Sharpening angle for BM630?

[KLJTech]

What angle should I use on my Sharpmaker to just touch up my Benchmade Skirmish 630? I have not allowed the knife to become dull but I would rather touch it up now and then and keep it sharp. I’ve watched the DVD that comes with the sharpener but it seems to me that the factory edge on say my Manix is a different angle than the factory edge on the Skirmish. I hope that this makes sense; I’m just trying to keep the edge the same as it came in the box.

Thanks in advance for any help.
Kevin

 

[Gryffin]

Blacken the edge with a Sharpie or similar marker, and try the 30° angle for a few strokes; check the edge, and see where the stones have worn away the black. If it's right down on the very edge, carry on at 30°; if the black is worn away up where the edge grind meets the primary grind of the blade, try 40° instead.

 

[Cliff Stamp]

I’m just trying to keep the edge the same as it came in the box.

This is often very difficult especially with jigs. Most knives are sharpened freehand on a combination of belts and buffers and the edge tends to vary from one blade to the next and even along the blade. Usually the tip and/or edge near the choil are different from the main body of the blade. This angle difference can be large as it 5 degrees per side. In general it is also very unlikely that the edge on the knife is optimal for what you are doing anyway.

-Cliff

 

[KLJTech]

Using a black marker on the edge (as Gryffin suggested) to see where the material is being removed sounds like a smart idea to me.

I use the Skirmish as an EDC (at least lately) but it mainly is used to open boxes (a lot of boxes for my business) and cut plastic ties. I think that my Manix is probably the best overall blade (edge) I have for cutting whatever needs to be cut. The Manix appears to my eye to have a more acute edge than the Skirmish. My assumption is (possibly wrong) that a good manufacturer like Benchmade and Spyderco would use the best angle for the edge on whatever knife that it builds.
With the Sharpmaker in mind what angle setting would you recommend for the Skirmish?

Thanks.

 

[Gryffin]

With the Sharpmaker in mind what angle setting would you recommend for the Skirmish?

Like Cliff said, it tends to vary from knife to knife, which is why I hesitated to specify which angle to use. Try the 30 first, if the factory grind is more obtuse, go with 40.

If it came from the factory with a 40 degree edge, you'll eventually want to reprofile it to 30 degrees. But that's a long and arduous task with a Sharpmaker on S30V steel; you really need a coarse stone or diamond for that, unless you've got a lot of time and patience and don't mind ending up with a right forearm like Popeye.

 

[DGG]

I would use the 40 degree setting. It will give you a very sharp edge that still has enough steel behind it to keep it from chipping or rolling over.

What you want to get is a "double-bevel" edge grind (see link for pictures). You will only sharpen the tiny micro-bevel primary edge at the very bottom of the blade. The larger secondary bevel will occasionally need to be profiled (or reprofiled) but you can use a good knife for many years before this is required. Just sharpening the micro-bevel is fast and easy since little steel is removed in the process.

Let us know how you make out, okay?

If you had a different sharpener I'd recommend a narrower angle but the 40 degree setting works great on the Sharpmaker.

Note: You want the micro-bevel edge to be at a higher total angle than the secondary bevel edge. In otherwords if the big edge is set at 30 degrees (common with Spyderco knives) you will want the micro-bevel edge sharpened at 40 degrees.

http://forums.egullet.com/index.php?showtopic=26036

 

[Cliff Stamp]

My assumption is (possibly wrong) that a good manufacturer like Benchmade and Spyderco would use the best angle for the edge on whatever knife that it builds.

Generally they usually have to think of minimizing damage and the fact that most don't use the knives as pure utility tools on most models.

With the Sharpmaker in mind what angle setting would you recommend for the Skirmish?

Ten degree primary and 15 degree micro if you are just cutting such soft materials. You don't want to recut the 10 on the Sharpmaker. If you run such a profile and hit a staple in the cardboard you will very likely put a visible notch in the blade. To make it durable enough to minimize visible effects from such contacts run a 15/20 profile and leave the 20 degree bevel wide enough to actually still see it.

-Cliff

 

[Gryffin]

Ten degree primary and 15 degree micro if you are just cutting such soft materials. You don't want to recut the 10 on the Sharpmaker. If you run such a profile and hit a staple in the cardboard you will very likely put a visible notch in the blade. To make it durable enough to minimize visible effects from such contacts run a 15/20 profile and leave the 20 degree bevel wide enough to actually still see it.

To KLJTech: Cliff tends to quote bevel angles per side, whereas on your Sharpmaker, they're the total included angle. So when Cliff says 10 degrees perside that's 20 degrees total; likewise Cliff's 15 is the same as the 30 on the sharpmaker, and his 20 is the 40 on your Sharpmaker.

To Cliff: He's got a Sharpmaker, presumably because he wants fairly accurate angles, and doesn't want to mess with hand sharpening; 10 degrees per side isn't really an option.

 

[Cliff Stamp]

... 10 degrees per side isn't really an option.

You can just put a block under one end of the Sharpmaker and change the angle. It is pretty easy to eyeball because 10 is just half of 20. Grind one side down and the move the block to the other side and grind that down.

-Cliff

 

[Gryffin]

You can just put a block under one end of the Sharpmaker and change the angle. It is pretty easy to eyeball because 10 is just half of 20. Grind one side down and the move the block to the other side and grind that down.

I don't suppose it occurred to you that people buy something like a Sharpmaker because it's simple to use? Hell, why not just tell him to be a "real man" and grab a protractor and a SiC stone and "roll your own", while you're at it? Whatever. Like you said, he's probably better off with a 30 degree edge anyway.

One of these days, you might wanna try answering a simple question with a simple answer. Sharpening a knife doesn't have to be rocket science, you know.

 

[gbaker]

I don't suppose it occurred to you that people buy something like a Sharpmaker because it's simple to use? Hell, why not just tell him to be a "real man" and grab a protractor and a SiC stone and "roll your own", while you're at it? Whatever. Like you said, he's probably better off with a 30 degree edge anyway.

One of these days, you might wanna try answering a simple question with a simple answer. Sharpening a knife doesn't have to be rocket science, you know.

Is this personal or something? Heck this is one of the few Cliff posts I completely understand. He is just giving the guy a few options.

To KLJTeck both Cliff and Gryffin know more than I but I use only a Sharpemaker and test the angles by applying a dry easer to the knife edge. Test it a few times on 30 Deg and 40 Deg to see which works best for me (i.e. whichever angle wipes off the most of the marker is the angle I use). I'm new to this an still honing (pun intended) my skill. Regardless I know my knives will cut to the bone - it’s been tested <grin>.

 

[GarageBoy]

Also, you really can't use a stone on the recurve

 

[Cliff Stamp]

Also, you really can't use a stone on the recurve

Use the corners.

Test it a few times on 30 Deg and 40 Deg to see which works best for me ...

Once you realize that the shaping of the edge doesn't require any precision or accuracy and you forget about aesthetic concerns then sharpening gets a *lot* easier. Anything sharpens rapidly if the relief grind is significantly less than the primary grind angle and the relief grind can be done freehand rapidly with no performance concerns. Just use the Sharpmaker to sharpen the final microbevel and do any shaping with a x-coarse benchstone hone or really coarse sandpaper.

Knife angles in general are way too high for what they are usually used. If you want to cut metals and such then you need the higher angles, like I noted in the above, but for most materials you are better off going much more acute. You get better control, cutting ability, edge retention and ease of sharpening. Spyderco runs as close to optimal as I have seen on production folders with many of their knives running bevels around ten degrees. You really don't want to take that fine cutting edge and put a bevel on it which is heavier than would be applied to a felling axe.

The only concern in general is that some steels are too coarse to take fine angles and will break apart. You can tell if this is happening because the edge won't respond to the higher grits, you can also see it readily even under low magnification, 10x is easily enough. M2 for example works really well in fine edge profiles, D2 does not.

-Cliff

 

[gbaker]

Once you realize that the shaping of the edge doesn't require any precision or accuracy and you forget about aesthetic concerns then sharpening gets a *lot* easier. Anything sharpens rapidly if the relief grind is significantly less than the primary grind angle and the relief grind can be done freehand rapidly with no performance concerns. Just use the Sharpmaker to sharpen the final microbevel and do any shaping with a x-coarse benchstone hone or really coarse sandpaper.

I understand, I just haven't attempted to reprofile any of my knives. Partially from laziness but mainly I have felt that my current skill, even with the Sharpmaker, is inadequate. My wife and mom may disagree since they've managed to cut themselves on knives I sharpened for them. The original poster said he wanted to maintain the same angles out of the box so that is how I responded. My reprofiling days probably won't begin til I get an Edge Pro.

The only concern in general is that some steels are too coarse to take fine angles and will break apart. You can tell if this is happening because the edge won't respond to the higher grits, you can also see it readily even under low magnification, 10x is easily enough. M2 for example works really well in fine edge profiles, D2 does not.

-Cliff

Well that is nice to know given I have a D2 BM Grip on order. Just out of curiosity what is considered to be a shaving sharp knife? I can get most of my knives to shave a few hairs dragging the knife across skin. Forget about raising the knife above the skin – no hairs get cut. Should a knife with say a 40 Deg angle be able to remove a whole swath of hair, 20 or 30 hairs, or just a few, if properly sharpened?

 

[Cliff Stamp]

... my current skill

Sharpening does take some skill and experience, shaping the edge however does not. You may be a bit hesitant to regrind a $150 knife initially but you can get rid of this on cheap knives you pick up at flea markets. They are usually heavy damaged anyway so you can't make them any worse.

Just out of curiosity what is considered to be a shaving sharp knife?

Like tactical it depends on who you ask. For me to consider a blade to be shaving sharp it should remove all hairs smoothly on both sides of the edge when cutting close to the skin and require no draw or slicing motion.

Should a knife with say a 40 Deg angle be able to remove a whole swath of hair, 20 or 30 hairs, or just a few, if properly sharpened?

Yes. The reason it gets harder to cut above the skin is simply because it is easier to bend the hairs if you exert a force closer to the end and thus they will move before the pressure of the edge on them is enough to cut them. This is why it demands a higher sharpness to allow them to be cut similar for example as to why it is easier to cut a piece of grass if you cut up from the ground rather than down towards it.

-Cliff

 

[KLJTech]

Thank you very much for all the feedback.

Kevin

 

[longbow]

Do yourself a favor and get a Lansky Sharpening system. Follow the directions and you won't have problem. Sort of easy to profile with one too, and use WD40 for honing oil instead of what they give you. You can get extra stones for it too. An extra coarse makes it easy to reprofile a gind to what you want it to be. I use mine on knives up to 7.5-8" long and works fine. keepem sharp

 

[kevtan]

KLJtech, skip all the rest of the clamping system and get the Edgepro Apex. If you dont like it they sell off real quick in the secondary market. Also, try to get the chefs choice magnetic diamond file with the 3 grits. They cost real cheep and you can just double sided tape them to the stones of the apex.