Final edge grinding tips?

Jbh blades

Jbh blades

Well-Known Member
Hey guys, I wondered if ya'll could share some of the ways you grind your final edges? I am hit or miss on getting the desired final bevel angle / height. I do all my grinding freehand and have no problem grinding the primary bevels where i want them. When working on the final edge there is so much less room for error that i sometimes find myself with one or two spots where i changed the angle and have high spots in the grind line. So what do I do? bring the rest of the line up to match which is just irritating to have to do. I can get them straight and sharp but IMO the secondary bevels look too high. Case in point, look at my first attempt at a modified tanto. Oh Its sharp, but the secondary bevel seems huge to me. It had to be to try to cover my mistake.

Is it a slow, steady and keep practicing kind of thing or am I missing the obvious?1-15-15 041.jpg1-15-15 052.jpg
 
Nice work! I'm new to knife making too, but I'll tell you how I approach the edge. I too do it free hand. I use a very light touch with the edge, and I lead facing the belt like I do on the bevel grind for the first two grits. Then as I get into the finer grits I flip it over, and point the edge down trailing the direction of the belt travel, again a very light touch with a smooth pull from heal to tip. Other than a light touch, practice is the only other thing I could advise. I have the same problem you're experiencing from time to time, but if I focus with a light touch, it's better.


Maybe someone with more experience will chime in.

Don
 
I do tend to be a bit heavy handed. That's something I've been working on. Remind myself to keep it light on the home stretch. Thanks for sharing your method!
 
the size of the secondary bevel is really going to depend a lot on how thin you get the primary bevel at the edge. I too freehand and had a similar problem in the past and I realized that in trying to leave plenty of meat on the edge for HT, after HT I wasn't taking it down far enough. I would recomend a measurement to get it to where you want it every time. I still don't measure it, but I keep a dime on my workbench just to check myself and have a constant to think about.

If you're primary bevel (say for a full flat grind) has reached the top and doesn't need to go further, I've found that a slight twisting motion with the wrist can put a little extra pressure on the bottom near the edge to take more material from there instead of the top. This will allow you to get the edge down to where it needs to be. Just keep it as flat as you can against the belt and it will produce a clean flat primary bevel.

When sharpening I use my 1x30 and flip it over on it's back. Learning how to sharpen on a stone has helped with this technique. I get the burr started with a worn out 120 grit belt and then use a cork belt to polish a little. At this point it's sharp. Then take it to an arkansas stone following Jay Fisher's sharpening method, then strop about 60 passes....razor blades don't slice like that.
 
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You might explore the idea of a flat grind with a convex edge.

Let's say for a small hunter/utility knife for example: I might take the edge down to .005" or .010" with a 400 grit belt. this would be my final grind after heat treat and before I start hand sanding. Then, I will use the same 400 grit belt and using a slack portion of the belt above my platen, I will put a convex edge down to pretty much sharp. My convex on a knife like this will go from the very edge of the blade up to 1/8" high or so. Meaning that it's flat ground until all the way down to about 1/8" from the edge. For that last 1/8" it is then 'rolled' down to sharp. I hope that makes sense.

After that, I do my hand sanding. You can easily cut yourself during hand sanding if you're not careful. By time I'm done with hand sanding, my knives are usually sharp enough to shave hair. At least sharp enough to slice paper. Then I usually do some etching for the hamon. By time I'm done with several etching and polishing cycles, the edge is now even sharper. When I'm all done with sanding and etching and the knife is finished, all that's left to do is strop the edge a few times on each side to polish smooth. This leaves the knife with a wicked sharp final edge.

I seldom have to use a stone and I never put the final edge on with a belt anymore. You really can't see much of an edge bevel on any of my knives at all. Basically I use hand sanding, etching, polishing and stropping to put my final edge on.

The edge is very sharp and very durable. But you can tailor that 'rolled' convex edge to larger knives and stouter geometry or for any other specific tasks by how thick you leave your edge before your convex roll or how high/low you start to feather that rolled edge.

Again, I hope that makes sense.
 
when you use the slack part of the belt,do you still have the edge up or do you do it facing down.
 
I'm curious what John says too, but the answer may depend on your grinder. Will yours run in reverse? I grind bevels with the edge up like normal, but when I go to sharpening, I reverse the direction of the grinder and use the slack between the platen and contact wheel. I keep the blade edge up so I can see the burr form. If you can't reverse your grinder, you can also use the slack between the top wheel and the drive wheel and see the edge burr if the edge is facing you.
 
I've seen videos, including bossdog sharpen knives on non-reversible grinders by just flipping the knife over with the edge facing down. I tried that for a minute but couldn't see what I was doing...guess like any of it, it just takes practice. That's when I had the idea of flipping the 1x30 on it's back. That way I can hold the same angle on the grinder that I do on the stone making it quick and easy to see. I've also done convex edges in this manner, which do work great. The only problem I've had with them is that you can't resharpen them on anything but a belt grinder. Most of my knives in other peoples hands means that they use a rod, stone or worse to sharpen knives. I don't do convex edges anymore for that reason.
 
I've always been a bit confused when people say that the customer can't resharpen the knife. I guess that's true if the customer is trying to recreate *exactly* the edge the knife comes with. I personally have never given two seconds' thought about the edge a knife comes with. I have always put my own edge on it to suit my needs. Knives that get used a lot get sharpened a lot, and I doubt I've ever put *exactly* the same edge on a knife twice. It's just never been an issue to me. If I don't like the edge, or that particular blade won't hold the edge I put on it for long, I will just fix it next time I resharpen it. Hunting knives, pocket knives, high end kitchen knives. I'm anal about the edges on my kitchen knives, but it's based on performance and what that particular blade will hold. But I don't obsess about the exact angle because I use waterstones on my kitchen blades and I defy anyone to prove that they get any kind of exact angle using freehand sharpening on stones, especially when they finish on a leather strop. Obviously you get really good at it over time, but an *exact* angle? How exact?

I guess a lot of people out there use Lansky, etc. and obsess over angles. I learned to sharpen freehand and it's all I ever did before I started making knives and had all this fancy equipment at my fingertips.

Am I just lazy? I'm being serious. Maybe I need to put a lot more thought into this. But I've sharpened my way all my life and it's worked really well for me.
 
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Jbh blades said:
Hey guys, I wondered if ya'll could share some of the ways you grind your final edges?
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hi, i use a jig so the edge is ground at 7 degrees per side. what has helped the most is a variable speed drive for the grinder along with a smaller drive wheel. when sharpening, SPEED kills. sparks mean that you heated spots on the edge to over 1500F. slow you belt down, 500 feet per minute belt speed seems to be a good target. get waterproof belts and wet grind. take your time, a 220grit belt at 500fpm is going to remove steel slowly, with the edge cooler and you will have more control(ability to maintain the angle you want).
just some thoughts.
 
First thing, I dip the blades when I'm sharpening on my 2 z 72 and like Scott mentioned I use a slower speed and most important, Fresh Belts!

Worn belts create heat fast! I do all of my sharpening work tip up. After my blades are HTed and ground down to 0 to 0.20 depending on the use of the knife I use a x weight 120 to make the final bevel. Then a 120 J-weight to convex it a tad, then a 600 for Americana/German or 15 Micron for Japanese or my customs, then It to the buffer with green Chrome to remove the wire/burr.

If you haven't created a burr/wire at your last belt or stone. It will not be sharp!
 
I do all my grinding edge up EXCEPT when I go to 'roll' that final convex part of the edge. For that, I personally use the slack portion of the belt up above my flat platen and do that with the edge down, rather facing me as it isn't really down on my grinder.
 
If you want to reproduce select angles with no deviation, this tool makes it possible. You can set any desired angle for an edge from 8 degrees per side to 20 degrees per side.
When I ship knives I include the edge angle along with a matching degree wedge so the new owner can maintain the original edge. Its easy for knife makers to change edge angles on their knives, not so much for people who just use knives.

orange%2Bjig%2B1.jpg
 
Laurence, what kind of a buffing wheel do you use with the green chrome? Hard felt, sewn muslin, loose?



then It to the buffer with green Chrome to remove the wire/burr.

If you haven't created a burr/wire at your last belt or stone. It will not be sharp![/QUOTE]
 
Sewn Muslin I find works great. Loose would be very dangerous. Felt, I've never tired but I don't think it would be dense enough.
 
rhinoknives said:
Sewn Muslin I find works great. Loose would be very dangerous. Felt, I've never tired but I don't think it would be dense enough.
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Laurence, the felt wheels I have are very hard; much harder than the sewn muslin. I must be doing something wrong when I try to polish my edge on the sewn wheel with green chrome. I use a very light touch, but always seem to dull the edge rather than polish it.
 
This may be a bit unconventional but once I have established a good visible burr I run the edge over the edge of my wooden bench. This peels the wire off then I hand strop on leather with green chrome. This leaves a "toothy" edge. If I want finer I go to leather with white compound, then .05 micron paste on a piece of balsa. Make a laser sharp edge but is a bit more delicate.

God Bless
Mike
 
what kind of jig do you use. I have a wilton square wheel and there is no slowing the old girl down.
 
sorry I missed the second page of posts. I like4 the idea of the upper part of the belt and the bubble jig. If anyone knows how to slow my grinder down would help,it was fine 20 years ago.
 
I haven't been on the forum since I posed the question. I want to thank ya'll for the advice you've shared. I've got two knives on the bench almost ready to put the final edge on. I surly will adjust my method and see if I can get the edge I see in my mind. Depending on the knife: I have been grinding my blades to .020"-.030" before grinding the final bevels. For example on a more heavy duty knife, say 5" blade 3/16" stock I usually leave it .030". A smaller blade and stock I usually grind to .020" or even .015". Is that sound reasoning or do you guys take your knives down to a standard thickness no matter the size stock?
 
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