My rule is if it don't shave, it’s pants. But for a working knife like that it just needs to shave but not take the arm off with it, for show it’s cool but not practical.
To cut to the chase a bit here as every mans got his own way and just stick to the Pingo for an example and in this case a factory edge revamp.
Kit for this job- Lansky system starting and ending with a worn medium diamond stone then finishing with the strop, my own that I make and I also use smuf poo. for other blades I might free hand, use the wet and dry method or belt sharpen. I've sort of learned over the years what works for me but especially since making knifes I've really had to up my game and adapt to the blade and not get stock in one system/rut.
So the blades 3mm and before the cutting edge was put on i'd bet that the final grind put the edge down to .5m. this is good and from that I knew that a 20degree set angle would match the factory grind as it was 1mm in width. what I mean by that is the surface that the stone will touch. .75mm would be 25degree and far too steep for such a blade and 1.3 (ish)mm been 17degree, only a tad less than 20degree but far too shallow for the blade, its intended use and the steel its self.
Just to touch on that with a few examples of the same blade thicknesses, and this is where Ian (longstrider) knows how and what to do with an edge to get the best from it.
1.Small 3mm flat grind hunting/prep knife, I would take this down to .75 mm before putting on the edge, then sharpen to 25degree and strop heavily. this is a strong edge for the 3mm stock, will not be all that effected by bone, less prone to chipping and will give a very sharp blade but durable. Also my utility knives are done the same way. Point being it’s thin but not too thin as you need to get the most from the edge, and ultimately what the steel can offer in terms of life.
2. The pingo/ukpk and so on. 3mm stock normally and a factory edge pre sharpen of .5mm. these are renound for been sharp and they will be due to the 3mm stock and pre grind thickness. The 20degree angle gives us a sharp fairly durable edge lending its self to been one of those blades that we know is sharp when you realy need it. its also easy to maintain as even the novice can touch it up, falling between the 20-25degree mark with an unsteady hand will still make it sharp if you know what I mean.
3. Last example, a pure cutting knife much like my leather trimmer. this again is from 3mm stock (O1 tool steel) and flat ground to almost zero. I then put a 17degree angle on it and then stropped the buggery out of it. I now have a very polished fine edge that will slice through the thickest leather with ease. if by mistake I hit something hard it kills the edge because im at the very limits of the steel. imho its a pants steel for such a tool but being high carbon, and I've followed the above theory I can get it back shaving very quickly.
ok I did not stick to been brief sorry mate. I hope that you can now look at all your knifes, examine the blade for its properties so stock thickness and what the factory edge width is. from there you can assess it a bit better and alter the angle to suite your needs.
A 4mm stock knife for general use for another example would be taken down to 1mm pre edge grind for a full flat knife or high sabre. this gives me the best place to start. all I need to do then is know the intended use and apply the above theory.
The humble Opinel is a reverse of the rule been around 2mm thick. here we have a very thin stock to start with, then they flat grind it down to zero nearly, quick swipe on a fine belt and sell it. sharp yeh, but dulls easily. due to the rake angle from 2mm to .25mm I choose a 25degree cutting edge. this is sharp still but gives better durability.
So we have a dull factory edge, we know the blade thickness, we know the pre edge grind thickness and what is the best compromise for the theory. yep spydy knows already and choose a 20degree angle, all be it some are off a tad and this will be down to the factory worker.
Good start and logically we will keep to that setting.
I start by a quick visual of the bevels looking for abnormality's, it was fine. I then move onto the cutting edge and look for any inconsistencies to the width, this is where the worker would have messed up or the jig is not set right. We were good in this case so onto the stone. Its a check I always do if I buy a second hand knife or a custom, it tells me how much time and thought was put into the final task of the build or how its been maintained. Parallel lines from plunge to tip!
So the stone and angle guide rod is checked on a flat serface, nipped up, checked again and then begin the first stage.
1. (recommended stone is a worn medium diamond or medium natural stone) first stage is simply slow to medium backwards and forwards movements over the edge starting at the plunge line to the tip in a very subtle sweeping motion covering the same part of the steel for no more than three times where possible.
I'm aiming for a truly flat bevel/edge free from the original grind marks and mess-ups. I want parallel lines all the way from the start. Once I get a rough burr coming on at any point of the knife I switch sides. Reason for that is I don't truly know how good the bevel is and I want to know that I have the best edge i can get, both parallel in width but a very accurate and consistent "V" shape all the way.
So the first stage might take a wee while, on the second side repeat what you did before so as soon as you get a slight bur forming swop over (i bet its in the same spot too!).
now we have a meeting point where the edge meets at a 20 degree angle and we must keep doing the same until the burr is formed all the way across the blade.
When we can manipulate the burr easily but still course its onto the next stage. Some old school people swipe the blade over some wood and call it done here, yanks for one, so I've seen......
2. (same worn medium or a fine diamond or natural stone) repeat the checking of the guide rods. Repeat what you did in stage one but move in one direction only which is towards the knife and with a little less pressure.
What we are doing here is just refining the flat edge and removing the deeper marks left by the last action. We want a few passes only on each side focusing on the edge been flat with no visual oddities and always been aware of the burr forming underneath. You won’t need many passes but its imperative that the last marks are gone and the burr is finer now and is intact all the way down.
Now do a quick paper test cut, it should slice well and shave with a bit of a pull. This would almost do for a working knife but.....
3. (same stone) now very low pressure on the stone working from tip to plunge line and just let it course over with only one pass in the same spot but moving away from the knife. We are really taking the burr fine now and just tickling it to move it from one side to the other. I will only repeat this four times each side max as you can destroy the whole process very easily now.
By now the edge is as flat as possible, the burr is super fine and present all the way around the cutting edge. It will shave, slice stuff well but its very weak in the sense that its been tweaked that much that the burr can roll far too much, you will have seen this before I think.
4. To the strop. Load it even with no patches, not too thick just a good surface coat.
I work from tip down. To explain why, remember we started on the stone from plunge line to tip, well we have micro serrations on a slight angle pointing from plunge line to tip(** those that start from plunge to tip are polishing over the lines, not along them). What we've done is refined them and finally pulled out the burr on stage 3.
Now we want to polish those micro serrations and as we are working away from the blade we are also replicating the same action in stage three. You will notice less marks on the strop as opposed to if you omitted stage three.
The way I start is to find my angle. Lay the knife flat, then moving forwards slowly, raise the spine up until you dig into the leather. Note the height, this is your stropping angle and the one you need to remember and work into memory.
Starting on the side with the burr first move with heavy pressure from tip to plunge line for ten passes, turn over and repeat. Now slice through some paper and note where and how the knife slices through. Repeat this process of ten passes per side four times. Paper test again.
Reload the strop and apply medium pressure when stropping with the blade.
Now repeat with six passes and six times per side.
Now repeat with four passes and four times per side.
Paper test
Now two passes and six times per side.
Now one pass and ten times per side.
Paper test
Final stage is to do one light pass on each side five times.
Watch your fingers it should now pop hairs off no problem, you will still see marks on the edge (look where I left it) but you will have a flat, semi polished blade.
Further stropping will polish the marks out even more but also create a mini convexed edge over time. I chose not to take it further on yours as I did not know how sharp you wanted it and wanted to give you the best start with the knife as I know how.
That did not stay short, but I hope that if you give it a try it will give you the results you want with other knives and will become part of your routine, plus develop your own methods.
best regards
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Originally Posted by tekbow
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