Gayle Bradley Sharpening Question

[TheSavageRabbit]

I have an 8 month old baby. My wife orders all of his diapers and formula over the Internet. I have way more card board boxes than can fit in my recycle bin each weak. I've been breaking them down with a VG10 endura, an O1 Randall Made Little Bear Bowie, and an S30V Military. The swept back blades on the Little Bear and military cut the best and the Military kept a reasonably usable edge the longest.

I just spent ten minutes slicing up card board and a platic wrap coated card board with my new Gayle Bradley. I cut them into small pieces just to see if I could wear down the edge. I made about 100 cuts give or take a dozen. When I'd done this with the VG10 Endura the edge quit wanting to pass through the material within (guestimate) 40 cuts. The O1 Randall became a chore around the same time. I don't recall how the S30V lasted.

When I went back in the house to feel the GB's edge, it seemed like it might have rolled just a tiny bit on one side. But it sliced paper just as it had earlier today. I have no comparison data or even a side by side test, so this is just based on impression. But the GB's edge qualified as "sharp" by my standards after going through more card board than anything else.

That quick report leads to this question. Does Spyderco have any recommendations for sharpening the GB's hollow ground edge on a Sharpmaker? (I only use a Sharpmaker.) I got the feeling that the 30 degree setting wasn't getting a good angle on the edge. I switched to the 40 degree setting with about 30 light passes on the edge of the white rods and then about 20 very light passes on the flat side of the white rods. The edge seemed to be as good as it was out if the box.

I don't have any experience sharpening a hollow grind. Before I settle in on using the 40 degree setting, is there anything I should know or consider?

I bought the GB because I thought the idea was cool. I never thought I'd edc it due to it's weight. I've carried it every day I've worn jeans. I'm surprised by how it kinda disappears when I clip in my RFP. It's not Chinese Folder good, but I'm stunned Ive taken to edcing this monster performer.

[Peter1960]

IMHO there is no difference in sharpening hollow or flat grind edges on the Sharpmaker, as long you use the right angle. Hope my answer helps :)

[Scottie3000]

There are some knives which have a hollow grind on the edge (sharpened with some type of cylinder perpendicular to the edge). This knife only has a hollow grind on the primary grind (Between the spine and the area behind where the edge begins to taper). the edge itself is flat. To most people this is a good compromise between the robustness of the flat sabre grind (Endura) and the slicing ability of the full flat grind which gives up a little bit of blade strength. This is why you Military is a 4mm blade thickness. It lets it be both strong and a good slicer where most knives of that size are a 3mm and smaller knives are 2.5mm.

Short answer: there is no difference at all because the grind of the edge is a flat surface just as Peter1960 said.

[kbuzbee]

Okay, I'll second the first two responses that you won't see any difference in sharpening between this hollow grind and your Mili's FFG but Mr. Rabbit seemed to have TWO questions in there:

1. Is there a difference between the two grinds?

2. What angle should I use?

Now I don't know much about M4 but I should think it would easily hold a 30 degree SM edge. In fact, I would think it could go even lower. Will it handle those insanely thin edges people like to put on ZDP-189 or S90V? Probably not. But what angle could you reasonably put on it? I'd like to know that too.

Yes, I realize the design purpose and to support that purpose you'd likely use a larger angle but for those of us whose EDC tasks are mostly light slicing (as opposed to batoning firewood :D ) a thinner edge would be nice.

I'm thinking 20 degrees inclusive would be okay. Yes??

Anyway, that's about where I'm thinking of taking mine. Opinions?

Ken

[catamount]

Stick with the 40 degree Sharpmaker setting for :spyder: factory edges. Trust me, it will save you lots of aggravation & frustration.

The 30 degree setting is for reprofiled knifes. If you can reprofile a knife, then you are an advanced sharpener and don't need to ask about Sharpmaker settings.

[kbuzbee]

The 30 degree setting is for reprofiled knifes. If you can reprofile a knife, then you are an advanced sharpener and don't need to ask about Sharpmaker settings.

I don't really agree with you here, Tom (sorry Bro).

1. I can and do reprofile edges all the time but I certainly don't consider myself an advanced sharpener in any sense.

2. Just because you CAN reprofile and edge doesn't mean you SHOULD. That is a cross between what the knife will be used for and what the steel will support.

So given all that, I DO plan to thin mine out a bit (when you send it to me Given the nature of M4 I'm actually thinking about convexing it just a touch. But I welcome input on what the steel will support.

Ken

[ChapmanPreferred]

I would guess, Spyderco would recommend using the Sharpmaker as Sal designed it to be used. Back bevel with the 30 degree setting and keep a micro bevel at the 40 degree side.

That said, I would personally sharpen the knife on the 30 degree setting with no micro bevel unless I experienced chipping or easy rolling of the edge, then I would add the micro bevel.

As far as the difference between the blade grinds (hollow vs full flat) there are some differences. Hollow grinds keep you in thinner steel longer than a full flat grind. You might feel a bit more resistance when making deeper cuts with a hollow grind than you do with a full flat grind. When sharpening the edge on either style of blade grind, I tend to use the same angles, but I seem to keep a more pronounced back bevel on full flat grinds.

I have been carrying the M4 Mule in place of my S90V Mule and it has been holding an edge very well!

Happy sharpening and New Year!

Doug

[catamount]

I don't really agree with you here, Tom (sorry Bro).

1. I can and do reprofile edges all the time but I certainly don't consider myself an advanced sharpener in any sense.

2. Just because you CAN reprofile and edge doesn't mean you SHOULD. That is a cross between what the knife will be used for and what the steel will support.

So given all that, I DO plan to thin mine out a bit (when you send it to me Given the nature of M4 I'm actually thinking about convexing it just a touch. But I welcome input on what the steel will support.

Ken

Okay, maybe not advanced. My point is this: If someone is asking which Sharpmaker setting to use, then, IMO, the best, and least confusing, answer is 40. Even if they happen to get a :spyder: with a factory bevel < 30 degrees inclusive, and can use the 30 setting to add a microbevel, the 40 will work just fine. If, however, the factory bevel is 30 degrees or greater, as most of them are, using the 30 setting will likely lead to much frustration. Been there, done that.

To put it another way; if 30 will work, so will 40, but not the other way around.

[kbuzbee]

Okay, maybe not advanced. My point is this: If someone is asking which Sharpmaker setting to use, then, IMO, the best, and least confusing, answer is 40. Even if they happen to get a :spyder: with a factory bevel < 30 degrees inclusive, and can use the 30 setting to add a microbevel, the 40 will work just fine. If, however, the factory bevel is 30 degrees or greater, as most of them are, using the 30 setting will likely lead to much frustration. Been there, done that.

To put it another way; if 30 will work, so will 40, but not the other way around.

100% agree and I pretty much knew you were going for that. Just wanted to expand the discussion some. Always room for growth.

Ken

[TheSavageRabbit]

Touched it up again at 30 degrees. Seems to have improved the edge, but I'm kinda splitting hairs (tried to avoid the pun). Going pig hunting today. If I kill a boar I'll test the blade on it's hide and cartiguous layer. I've seen that layer stop a .45 acp ball at 10 feet.

[Peter1960]

[...] To put it another way; if 30 will work, so will 40, but not the other way around.

Fine summary!

[gunmike1]

Very good discussion right in my wheelhouse. My Bradley was under 30 from the factory from the factory, and if I only had a sharpmaker I would have gone with a 30 degree micro on CPM M4. I'm a sharpening nut, and very experienced with M4, so I pulled out my Benchstones and started with a DMT XX Coarse to thin the edge to 9 degrees per side, or 18 inclusive. The hollow grind is even nicer than a FFG when thinning edges because as was mentioned above you get in to less steel, so the bevel on my Bradley is less pronounced than my similar angle bevel om my Mule. I polished my Bradley's edge out to 16000 grit on my stones, then .3 and .05 microns to make it the sharpest knife in my house. It really is amazingly sharp and it sharpens up really crisp with minimal to no burring, and the heat treat is as good as, if not better than the Mule, which is 62.5 RC. From my experience CPM M4 easily takes and holds 20 degree inclusive edges.

I have skinned 2 pigs, including a 400 lb monstrous wild boar that I got a couple months ago. That pig took 4 people to drag, and we actually had to hook him up to a truck to drag him up to where we gutted him and then struggled mightily to get him in the truck bed. He broke the steel beam we had him hanging from he was so heavy, and he was just a monstrous sucker. Anyway, we got him completely skinned out and cut off all of his legs at the knee joint (lots of bone contact, including some light prying) and the head. The massively thick hide probably weighed at least 70 lbs, and was amazingly thick in his back "armor" area. The Mule M4 was still cutting nicely at the end of the hours we spent getting this boar ready for the butcher, and it had not one chip from all of the cutting around and on bone. CPM M4 is a great steel, especially with Spyderco's heat treat to 62.5 RC. It gets extremely sharp, has great edge retention that leaves S30V in the dust, and has very good toughness for a steel with such tremendous edge retention. The Gaylr Bradley should make an excellent skinning knife, as the hollow grind with the thin edge on my Bradley looks like it would do the slicing cuts of skinning even better than my Mule's flat grind with a similar edge thickness. CPM M4's edge retention can stay going through the largest game, and as long as you wipe it down and don't leave it wet it won't corrode. It may show a little discoloration, but it won't rust unless you really get careless with it. CPM M4 is a wonderful all around steel for utility, skinning, and most anything you can think of. For all around edge retention, toughness, and exceptional sharpness CPM M4 is a great choice.

Mike