Sharpmaker - not very precise

N

nuggetz

Joined
Jul 25, 2013
Messages
39
I really wish the manufacturing tolerances for the stones themselves were better. I find that the angle of the left stone is different than that of the right stone. The stones themselves are nowhere near flat and the thickness on different parts of the stone varies as well. Would there be any benefit to flattening the stones? When I look at the stones head on I feel that there's they're sitting on different planes. Couple that with rotating a stone to a fresh side while sharpening and that'll introduce more inconsistencies no matter how straight you try to keep your hand. Not sure if the base is faulty or just something we have to live with when using this system but there's a lot of play where the stones sit in the base.

What guarantees that both stones are sitting at the proper angle? It depends on the condition of the ends of the stones and the cutouts of the triangles in the plastic base. I know things aren't quite right. If I do a stroke on the right side and compare it to the left it feels different if I rotate the entire base without swapping the stones and repeat the same strokes which tells me that the angles are different on each side.
 
"(...) If I do a stroke on the right side and compare it to the left it feels different if I rotate the entire base without swapping the stones and repeat the same strokes which tells me that the angles are different on each side."
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It's actually more likely that the 'difference' in angle you're feeling (as opposed to measuring) is the difference in bevel angles on each side of your blade. This is VERY common with knives ground by hand (from the factory/maker), and the overwhelming majority of knives' edges are just that: hand-ground. A lot of complaints about the angle mis-match of asymmetrical factory edge grinds can be found in the many Sharpmaker-related threads on the site. The defect in the edge grinds is more noticeable on the Sharpmaker, especially if one side of the edge grind or the other is outside the Sharpmaker's limits (wider than it's own 15/20° settings, per side). The 'fix' for such a problem is to regrind the edge to be symmetrical and within the useable limits of the Sharpmaker's settings. Some refer to this as 'indexing' the edge to the tool. Ideally, re-grinding a blade's edge to 30° inclusive (15°/side) or less makes the results much more rewarding, when touching up on the Sharpmaker.

There is a little angle variability (flatness, set angles) and movement (wobble) in the Sharpmaker itself, but that accounts for much less variation in finished results than does the variability in the user's own hands & stroke. The Sharpmaker makes accurate results somewhat easier to achieve by hand, by orienting the rods in a vertical configuration that suits the natural slicing motion of the user's hands. But it's still a 'freehand' system nevertheless. In the tens or dozens or hundreds of consecutive strokes a user will make, to sharpen a blade, there's no way each and every stroke is going to happen at the same exact angle, even on this sharpener. There's bound to be at least a degree (or three) of wobble in the user's hands, especially the longer the work goes on, due to muscle fatigue or loss of focus.


David
 
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Actually, its not the angle of the bevel since I rotated the entire sharpmaker base so that the stones on the left are now on the right and vice versa and it feels different. If it was the bevel and not the angle produced by the SM then the strokes would feel the same. I understand that if the left side of the knife was ground at 24 degrees and the right side at 20 then the left hand stroke would feel "smoother" than the right since the edge wouldn't be making contact with the stone. In my case, I can repeat the strokes with the only difference being that the entire sharpmaker was rotated so that the left and right blades were swapped. I didn't swap the stones themselves since I wanted to use the same sides of the stones and not introduce any other variables for the test and it feels different which tells me its the stones/angle of the sharpmaker.
 
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There's also the difference in feeling by just using one hand. If you are that OCD, you could try switching hands when you switch sides.
 
Get a digital clinometer and measure the angle of the dangle. You can correct the "factory" settings with shims under the base.
 
I think the Sharpmaker is the wrong device to use if you are looking for accurate angles. I was able to achieve great results with it, but it was largley by feel, making minor adjustments as needed. A guided system would be more to your liking if you are concerned with angle accuracy.

I stopped using the Sharpmaker when I got tired of cleaning the stones in the middle of a shapening session. Power is the way to go.
 
never too sharp said:
I think the Sharpmaker is the wrong device to use if you are looking for accurate angles. I was able to achieve great results with it, but it was largley by feel, making minor adjustments as needed. A guided system would be more to your liking if you are concerned with angle accuracy.
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Actually, I picked up a Lansky system with the hopes of profiling my edges to be 20 degrees but setting the Lansky to 20 degrees doesn't mean you'd get 20 degrees. Still trying to find someone who knows how far off the edge of the clamp the edge of the knife has to be in order to get close to 20. The rest I could do with the Sharpmaker
 
nuggetz said:
Actually, I picked up a Lansky system with the hopes of profiling my edges to be 20 degrees but setting the Lansky to 20 degrees doesn't mean you'd get 20 degrees. Still trying to find someone who knows how far off the edge of the clamp the edge of the knife has to be in order to get close to 20. The rest I could do with the Sharpmaker
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Oof! Man, pull out your old trigonometry formula and see what difference it makes...edge protruding 1/2" vs 3/4". I'm curious to know the difference in angle this creates, but I'm guessing its going to be pretty laughable. Hopefully someone smarter than me will come along and do it. :-). But even if it changes by a full degree (which im sure it wouldnt come close to doing) is it going to matter if you sharpen at 19 instead of 20? OCD can actually make for sharp edges, but there is a point at which it is too much. Just my ¢.02.
 
Surfingringo said:
Oof! Man, pull out your old trigonometry formula and see what difference it makes...edge protruding 1/2" vs 3/4". I'm curious to know the difference in angle this creates, but I'm guessing its going to be pretty laughable. Hopefully someone smarter than me will come along and do it. :-). But even if it changes by a full degree (which im sure it wouldnt come close to doing) is it going to matter if you sharpen at 19 instead of 20? OCD can actually make for sharp edges, but there is a point at which it is too much. Just my ¢.02.
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What I'm trying to do is reprofile an edge so that any follow-up work with the sharpmaker doesn't require two hours of my time to get a good edge. There have been plenty of people on this forum in many different threads preaching that the Sharpmaker is not a good reprofiling tool. There are also plenty of people complaining that they stroke their edges on the SM stones for hours and never get a sharp edge. Thats because the bevel angle on their blade differs from the 20 or 30 degrees that the SM produces if used as marketed. The Lansky is the right tool to get you close but how many degrees off from 20 would you need to be in order for the Sharpmaker to be ineffective? Im trying to avoid setting the Lansky too far in either direction and would ideally like to be as close to the selectable angles as possible. That's where the trigonometry comes in. Has nothing to do with OCD:-)

Trust me I agree that producing exact angles in general is not important but in this case it's a bit different. In hindsight I should've just purchased the diamond stones for the Sharpmaker and called it a day.
 
nuggetz - how long have you been sharpening knives if I may ask? It seems that you get somewhat upset about the non-perfect sharpening devices out there and that is usually a beginner complaint. I was the same, blaming the device/stone/clamp for poor results!

You may have a lemon sharpmaker although I have not heard yet of one like yours. Many of us have used the sharpmaker for quite some time and maybe all it needs is working on your technique. And of course if the edge angle is anywhere more than 20 dps, you will have to grind away quite a bit of metal. Read OwE answer again, remember that even if you use the same hand, the motion on the left stone is different than the motion on the right stone. Make sure your surface is flat that you put your Sharpmaker on (horizontal, use a bubble level to find out). Your lansky or any other clamp device is also not perfect. Your change your angle depending how tight you screw it on any time plus the "set angle" might not be absolute correct. Plus, if you have a longer blade, the angle is going to be different from the edge near the clamp compared to the edge at the tip for instance due to longer Adjacent (the angle gets more obtuse the further away you are from the clamp!).

So, what are you going to do about all this? Do you want a sharp knife or are you one of those folks that want to have the perfect centred, hair popping edge just because?

Here is my advice for what it's worth: Get a Norton Crystolon combi or a Norton India combi stone, read how to sharpen a knife freehand, dig through all the threads here on BF, read the stickies on Maintenance and Tinkering and practice. Come back with questions that (for sure) will occur, that can be answered more specifically and try to not blame devices for poor results.
 
nuggetz said:
What I'm trying to do is reprofile an edge so that any follow-up work with the sharpmaker doesn't require two hours of my time to get a good edge. There have been plenty of people on this forum in many different threads preaching that the Sharpmaker is not a good reprofiling tool. There are also plenty of people complaining that they stroke their edges on the SM stones for hours and never get a sharp edge. Thats because the bevel angle on their blade differs from the 20 or 30 degrees that the SM produces if used as marketed. The Lansky is the right tool to get you close but how many degrees off from 20 would you need to be in order for the Sharpmaker to be ineffective? Im trying to avoid setting the Lansky too far in either direction and would ideally like to be as close to the selectable angles as possible. That's where the trigonometry comes in. Has nothing to do with OCD:-)

Trust me I agree that producing exact angles in general is not important but in this case it's a bit different. In hindsight I should've just purchased the diamond stones for the Sharpmaker and called it a day.
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Here's the thing. All you really need, in order to get hair-popping edges in just a few passes on the SM, is an existing edge grind either at or less than 30° inclusive. It doesn't need to be exactly 30/40° inclusive to do so. Nor does it need to be perfectly symmetrical; a variation of even 2-3° per side isn't going to produce any real noticeable cutting degradation, so long as the apex is complete and crisp. So long as you have that acute edge, set within the angle limits of the SM, it can be brought back to hair-popping in perhaps 10 passes per side (assuming you keep up with touch-ups, and don't let the edge get too dull).

On your Lansky, shoot for putting your edge about 3/8"-1/2" from the front of the clamp. That'll get you very close to the 15°/side starting off point.


David
 
Obsessed with Edges said:
All you really need, in order to get hair-popping edges in just a few passes on the SM, is an existing edge grind either at or less than 30° inclusive.
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Nuggetz,
If you take away only one thing from the advice given above (all of which is correct by the way), I think the above sentence is what you want to remember. The SM is a good product for the $. However, even how much sideways pressure you use when trying to sharpen a knife using the SM can impact your final result. Too much pressure and you'll be pushing the edge from side to side; too little and you may not be removing enough metal to touch up the edge. The trick is to try doing it one way with the SM and if that does not work, try something else with the SM. After all, if you keep doing the same thing, you're going to keep getting the same result. Too, there is a lot to be said for learning how to sharpen freehand. Possessing the skill itself can be rewarding and it does not have to take any longer to sharpen freehand than it does with a Lansky or SM.
 
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