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Ed Caffrey's Workshop Talk to Ed Caffrey ... The Montana Bladesmith! Tips, tricks and more from an ABS Mastersmith. |
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#1
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gringing a concave
Dear Ed, I have some orders for knives with a concave shape blade (like a Krambit) I normally grind my blades edge up, and have had good luck with straight or convex (up-swept) blades. When I try to do a concave blade this way, I get 2 or 3 straight or "flat spots" in the curve. I start out with a curve blade, and end up with a real mess! I'm grinding against a flat hard platen, is this the problem? Do I need to make some kind of rounded or curved platen to allow the belt to curve? This is "way out there" for me! How do you do it? Thanks! Jon
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#2
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Jon, are you talking about a hollow grind?
Done with a wheel? __________________ Blade Show Table 8-Q What do you do when you see your ex in pain, limping and bleeding? Relax. Take a deep breath. Reload and then shoot again. http://www.andersenforge.com/ |
#3
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No, I think that he means a blade that curves toward the edge, at least from the way that I read his post. I think that he's having problems with flat spots in the curve of the blade as he grinds the bevels into the downward curve of the blade. No sage advice from this quarter as I still have a little problem at that with a trailing point blade.
Doug __________________ If you're not making mistakes then you're not trying hard enough |
#4
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There are a variety of solutions that folks use. Personally, an easy solution that I stumbled upon by accident was to grind as you normally would with the flat platen, paying special attention to the "recurve" area of the blade.....keeping those "flats" to a minimum.....then using a very tight slack belt, cleanup/blend those "flat spots" near the end of my finish grinding.
It takes some practice, and time, and you will end up with a gently covex......but that's what I prefer anyway. It's just like any other issue we run into when we're doing something new/different from what we're used to.......take it slow, keep a clear mind, and THINK twice as much as you grind......in the end your solution may not be the same as mine, but you'll find a solution that works FOR YOU. __________________ WWW.CAFFREYKNIVES.NET Caffreyknives@gmail.com "Every CHOICE has a CONSEQUENCE, and all your CONSEQUENCES are a result of your CHOICES." |
#5
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concave blade shape-- like a Krambit
Yes Doug, you are right- I was talking about a blade shape, not the actual grinding of the edge to a "convex" shape. Through this process I have gained a new respect for those who can grind edges on a blade that curves forward-- as in a "Krambit" style fighting knife. My first attempt, I started with a forged blade about 1-1/4" wide (from spine to edge) and finished up with the blade about 7/8" wide!!! (with some very ugly flat spots) I didn't even want to put handle's on it, but the customer saw it and still wanted it finished, and paid for it!!! Then to make things worse, he wants another!!! He raves about the curved blade's cutting ability, so I guess as long as he's happy! Anybody else have advise, please jump in here! Thanks ED!!! Jon
Last edited by jonwelder; 02-25-2013 at 07:30 PM. |
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advice, art, blade, blades, easy, edge, flat, forged, forged blade, grinding, handle, hollow grind, knife, knives, make, post, solutions |
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