Stropping: angle plus pressure

Excellent tip about finding the correct stropping angle. This always bugged me because of the 'give' in leather, but this tip makes sense and worked well for me. Thanks.
 
Magnaminous_G said:
I'm going to... finish with bare leather.
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I only charge one side of my strop with abrasives. I treat the other side with Fromm Strop Dressing. It keeps the leather from drying out, and gives the leather the just right amount of "grab". It's a lot easier to apply than abrasives, and cleaner, too. I'm thinking about getting a second Bark River strop, and just treating both sides of it with Fromm Strop Dressing.
 
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handamerican said:
and it's very easy to dub and dull a good edge with any leather.
....
at the end of the stroke just stop - stop and pull the blade up and off the leather.

If you pull the blade off of the leather at the end of the stroke in an arc, which is a very normal thing to do, you will have undone all of your work.
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Sorry to be late into this thread.

I confess to being one of those people who managed to make a good edge dull by stropping -
of course that was years ago -

the BIGGEST hint - which I had diligently ignored - was how to flip the blade over to strop the other edge

I got so frustrated with stropping and getting duller edges that I was about to give up - when I recalled the advice and lifted the blade off the leather the unintuitive way with edge first, totally stopping any contact - and that was all there was to it, I had sharper/better edges after stropping.

Before I had done exactly as described - as if continuing the strop stroke/arc and lifting the spine first - to flip the blade over for the other side - unbeknownst to me I was actually raking the edge - hence the dulling -

Stopping and lifting edge first or rolling the blade over its spine to flip over the blade solved that.

Once practiced - rolling over on the blade's spine to flip the blade over then comes naturally -
even if it does not seem as fluid as flipping over the knife over its edge........

--
Vincent

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Can someone please further explain the below portion of Keith's post? I am new to knife sharpening and I cannot picture in my head what exactly he is referring to here. Do you not need to arc the stroke in order to get to the point of the blade?

handamerican said:
Once the edge bites pull back with light pressure and at the end of the stroke just stop - stop and pull the blade up and off the leather.

If you pull the blade off of the leather at the end of the stroke in an arc, which is a very normal thing to do, you will have undone all of your work.

Keith
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blueorb said:
Can someone please further explain the below portion of Keith's post? I am new to knife sharpening and I cannot picture in my head what exactly he is referring to here. Do you not need to arc the stroke in order to get to the point of the blade?
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Yes, to some extent you do. I think what Keith was emphasizing, is to make sure to stop all motion at the end of the stroke, before carefully lifting the edge from the strop. This, as opposed to 'sweeping' the blade up and away from the strop, at the end of the stroke, which risks rounding off the edge.

With regard to lifting the blade for stropping the very tip, I usually strop in 'sections' of the edge, at a time. Make a few passes in the straighter portion of the edge, using the technique as described by Keith. Then, do some separate passes on the belly/curved portion (which does obviously require lifting the blade a bit, to fit the arc of the belly). Then, I focus on the straighter portion near the tip only. This can make it somewhat easier to control the angle of the blade, for the specific portion being stropped. With practice and experience, one can blend these together to do most or all of the blade in one carefully executed pass.
 
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This is my way of sharpen a convex edge – and strop it with a “leather sharpener”.

http://youtu.be/nynku3GQOoY

I use an Angle Cube to show that I sharpen this knife with 3,5 convex sphere. (I also sharpen it in exactly 27 degrees on its cutting edge).

I start with a ceramic sharpener and shows how the angled guide rod works. I paint some marks on the edge – and take away some small parts of the markings with different parts of the sharpener – and take away the complete markings by using the complete length of the sharpener.

I change to a 24 cm long leather sharpener (strop) – but I only use a part of the sharpener – that part decides by the stop screws you can see on the guide rod (the length of the part of the sharpener I use decades the convex sphere degrees).

I can move the leather strop also against the edge if I like to, the knife is locked in its position by strong magnets and do not move – the sharpener is locked in its angle = the edge can’t slice the leather (works also on flat edges).

I use 3 micron paste on the leather sharpener. The polishing is not ready yet – but the edge push cut paper.

Thomas
 
Even with great exercise in art & discipline of stropping, convexing is almost guarantee...

For mere mortals - edge can only be strop so many times before it's too convex - which effectively dull for cutting stiff/wedgy materials. When cross slice newsprint and it steered right (for right hander, opposite for left hander), then the edge is too convexed. The side of the paper holds by hand is effectively more stiff than the cut-off/wedged side, therefore it will steer away. Time to sharpen or hone the edge.

Is it possible to repeat strops and preserve sub-micron edge (for non hollow grind blade) at consistent/repeatable angle +- 5 degrees? Alternative freehand methods?
 
bluntcut said:
Even with great exercise in art & discipline of stropping, convexing is almost guarantee...

For mere mortals - edge can only be strop so many times before it's too convex - which effectively dull for cutting stiff/wedgy materials. When cross slice newsprint and it steered right (for right hander, opposite for left hander), then the edge is too convexed. The side of the paper holds by hand is effectively more stiff than the cut-off/wedged side, therefore it will steer away. Time to sharpen or hone the edge.

Is it possible to repeat strops and preserve sub-micron edge (for non hollow grind blade) at consistent/repeatable angle +- 5 degrees? Alternative freehand methods?
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Can this be stropped out to a dull convex edge. I like about 40*, free hand sharpened and stropped cleaver. And some common sense when using the d*mn thing. My cleaver doesn't need to push cut news paper.

2-cleavers-shun-wu.jpg
 
You can greatly minimize the risk of 'over-convexing' on a strop, simply by stropping on a firmer substrate. Reduce the thickness or softness of leather, or use wood (anything from balsa to hardwoods), or even strop on varying thicknesses of stacked paper over a hard backing. The less 'give' there is in the stropping substrate, the less likely the edge will get rounded off. More often than not, most of the issues I've had with over-stropping have resulted in removing too much of the the 'toothy' bite of the edge, and less to do with excessively rounding or convexing it.

As with all sharpening, good technique trumps all. Low angle and very light pressure will also minimize the chances of rounding off an edge on a strop. If and when the edge does become a little too dull, one can simply 'strop' the edge on some more abrasive material (sandpaper), and the edge can be restored that way. That's how I usually do it. :)
 
Obsessed with Edges said:
You can greatly minimize the risk of 'over-convexing' on a strop, simply by stropping on a firmer substrate. Reduce the thickness or softness of leather, or use wood (anything from balsa to hardwoods), or even strop on varying thicknesses of stacked paper over a hard backing. The less 'give' there is in the stropping substrate, the less likely the edge will get rounded off. More often than not, most of the issues I've had with over-stropping have resulted in removing too much of the the 'toothy' bite of the edge, and less to do with excessively rounding or convexing it.

As with all sharpening, good technique trumps all. Low angle and very light pressure will also minimize the chances of rounding off an edge on a strop. If and when the edge does become a little too dull, one can simply 'strop' the edge on some more abrasive material (sandpaper), and the edge can be restored that way. That's how I usually do it. :)
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:thumbup: Good advices, I do practice them. For charged-strop, I tried many surfaces & substrates - including 3m film on glass. It comes down to a simple scenario - say an edge loss 100nm height or looking straight down the edge and its thickness increased/dulled by additional 150nm. In order to preserve the edge geometry, we need to remove uniform 100nm from starting from cutting edge all the way up bevel primary shoulder. Low pressure at exact bevel angle will still convex the edge due to surface flex & lap curling up. Low pressue at lower than bevel angle force more pressure toward the shoulder so metal abrading more toward the shoulder, less near the edge and perhaps perfect at the edge, aha it's convexing still. Consistency is ellusive, there must be a better way?
 
I am fairly new to stropping, that is to say, it's something I recently decided would be worthwhile to to add to my knife sharpening regimen. Over the past couple weeks I have spent countless hours experimenting with different substrates (pieces of old belt leather, bare MDF, bare leather) charged with diamond compound in different grits. Basically, I have been trying to find something that works, and is within a fairly small budget. My results thus far have been fair, at best, and I could be mistaken, but it seems like I am spending an excessive amount of time stropping.

When I sharpen, I use a Lansky guide with my Diafold hones and I have no problem getting knives sharp this way. As far as stropping goes, I read somewhere on here about someone using a hone, covered with paper first-aid tape and charged with compound, as a strop. The concept makes perfect sense to me, and as far as I can see it should work perfectly using edge trailing strokes. Has anyone tried, and gotten good results with this method? If so, would you describe your technique? Thanks!
 
When used with compound, virtually any material on a smooth, flat surface can be used with great effectiveness. I have no doubt the tape could work. Each and every substrate will produce different results with a given compound, due to differences in softness, texture and how the compound embeds itself in the material. This is a great thing, because it gives you an almost infinite number of ways to fine-tune your stropping to your blades. Different steels will respond in their own unique ways to a given stropping 'recipe' (compound + substrate + pressure + angle + speed of stroke + etc...). There's never any excuse to stop experimenting with something new.
 
Obsessed with Edges said:
When used with compound, virtually any material on a smooth, flat surface can be used with great effectiveness. I have no doubt the tape could work. Each and every substrate will produce different results with a given compound, due to differences in softness, texture and how the compound embeds itself in the material. This is a great thing, because it gives you an almost infinite number of ways to fine-tune your stropping to your blades. Different steels will respond in their own unique ways to a given stropping 'recipe' (compound + substrate + pressure + angle + speed of stroke + etc...). There's never any excuse to stop experimenting with something new.
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The reason I am asking is because I use DMT Diafold hones with my Lansky clamp, and I realized that there is quite a big jump between my EF (9 micron) hone and my EEF (3 micron) hone, and nothing to fill the gap. I do have some 6 micron DMT paste, which it seems could technically be used on a strop after the EF hone before progressing to the EEF hone. Therefore, using the paper tape with compound in the manner described above would would allow me greater consistency and efficiency, as I would not need to remove my knife from the clamp to strop, could maintain a consistent angle, and could progress directly to the EEF hone afterward. Any thoughts?
 
Alcoholiday said:
The reason I am asking is because I use DMT Diafold hones with my Lansky clamp, and I realized that there is quite a big jump between my EF (9 micron) hone and my EEF (3 micron) hone, and nothing to fill the gap. I do have some 6 micron DMT paste, which it seems could technically be used on a strop after the EF hone before progressing to the EEF hone. Therefore, using the paper tape with compound in the manner described above would would allow me greater consistency and efficiency, as I would not need to remove my knife from the clamp to strop, could maintain a consistent angle, and could progress directly to the EEF hone afterward. Any thoughts?
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This is where the combination of the substrate + compound makes most of the difference, as opposed to the particle size alone. The 3 micron hone will likely be more aggressive (cut more deeply) than the 6 micron paste on a strop. Because of the extra 'give' in the strop's substrate, combined with the fact that the paste won't be as firmly embedded in it, compared to the diamond permanently embedded in the nickel (over steel) on the hone, the 6 micron paste won't cut quite as aggressively into the steel.

I wouldn't worry about the perceived gap in between the 9 micron and 3 micron hones, and just follow those with the 6/3/1 micron paste, in that order. If you are concerned about that gap, just spend a little extra time with the last 2 hones (9/3 micron), before using the 6 micron paste. Finish the 9 micron step with some very light strokes to smooth out those scratches somewhat. Then, take your time with the 3 micron hone, to ensure the 9 micron scratch pattern is completely cleaned up, also finishing with very light strokes. Then go to the pastes on the strop. That sequence should work very well.
 
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Obsessed with Edges said:
When used with compound, virtually any material on a smooth, flat surface can be used with great effectiveness. I have no doubt the tape could work. Each and every substrate will produce different results with a given compound, due to differences in softness, texture and how the compound embeds itself in the material. This is a great thing, because it gives you an almost infinite number of ways to fine-tune your stropping to your blades. Different steels will respond in their own unique ways to a given stropping 'recipe' (compound + substrate + pressure + angle + speed of stroke + etc...). There's never any excuse to stop experimenting with something new.
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Based on this statement I put some buffing compound on a board and stropped my GEC cattleknife. I've been having a hard time getting the wharncliffe sharp enough. Lo and behold the new method worked. It's really true that you have to experiment and different steels need different methods. Thanks for the inspiration!
 
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