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Help grinding a recurve
- Thread starter kile
- Start date
Bill Siegle
Knifemaker / Craftsman / Service Provider
- Joined
- Oct 3, 2000
- Messages
- 6,820
I have done a few hollow ground recurves and for me the trick is to lighten up the pressure on the wider areas so the grinder doesn't bite too much.It's tricky but try it. Also use newer belts. They allow you to get better control on more complicated grinds. Just keep at it and once you get the 1st one you'll know how to do them forever.
- Joined
- Jan 24, 2003
- Messages
- 2,767
Bill is exactly right. I've done them on a grinding wheel and finished with a pedal powered sandstone wheel with water. To Mr. coot, that was over 40 years ago, but old tricks stay with us, huh, Bill? The pressure is the whole thing, AND DON'T HURRY when making this grind.
- Joined
- Jul 8, 2002
- Messages
- 1,240
What I found to work for me is to push the tang towards the grinder when you get to the recurve. This puts less of the contact wheel in contact with the knife and you can track the recurve better. But the major draw back is that you can really gouge the blade quickly, so go slow with a light touch.
I am going to try what Bill and John said the next time I do one and see what happens.
Here is a pic on how mine turned out:
Recurve
I am going to try what Bill and John said the next time I do one and see what happens.
Here is a pic on how mine turned out:
Recurve
- Joined
- Mar 30, 1999
- Messages
- 89
All good advice. light pressureand a slight tilt toward the tang are important. Another thing I do: I scribe on all my blades theedge line I want to follow. These are two parrallel lines about .025 apart right on the edge where my finished edge will wind up to be. (coarse grinding the edge of the blank before marking, 60-80grit, done while profile grinding the entire blade whether from band saw or laser, will show the scribed guide lines better).
- Joined
- Mar 30, 1999
- Messages
- 89
I pushed the wrong key and ended the last post before I was finished. Good thing I don't have any CNC equipment to screw up!
Any way, to continue: I'm real careful to follow the scribed guide lines as I grind If the edge is consistent with the line (a uniform thickness at the edge) and the blade was already profiled with a recurve, Then the bevel edge on the side will automaticaly follow the recurve of the blade. BOB
Any way, to continue: I'm real careful to follow the scribed guide lines as I grind If the edge is consistent with the line (a uniform thickness at the edge) and the blade was already profiled with a recurve, Then the bevel edge on the side will automaticaly follow the recurve of the blade. BOB
- Joined
- Mar 30, 1999
- Messages
- 89
I pushed the wrong key and ended the last post before I was finished. Good thing I don't have any CNC equipment to screw up!
Any way, to continue: I'm real careful to follow the scribed guide lines as I grind If the edge is consistent with the line (a uniform thickness at the edge) and the blade was already profiled with a recurve, Then the bevel edge on the side will automaticaly follow the recurve of the blade. BOB
Any way, to continue: I'm real careful to follow the scribed guide lines as I grind If the edge is consistent with the line (a uniform thickness at the edge) and the blade was already profiled with a recurve, Then the bevel edge on the side will automaticaly follow the recurve of the blade. BOB
- Joined
- Oct 26, 2000
- Messages
- 2,468
Can a recurve blade be flat ground?
- Joined
- Mar 19, 1999
- Messages
- 620
Thanks for the advice guys,
Peter, yes a recurve blade can be flat ground, for me it is much easier than hollow grinding a recurve. I have another question guys, I am using a 2X72 grinder, and I was wondering if the recurve could be too extreme for the width of the belt? I don't know if this makes sense, but I took Bob's advice and just tried to keep the edge nice and parallel. It worked the grind came out OK, but it is a little flat on the concave part of the curve on both sides, and the grinds are almost mirror images of each other on both sides(I know that is the way it is supposed to be, but I would think if I screwed up I wouldn't have done it exactly the same on both sides? To give you an idea of the recurve on this blade, it is about the same as the Darrel Ralph Camillus CUDA EDC. I am grinding it on a 12" wheel which I am sure is making it more difficult than if I did it on my 8" wheel.
Thanks again to everyone for the advice.
Kyle Fuglesten
Peter, yes a recurve blade can be flat ground, for me it is much easier than hollow grinding a recurve. I have another question guys, I am using a 2X72 grinder, and I was wondering if the recurve could be too extreme for the width of the belt? I don't know if this makes sense, but I took Bob's advice and just tried to keep the edge nice and parallel. It worked the grind came out OK, but it is a little flat on the concave part of the curve on both sides, and the grinds are almost mirror images of each other on both sides(I know that is the way it is supposed to be, but I would think if I screwed up I wouldn't have done it exactly the same on both sides? To give you an idea of the recurve on this blade, it is about the same as the Darrel Ralph Camillus CUDA EDC. I am grinding it on a 12" wheel which I am sure is making it more difficult than if I did it on my 8" wheel.
Thanks again to everyone for the advice.
Kyle Fuglesten
- Joined
- Oct 18, 2001
- Messages
- 20,978
kile - from watching and listening to Bob Dozier's excellent grinding demonstration at the Blade Show, I've learned two (of many) things relative to this issue:
1. use a smaller width belt. Bob rips some of his belts down to 1/2" - although those are probably more for shaping handles, etc. While I have yet to grind a recurve myself, I have spent a lot of time sharpening recurve knives of different shapes and sizes and the smaller belt width really helps along the recurve edge.
2. use the smaller wheel. Bob said use the 8" wheel for small hunting knives and recurves. 10" for bowies. 12" for the bigger stuff.
Again, just repeating what I heard.
laredo - you gotta stop posting pictures of that blade..!!!
I get green with envy (to match the jade
) every time I see it. What a beauty!
Dan
p.s. I must admit that, to me, it's strange to see a recurve with a hollow grind. I agree that they can look great and maybe even slice better, etc. However, most of my experience with recurves comes from khukuris - which are all either flat-ground or convex. The one time I got one with a hollow grind - it broke when I used it.
1. use a smaller width belt. Bob rips some of his belts down to 1/2" - although those are probably more for shaping handles, etc. While I have yet to grind a recurve myself, I have spent a lot of time sharpening recurve knives of different shapes and sizes and the smaller belt width really helps along the recurve edge.
2. use the smaller wheel. Bob said use the 8" wheel for small hunting knives and recurves. 10" for bowies. 12" for the bigger stuff.
Again, just repeating what I heard.
laredo - you gotta stop posting pictures of that blade..!!!
I get green with envy (to match the jade
) every time I see it. What a beauty!Dan
p.s. I must admit that, to me, it's strange to see a recurve with a hollow grind. I agree that they can look great and maybe even slice better, etc. However, most of my experience with recurves comes from khukuris - which are all either flat-ground or convex. The one time I got one with a hollow grind - it broke when I used it.
- Joined
- Feb 14, 2000
- Messages
- 1,204
One thing on a recurve blade,I have learned is at the plung cut you have to work of the corner of the wheel.I keep the blade moveing sideways all the time and I end up with a rounded plung cut that looks like Neil Blackwoods grinds.The rest of the blade is the easy part.if you are taking the hollow around the belly of the blade all you do is start to pull
the handle of the blade toward you as the blade gets near the tip.One thing is watch you do not get a thin spot right before the end of the blade.What it all comes down it is pratice there is no way around it.Onething I did was I profiled some wood knives and praticed on them,you see what are are doing and what your hands need to
do to get the grind you want.Try the wooden knife trick and it will advance your ginding to a new level.Hope this has helped you out
the handle of the blade toward you as the blade gets near the tip.One thing is watch you do not get a thin spot right before the end of the blade.What it all comes down it is pratice there is no way around it.Onething I did was I profiled some wood knives and praticed on them,you see what are are doing and what your hands need to
do to get the grind you want.Try the wooden knife trick and it will advance your ginding to a new level.Hope this has helped you out
- Joined
- Oct 9, 2002
- Messages
- 1,419
I admit they are not easy, but I actually use a cheater method that I suspect many factory styles use. Take a look, the grind actually varies as you go along, so that you can still use a 2inch wide belt and not have to do the little dance and jig every singel time you "wipe" the blade across the belt. The grindline doesnt follow the edge profile. Needless to say, the edge thickness along the edge can vary a bit which I account for by slight variations in the angle of the grind. I find that easier than wiggling the blade for every single pass on the grinder. This is even easier, I am told, with hollowgrinds, as the thickness behind the edge varies even less. There are factory models where the grindline is straight, and the edge is recurved. I hope you get what I mean. Jason.
