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I will try to help you with what little knowledge I have. You simple have not taken the convex all the way down to the edge. You will have to work until all the sharpie is gone from that side. BUT!!! If you just work one side you will have an uneven bevel. So you need to do a ratio. 1 pass on the good side to 2 or 3 on the side showing sharpie. (Interesting fact, I have had times like this where the line of sharpie is so small as to be visible only under magnification.) Raising the spine just slightly would shorten the job but if you like the angle just work a while longer. Or you could use a coarser grit.

Also, you need to get that spot near the kick on the side in the first pic. You can lower the handle of the knife below the stones surface and the paper will just contact one spot. This helps when you don't want to work the whole edge.

Don't give up my friend! It will be worth the effort!
 
Pord said:
Thanks for your reply!

Besides the part near the kick does that side look like I am getting the right idea? I will for sure go back over and work that spot. My form could obviously use work.

If I was to raise the spine a little on the side that has the Sharpie showing would I have to (or should I) do the same on the other side?

Random question while I am at it: How long does a piece of sandpaper last for a job like this? They go from black to gray quickly and seem to not be as coarse as they were before.
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Stop and clean it off with an eraser, often. If you don't it will clog up with removed steel and abrasive fragments and the paper will croak very quickly.

Take your time with the sandpaper and it will come around. Keep the angle nice and acute and consider switching to a backing with less give, create the convex with a bit of wrist motion instead of trusting the mousepad to make an edge with a good arc. You'll have more control over the process. You might also consider switching to a cheap surrogate knife to learn on, you could even use a plastic knife etc, just to get the hang of forming the convex. Return to your SAK with more confidence.

Martin
 
HeavyHanded said:
Stop and clean it off with an eraser, often. If you don't it will clog up with removed steel and abrasive fragments and the paper will croak very quickly.

Take your time with the sandpaper and it will come around. Keep the angle nice and acute and consider switching to a backing with less give, create the convex with a bit of wrist motion instead of trusting the mousepad to make an edge with a good arc. You'll have more control over the process. You might also consider switching to a cheap surrogate knife to learn on, you could even use a plastic knife etc, just to get the hang of forming the convex. Return to your SAK with more confidence.

Martin
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Better advice than I had. Didn't know you could clean sandpaper. Should I use a large pencil eraser?
 
Squashfan said:
Better advice than I had. Didn't know you could clean sandpaper. Should I use a large pencil eraser?
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A big pink eraser works great, as do small pieces of the crepe rubber used to clean sanding belts. One of my Washboard videos I use the board like a file, business side down, and sharpen a machete resting across my knee. Is a fairly short video and the tool didn't need a lot of work, but by the end there's a big dark spot on my knee - all stuff that gravity helped remove from the paper. All grinding produces swarf, it has to be accounted for or it will mess with the operation of the abrasive, some more than others. I'm a bit obsessive about it, especially with sandpaper. Failure to keep it clean will ruin it very quickly, keep it clean with light pressure and it can last a looong time. Most of the time I have to swap it out is for nicks in the surface, not from depleting the abrasive.

Martin
 
Pord said:
Thanks Martin! That is good to know! I thought I was going to blow through paper.

Do my photos show that I am getting the idea? Should I go and get 220 or stick with my 400 to reprofile?
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Photos look like a good start. Remember, all you're doing is grinding down the shoulders and then blending what's left into a nice shallow arc.

I'd stick with the 400 for now. The SAK steel is not that tough, and any deep scratches will need to be fixed later. Easier to take your time with the 400. Also have to recommend you place the offhand fingertips right on top of the spot you're working on. This will be a big help when you clean up the area around the kick at the base of the blade. Keep marking the blade face with Sharpie and zero in on the areas that aren't getting hit. As it all thins out you'll catch up with the apex and you'll end up with a convex that's also maybe a bit more acute than what you currently have.

Don't be concerned with getting it all done in a hurry, if possible learn on another knife that has no value to you. Is somewhat tragic to come across old knives in a box/drawer that one has ruined learning on, spoken from experience.
 
Pord said:
So don't angle the knife to take the Sharpie off the edge, but rather continue to work the knife's shoulder at a shallow angle until I reach the apex?
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This will give you a better slicer.

I have done large fixed blades with nothing but sand paper/mousepad (though now I use a much firmer, thicker, heavier, rubber mat from Tandy leather).

I convexed a FBMLE (.32 thick, 10 inch blade beast) using just the mousepad/sand paper, then strop method).


For a knife that size, 400 grit should be fine. It'll get there.
 
Pord said:
Though it's not necessary?

Though I am sure my technique is poor, I still feel as though this is taking much longer than what I have read from other people's experiences.

Another thing is I swear that my sandpaper is getting dull in no time at all. I tried the eraser trick, but I think I need a different eraser.
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Do away with the mousepad; they're much too soft, so grinding will be slow and edges will get rounded off. Instead of that, use the sandpaper over a firm or hard backing, like harwood or glass/stone. Same stropping technique as always. The natural rocking of the hands in the freehand motion will take care of the convex. The resulting edge will be crisper and the sandpaper will work MUCH faster on the harder backing; especially on thin SAK blades (X50CrMoV15 steel), as this steel is quite easy to grind.

An easy trick for convexing traditional folder-sized blades of thin and simple steel is to simply thin the edge to a more acute (~30° inclusive or less) V-bevel in conventional fashion, using something like a Fine diamond hone, or a Fine-grit SiC or AlOx stone. Then strop it on a hard-backed strop of denim, using an aggressive compound such as the stick/crayon-types used for 'cleaning' stainless steel. These are relatively small-grit but still very aggressive polishers in aluminum oxide, and will both convex and polish blades like these very, very quickly. This is how I've been doing such blades; in fact, I just did this to a Case Sod Buster (large 2138 SS pattern) in 420HC last night, using a Fallkniven DC4's diamond side (25µ) to thin the grind, then stropped it on an 18" paint-stirring stick (Home Depot) with denim firmly affixed to it; the compound used was the #2 compound from Sears (grey aluminum oxide). Followed that with some light stropping passes on a leather belt (free-hanging, like a barber's strop) with green compound. Worked like a dream. :thumbup:


David
 
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Pord said:
I will give a harder surface a try and get back to you. I was under the impression that the slack in the mousepad is what made the convex.

I thought about using my Sharpmaker on the 30 degree setting to thin the edge before I convexed, but I didn't.
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It does, but as you've found, it's softness will also make progress very slow. And when the edge gets closer to being apexed, that softness will tend to allow the sandpaper to wrap around the apex and dull it, so it becomes more difficult to refine it. Both of these drawbacks can be eliminated in using a firmer backing, as it makes the sandpaper work more aggressively (less 'cushion' under the abrasive), and the firmer backing will minimize the tendency to roll around the apex; even more so, if the sandpaper is firmly-affixed with some glue or temporary adhesive, which keeps the paper itself from lifting from the backing and wrapping around the apex.

Very thin blades like the SAK's don't need much 'help' from a soft backing to introduce the convex. The little bit of rocking back & forth via the hands will give it enough. And if a little more help is needed, a thin layer of fabric (like denim) in between the sandpaper and hard backing could also be used, or the convex can be introduced via the aggressive compound + denim stropping method I mentioned before.


David
 
Squashfan said:
Sounds like a burr to me. Does it feel sharper one side of the blade than the other?
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Most likely^

You're probably into the realm of basic sharpening now. Raise burr, flip, remove, refine.

I would put a sheet or two of newspaper over your book cover and strop it with a bunch of pressure. That should shine up any burrs nicely and allow you to see them better. Use strong overhead lighting, hold the SAK with the blade horizontal, edge facing down, blade broadside at eye level. Slowly rock it back and forth so the light plays down the face of the blade - you're looking for a small lift of steel that's at a different angle than the edge - will look like a halo or corona just off the cutting edge. Switch sides and inspect, the burr might not be continuous.

If its real small, you can apply some black compound to the newspaper and strop on that. If its larger you can remove it with some very light leading passes on the sandpaper at the original grind angle, like you're dusting the edge on the slack of the paper.

Also looks like the heel could use a little more work. Once you wrap your head around what you're doing on that convex job, its actually very easy to convex and maintain on a traditional hard stone, that will also make it easier to hit the region at the base that tends to be a real hassle with wet/dry on a yielding surface.

Check out the user's manual on the site linked through my signature below, has lots of general tips for sharpening, convexing, burr removal, very easy to read.

Martin
 
Pord said:
(...)
At this point it will cut paper decently, but will not shave (seems to pull hair more than cut it).

Thoughts?
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Either burrs or incomplete apex, or both. The apex angle may be somewhat steep (wide) as well. As Martin noticed, I'm also seeing what looks like most of the original V-bevel in the rear 1/4 portion of the blade or so, and also in the portion near the tip (think I still see some Sharpie ink there as well). That also hints that the edge overall may not be fully apexed, and/or the edge angle may still be too wide. It's something that can more easily be fixed with a HARD backing under your sandpaper (hardwood or stone/glass), or using a Fine-grit diamond or SiC hone to thin the edge grind first (all the way back to the ricasso), before attempting the convexing on softer backing. That difficulty in grinding the thicker edge portion at the rear is one of the major reasons I moved away from using softer backing under sandpaper.


David
 
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From my experience failure to shave is never because you have a burr. A burr is weak, but it is also very fine. If you are using a stropping motion and have a burr it would probably shave, but break off rather quickly. I suspect either you are not fully up to the edge or you have rounded the edge (convexed it to a too obtuse angle).

It sounds like you have thinned down your edge reasonably, but need to remove a bit more material at a sufficiently acute bevel. You have already convexed sufficiently for edge strength with a streamlined profile. I would go back and try a very modest number of strokes on the sharpmaker using the brown rods in the more acute 15-degree angle holes. The Victorinox alloy doesn't do well with much less than that angle without using diamond hones. On the other hand I get a shaving edge with this as a final step. Try about 10 strokes alternating sides (5 per side). See if the blade starts to shave. If it does try just a couple strokes per side with the white rods in the 20 degree slots.

Strops really only make sense for your final edge if they are smooth, stiff and you use extremely light pressure. The problem is that a strop rolls around your edge if it is soft or you use pressure. This is a case where less is more. After the sharpmaker you could try stropping just a couple strokes lightly. That might enhance the edge (hasn't worked for me with my Victorinox SAK). I sometimes "strop" on the white sharpmaker rods in an edge-trailing stroke.
 
At least for restoring a zero convex grind (and this works for creating a convex edge too) I like more and more using waterstones. It gives you complete control over the geometry. There is quite a learning curve but honestly I think less difficult than doing a good job of sharpening a v-edge.

The way I like it is using alternating hands, the waterstone is 90deg in front of me, the front end of the stone almost touches my belly. I use the free hand fingers for pressure points and the knife holding hand does forth and back motions across the entire stone surface. That way there is quite a consistent slight rocking motion (more obtuse near the front, more acute near the end of the stone) as long as you keep the knife somewhat tight in your hands. The pressure point-fingers as well as the starting position on the stone (close to you or further away) dictate whether you are more towards the flats or more towards the apex. That way I can control the final edge angle. I noticed about half an inch of the blade that is being abraded that way for a given starting position, for an 8.5 inch long stone that is. Not really intentional rocking motion though.

A 3000 grit stone is the last one and I try to reduce a burr as much as possible but without changing the above motion (so no micro bevel or different grind pattern). Then I strop on Martin's washboard (no risk of further obtusing/rounding the edge) or on tightly glued denim on wood with Mother's Mag to get rid of the last burr.

For maintenance (I usually maintain the entire convex bevel to keep the acute geometry) I again use the washboard the same way as the stones above with 2 sheets of printer paper and compound but this time only edge trailing towards me but with the same principles (I could use a longer washboard - hint, hint ...). I go back to the stones only if I have a chip or more restoring/geometry change is necessary.

Ok, that was too long....
 
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