay too where a smooth stick will leave a rough gouge and pull up loose balls of clay that smear under the stick).

Different kinds of steel react a bit differently, sort of like harder, softer, dryer or stickier clay or maybe with some grit in it, so they'll react slightly differently to different stones.

I posted some microscope pictures of stainless steel polished on a Shapton 5k stone, a Spyderco ultra-fine, a Lansky blue sapphire hone and a Naniwa 10k stone on this thread http://www.knifeforums.com/forums/showtopic.php?tid/783146/ Also a comparison of the matte surface produced by natural stones compared to the bright surface left by artificial stones and a pic of some scratches I made with a diamond scriber that show how the metal flows like clay on this thread http://www.knifeforums.com/forums/showtopic.php?tid/783383/
 
Wow, great pictures and information, yuzuha, thanks! Now I'm going to try and re-read that thread to understand all the technical details!
 
Pam very interesting threads. I cann't help but think about all the talk about carbides being pulled out or falling out of edges must have alot to do with how they are being sharpened. I'd guess depending on the abrasive and carbide type they can be pushed, rounded, pulled out, or sharpened. Getting the best edge is complacated. One day I may get a handle on understanding it. :)
 
ROFL, everything gets complicated if you look at it too close! ^0^

Large carbides do complicate matters... I haven't experimented on D2 under the scope, but I'd guess it acts like medium clay with small soft rocks in it. A diamond stone would be hard enough to grind down the carbide particles and sharpen them along with the matrix steel, while an Arkansas stone (which is softer than the carbides) would tend to round them a bit and push them deeper into the surface (or tear some loose ones out) and the blade would tend to skim along the surface of the stone on top of the carbides (which, I would think, would tend to make sharpening D2 on Arkansas stones rather slow going, at least on the finer polishing stones. The soft, coarse ones probably work okay since they'll just take out the carbides along with the shavings).

It also makes it easy to understand that old saying that "D2 takes a lousy edge and holds it forever"... make the bevel angle too small and there won't be as much steel surrounding the carbides on the edge to hold them in so they can easily be kocked out by something that puts sideways pressure on them, and if that happens, the edge would look more like a microscopic saw.

With diamond and waterstones, I can get a smooth edge on my Queen D2 whittler whether I sharpen it at 8 degrees per side or 18 per side, but then when I actually whittle with it, the thin edge quickly becomes very toothy, while the thicker edge stays nice and smooth. So, I think carbide size is just a factor in how low you can make your bevels on a particular steel and still have a durable edge.

Stropping would probably be like lapping... home made telescope mirrors are polished on asphalt laps, gem polishers often use tin laps and machinists use soft gray cast iron laps. Generally, the lap needs to be softer than the thing you are lapping because the loose grit rolls around and eventually sinks into and embeds itself in the softer surface. At that point it pretty much stays there while it scratches the harder surface that is being lapped.

Leather (or cardboard etc.) is a soft fiberous material with lots of little pores where grit (like your chrome oxide or aluminum oxide strop powder etc) can get trapped and held while it scratches the steel so it is sort of like a flexible lap (or stiff polishing cloth) that will compress under the weight of a blade, bending to hug the surface, and then spring back up behind the blade edge. This would help break off any burr steel that got smeared past the edge, but the contact angle at the edge would be greater than the bevel angle and tend to round the edge if you strop too much (after the burr is gone).

Anyway, when I first started stropping, I stropped the smoothest dull edges you've ever seen. But, thinking about how everything has some flexibility on a micro-scale, got me to try stropping by setting the bevel flat on the strop, making only one or two passes to deburr and then lowering the spine slightly so the very edge is a tiny fraction of an inch above the strop with the idea that when the leather springs back it will just barely graze the edge at about the same angle as the bevel at that point. Took a bit of practice, but worked pretty well once I got the feel of how to lower the spine enough to keep from rounding my edges (too far and it doesn't do anything but polish the corner between the bevel and the relief bevel).
 
yuzuha said:
Waterstones have sharp loose grit so they are like ...
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Have you seen Lee's pictures of natural vs man made waterstones, the natural ones look like flaky pastry and are very different than the man made ones under magnification.

-Cliff
 
Cliff Stamp said:
Have you seen Lee's pictures of natural vs man made waterstones, the natural ones look like flaky pastry and are very different than the man made ones under magnification.

-Cliff
Click to expand...

No, I did an electron micrograph of a natural stone where the grit does look like pastry, or little pototo chips, several years ago before the internet filled up with so much commercial stuff that you can't find anyhing anymore, and lost the link in a crash 3 computers ago.

If you have links to those pics, I'd sure love to see them!
 
The pictures are in his book, he has a bunch of them of abrasives, edges, etc., interesting stuff. A lot of the comments about the quality of the japanese hones tends to almost border on the mystical. He does advance the idea that the natural stones work better on the harder japanese alloys, and this has been reported on the wood working groups for some time, but there you are also seeing the effect of rod vs stone, so it is also contact area influenced.

-Cliff
 
Here's an odd one for you. This is a polished hunk of O1 tool steel that has seen better days. Got any idea what the black spots are? Maybe carbon coming out of solution and forming hunks of graphite or maybe some sort of carbide? Most of them form pits but a few seem to stick up out of the surface (not sure if there are any in this pic, most of them seem like pits with discolored halos around them)

 
Thanks, hadn't thought of that.... Could be. I didn't grind too deep... only started out with 2k grit and didn't grind all that long. Maybe I'll drop back to 220 and take off a thicker layer to see just how deep it goes.
 
I don't know. Would kind of depend on your screen / pixel size I would think. With my scope camera takes 1280x1024 pictures and with my screen set to 1280x1024 resolution and a 5x objective lens, a 1mm thick slide shows up as about 900 pixels wide and takes up a bit over 10.5 inches on my screen so I'm guestimating about 270 - 280x which would be about 560 for the 10x, about 1,300-1,400x for the 25x and about 2,300 for the 40x.

You might want something different for looking at knives though.... that scope is designed for transparent objects so the light comes from below, and the working distance of higher powered objectives is only a fraction of an inch so you wouldn't have much room to squeeze in a reflected light from above. Not to mention that you won't be able to squeeze anything very thick onto the stage (not much room between the ends of the objectives and the stage so you probably couldn't tilt a knife blade in there. It would be a good deal if you want to look at regular microscope slides and things though.

For knives and things you'd probably want something more like http://store.amscope.com/s560-a.html and one of their top 3 cameras (left to right top to bottom. #3 looks just like the LW scientific MiniVid that I'm using) http://amscope.com/PhotoM.html That would give you plenty of room under the scope (which can be raised or lowered on the pole too) and has the proper top-down lighting. (looks like they have some nice packages here http://amscope.com/DigitalLP.html ) There are also video inspection systems like this http://www.truevisionmicroscopes.com/scopes/video/tv009a000c.html that would probably be good and a bit cheaper than a full stereo zoom scope.
 
ok. My monitor is set at 1280x1024 and has a .20mm pitch. I guess I should go with the 1.3MP camera, or find something to adapt my 4MP point & shoot.
 
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