some help please

T

Tar18

Joined
Oct 3, 2012
Messages
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Hi folks. I was hoping some one would be able to explain to me what is happening when I am attempting to sharpen a knife. I am doing 4 knives that are being used as a boning knife when the lad is cutting up a deer for the boys. I have been using my SM because the blades are so small about 1/4 to less than 1/2 inch wide, I could not use them in my Lansky. I have noticed down near the point that one side is a little sharp while the other side is not. It actually feels rounded, if I can call it that. I have used the SM before so understand it and how to use it, but this I am not sure of what is happening. Is is something that I am doing or not doing that is causing this. BTW the rest of the blade is starting to have a nice edge to it and it is only near the point.
Any help would be super.
Thanks
Regards
Tar :)
 
I don't use a Sharp Maker but use the stones free hand.
In any case it sounds like you need to focus on the rounded area and keep working in that area with the coarsest stones you have until you flatten the rounded area and make a fairly flat plane / bevel that intersects with the opposite side. You probably know this is called apexing. Then work both sides a little more to get rid of the bur that will form about that same time and you should start to get sharpness down near the point.

One question : is the tip bent ? That could be causing some inconsistency in the way the bevel forms.
 
Wowbagger
Thanks for the comment. The point is not bent, I already checked that out to make sure. I will give what you suggest a try to see if I can get the one side better.
Regards
Tar :)
 
David Martin said:
It could be flexing and not taking the grinding near the tip. DM
Click to expand...

:thumbsup:
If the blade is a boning knife, or flexible like that, I could see that being an obstacle to getting the tip sharp.

Fillet knives drove me crazy in that respect, before I started sharpening them on bench stones with my off-hand maintaining some fingertip pressure directly above the bevel at the tip, to keep it in contact on the stone. Otherwise, if just doing it one-handed, as on an SM or other device (stone held in other hand, etc), the flex of the blade, aft of the tip portion, will lift the tip away from the hone, if any pressure at all is applied from the handle end. And done one-handed, if virtually no pressure is applied via the handle in the effort to prevent flexing, the contact has to be so light as to make grinding progress extremely slow.

It'd be pretty easy to verify. Use a stone on the bench, or a piece of sandpaper on a hard surface, to test for flush contact at the tip. Just lightly press the end of the blade down with a fingertip, into the abrasive and draw it to the very tip, lifting the handle to follow the curvature to the tip until just the point of the tip is scribing a line along the surface of the abrasive, all while still maintaining that fingertip pressure directly above the bevel. It should be easy to verify if the the bevel near the tip is finally being ground as it should be.
 
Use a Marker on the edge.

Sounds like you are not getting full contact with the stone on that side
 
I think david first touched on it ... it would be my guess the boning knife is flexable and flexing just enough to not get a consistant pressure ... may want to hold the rod in your hand and pinch the blade about mid way and work the tip.
 
Hi folks sorry for the delay in answering but had a power outage and no computer yesterday.
I will try and describe the knife and what I am seeing. It has "Capital" on the handle so assume that is the make. The spine is just a tad over 1/16 of an inch and does not narrow until just before the tip. At the widest near the handle the blade is just about 1/2 inch. It does have a hollow grind to it. Oh I have done up some filet knives and did not have this problem. I then remembered to use the black marker trick. This is what I saw and hope someone can explain what I am seeing. I use a loupe every time I sharpen just to check the edge. I noticed that the black marker was off from the edge up all the way up towards the blade tip and then noticed that about an i inch or so from the tip the black marker was still showing along the edge and above it no black marker. The other side and the black marker was gone along the edge all the way to the tip. Oh by the way the blade narrows done to less than 1/4 of an inch towards the tip. Now not sure how many times this knife has been sharpened so maybe it is just worn down to that size. One more thing. There is very, very little flex to this blade and I assume because of the thick spine.
Now this is showing me something but as I am still learning, I am not sure what this is telling me. I also hope that the way I have described it makes sense to you folks.
Thanks for all of the help
Regards
Tar :)
 
"...about an i inch or so from the tip the black marker was still showing along the edge and above it no black marker."
Click to expand...

Sounds like the edge grind on that side is much wider in angle than the preset angle of the Sharpmaker. That's why ink is being removed above the edge, but not down to the edge. From your description of the opposite side:
"...The other side and the black marker was gone along the edge all the way to the tip."
Click to expand...

...it looks like that is within the Sharpmaker's set limit, as the Sharpie ink has been removed all the way to the edge.

Put differently, it sounds like the grind near the tip is asymmetric, i.e., the existing angles are different on each side.

Without completely regrinding the tip to make it more symmetrical, you might have to compensate by turning the blade's spine away from the SM's rod slightly, on the wider-angled side, until the contact is flush to the edge and you see all the ink being removed from that side, all the way down to the edge.
 
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Thank you David, again. I must say that you and a few of the other folks on this board sure know how to explain so that I get to understand what I am doing.
Now I understand and will do as you suggest.
Thanks to all of the others who have helped me.
Regards
Tar :)
 
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