Putting the final edge on

I don't think it's hooey.

I don't particularly like sharpening wet but I do it. It's messy and I had to find belts that work with it but I sharpen wet because I proved to myself that it makes a difference.

Anybody here who has a strong opinion on this subject who hasn't actually tested it for themselves should, it's very simple.

If you have several blades that are identical it is extremely easy to test it for yourself. There are two basic tests. The first one is obvious, sharpen two blades the same way but do one wet and one dry, cut an identical amount of the same media (identical cardboard) and observe the edge under bright light and magnification. Repeat it a couple times. This isn't rocket science.

The other thing to look at is "how far out of whack does my process need to be to cause a major problem". Use a slightly more dull belt than you normally use, dwell a bit slower, use a tad more pressure etc. What happens in a worst case scenario if your technique isn't quite up to snuff on a particular blade. This one was the big eye opener for me. Running a used 120 ceramic at 1000 SFM, simply allowing a hair more heat than I normally do caused soft areas in the edge running probably a full millimeter up into the blade, so not only was the edge damaged, the blade was damaged. My fingers weren't burnt and there were no colors run to warn me I had a problem. And this was in D2, which stays pretty hard up to over 900F. This was eye opening and why I won't risk grinding the edge in dry because it's really easy to screw it and not even know it.

Can grinding the edge in dry be done and work reasonably well? Unless you're talking about sharpening razors, of course. Is it a reliable high quality process? I proved to myself that it is not.

If a person grinding their edge in dry will try these two very simple tests on their work they may learn something. The entire test doesn't take an hour from start to finish. It just requires some objectivity, a light source and 10X magnification.
 
Thanks for finding that, I completely forgot to look for it.

I don't think it's hooey either. There are probably factors that are hard to qualify, but I've never heard of sharpening a straight razor on powered equipment. Other than that, I default to whatever mete says because he's probably done more research than any of us. :)
 
Fiddleback said:
I use a 1x42, then go to a final sharpening by hand. Never once have had an issue with an edge that wasn't abuse induced. I think the study that everyone freaked out about was a big fat red herring. I'd put my edges against anyone that wet sands theirs. Whole lotta wumpa lumpa fluff worry, but not any real world effects.
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One study does not science fact make.

That study would have to be repeated several times and with the method standardized before a conclusion could be satisfactory.

People like to repeat the study but often neglect to mention that almost everyone making knives are taking them to the grinder post heat treat to finish out as well as putting an edge on it.

If they measure the temp of the steel on finishing out the blade they would see high temps as well if measured by a thermo couple for fractions of a second

Time and temperature is everything. To demonstrate that... what would people think would happen if a person was exposed to -240* F? Most would think a person would freeze. But the fact is people sit in Cryotherapy tanks for several minutes at -240* F all the time for therapy with no ill effects and without freezing.

Time and temperature makes all the difference.
 
I use my knives too, and more importantly, I warranty them. They aren't coming back with edge failures. The edges are working. How does one account for this in the conclusions associated with the study? Sometimes a study is mostly academic and ignores the thousands of years of real world data. Edges did not SUDDENLY start working out after/because of this study. Really in the grand scheme of knifemaking technology, this one didn't make much of an impression at all. I don't know of one maker in the Georgia Knifemakers Guild, not one of the masters in the group, that believes and does this. These men, I guess, make knives with poorly functioning edges? This is a forum issue only IMO.

In addition, I can't wet sharpen 01. But it would be funny to see folks try it.

Now, you can definitely mess one up putting the edges on with a grinder. Its touchy and takes practice. I agree with that part. And, imo, once that step is done, you still need to refine the edge by hand. Your 'micro' overheated spots are likely so thin that they get sharpened off during the hand refining part.
 
Fiddleback said:
I use my knives too, and more importantly, I warranty them. They aren't coming back with edge failures. The edges are working. How does one account for this in the conclusions associated with the study? Sometimes a study is mostly academic and ignores the thousands of years of real world data. Edges did not SUDDENLY start working out after/because of this study. Really in the grand scheme of knifemaking technology, this one didn't make much of an impression at all. I don't know of one maker in the Georgia Knifemakers Guild, not one of the masters in the group, that believes and does this. These men, I guess, make knives with poorly functioning edges? This is a forum issue only IMO.

In addition, I can't wet sharpen 01. But it would be funny to see folks try it.

Now, you can definitely mess one up putting the edges on with a grinder. Its touchy and takes practice. I agree with that part. And, imo, once that step is done, you still need to refine the edge by hand. Your 'micro' overheated spots are likely so thin that they get sharpened off during the hand refining part.
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You're almost entirely missing the point, I think, Andy. NO ONE is claiming that you get catastrophic edge failure this way. What they're saying is that, overheating even for a microsecond at the temperatures described causes a weakness that reduces the integrity of the edge and doesn't allow MAXIMUM effectiveness of your sharpening.

No one is claiming that other makers are "doing it wrong" or that it even needs to be portrayed in such a black-and-white method, but this much I'll tell you... If a PhD metallurgist who's responsibility it is to find the threshold of such materials - in conjunction with numerous fellows and peers, suggests that his study reached these conclusions, opens his information to those interested FREELY, and encourages discussion and debate, I'd say that other makers that aren't even willing to question their methods in hope of improving their end result have already set their own performance caps.

The thing that drives me nuts about this stuff is that, outside of the knifemaking world, information like this is shared and utilized, rather than shunned and scorned because it questions convention. I've never managed to understand why we as a group are so willing to convince ourselves that no one else 'gets it'. The folks that are performing these studies are MORE driven than we are, they're not isolated in labs and texts!!!! Find out who they are, before you decide that they're disembodied white lab coats!!!!
 
I just wanted to add that I don't wish to single anyone out in my last post, and that includes you, Andy!

We, as knifemakers, tend to be confronted by new information that might conflict with our processes as attacks on our ways, rather than examining the information objectively. Worse still, we immediately refute the information as wrong and seek the endorsements of those we know and respect, whether they may be more knowledgable on the subject or not.

Nathan, thanks for continuing to participate here.
 
My only real concern comes with acute stability. Knives that have an apex of 30° or over (most) don't seem to roll, chip or hang on to a tenacious wire edge like a more acute edge, at least in my dealings.

I mentioned a straight razor. Most consumers are going to use whatever edge is initially put on their knife, many will keep using it until dull and beyond, some will just buy another knife. Acute knives perform better, that cannot be argued. The important part of sharpening is finding the most acute edge that you can get taking the steel and substrate cut into consideration. That's usually left to the consumer, and rightfully so. Some customers are ham fisted and abusive, some are slicers and dicers and maintain their knives. Finding the absolute critical threshold is probably a rare priority, but for those of whom it matters, well, they're going to want their edges uncompromised in any way.
 
No biggie Matt. I respect you and Nathan and I'm not trying to get under anyone's skin. I do however disagree on the importance/relevance of this information.
 
That's a beautiful blade. As far as sharpening goes, there no right or wrong. I've basically abandoned sharpening to a certain angle, but I sharpen low, consistent inclusive edges. It takes time and practice. Have fun learning and enjoy your blade.
 
Nathan the Machinist said:
I don't think it's hooey.

I don't particularly like sharpening wet but I do it. It's messy and I had to find belts that work with it but I sharpen wet because I proved to myself that it makes a difference.
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Mind if I ask what belts worked out well used wet? I typically use the trizact belts for sharpening. I know that the trizact abrasives used in car sanding are always used wet but I didn't see anything about the belts being used that way. Only thing I saw that was expressly a wet belt on trugrit was the diamond ones here: http://trugrit.com/index.php?main_page=product_info&cPath=1_145_151&products_id=5912

Also, are you using flood or mist coolant? Straight water I assume no?

I'll see if I can do some micrographs done both ways and post the differences. My scopes aren't made with that intent but they should be able to do an ok job anyway.

-Sandow
 
Sandow said:
Mind if I ask what belts worked out well used wet? I typically use the trizact belts for sharpening. I know that the trizact abrasives used in car sanding are always used wet but I didn't see anything about the belts being used that way. Only thing I saw that was expressly a wet belt on trugrit was the diamond ones here: http://trugrit.com/index.php?main_page=product_info&cPath=1_145_151&products_id=5912

Also, are you using flood or mist coolant? Straight water I assume no?

I'll see if I can do some micrographs done both ways and post the differences. My scopes aren't made with that intent but they should be able to do an ok job anyway.

-Sandow
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3M 977 120 grit, edge leading
3M 40 micron lapping film, edge leading
3M 15 micron lapping film, edge leading
micro bevel on 3M 15 micron, edge trailing
Light pass on oil stone to remove burr

It takes about 10 minutes total per blade, but I get a polished hair popping edge that looks really nice.


edit to add:
my technique: http://youtu.be/u0Iu_EEyEIU

the results : http://www.bladeforums.com/forums/showthread.php/1174677
 
I love micron belts, I hate micron belts.

They actually SOUND like razors when they're moving on the grinder, and if you're not careful the edge of them cuts that way, too... But there's nothing that finishes like them.

Nathan, any reason you're using 120 977's and not 707's? Do you prefer the stiffer backing for this?
 
I use micron belts/leather for my hand sharpening as well. I love the finish they give the edge.
 
Nothing worse than cutting your knuckle open with a micron belt; paper cut from hell. All I'd use them for is sharpening but more carefully now.
 
Matthew Gregory said:
Nathan, any reason you're using 120 977's and not 707's? Do you prefer the stiffer backing for this?
Click to expand...

I went with stiff belts for sharpening because I thought they'd be more like the stone I was accustomed to. That said I've used j flex belts for the job with good results. You want a belt that doesn't get wonky when it's wet. I hate it when a belt won't lay flat and you get an inadvertent recurve in your edge. This is more of a problem when sharpening knives with relatively straight sections.
 
There are too many variables to be able to measure the outcome consistently; when it comes to setting edges on a moving belt, wet or dry. How sharp is the belt how much pressure is being used and what sfm is the machine running. I hand finish after the belt work 120, 220, 400, 600, 1200. I think you have to keep in mind that steel is being removed with the 120, 220 belts with more polishing when it comes to the 400, 600, 1200 belts. If you lighten the pressure as you approach the lighter grit belts and then finish on a diamond plate @ 350/600 using kool mist or the like to keep the abrasion friction low I've never had edge issues.
I'm not saying setting edges on a belt "cannot" be an issue, it surely can; but only if its made an issue by disregarding basic science or not being aware of what you are holding in your hands.

I have watched videos of people putting convex edges on blades, using the area above the 2" small wheel and the platen edge and using such pressure as would surely eliminate all the hardness from the edge of the blade and do this repeatedly. Its all in the technique.
 
Fred, good to see you are still around posting occasionally---I must say that I have to agree with Fiddleback on this issue in general. One question I have is: How do the respected major mfgs. put their final edge on their knives? I would suppose it is some sort of automated process--I think that would tell a lot about what is critical about putting a final edge on a blade.

Adam, I figured that was a spouse or child in your pic--thanks for the tip on the app.

Nathan, I found that very interesting how you put the bevel and final edge on your blades. Neat video--Thanks
 
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