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The Folding Knife (& Switchblade) Forum The materials, techniques and the designing of folding knives. |
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#1
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Sharpening questions
I am about to finish up my second folder and want to put a nice correct edge on it. Currently I am using a belt grinder and do passes up to 600grit. The edge is sharp and looks like a V. When I compare this to a bought knife there are some differences. The bought knife has a taper and then bumps down to a steeper V. I hope this makes sense.
I picked up a lansky sharpening system and would like some help and guidance. I have not shaped this blade yet, still have heat treating etc to do. Do I continue with what I have done in the past and basically make a V or is there another way. The Belt sander way seems to take out the degree and takes it from .095? to edge. I may just be completely wrong. Thanks |
#2
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The way a knife is correctly sharpened generally depends on the steel type, and the Rc hardness...blades that are overly hard must have a steeper "V" to lend support to the edge and keep it from chipping. Softer blades will tend to have less of a "V" because they won't chip.
Ideally you want the steel to be the proper hardness for the type of grind and the type of edge you intent to put on it. For example, with most of my forged blades, I shoot for a final edge Rc or 57-59, BUT, I also generally flat grind the majority of the blade, and the final 1/4" or so towards the edge is convexed to a "zero" edge bevel....meaning that there is either a very small "V".....or none at all. The more obtuse the "V", the more cutting resistance a blade has. The shallower the "V", the less cutting resitance. That might sound like "splitting hairs"....but it makes a HUGE difference in how a knife performs. I actually sharpen blades in two different manners..... One is for a using blade, which is hand sharpened on a fine India Stone. That is the edge I put on knives that I know are going to be used. This method produces a very aggressive cutting edge, that may not necessarily shave hair, but works very well for most "using" situations. The second type of finished edge I apply is what I call a "collector" edge. I use a worn out 400 grit belt, then a worn out 600....then a light edge buff to knock off the wire edge..... this edge will shave hair like crazy, but it's not as durable or long lasting as the first method I mentioned. One way I judge a makers skill level is when I look at photos of knives...if I see a huge "V" on a blade's edge, its a dead giveaway that the maker simply doesn't know or understand blade geometry in relationship to cutting. __________________ WWW.CAFFREYKNIVES.NET Caffreyknives@gmail.com "Every CHOICE has a CONSEQUENCE, and all your CONSEQUENCES are a result of your CHOICES." Last edited by Ed Caffrey; 12-04-2014 at 08:55 AM. |
#3
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Ed thank you. I think I understand what you are saying. The cutting edge is really just at the bottom and should not be the entire blade from the top to the bottom. The blade should be ground and then near the bottom be taken down more. So there is really Two V in the blade a larger one then small (sharp) at the bottom.
Am I right? |
#4
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Most of my blades are utilty types of pocket size with a general purpose edge honed to shaving sharpness at 44 degrees off the center line which I establish on a simple jig over a tight but unbacked 400 grit belt. This arrangement gives the edge an 'apple seed' geometry which is very robust. This edge is a 'secondary bevel' which is created from a blunt edge of about 3/64"--sometimes a hair thicker or thinner depending on the intended purpose of the knife.
I do very few 'zero grinds', but they sure look awesome! __________________ Andy Garrett https://www.facebook.com/GarrettKnives?ref=hl Charter Member - Kansas Custom Knifemaker's Association www.kansasknives.org "Drawing your knife from its sheath and using it in the presence of others should be an event complete with oos, ahhs, and questions." |
#5
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Could anyone post some photos of the process of sharpening. I have something in my mind as what I think the process is. I guess I am looking not so much as the sharpening steps but what the blade looks like prior to actual sharpening. My thoughts are you get the blade down to a dime thickness, heat treat and temper, then sharpen the dine edge with a stone or belt. My current blades start at the back spline and taper down to edge. I see all the really nice knives that start at the back spline and taper down and then have another taper at the cutting edge.
If anyone can provide me with a good reference book I would appreciate it. |
Tags |
apply, awesome, belt, bevel, blade, blades, collector, edge, flat, flat grind, folder, forged, grinder, hand, heat, knife, knives, man, sander, sharp, sharpening, steel, stone |
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