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Post by m1ch43l8 on Dec 19, 2012 21:35:25 GMT
Hi all, I have literally zero experience sharpening swords/blades/knifes I have been looking into a few newbie friendly methods for getting a sharper convex edge on some swords i own. The three swords in mention: Cold steel Kukri - this came butter knife sharp dull as anything Cold steel Grosse Messer - came pretty dull it can't cut through water bottles and have read this is a known issue CAS Hanwei tactical katana - came meh sharp it can cut through water bottles but i would love to get it sharp enough to pro-form those "zero distant cuts" like in this video The two method that have stuck out are mainly the "sandpaper backed mouse pad" and "finger backed sandpaper" techniques the finger one i don't quite understand as some sat to just cut a small 2cm x 2cm square and run it up and dome the blades edge in a vertical motion and your finger will contour to the appleseed/convex geometry shape. Also there is one guide featured in this forum where "Rob" on here says to do it "with a longitudinal or 45 degree motion" (I don't quite understand what this means however). I have purchased some 400,800,1200 grit metal working sandpaper (these are the highest available grades from my local hardware store/bunnings) and planed on starting on the kukri 1st then the grosse messer and if they work out well then touching up my CAS tac kat which apparently has a micro convex edge (which i also don't know what that means). Just wanting some help and opinions of guys with may more experience than my own as to which method you think may work best and be the easiest and most forgiving/newbie friendly way in creating and sharping convex edges. Kind regards Michael
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Post by Lord Cobol on Dec 20, 2012 4:59:31 GMT
I think the mousepad & finger sandpaper methods are equivalent. Fingers & mousepads both give about the same amount of cushioning behind the sandpaper. Mousepad may be better for a big project; finger better for light touch-up. It depends partly on whether you have a mousepad handy.
With either method I move diagonally. Example: with mousepad and a dull machete, I make a few strokes diagonally left-to-right, then right-to-left, then turn the machete over and repeat -- always edge facing me and moving the machete away from me, so the edge can't bite into the paper.
Auto supply stores in my area have more fine-grit sandpaper than the hardware stores do. Up to 3000, but it is pricey.
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Post by aussie-rabbit on Dec 20, 2012 7:21:43 GMT
The Kukri has a bevelled edge, if you want an apple-seed edge you will need to re-profile the entire edge losing about 1/4 of an inch or so, alternatively glue some 400-600 paper to a stick about two inches wide and two feet long (50mm x 600mm) and use it like a file, push along the edge at a 45 degree angle (clamp the Kukri to a flat surface.) Change sides and repeat till sharp.
Use the mouse sander here, remember to work towards the edge not towards the back, start with 600 and work your way up.
Use the finger plus paper here, have patience and work a small section at a time, you will need to get higher grade paper - go to a paint shop or automotive supplier (Repco) etc. you should be able to get 2000 grit without too much trouble.
You mentioned Bunnings, so where in Aussie are you ?
Your video link -
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Post by m1ch43l8 on Dec 20, 2012 17:52:35 GMT
ricky/dadaochen Thank you for that explanation I did learn a thing or two on different types of convex edges and geometry. So what you are saying is no amount of mousepad/finger sharpening will help even though it sharpens the edge it leaves the original convex/geometry which is lousy to begin with and for optimal cutting/slicing with no drag and I will need to learn how to re-profile the convex back further on the blade to be able to improve my tactical katana. Well as much as i'd love to be able to do that i think i would end up messing my blades up perhaps i should just sharpen the edge on what have now knowing it will not compete with a blade of zero bevel geometry with a convex placed further back and look into purchasing a katana/wak/tan with better geometry with the convex placed further back with zero bevel in the future (can you recommend some budget models/brands i can look into? pref <$300-$500). I think however profiling a blade in this way may make it less "meatier" and more brittle and unsuitable for medium to hard targets and more prone to chips. At this stage i really prefer tougher blades that can cut hard targets and not chip. I am i correct on this or way off?
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Post by m1ch43l8 on Dec 20, 2012 17:55:20 GMT
Thank you for that detail i think i will try this method 1st on a $1 kitchen knife as my 1st go then my grosse messer.
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Post by m1ch43l8 on Dec 20, 2012 18:13:59 GMT
@aussie-rabit
Thanks for that break down i think i will try the mouse pad on the messer and finger on the tac-kat as u suggested. The re profile sounds harder that it's worth the way you described it on the kukri so i might just leave the bevel and try sharpen it some other way.
I don't quite understand how to use the finger method though do you slide back n forth or just towards the blade edge like the mouse pad technique? I noticed paul says to run it up and down the edge on a 30 degree angle but another thread on here says to go diagonal towards the edge. Also are you saying to start at 2000 gritt on the finger method?
I'm from st-peters Sydney so yea just down the read from a rep-co. Great to see so many aussies on here, where in this great southern land are you located?
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Post by Svadilfari on Dec 20, 2012 20:47:49 GMT
Well, not going to comment on he sharpening methods..have no experience there. But you can get finer grade Wet and Dry papers at your local auto supply shop..look in their car detailing sections. But I'm surprised you couldn't find some at Bunnings - did you check their Paint section..that's where I've usually found it ?
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Post by Lord Cobol on Dec 20, 2012 22:14:11 GMT
I think what Ricky is doing is a narrow convex edge, and his complaints against other convex edges are mostly that they are too wide an angle at the extreme front edge. Am I close ? (A sketch of the profile he aims for would help)
If I'm right then that's pretty close to what I was doing with the machetes I used to try to teach myself sharpening.
My technique varies in detail from Ricky's, but I think it is largely equivalent: I use a large left-to-right (and reverse) motion to cover the entire straight part of the edge on a latin-style machete in one stroke, which I think/hope helps a beginner like me keep it all uniform. (But that might not work on a curved blade?) Instead of a rocking motion in each stroke I pick an edge angle, do a set of strokes with it (right-to-left, left-to-right, then turn over & repeat), then I pick another edge angle and repeat. Some of it is as low an angle as I can get without letting the side of the blade scrape the sandpaper -- maybe 15 degrees. Most of it is steeper angles. With sandpaper & mousepad you don't need to worry as much about a rocking motion like Ricky uses because the cushion of the mousepad gives some of the same effect automagically.
For a factory-dull machete, sandpaper only comes in near the end of the process. If I'm in a hurry I start with a cheap edge-eater accusharp-clone to get the blunt part of the edge down from about 1.5mm down to something that won't take forever to grind down, but not down to an actual edge. Then I switch to the coarse side of a whetstone. This is to save money -- a home-depot coarse/fine whetstone costs about the same as a packet of coarse sandpaper, but lasts longer. That evens out the rough spots from the edge-eater and gets me close to an edge. Then I use the fine side of the whetstone before finally switching to fine sandpaper+mousepad. That helps smooth out whatever bevel-angle transitions I might have left with the whetstone.
This is for machetes which might used for real machete work on darn near anything, not just carefully selected cutting targets. There is also some practice on cardboard tubes like rolls of fabric come on -- not perhaps ideal targets, but we get them free from work.
Disclosure / noob-warning: I haven't done this on expensive swords. I'm new to the sword thing and I've been reading up and learning/practicing sharpening on cheap factory-dull machetes.
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Post by aussie-rabbit on Dec 22, 2012 14:58:14 GMT
I was working from the original question - vis "I have been looking into a few newbie friendly methods for getting a sharper convex endge on some swords i own." Rather than start another thread on what constitutes a convex edge
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Post by Sir Thorfinn on Jan 2, 2013 14:34:15 GMT
From a purely mechanical standpoint, could you reprofile your edge to say 20 degrees, then do 22 degrees, 24 degrees, 26 etc until you got to the actual final edge at say 30 degrees, or 60 degrees inclusive? With the really high end sharpners, you can do this, and the edge looks a little facetted. My thought is even a 40.00 Landsky kit could do this, assuming it puts the correct final edge on the blade. Which brings up the question, what would this shape convex edge do with a cut? It would be an awesome way from a machinist view to control the final edge profile.
Maybe i'll do one like that to test. I just got a Cold Steel Kopis Machete, and the factory edge is...well... terrible.
I'll try to get pictures as I go, but I'd love to hear from you all on what you think this method will do.
Sorry if I took this off topic...
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Post by m1ch43l8 on Mar 1, 2013 20:02:28 GMT
I get ya yes if you could hold the blade straight in theory that should be another easish way to make a rough convex edge. Please let me know hoe you go or if you try another method...
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Post by Sir Thorfinn on Mar 24, 2013 15:06:12 GMT
So an update and a question. I am one opf the insane people who have a 'Wicked Edge' sharpening system. IMO, best in the world right now. I took my Kopis Machete, and did a perfect 16 degree bevel, polished to near mirror, not hair popping sharp, but *way* past shaving sharp. This gave me a 32 degree inclusive edge. Scary sharp. I went and did some cuts, and it was near effortless. Keep in mind this is with a flat grind, so this made the actual edge polished to about 3/8". I put it back in the vise, touched up the edge, and proceeded to do 2 degree increments out, so I had 16-18-20-22-24. This took about 2 weeks...and there is no practical way to get a picture of the result, as it was just bizarre and ultimately useless. The look of the edge was smooth facets, so it was pretty easy to see how the convex was positioned, and where the edge was thickening. Here's where it gets wierd, the extra bevels made the same cuts very inefficient, and you could almost feel them rattle the bottle like a saw blade. Also the bottle sides were far rougher. So smooth transitions to the various angles in a convex bevel is the way to go. As an aside, the machete now has been ground flat to restore the edge from some wood chopping, nail hitting, and concrete. It is a piece of junk steel after all.
So my question. Mousepad sharpening, has anyone tried harder closed cell foam? will this do the same?
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Post by Lord Cobol on Mar 24, 2013 16:38:31 GMT
Was the "16-18-20-22-24" total angle or edge angle? In other words, were you making the front edge blunter or making a smoother transition between the edge and the side? If it was 24-edge / 48-total then maybe you made it too blunt and should have gone in the other direction?
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Post by Sir Thorfinn on Mar 24, 2013 19:26:21 GMT
Sorry, those were the individual edge angles, so inclusive the edge would have been: 32-36-40-44-48 I've got a sword with a plain convex edge, lots of metal toward the edge, and this was worse. I think it was the transitions, not smooth so added friction in the cut.
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Post by Bluntsword on Mar 25, 2013 0:23:18 GMT
Hi Guys, I'm still trying to get my head around what a zero bevel is and the different edge angles like above post, is below drawing correct?
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Post by aussie-rabbit on Apr 10, 2013 15:20:26 GMT
1 is a hollow grind, 2 is a zero grind, 3 is a bevel grind, 4 is a chisel grind, 5 is a compound bevel and 6 is a convex. Niku has a differential curve.
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Post by Sir Thorfinn on Apr 12, 2013 19:37:28 GMT
The shapes look right. I can say I have some personal confusion as I have not closely examined the higher end 'appleseed' edges. Its something you need first hand to look at. I can say I've had some fun ruining edges on 2 junk blades practicing. And eastern swords...no experience at all....
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Post by Lord Cobol on Apr 12, 2013 19:56:30 GMT
I'm not sure, but I think #6 is more like the "zero bevel" and #5 is what they are trying to avoid (?)
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Post by aussie-rabbit on Apr 20, 2013 14:36:28 GMT
No. 6 is the bullet profile and closest to an appleseed edge.
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Post by Bluntsword on Apr 21, 2013 0:33:11 GMT
Hi everyone, thanks for helping me understand. The diagrams really helped.
2 = mat cutter (soft targets) 6 = battle geometry (medium/hard targets)
So is zero bevel, in between the two?
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