sharpening a recurve blade

[John E Woven]

Hi, I'm wondering about re-profiling and re-sharpening a blade with a recurve in it. The knife in question is a Benchmade 710d2, and I would like to take advantage of the strength and durability of the D2 steel by re-profiling the blade from the standard 20-25 degree per side it comes with.
What sharpening systems are there that can do this ?
Is there a steeper angle that is recommended for the improved edge retention of the D2 ? I've heard figures ranging from 24 degrees inclusive (!!!) up to 40 degrees inclusive

Thanks.

 

[richard j]

what kind of sharpener do you have to sharpen with now? i use paper wheels to sharpen with and they work great for just about any type of v edge. check out this thread on the paper wheels. http://www.bladeforums.com/forums/showthread.php?t=578787

 

[John E Woven]

I haven't sharpened the 710 yet.

I currently use just a regular stone with a coarse and fine side. Cheap thing, works alright on the 154cm on my mini-grip (after hitting it with the steel and stropping it, it's sharp enough to shave hair with)

 

[THG]

Well since it's a recurve blade, you'll have to use sharpening rods of some sort. You can use Spyderco sharpmaker rods and Spyderco files or DMT rod sharpeners. I guess they also have wheels that are thin enough or shaped to do recurves. I think you can use a belt sander, too, if you have a belt that's thin enough.

 

[Obsessed with Edges]

I used a Lansky guided rod system to reprofile a ZT-0350 in S30V (also a recurve). You don't necessarily need round/oval rods or files to get it done. In the case of the Lansky hones, they are about 1/2" wide (flat surfaced). They are narrow enough so as to be effective in a task like this. And, since you're going more acute with the edge angle, the radius of the recurve will, in effect, be less of an issue (the curve effectively becomes 'flatter' as the bevel angle is reduced). The key is to use LIGHT pressure with the hones, as the corners of the hones will be making most of the contact with the edge. Diamond hones would work best in a setup like this, they'll allow you to remove a significant amount of metal using the coarser grits at LIGHT pressure.

I don't knock using round or oval hones/files, but most of these are available only in Fine/Extra Fine grit (ceramic or diamond). For heavy metal removal (reprofiling), especially with harder/tougher steels like D2 or S30V, you want to do most of the 'grunt work' with as coarse a grit as possible. Most coarse/extra coarse diamond hones are FLAT, so narrower is better for recurves, if you choose to take that route.

 

[John E Woven]

Would something like a Spyderco Sharpmaker set on the 30 degree inclusive setting be good, or can / should I go with a steeper angle ?

Thanks for the tips, Obsessed with Edges.

Been wondering though: If you vary the distance you seat the blade, wouldn't that change the angle of your sharpening ? How does the Lansky system deal with this ?(exaggerated) drawing..

 

[Josh K]

Would something like a Spyderco Sharpmaker set on the 30 degree inclusive setting be good, or can / should I go with a steeper angle ?

Thanks for the tips, Obsessed with Edges.

Been wondering though: If you vary the distance you seat the blade, wouldn't that change the angle of your sharpening ? How does the Lansky system deal with this ?(exaggerated) drawing..

It doesn't, at least not really. Neither does the Edge Pro though I could be mistaken.

 

[Obsessed with Edges]

Would something like a Spyderco Sharpmaker set on the 30 degree inclusive setting be good, or can / should I go with a steeper angle ?

Thanks for the tips, Obsessed with Edges.

Been wondering though: If you vary the distance you seat the blade, wouldn't that change the angle of your sharpening ? How does the Lansky system deal with this ?(exaggerated) drawing..

Yes, varying the positioning of the clamp on the blade will make a difference in angle. Your drawings are good, they illustrate this point very clearly. I think most who've used the Lansky for reprofiling are aware that the angle markings on the clamp are essentially meaningless. Same applies to any clamp & guided rod system (Lansky/GATCO/Aligner). The width of the blade beyond the edge of the clamp will determine, more than anything else, what the 'real' angle will be.

I pay absolutely no attention whatsoever to the marked settings. Generally, I use the lowest possible position on the clamp anyway. With small & very narrow blades (< 1/2" wide or so), you'll probably have to use a higher setting to prevent the hone from colliding with and 'sharpening' the clamp. The great thing about reprofiling is, you don't really need to focus on attaining a specific angle measurement for your bevel. With more acute edge angles (which produce wider bevels), it's MUCH easier to maintain the reprofiled edge with light, freehand passes on a fine/xtra-fine stone or on a strop.

 

[THG]

Would something like a Spyderco Sharpmaker set on the 30 degree inclusive setting be good, or can / should I go with a steeper angle ?

The Sharpmaker will work. The angle is your choice, but the Sharpmaker only offers 40° and 30°. Of course, you can vary it with your own hands by tilting the knife.

Been wondering though: If you vary the distance you seat the blade, wouldn't that change the angle of your sharpening ? How does the Lansky system deal with this ?(exaggerated) drawing..

Yes, it matters where you put the clamp. If you don't put it in the exact same spot every time, you will change the angle each time you sharpen. That's why I don't recommend clamp systems for regular sharpenings. I profile knives with a clamp and then sharpen by hand from there.

If you want to sharpen with a clamp, you've got to find a sweet spot where you're sure you can get the clamp exactly in the same position every time.

 

[John E Woven]

Just as an update: I ended up buying a sharpmaker. in a few minutes, you can easily make a 710d2 sharp enough to seperate hair. The recurve is no problem at all

Amazing stuff.