So im still struggling with the final edge. I have a nice flat grind, I start my bevel at 45 degrees and lower my angle until I reach the spine. One thing ive noticed is that im not able to reach the spine with my jig, I can have it almost flat and it still wont reach the spine. SO ive been finishing the flat grind by hand. But when I go to put a 15 degree edge on my knife, i get this big exaggerated bevel not a nice micro bevel like I see most knifes have. What am I doing wrong? Thanks!
Final edge continued
- Thread starter remfallen
- Start date
Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
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Let's talk numbers:
The bevel angle on most knives is around 4° to 7°. A .10" thick knife with a 1.5" height has an "edge" angle of 4°.
If you want the secondary bevel (cutting edge) to be 15 degrees per side, it should make a edge line about .020-.030" high. (Assuming the edge is .010" thick at .020" from the edge it would be 30°.)
All this is why I hate jigs. They may or may not be ny good at getting precise angles. They don't allow you to follow the edge.
Forget jigs and angles for now.
Turn the grinder off and place the knife on the platen at just a little angle. Make some wedges of cardboard and see what 10°, 15°, and 20° look like. Try to place the knife at those angles. Now try it on a running grinder. It will not take long to get a clean edge angle. If it gets wider and thinner you are twsting the knife. Once you v]can get a clean line, test teh edge. If it cuts like you want - OK. If it isn't as sharp as you want, lower the angle. If it chips tooneasily, increase the angle. It won't be long before you never care what teh actual angle is.Youn will know how to hold the knife for a camp edge, a hunter edge, or a kitchen knife edge. No mechanical jig will ever teach you that.
Now, here is the best jig you can get to grind blades The Bubble Jig. That's because it really isn't a jig. It is a n angle guide and teaching tool. It is for sale in The Exchange and made by one of our long-time members Fred Rowe. It will show you what every angle you want looks like.
The bevel angle on most knives is around 4° to 7°. A .10" thick knife with a 1.5" height has an "edge" angle of 4°.
If you want the secondary bevel (cutting edge) to be 15 degrees per side, it should make a edge line about .020-.030" high. (Assuming the edge is .010" thick at .020" from the edge it would be 30°.)
All this is why I hate jigs. They may or may not be ny good at getting precise angles. They don't allow you to follow the edge.
Forget jigs and angles for now.
Turn the grinder off and place the knife on the platen at just a little angle. Make some wedges of cardboard and see what 10°, 15°, and 20° look like. Try to place the knife at those angles. Now try it on a running grinder. It will not take long to get a clean edge angle. If it gets wider and thinner you are twsting the knife. Once you v]can get a clean line, test teh edge. If it cuts like you want - OK. If it isn't as sharp as you want, lower the angle. If it chips tooneasily, increase the angle. It won't be long before you never care what teh actual angle is.Youn will know how to hold the knife for a camp edge, a hunter edge, or a kitchen knife edge. No mechanical jig will ever teach you that.
Now, here is the best jig you can get to grind blades The Bubble Jig. That's because it really isn't a jig. It is a n angle guide and teaching tool. It is for sale in The Exchange and made by one of our long-time members Fred Rowe. It will show you what every angle you want looks like.
Jesse Latham
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This has more to do with your edge thickness than degrees of bevel. Grind a thinner edge.
Cushing H.
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Agreed.
I do agree with that. And when I said exaggerated bevel I meant exaggerated cutting edge. I’m trying to get a thinner blade and grind the main bevel down much further so I have less material behind the cutting edge but I sat there with a 40 grit yesterday and took away material forever on two flat grind knifes and it didn’t seem to get any thinner. Not sure what I’m doing wrong. Maybe I gotta start with a thinner stock? This stuff is .125. I’d imagine a 10 degree cutting edge doesn’t look that exaggerated if the behind cutting edge material is much thinner.
Pictures from your jig and knife would help us to give better advice .
Richard338
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It's probably technique. You are walking the grind up towards the spine, but not thinning the edge. I think we all assume that you are grinding edge up. Is that true?
I think that he use file jig . . . .
I’m trying to get a thinner blade and grind the main bevel down much further so I have less material behind the cutting edge but I sat there with a 40 grit yesterday and took away material forever on two flat grind knifes and it didn’t seem to get any thinner
Negative I use a belt sander
So I scribe the center lines, then grind at a 45 degree angle to those lines to start, and then drop 10 degrees every time I reach the scribe lines there after.
Then we really need to see some pictures from knife , jig you use and belt grinder . 40 grit belt remove steel very aggressively . . .. .
Yeah I’m working on getting some uploaded. I’m not using the jig the whole time. I start with the jig but I run out of angle on the jig about halfway to the spine, so then I switch to freehand.
Richard338
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Edge up?
Yes
Ok , I am trying to understand .....when you say that you *run out of angle on jig * you mean that you can not anymore change/increase angle on jig ?
That is correct, I set it at a 45 degree angle to start, grind down to the scribe lines, and then lessen the angle on the jig 10 degrees and then grind to the scribe lines again, and complete this process over and over. I usually run out of jig angle before im able to meet the spine with the bevel
Here are the pics.
This is the jig, it has a kitchen knife I'm working on currently. The kitchen knife has a 10 degree angle for the cutting edge. The cutting edge seems to be wider than that of say a store bought kitchen knife. Thats what im trying to figure out. I think it has to do with the amount of material that is still left behind the cutting edge making the blade thicker.
https://ibb.co/LxLqPDF, https://ibb.co/z708f00
Here are two of the other knifes ive made, keep in mind these do not yet have an edge.
https://ibb.co/6vWMt7Y, https://ibb.co/V92xpPq
I know these all look rough, and there were steps skipped but these are the first ones ive made and are more for learning.
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Did you mean to add text to this?
I don t understand how that can happen ? Work rest is 90 degree to platen behind belt ?