When do I change???

Y

yozuri82

Joined
Feb 13, 2002
Messages
95
I have a BM 710Hs and a Spyderco Sharpmaker. I have searched and watched the video that came with the sharpener. I just have one question. How do you guys know when to change stones and when to stop? The Sharpmaker video says to do about 10-20 slices on each side of the knife with each stone. How do you tell when enough is enough?? I do not want to over do it and make the knife worse than it is. I have practiced on my Delica and other cheap knives, but I really do not know when to stop and what I am looking for (of course I am looking for the knife to be sharp :rolleyes: ). I have read that the 710hs might require extra strokes the first time anyway. Any helpful hints or ideas...
Thank You.
 
When I'm touching up a blade, I will do ten strokes on each side, alternating rods (left, right, left, right) on each grit, medium and then fine. I usually just use the corners.

If I'm reprofiling a new blade that may not be set at the same angle as the Sharpmaker, I will do thirty to forty strokes on each side, especially with the medium stones. Once the angle is set, the fine stones are good for ten each side.

There are two simple ways to tell how well you're doing. The nail test and the marker technique. On a new knife, use a marker to blacken the secondary bevel. Then when you sharpen it, you will see if you're sharpening the entire bevel or not. Once you get this right, test it by touching the edge lightly to a fingernail. If it sticks, it is very sharp. If it slides off, it is dull. Mostly, you'll get a slight catch, somewhere short of very sharp.

Have you seen the BladeForums.com Knife FAQs? There's a FAQ on knife sharpening which may help.
 
Thanks for the good response Esav. Just to make sure I got you right...you use a black magic marker and mark the edge of the knife where I am going to sharpen and start to sharpen it and make sure I do not see any black marker when I am done correct...
 
yozuri82 said:
Thanks for the good response Esav. Just to make sure I got you right...you use a black magic marker and mark the edge of the knife where I am going to sharpen and start to sharpen it and make sure I do not see any black marker when I am done correct...
Click to expand...

You want to apply the marker to the edge of the knife and then take a couple strokes and see where it's being taken off. If there is still black marker along the very edge then you aren't sharpening the edge yet. Keep using the grey stones until you start removing marker from the edge. You might want to pick up a small maginifer like a jewlers loupe to help see what's going on.

There is no set # of strokes for this. It might be 30, it might be 300. Depends on the knife, the steel, the hardness, and the angle that was set by the factory.
 
WadeF said:
You want to apply the marker to the edge of the knife and then take a couple strokes and see where it's being taken off. If there is still black marker along the very edge then you aren't sharpening the edge yet. Keep using the grey stones until you start removing marker from the edge. You might want to pick up a small maginifer like a jewlers loupe to help see what's going on.

There is no set # of strokes for this. It might be 30, it might be 300. Depends on the knife, the steel, the hardness, and the angle that was set by the factory.
Click to expand...
Thanks for the response WadeF. I think I understand it now. And I just use the white stones to get it as sharp as I want right??
 
When you are talking about a 710HS, you've got a knife with very tough steel, and if there's a lot of reprofiling to do, even the SharpMaker's gray stones will take hundreds of strokes to do the job. This is not good, because you will tire long before that, and your hand will not be steady, and you will mess up the job.

You would need diamond rods, which are an additional cost. But start with the gray and see what's happening. Use the white only when the job is done, to polish the edge. For some purposes you will find not polishing the edge is best: leaving it "toothier" gives it a microserrated bite in cutting coarse materials.

Wade is also right, that using the marker, you may see the top of the bevel or the edge is not being sharpened.

In any case, use steady, even, light pressure on each stroke. Pressing too hard will make for an uneven edge.
 
Esav had a piece of advice that everybody glossed over but it is the most important part of the answer. The nail test he described is done by touching the edge to the thumbnail at an angle. Then at the opposite angle. One angle should allow you to feel the burr that is turned in the direction opposite the stroke of the stone. You should be able to feel the burr in the opposite direction after stroking the side with the burr with the hone. When this is the case, then it is time to move to a finer grit. It has nothing at all to do with the number of strokes it took you to get there.

Learn to feel for the burr and from that point on you will understand what you're doing with the sharpening process and be able to monitor it. Stroke lightly. Feel the burr on the side opposite the side honed. Then stroke the side with the burr lightly and then feel the burr on the other side. The burr will be there until you reach a grit that is finer than around #5000. At that point you won't feel a burr any longer but you'll be way, way, way beyond what a Sharpmaker can do.

There are two elements to the sharpening process. One is forming an angle that is as acute as the hardness of the steel can maintain under normal use. The second part is polishing the bevels that form the edge. Feeling your progress with the thumbnail is not only easy, it is critically important to monitoring your progress. Without that you're just guessing and hoping.

I regularly sharpen Japanese kitchen knives to a #8000 grit waterstone which puts a mirror polish on the bevels. A sharpmaker would dull those edges pretty severely. In fact, even a leather strop would dull them a little by slightly rounding hard angles. I couldn't get the job done without regularly monitoring my progress with the thumbnail test. It is an essential part of the process from coarse grinding to fine finishing. I use the same test when steeling knives or even when I machine sharpen them commercially. Take care.
 
You must log in or register to reply here.
Back
Top