Angle advice

[pigeonofdespair]

asdasdasdasd

 

[StretchNM]

Are you, in your terminology concerning 20 and 40 deg angles, mixing in the "inclusive" angle?

If a knife is sharpened at 40 deg inclusive, each edge will be ground at 20 degrees. If a knife is sharpened at 30 degrees inclusive, each edge will be 15 degrees. Not a single knife I own has come from the manufacturer sharpened at either 30 or 40 degrees. Most are at something between 38 and 50 degrees. Additionally, not a single one has ever come ground where both edges are exactly the same (i.e. 19 deg on one side and 22 deg on the other).

Since getting my Sharpmaker shortly after Christmas (read: beginner), here's what I do:
If the knife comes very sharp when I get it, I use it until it begins to lose its edge. Then I use a black magic marker on the edge along with the Sharpmaker to find approximately what angle its ground at. Then I touch it up with usually just the white fine stones until I restore its very sharp edge. I don;t usually regrind the primary bevel until I get tired of playing around guessing which angle to use on the Sharpmaker.

To regrind, one way is to put a 5"x1"x1/4" piece of wood under one end of the Sharpmaker (in effect raising the end up 1/4"). With the stones in the 30 degree holes, you will now be able to regrind the primary bevel to 25 degrees (12.5 per side). However, the Sharpmaker medium stones are NOT coarse enough to regrind a bevel, at least not in any reasonable amount of time. You can wrap the rods with 220 or 320 wet/dry paper and grind away until you're happy. Try to do each side with the same number of strokes and pressure so you don;t grind off-center. This will take some time and several strips of wet/dry, replacing as needed. You could also lay a coarse grit diamond benchstone against the Sharpmaker rods making your work go even quicker.
Remember to swap ends with your little 1/4" spacer block as you grind each side.

When you're done grinding and are sure you're honed each bevel all the way to the "edge", you can remove the spacer block and hone the edge on your medium Sharpmaker stones. If you were working with the spacer block and the stones in the 30 degree holes, your re-ground primary bevel will be at approximately 25 degrees. Now, without the spacer, your secondary or "micro-bevel" will be at 30 degrees (15 deg per side).

Finish with the white stones and, if you like, on the last 7 or 8 strokes, using super-light pressure, you can angle the blade just slightly away from each Sharpmaker rod. This would be akin to super-super light grinding at about 34 or so degrees.

 

[StretchNM]

Hi,

Other questions:

For example if a blade has been sharpened to a 40deg angle and you want to bring it down to a 20, I would assume you simply sharpen it down to a 20 deg angle and there's nothing else to it. However is it possible to sharpen a blade with a 20 deg angle up to a 40 deg angle?

To sharpen a knife UP to a more shallow angle, you don;t have to "re-grind" the primary bevel. For example, if you have a knife blade beveled at 30 degrees inclusive (this is 15 degrees per side), you would sharpen it on your SHarpmaker using the rods in the 30 degree holes. If you wanted to change the angle, just sharpen it using the 40 degree holes. Just keep sharpening it at that angle and, each time you sharpen, more of the primary bevel will wear away until eventually the entire primary bevel is at 40 degrees (20 per side).

 

[pigeonofdespair]

Oh ok that makes sense, the inclusive angle part especially.

Any thoughts then if it would be worth it to sharpen the S30V to 15 deg?

 

[Dog of War]

Since I've been reading these forums I'm beginning to understand the importance of an angle. So I'm wondering which angels I should be sharpening my two knives to for maximum preformence.

IMO an excellent starting point for the great majority of knives is to sharpen the primary edge at 12 degrees per side. I do this with everything from light-duty folders to large choppers, and with most steels, for most the work I do, this gives you an edge that's still plenty strong.

In addition to better cutting performance, keeping the knife sharp with your Sharpmaker becomes very simple with the edge angle reduced like this. Trying to maintain a 15 deg/side edge with the Sharpmaker can mean a lot of work (unless you want to invest $65 or so in a pair of diamond sleeves for the Sharpmaker.) But with the edge angle reduced like this, you just apply a tiny secondary bevel or "microbevel" with the Sharpmaker to keep it sharp, removing only a very small amount of metal each time.

Unless you've got a belt sander, EdgePro, or other means of taking the edge down like that, you can use a large bench stone held at the desired angle in a vice to reprofile the edge ... sort of like a heavy-duty, one-sided Sharpmaker. I do this often enough I made a special jig to hold a bench stone:

I'm sure you get the idea. Remember the angle isn't all that critical, and like with the Sharpmaker, you shouldn't have a problem holding the angle quite close with this method anyway.

If it should turn out that you're doing really heavy work and need a more obtuse edge, you'll even find the work reprofiling wasn't wasted: just add another small bevel at, say, 15 degrees, and you'll have a multibevel edge which still gives better cutting performance than a single bevel 15 deg/side edge.

Finally, some will tell you 12 deg/side is actually pretty conservative. If you decide that's true, just take it down to 10 deg/side, 8 deg, or whatever you like ... everything still applies just the same.

BTW, that is a great user name, pigeon. Reminds me of a hilarious Far Side cartoon about "the chicken of depression."

 

[StretchNM]

Oh ok that makes sense, the inclusive angle part especially.

Any thoughts then if it would be worth it to sharpen the S30V to 15 deg?

As you learn about this, you'll hear some guys calling it "re-profiling". They mean the same thing as what we're talking about. But "re-profiling", by definition, is actually changing the profile of the blade. An example would be changing the degree of sweep between the straight part of the blade and the tip. That's "re-profiling". The arguement could be made that, when you change the bevel angle, you're re-profiling if you look down the blade from tip to choil....but it's a technicality at best.

I have a Benchmade 210TK that I just re-beveled to 12-1/2 degrees. It has S30V steel and, although the re-grind was recent, so far I like it. Mind you, the BM210 only has a 2-1/4" blade, and I don;t know if a longer blade would hold up as well (in S30V) sharpened at a steep angle, but I would think it should.

I tend to agree with Dog of War that most knives are ground too shallow. Almost all arrive from the mfr at about 38 to 50 degrees (inclusive! remember! ). Too steep for me. I want my micro-bevel, like Dog of War said, at 15 degrees (30 inclusive), so my primary bevel must be steeper, hence the 12-1/2 degrees. Now, it doesn;t matter if you choose a little steeper angle like 12 degrees, or 10 degrees, but, with a 15 degree micro-bevel, I wouldn;t want the primary bevel any more shallow than 12.5. See? Steeper is ok, more shallow is not in this case.

If you re-bevel your knife to 12.5 with a 15 deg micro-bevel, and you don;t like it, just change it back over time. Say you decided that you really did like the 20 degree bevel that it had originally. There is no need to regrind, just charpen the thing on your Charpmaker at 40 degrees. Keep doing that and, over time, you'll be back where you started. The beauty is, BOTH edges will be ground at the same angle (within a degree or two). Unlike when your knife came from the mfr. I don;t even have to see it to know.......the angles vary from edge to edge.

 

[pigeonofdespair]

asdasdent step.

 

[StretchNM]

I think you have the micro-bevel idea right. Actually...to be absolutely correct, let's do it this way. The knife blade itself has a bevel....say about 7 or 8 degrees. This is the part of the blade where the maker's stamps are and such. Then, there's the "edge"...... this is shiny even if the blade is coated black. The "edge is what we want to grind down to, say, 12-1/2 degrees. We want both sides of this "shiny edge" to be at 12-1/2 degrees. Add those together and you have a 25 degree "primary bevel"..... or "primary edge". There. That's a shiny, sharp edge at the bottom of maybe a black blade.

Now, we want a tiny, tiny little bevel at the bottom of that shiny, sharp, 12-1/2 degree edge. Even under a lighted desk lamp/magnifyer, we'll have a time seeing this tiny, shiny, little edge..... or "micro-bevel". But it'll be there if we want it to...we don;t have to have it, but it'll be easier to sharpen up nice and sharp if we have it. So...we want it. And it'll be, if we want it to, about 15 degrees on each side (or 30 degrees inclusive).

Your picture has it about right.

Problem is, our knives come from the mfr with a much steeper shiny, sharp little edge at the bottom of the black blade. Usually that edge is about 20 degrees or more (40 degrees or more inclusive). We want that shiny edge to be 12-1/2 degrees! So.... we have to re-bevel the knife blade.

Please don;t assume your Sharpmaker, even if you go through all four steps, is going to "re-bevel" that edge from a shallow 20 degrees to a steeper 15 degrees. The coarsest stone in the kit is the medium rods.....it won;t cut it. That's too much work. You need something else...hence the wet/dry 220 or 320 grit; or a coarse diamond stone; or a belt sander; or a file.

Once you get the "primary edge ground down to 25 degrees (12.5 per side, remember?), THEN you can use the Sharpmaker medium stones (in the holes marked "30 degrees"), and with no 1/4" block under the Sharpmaker, to hone the "secondary bevel", or "micro-bevel", at 30 degrees. Finish up with the fine white stones, making your last few passes very, very light.

 

[pigeonofdespair]

asdasd

 

[Dog of War]

Okay this is becoming a lot more clear, a few more questions.

For clarification the science behind the primary bevel and microbevel would be this: You are reprofiling your blade using a very hard sharpening stone to the 12.5/side angle. Now the edge is a 25 inclusive angle from top to bottom. Now using a less coarse stone your sharpening the blade at a 15/side angle thus forming a microbevel , the primary bevel is left untouched because the less coarse stone is unable to affect work done by the very hard sharpening stone. Is that correct?

Yes, in fact the way you've described it is excellent.

Of course when you add the microbevel, a tiny amount of metal is removed, but the primary bevel is largely untouched. You can see why maintaining this microbevel is much easier and quicker than always having to work on the whole primary bevel each time you need to sharpen.

if I have the 25 inclusive primary bevel, and the 30 inclusive micro bevel will this be able to be maintained in the field, or is the sharpmaker really necessary for touch ups. What are the benefits of having a primary bevel and a micro bevel?

In the field I don't think most here feel it's necessarily to maintain exact edge angles. A small, dual-grit diamond sharpener like those made by DMT is very handy, for example ... if you sustain serious damage to the edge, just try to match the primary angle as close as you can with the coarser grit, work it until the damage is removed, then using the fine side and a slightly greater angle you apply a small microbevel to get that final edge. Other types of small pocket stones will work as well, or even a small ceramic rod, they're just not as fast as the diamond hone.

It sounds to me like you've got the concept down pat, and that's the important part. There are lots of ways to implement it, but all leading to the seem desired result.

BTW, thanks for making that clarification about reprofiling, StretchNM. I agree it's much more accurate and clear to say something like "reducing the primary edge angle." Will try to watch that in the future.

 

[StretchNM]

So to recant: Sharpen the blade using the wet/dry 220 or 320 (whats the difference) + the piece of wood using the sharpmaker to attain a 25 inclusive bevel. Then go through steps 1 - 4 on the sharpmaker with the 30 deg setting to attain a 30 deg inclusive micro bevel.

The difference between 220 and 320 is 100 Ok, ok, 220 is a coarser grit.

You mentioned you don't like to change the primary bevel, could you elaborate on this, why not? As it stands right now my knife is sharp and this will be used in the field.

I don;t remember saying I don;t like to change the primary bevel. I don't mess with it at first, as the blades, when new, are usually sharp and function well. I gress up the edge when it needs it, but I don;t re-bevel the edge until I get tired of dealing with the more shallow, obtuse edges that mfrs put on their knives.

So if the sharpmaker stones arn't strong enough to change the angle profile then what is happening when I sharpen the blade at the 30 deg angle setting??

The Sharpmakers stones "strength" has nothing to do with it. It's the "grit" that's important. The medium stone is finer than 600 grit. That ain't enough to re-bevel an edge. To re-bevel the primary edge, you have to remove quite a bit of metal. Use a coarse grit (such as 220 wet/dry, or diamonds, or a file). THEN, go to your SHarpmaker stones. By the way, you don;t have to have a micro-bevel if you don;t want one.

You'll understand all this once you do it. If your knife is fine as is, then you need do nothing.

......BTW, thanks for making that clarification about reprofiling, StretchNM. I agree it's much more accurate and clear to say something like "reducing the primary edge angle." Will try to watch that in the future.

I can;t take credit for that Dog of War. I started a thread wherein I asked for help "re-profiling" my RAT-3, and one of the sharpening experts corrected my terminology. I think I kindly already knew it, but I was oblivious to it.
Also, I don;t remember you using the term incorrectly. I wasn;t refering to your post when I "defined" reprofiling. I was just thinking that the Pidgeon was going to start seeing people use the term sooner or later and it would add to the confusion.

 

[pigeonofdespair]

asdasdsad

 

[Dog of War]

Maybe a (crude) illustration will help.

The first "V" figure we'll say is the 30 degree edge you're starting with.

In the second figure, the blue lines represent the new 25 degree edge you create when resharpening at the lower angle ... the area between the black and blue lines on each side being metal you remove.

Finally, in the third figure we add a 30 degree microbevel, shown in red (grossly exaggerated in size so you can see it here, and my angles are certainly not perfect.)

Hopefully that helps you visualize how the new, very tiny, 30 degree microbevel "fits" on the new, more acute primary edge, "within" the old profile of the 30 degree primary you started with. If not, maybe Stretch or someone else can explain it better, it is a little hard to verbalize.

What are some methods for determining progress when re edging a blade, when do I stop? How do I know I got my 25 angle and can start on the microbevel?

Kind of short on time here, but the tried-and-true method is to sharpen one side until you can feel a burr raised on the other side; the burr being a very fine, tiny strip of metal that gets bent over rather than removed when you've gotten to where you're sharpening all the way to the edge. You then sharpen the other side until you raise a burr on the first side ... that way, you know you've completely sharpened all the way to the edge on both sides.

The burr (or wire edge) then needs to be removed, and usually with high quality steel just a few lighter swipes on your medium or coarse stone at the same sharpening angle will get rid of most of it. Then when you apply your microbevel, the steeper sharpening angle should remove any trace of burr/wire edge. There are a number of tricks for "stubborn" wire edges ... and volumes have been written here about the subject. But that's it, in a nutshell.

 

[StretchNM]

Man...we needed those drawings! That should be clear.

Dog of War is right when knowing "when to stop". However, if you're re-beveling from a 30 degree edge down to a 25 degree, for example, you don;t want to grind away at one side all at once. If you do that, grinding away until you get the burr, you will by that time have ground the blade way off center.

First, grind away on one side for say...oh twenty or thirty strokes. When I re-bevel an edge, I grind on both the down and up stroke. Then, switch your kittke 1/4" spacer block to the other side of the sharpmaker. Switch your triangle stone (wrapped in 220 or 320 wet/dry, remember?) too. Now grind away on that side for twenty or thirty strokes. Do this back and forth for about 100 strokes or so. Then, take a Sharpie pen or black magic marker and color the primary bevel with it. Now, grind a few passes on the sandpaper-wrapped stone to see how much more you need to go. You'll understand when you do it..... reading it here doesn;t do it justice.....especially if I'm the one explaining. No wonder you're having a problem with this...it's ME explaining it!

Now, when you've ground a couple hundred strokes or so (hehehe, yea, depending on the steel and how much angle you're grinding off, it can take alot more than that even), you're starting to get close to where the 25 degree bevel (12.5 per side) is beginning to meet at the very edge (read: starting to get sharp). NOW is the time to start looking for the burr and doing what Dog of War said. Once you get that fine burr alng the edge, or even if you don;t but you're sure anyway that the edge is sharp, you can move on. Make sure you've done the whole length of the edge, though before moving on.

Now you can unwrap the sandpaper from your triangle stone and remove the 1/4" spacer. Place both medium stones in the Sharpmaker in the 30 degree holes. Now, do what the Sharpmaker DVD says to do. Take 15 or so swipes on each edge on the corners of the triangle rods. Take 20 swipes if you like. IF you want to, take 15 or 20 swipes on each edge on the flat sides of the medium stones.

Now, swap the medium stones for the white ones. Do the same thing. On your last few passes, say the last 5 or 6, makes your strokes on the white stones very light... with almost no pressure. Just enough pressure to keep the blade in contact with the stone. There you go.

Now. Here's what you have. Pretend your knife blade is black. It is right? Good. From the spine (top of the blade) to the edge, the blade is ground at say, 8 degrees. Down near the bottom of this black blade is a shiny portion. That's the primary bevel and the shiny portion will appear to be about 1/16" to 1/8" to 3/16" wide... or high....or extending "up" into the black. This primary bevel is ground at 12-1/2 degrees (plus 12-1/2 from the other side makes 25).

Now, down at the very bottom of this shiny bevel is a tiny-shiny bevel. This bevel might be 1/64" wide...let's say. It's the "micro-bevel" and it is ground at 15 degrees (plus 15 degrees from the other side makes 30). SEE Dog of War's diagram.

When you do it to your knife, all will become clear to you.

I can;t believe I typed all of this. I am drunk on typing. I am typing while intoxicated.

 

[pigeonofdespair]

sadsd

 

[Dog of War]

Man...we needed those drawings! That should be clear.

Dog of War is right when knowing "when to stop". However, if you're re-beveling from a 30 degree edge down to a 25 degree, for example, you don;t want to grind away at one side all at once. If you do that, grinding away until you get the burr, you will by that time have ground the blade way off center....

Thanks again, Stretch, for taking the time to elaborate after I was being lazy/hurried. My only excuse (I think ) is that I've resharpened so many factory edges lately, which many times means one side gets most the work. I've got a Benchmade that will probably take years of sharpening to get the edge somewhat centered.

 

[StretchNM]

I love my BM Nimravus, but I have to say I'm dissapointed with the way the edge came from the factory. It was approx. 17 degrees on one side and about 23 on the other (these are approximate off course because I couldn;t "accurately" measure them). It was very sharp and all other grindings were very nice, including edge centering, but it bugged me for them to be so far off on the edge degrees.

I've since reground it to 12.5 as we've been discussing. Both sides are even, the knife is sharp, the edge is centered, and I'm happy.