Sharpening Questions for super steels

D

drebs

Joined
Dec 6, 2014
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Hey guy's I just got a M4 GB and A Manix S110V and Another M4 mule on the way. I'm getting a Apex edge pro to reprofile them, Take them down to 20 inclusive.

What confuses me is when People Like Ankerson talks about having .005 behind the blade is that just another way of saying a 16 inclusive or something?

Also I've read if you touch these up ever so often on a 400-600 grit it will hold a working edge must longer than working up to the 6000 polish.. To maintain that edge would you use a 600 grit ceramic, aluminum oxide, Diamond steel sharpening rod or other?

Also at that 600 grit would you strop it or keep it at 600?

Finally when Stropping I've been running it forward bringing the angle up till it catches, then stropping it back at that angle, should it be a little bit less or more? I've seem to get better results right on the catch angle with M4 and A bit better at less with the s30v, a bit confused.

I can sharpen but am new to the various in depth techniques for it.

Thanks, Drew
 
Behind the edge refers to blade thickness. Right where your edge bevel ends and the blade begins, that thickness is behind the edge thickness.
You can have 20 inclusive angle on a very thick knife, bevels will be longer, but behind the edge it can be the same 0.25" :)
In short, you need thin blades to improve cutting performance. Blade needs to taper and be very thin to begin with, then you grind whatever edge, but with low behind the edge thickness you can do 15 per side and still outcut in most situations a knife with more acute edge, but thicker behind the edge.
Hope that helps.
 
It does thanks I will youtube how to thin an edge and find out how to go about doing that after using an edge pro on it, thanks
 
You would need to regrind the blade to reduce the shoulder width (behind the edge width). That's a job for a pro.

To reprofile an edge to 20 degrees inclusive, you will make the edge shoulders wider because you will be extending the edge bevel into a thicker part of the blade. We should be talking about an edge shoulder width @ a particular edge angle (such as: edge shoulders of 0.017" @ 15 dps), because you need both measurements to determine the acuteness of the edge profile.

The grit size is going to be like ice cream: everyone likes a different flavor. Ankerson likes to sharpen with a 400-grit SiC stone. I have much better luck refining the edge much further with a Wicked Edge system -- starting with diamond stones and going through to 1600-grit ceramics, followed by stropping with diamond paste (0.5 micron). What works best for you will depend on technique and also on how you plan to use the knife.
 
Great steels, I have a Native 5 in s110v and I resharpened the factory edge to 17 degrees per side (dps) on a diamond Lansky. I left the edge at the fine grit finish (super fine) with cutting oil. Sharp is an understatement! It will cut TP with just light pressure. It's for everyday rough stuff and man does it cut. I would take it slow and try out different things as you go. As far as stropping for working edges, I eliminate the wire edge by going back and forth on the guided stone until it's gone, then strop with newspaper. Murray Carter does and he says it's about 16,000 grit. Remember that steel really resists sharpening, take your time it will get there.
 
Drew, Ankerson is speaking of a 400 grit crystalline stone. That's what he normally uses to sharpen on. Any steel. For touch ups he may strop it with 600 grit SiC slurry applied. At the finest, that's about all he works his blades on. He gets great long lasting edges. DM
 
Twindog said:
You would need to regrind the blade to reduce the shoulder width (behind the edge width). That's a job for a pro.

To reprofile an edge to 20 degrees inclusive, you will make the edge shoulders wider because you will be extending the edge bevel into a thicker part of the blade. We should be talking about an edge shoulder width @ a particular edge angle (such as: edge shoulders of 0.017" @ 15 dps), because you need both measurements to determine the acuteness of the edge profile.

The grit size is going to be like ice cream: everyone likes a different flavor. Ankerson likes to sharpen with a 400-grit SiC stone. I have much better luck refining the edge much further with a Wicked Edge system -- starting with diamond stones and going through to 1600-grit ceramics, followed by stropping with diamond paste (0.5 micron). What works best for you will depend on technique and also on how you plan to use the knife.
Click to expand...


I actually just ordered some congress sic stones at 600 they are incredibly affordable. Anyway I'm not up to free hand sharpening yet. What are your feelings on the wicked edge vs the apex edge pro? And how thin would you recommend reprofiling a m4 & s110v on a guided system without getting into thinning the edge behind?
 
Gator97 said:
Behind the edge refers to blade thickness. Right where your edge bevel ends and the blade begins, that thickness is behind the edge thickness.
You can have 20 inclusive angle on a very thick knife, bevels will be longer, but behind the edge it can be the same 0.25" :)
In short, you need thin blades to improve cutting performance. Blade needs to taper and be very thin to begin with, then you grind whatever edge, but with low behind the edge thickness you can do 15 per side and still outcut in most situations a knife with more acute edge, but thicker behind the edge.
Hope that helps.
Click to expand...

Thanks for this post. I've been trying to get a clear picture of what ".015" behind the edge" (for instance) means.

I'm still a little confused. You said, you can have a thick blade with a long bevel and still have .025" behind the edge. Wouldn't a certain degree angle with a longer bevel (side)automatically lead to a greater thickness? And couldn't you have a small behind the edge thickness and have the knife taper very quickly out after that so it really wouldn't matter much with the total taper of the knife mattering more? I mean, how do you measure right at the edge of the bevel?

Maybe blade taper itself is assumed to be constant? That way behind the edge thickness would kind of be a measure of that.

Not even sure how to phrase my questions well.
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Please take this as a request for knowledge and not an argument. I found your first post quite informational and I'm just looking for more.
 
davek14 said:
I'm still a little confused. You said, you can have a thick blade with a long bevel and still have .025" behind the edge. Wouldn't a certain degree angle with a longer bevel (side)automatically lead to a greater thickness?
Click to expand...

It's geometry so there is some interplay between the 2 things. If you ground a blade to a certain angle and thickness, then sharpened the edge, different sharpening angles would make the sharpening bevels taller or shorter, and thus the thickness where the sharpening bevel ends would change a little bit. I don't know how they measure it, maybe carefully put the tip of your calipers or micrometer right on the blade where the sharpening bevel ends.
 
I'm sure someone will correct me if I'm wrong. Here's how I see these measurements and comparisons:

Measuring the "thickness behind the edge" is done with calipers held at the spot on the blade where the edge bevel transitions to the main body of the blade. Seems like a tough measurement to get right and make it repeatable, but this is pretty much the only way to do it without making assumptions and doing math on some other measurement.

The inter-relation of the angle and the thickness is simply based on a triangle. If you know the edge angle and you know the thickness, then you know one of the sides of the triangle. Knowing those two things, you can calculate the length of the other sides of the triangle. If you think of it in terms of half of the edge angle, then it gets easier because it's a right triangle.

The lessons of these measurements are pretty simple too: Thin is sharp. The smaller the edge angle, the better it cuts. The thinner the stock is behind the edge, the better it cuts. There's a good reason why box cutters and utility knives are made out of very, very thin stock. It cuts better. Thin is sharp. Even dull utility knives still cut. Thin is sharp.

Brian.
 
Yes, the measurements are taken in that manner. With a Vernier Caliper. Don't complicate this. It's simple. DM
 
That's exactly what I meant. If you have a longer sharpened edge and you have an angle then you have the other non-hypotenuse side and it would be constant.

It kinda seems like the behind the edge thickness is almost a measure of blade thickness/taper. You'll meet the blade sooner at a smaller thickness with a thinner blade.

Remember SOHCAHTOA? Here's the mnemonic I learned.

Some Old Hippie Caught Another Hippie Tripping On Acid

This is neat stuff. I'm a learnin'
 
It's not the sharpened edge, but the bevel that gets wider (longer). Most blades get thicker as you move toward the spine, not counting the flats on a saber grind. (Hollow ground blades are more complicated.)

When you make the angle of the edge bevel more acute, it will intersect the blade closer to the spine, meaning the edge shoulders will be wider. So a 15 dps edge angle will have more narrow edge shoulders than a 10 dps edge angle on otherwise identical blades; and that's because the 10 dps edge bevel will be wider (the distance from the edge apex to the edge shoulders), meeting the blade at a place that is wider than the blade is at a point closer to the apex.

You may get a knife with a 20 dps edge angle and reprofile it to 15 dps. When you do, the edge shoulders will get wider.

For high performance, you want as acute an edge angle with as narrow edge shoulders as your cutting tasks can handle without damage.

In trig, when you increase the edge angle, you will make the side opposite wider (longer). And the hypotenuse side and the side adjacent will also be longer.

I like the SOHCAHTOA.

My mnemonic:

Sign Of Heaven
Cannons Aimed High
Two Oceans Apart.

I like yours better, if I can remember it.
 
Twindog said:
It's not the sharpened edge, but the bevel that gets wider (longer). Most blades get thicker as you move toward the spine, not counting the flats on a saber grind. (Hollow ground blades are more complicated.)

When you make the angle of the edge bevel more acute, it will intersect the blade closer to the spine, meaning the edge shoulders will be wider. So a 15 dps edge angle will have more narrow edge shoulders than a 10 dps edge angle on otherwise identical blades; and that's because the 10 dps edge bevel will be wider (the distance from the edge apex to the edge shoulders), meeting the blade at a place that is wider than the blade is at a point closer to the apex.

You may get a knife with a 20 dps edge angle and reprofile it to 15 dps. When you do, the edge shoulders will get wider.

For high performance, you want as acute an edge angle with as narrow edge shoulders as your cutting tasks can handle without damage.

In trig, when you increase the edge angle, you will make the side opposite wider (longer). And the hypotenuse side and the side adjacent will also be longer.

I like the SOHCAHTOA.

My mnemonic:

Sign Of Heaven
Cannons Aimed High
Two Oceans Apart.

I like yours better, if I can remember it.
Click to expand...

Ok that makes perfect sense. Do you have a recommendation on a M4 GB and S110v
manix 2, how narrow to reprofile from the factory edge without my ability to
grind behind the edge while keeping the shoulders at a good width, not getting
to wide on em?
 
For the Manix II, I'd have someone regrind the blade to give you narrower edge shoulders. Check out Ankerson's thread. I think that he had Big Chris thin out his blade, and the results were incredible. (I'm writing this from memory, so check it out with Ankerson or Big Chris.)

The Gayle Bradley is another story because it's already pretty acute, and it's a hollow ground blade. On my GB, which I reprofiled to 15 dps (meaning I made the edge shoulders wider), the edge shoulders are now 0.0205 inches. I'm not sure you would want to regrind that blade, but a more acute edge angle may take you up into the part of the blade that is getting more narrow. I don't know. You could do the GB by just reprofiling, but you might be better off leaving it alone. A knife smith will have a better sense of this than me. Personally, I'd reprofile it to 15 dps and leave it alone after that.
 
Twindog said:
For the Manix II, I'd have someone regrind the blade to give you narrower edge shoulders. Check out Ankerson's thread. I think that he had Big Chris thin out his blade, and the results were incredible. (I'm writing this from memory, so check it out with Ankerson or Big Chris.)

The Gayle Bradley is another story because it's already pretty acute, and it's a hollow ground blade. On my GB, which I reprofiled to 15 dps (meaning I made the edge shoulders wider), the edge shoulders are now 0.0205 inches. I'm not sure you would want to regrind that blade, but a more acute edge angle may take you up into the part of the blade that is getting more narrow. I don't know. You could do the GB by just reprofiling, but you might be better off leaving it alone. A knife smith will have a better sense of this than me. Personally, I'd reprofile it to 15 dps and leave it alone after that.
Click to expand...

Gotcha, I'm new to this do you know how to get in touch with any blade smiths or knowledgeable people? Would you Pm on here or do you just hope one of them responses to a post? I've read great things about taking a GB to 20 inclusive but don't know if they did any thinning.

So last question if I did a 20 inclusive then id want to do a 30 inclusive, 15 dps for side for a micro bevel or more? or leave it alone and just leave it flat grind?

And if just maintained (not re profiled ) how do i know the angle on it now? just run it on 30 or 40?
 
Last edited:
You can look at the service offerings in the custom shop. Some grinders advertise there:
http://www.bladeforums.com/forums/forumdisplay.php/870-The-Custom-Shop-Services-Offered

I'd find a grinder with experience who can answer your questions. I wouldn't go to 20 degrees inclusive unless I had a good reason to do so. Edges that acute have advantages and disadvantages, and a lot of what an edge can hold depends on the heat treat, which you usually won't know much about with a production folder.

You can figure out the existing angles in a number of ways, depending on what equipment you have. If all you have is a stone, then paint the edges with a Sharpie and prop the stone up at 20 degrees off vertical, kind of like the Spyderco Sharpmaker. Then make a light pass with the blade held vertically. Depending on where the ink is scraped off, you can tell if the angle of the stone is more or less then the angle of the edge. Use a protractor or cell phone angle finder or Angle Cube or something to measure the stone angle. Keep adjusting the angle until the stone is parallel to the edge and the ink is cleanly scraped off the full width of the bevel. Then you'll know the angle.

There are also measuring devices, such as a laser protractor.
 
Twindog said:
You can look at the service offerings in the custom shop. Some grinders advertise there:
http://www.bladeforums.com/forums/forumdisplay.php/870-The-Custom-Shop-Services-Offered

I'd find a grinder with experience who can answer your questions. I wouldn't go to 20 degrees inclusive unless I had a good reason to do so. Edges that acute have advantages and disadvantages, and a lot of what an edge can hold depends on the heat treat, which you usually won't know much about with a production folder.

You can figure out the existing angles in a number of ways, depending on what equipment you have. If all you have is a stone, then paint the edges with a Sharpie and prop the stone up at 20 degrees off vertical, kind of like the Spyderco Sharpmaker. Then make a light pass with the blade held vertically. Depending on where the ink is scraped off, you can tell if the angle of the stone is more or less then the angle of the edge. Use a protractor or cell phone angle finder or Angle Cube or something to measure the stone angle. Keep adjusting the angle until the stone is parallel to the edge and the ink is cleanly scraped off the full width of the bevel. Then you'll know the angle.

There are also measuring devices, such as a laser protractor.
Click to expand...

Thanks twindog
 
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