Sharpmaker vs. Recurves!

[pbpasquale]

Hey everyone. Last night I spent quite quite awhile sharpening my new BM 710 on the Sharpmaker. Although the knife is sharper than when I received it, it doesn't have that WOW factor; particularly at the back of the concave part. I used primarily the corners of the of the stones at 20 degrees after back beveling a bit at 15 degrees. I have also read that it is better to use the flats of the stones and that it is easier to sharpen each portion of a recurved blade seperately. I am hoping that I can get a consensus from some of you sharpening gurus on the best techniques to use with the Sharpmaker for sharpening recurved blades. Thanks and Semper Fi to all the Jarheads out there!

 

[amroc]

I don't use a sharp maker, I'm using an old Crock Stick system (exact same idea, but with circle rods instead of triangle) and with my BM 710, I've found that you have to hold the knife at a few angles as you go along. Think of it as trying to stay perpendicular to the edge, not just the spine. So with a BM 710 you'll have a tilt forward, backward, finished by forward. Does that make sense? Also, D2 gets sharp, but not as smooth as say, CPM-S30V, in my observations. I'm sure there are others on here that can help you out more. Youtube might have some information as well.

 

[yablanowitz]

You will likely get a better edge on the concave section of the edge by using just the corners. It won't hurt anything to do the whole edge that way. My experience with BM edges is a few years out of date, but back then they often came with 40 degree or larger edge angles. Coupled with the wear resistence of D2 steel (that's what my 710 is, I don't know about yours) you are looking at a long, wearying session on the corners of the brown rods at 15 per side/30 included to set a new backbevel if you want that wow factor edge. A little probably won't do anything, but blackening the edge bevel with a Sharpie and taking a couple of passes on each side will tell you for certain where you are removing steel.

 

[THG]

How do you use the flats on the 710? I don't think you can with the recurve.

 

[Jason B.]

I don't use a sharp maker, I'm using an old Crock Stick system (exact same idea, but with circle rods instead of triangle) and with my BM 710, I've found that you have to hold the knife at a few angles as you go along. Think of it as trying to stay perpendicular to the edge, not just the spine. So with a BM 710 you'll have a tilt forward, backward, finished by forward. Does that make sense? Also, D2 gets sharp, but not as smooth as say, CPM-S30V, in my observations. I'm sure there are others on here that can help you out more. Youtube might have some information as well.

Well put but you also need one more movement, as you get to the belly of the knife the handle of the blade must be lifted away from the stone. In the OP's case it would be in the direction of the other stone. Imagine it like making a wave motion or following a "S" in two directions, vertical and horizontal.

 

[amroc]

Well put but you also need one more movement, as you get to the belly of the knife the handle of the blade must be lifted away from the stone. In the OP's case it would be in the direction of the other stone. Imagine it like making a wave motion or following a "S" in two directions, vertical and horizontal.

Is that using the flats or the corner? I would try to keep my blade forward and not move it side to side really at all on my crock sticks. That's how I've done my 710 before. Recurves are a PITA to sharpen sometimes, but I love the power you get out of them when they're done right.

 

[Jason B.]

Is that using the flats or the corner? I would try to keep my blade forward and not move it side to side really at all on my crock sticks. That's how I've done my 710 before. Recurves are a PITA to sharpen sometimes, but I love the power you get out of them when they're done right.

No need to use the corners the flats work fine. If your keeping your knife perfectly vertical and horizontal your not keeping a consistent angle throughout the curve of the blade. Think of it like this, you must follow the curve of the blade and the angle.

 

[stitchawl]

The 710 is my EDC and has been for years. And for years I've been doing my touch-ups on it using a Sharpmaker. (I use an EdgePro for actual sharpening.) It's important to understand that you must change the relationship of the spine to the stone as you draw the knife downward. If you keep it horizontal throughout the draw you won't be getting the proper angle in the recurve or at the tip. Look at the contact point from the side; you must keep the edge, and not the spine, perpendicular to the stone. This will mean that you must move your wrist in a wave motion as you draw down the stone. Use either the corners or the flats. The rods are thin enough so it really don't make that much difference.

Stitchawl