First toothy edge

[Mark Reich]

Maybe if it would have been significant we'd remember better, Mike.

[grepper]

Mr Grepper, have you experimented rolling your toothy edges compared to the very same edge, just taken to higher refinement?

Most people think refined edges are more stable than toothy edges. It makes sense, but I'd really like to know if that holds water.

The toothy thing started for me years ago before I got an edge tester.  I had a freshly sharpened blade with a sharp polished edge.  My wife wanted to cut through some plastic mesh.  Confidently I gave her the knife, and much to my horror it could barely cut through the stuff.  It just rode back and forth on the surface.  The only way to get it cut was by brute force pulling it through the plastic threads.  My friend was observing this and immediately availed himself of the opportunity to blurt out something to the effect that I was not able to even sharpen a knife!  Very embarrassing.  

That was the impetus for and when I first started experimenting with toothy edges.  I found that all it took was a bit of tooth on the edge to cut through the plastic stuff.  That little bit of bite grabbed just enough to break the slippery plastic surface.  I never looked back.

One year was very bad for growing tomatoes.  It wasn’t just me, many folks around MI complained of the same thing.  Tomatoes would not ripen correctly.  They’d turn red, but only on the surface leaving the center green and unripe.  Very strange.  Left on the vine or brought inside to ripen the outer layers would just rot and they would not ripen normally.  The skins were thick and tough, the next layers gooshy, mushy and rotten and centers green rotten crap.  Tasty, eh?

I gathered a bunch of nice mushy ones off the ground, and sharpened two blades, one polished and the other toothy.  At first both blades were able to cut the tough skins without mashing the tomato rot underneath.  But soon the polished edge started riding on the surface of the skins but the toothy edge just kept cutting.  

I have taken images of polished vs toothy rolled edges, but at the moment I have no idea where they are.  What I saw, and this makes sense, is that polished edges roll into a perfectly smooth long roll while toothy edges roll irregularly.  That irregularity apparently maintains some “bite” whereas the polished edges just ride on the surface of stuff.

I did find this image of a rolled polished edge.  You can imagine how that long, smooth roll just rides on the surface of stuff like tomato skin, etc.

   

That image is part of this thread:
http://bessex.com/forum/showthread.php?t...10#pid1310

I've done the same type of experiment by putting onion and garlic skins flat on a cutting board.  While the polished edge is super sharp it does fine, but does not keep cutting like a toothy edge does.  At least from what I've seen, a super sharp freshly sharpened polished edge is great but a toothy edge maintains "bite" and is more useful longer.  Of course other folks may get different results, but that's what happened for me.

So, to answer your question Mr. Mark, no.  I have not done extensive testing with with sharpness readings, etc., but in actual use I've found toothy is better, useful longer and that bit of "bite" does great for initially breaking the surface of broccoli and tomato skins and stuff like plastic rope allowing the cut to begin. 

It's like when the blade is riding on a tomato skin all it takes a a poke from the tip of the blade to start the cut.  After that even a lowly polished edge will finish the cut without smashing the tomato.  Like trying to slice through a branch with a knife compared to a saw.  A knife just doesn't cut it but a saw breaks the fibers and cuts through.

[SHARPCO]

grepper. 

I heard that the edge finished with poly diamond compound is better slicer than aluminum oxide compound. So I'll try to finish the edge with 4 micron poly diamond emulsion. I expect to be able to make a pretty aggressive edge with it. Do you think toothy edge is better than this?

[grepper]

I’m not sure I understand your question Mr. Sharpco.  If you are asking if diamonds cut steel better and make deeper scratches in the bevel that extend to the edge and result in a toothy edge better than AO, then maybe.  I suspect, can’t prove, that diamonds are sharper and make a more aggressive cut or scratch in the bevel, but then what grit AO?  How much pressure? There are so many variables.

If you think about it, there is nothing magical about diamonds or ceramic or AO, they are all abrasives capable of cutting steel.  Diamonds or ceramic such may stay sharper longer and produce more angular bevel scratches.  Is that “better” than a new AO belt?

A toothy edge is a toothy edge regardless of if it is created with a diamonds, AO, special sauce, magic dust or a rasp for that matter.  The difference is how deep the scratches in the bevel are that make a more or less toothy edge.  I’m no expert, but I would guess the aggressiveness of the edge is more dependent on the coarseness of the abrasive than the type of abrasive used, as well as how your deburring method reduces/preserves tooth.  

Experiment.  Sharpen some edges, use different abrasives, use your new microscope and take some images.  Post your images, results and hypotheses on the Exchange.  I for one will be very interested in what you find out!

[SHARPCO]

Experiment.  Sharpen some edges, use different abrasives, use your new microscope and take some images.  Post your images, results and hypotheses on the Exchange.  I for one will be very interested in what you find out!

Thank you grepper. 

I'll keep trying.

[grepper]

Mr. Sharpco, I think you have progressed in your sharpening to the point that some of these advanced questions you ask are difficult for other folks to definitively answer.  No disrespect intended to anyone, but when you get into very detailed questions like if poly diamond or AO will make a better slicing edge you are more likely to get opinions rather than experimental data that you can analyze and act upon.  There are just so many variables involved in your question it’s very difficult to provide a yes/no, black/white, do this or that answer to.  

Yours are good questions and honestly I don’t know the answers.  That’s why I’m hoping you will experiment and post your results.   Your experimental data will aid all of us all by adding to the general body of information available to the sharpening world.  No doubt somebody else will have the same questions and may find your results helpful.

I completely understand that experimenting, documenting and sharing the information is a time consuming and often thankless task.  Been there, done that.  For me at least, actually doing it and learning from experimenting is well worth the effort.  IMHO, there is a big difference between actually doing, seeing and proving compared to simply acting on the opinion of others.

Anyone who even asks the difference of how poly diamond compared to AO effects the edge is obviously no beginner.  At this point I bet you are more knowledgeable than you may give yourself credit for!

[SHARPCO]

Mr. Sharpco, I think you have progressed in your sharpening to the point that some of these advanced questions you ask are difficult for other folks to definitively answer.  No disrespect intended to anyone, but when you get into very detailed questions like if poly diamond or AO will make a better slicing edge you are more likely to get opinions rather than experimental data that you can analyze and act upon.  There are just so many variables involved in your question it’s very difficult to provide a yes/no, black/white, do this or that answer to.  

Yours are good questions and honestly I don’t know the answers.  That’s why I’m hoping you will experiment and post your results.   Your experimental data will aid all of us all by adding to the general body of information available to the sharpening world.  No doubt somebody else will have the same questions and may find your results helpful.

I completely understand that experimenting, documenting and sharing the information is a time consuming and often thankless task.  Been there, done that.  For me at least, actually doing it and learning from experimenting is well worth the effort.  IMHO, there is a big difference between actually doing, seeing and proving compared to simply acting on the opinion of others.

Anyone who even asks the difference of how poly diamond compared to AO effects the edge is obviously no beginner.  At this point I bet you are more knowledgeable than you may give yourself credit for!

grepper. 

I absolutely agree with you. 

I have sharpeners, edge sharpeness tester, microscope, edge protractor, and hands to use knives, so I have no reason not to do it. 

Thank you again.

[Mark Reich]

I went through a period of polished edges, but maintaining that level of sharpness was detrimental to the lifespan of some very expensive blades. Trying to keep your blade under 100 BESS just isn't practical.

I think it takes some refinement to get below 100 BESS, and once you're there it doesn't last long. The sharper you get, the more tenuous that edge becomes. It's normal to see something like 50 BESS turn into 75 BESS overnight... without any help whatsoever. Opening the daily mail can be disastrous. One UPS box later that fine pinnacle of sharpness won't want to cut a piece of string.

I've been measuring the knives I sharpen on 140 grit Atomas, and I know they should be about BESS 175-200, fresh off the diamond plate. There is a mighty big difference though. I can open mail for a couple weeks, boxes too, and guess what. Without any help at all, my blade can measure Sharper. It's like that coarse an edge takes some breaking in.  

Mr Sharpco, when people say 4µ PDP leaves a "toothy" edge, you have to adjust your binoculars down to a completely different calibration. Yes, it's more aggressive than 4µ CBN, and CBN is more aggressive AO, but about the only way you're going to be able to make that sort of determination would involve shaving with a straight razor. The difference is noticeable- on your face.

On a typical stainless kitchen knife it makes a difference for about 10 cuts of 3/4" rope. Then it's really just a 4000 grit edge that went from 100 BESS to 175 BESS, and the microscopic teeth have already lost their crispness. A more tangible advantage of PDP is that it cuts steel much more efficiently- especially wear resistant steel. In other words, it's great on a hone because it doesn't take as many strokes to affect the edge. Less strokes means less chance for mis-strokes, and that is significant to me.

The kind of tooth Mr Grepper and I shoot for is much different than any compound is capable of. 150 grit tooth is... well, mathematically it's 27X coarser than 4µ (4,000 grit). It's like comparing marbles to basketballs. 

Also, I  agree with Mr Grepper that you are plenty capable of making your own determinations, and we will be more than happy to hear your conclusions. 

[grepper]

Mr. Mark uttered, "The kind of tooth Mr Grepper and I shoot for is much different than any compound is capable of. 150 grit tooth is... well, mathematically it's 27X coarser than 4µ (4,000 grit). It's like comparing marbles to basketballs."

Well put Mr. Mark.  Personally, I don't consider a 4,000 grit finished edge to have anything to do with a toothy edge.

[SHARPCO]

Mark,

I know how long the serrated edge lasts. So I'm attracted to the toothy edge. The polished edge loses its sharpness even if it gets a bit dull, but the toothy edge is not.

I like your method of using 140 grit Atoma. It will wear less edge than belt.