Grinding knife bevels, How to?

T

Tmac

Joined
Feb 22, 1999
Messages
375
I’m looking to start making my own knives and I don’t have a good grasp on how to grind the knife bevels. I’ve read the Barney/Loveless and Boye books and they both approach the situation differently (but I’m still not clear on the how to). I would like to know your ways, anyone’s, I’ll try them all, combine them and see what works for me. I’m doing basic stock removal with a Grizzly G1015 grinder (2x72” w/8” wheel). I’m looking to do 4” drop point full tang fixed blade for my first attempts. I would like to try a full flat grind and a full hollow grind (top to bottom, if poss. with my equipment). I’ll listen to any other grind types you would like to share knowledge on (I’ll try it all). Let me know any fixtures, gadgets or tricks of the trade along with things not to do, relying on your past experiences. If I need to provide any more info let me know.

Thank you very much for your time.

Tom
 
You are limited to the height of the hollow grind you can do by the diameter of the wheel so with this in mind start at the 3:00 Oclock position on the wheel and hold the cutting edge upwards so you can see the center line of your steel blank. Press the blank forward into contact with the belt.
Grind material away until you are about 1/64" from the center line then slowly move the blade side ways to extend the grind to the tip. I start grinding from the ricasso.
Turn blade over and repeat.

If you have held the blade vertical during the grinding you will have a full hollow grind on each side and the grinds will match.
Usually you will find that one side is ground higher than the other. Only practise will rectify this problem so go out and buy a lot of mild steel and practise until you can get pretty close then try with a knife steel. Throw away the mild steel.

With and 8" wheel on 1/8" stock I think the maximum width of grind is about 5/8" top to bottom unless you drag it out and that weakens the cutting edge.

If you do not have a flat ginding attachment start with a shallow hollow grind and draw file the blade into a flat grind.

There is no easy way that I have found ecxept to practise grinding as much as possible and don't get frustrated.

------------------
george
www.tichbourneknives.com
sales@tichbourneknives.com



[This message has been edited by george tichbourne (edited 15 September 1999).]
 
Follow Georges' advice, it's real good!! In addition: After you lay out your edge guide lines, and before you start to grind your bevels in, grind a bevel from you layout lines about 45 dregrees.( hard to explain but what you are trying to do is brake the edge of the unground steel so it does not rip the grit off your belt. Kinda like you were trying to sharpin you knife before you put in the bevels. Hope that's clear! It's an easement so your belt dosen't see a sharp edge.
I flat grind. It goes the same way as hollow grinding except when you get off track it is easier to fix with a flat file! Don't be afraid to go to the file! When you start, don't try to take your bevel all the way to the spine. Lay out the top of your bevel with lay out dye or felt marker and try for the line. Same on both sides please. Lite cardboard templates work for me. Then if you grind into your layout line you can raise it and no one will ever know!! If you try for the spine and you goof, you made scrap! Later for that!! Grind edge up! When you try to move a line up or down, find the flat you have made (or hollow) and just add pressure hi or low as you need to go. Try not to grind a scond flat (or hollow) just with pressure move the one you have! Grinding takes practice!!!! If I haven't ground for a while, I go to mild steel to get the feel again. Go slow and have fun!!

I hope I have been of some help!

Doug
 
Ok, here goes with an attempt to explain an alternative grinding technique. I grind edge down on an 8 inch burr king. I have an extension clamped to the tool rest that is the same width as the wheel, and about 4 or 5 inches long. I use a small square push stick just about an inch square and long enough to hold comfortably. This is the trick. grind an angle on the nose of the push stick about half way down so that only the bottom half inch or so is pushing the steel against the wheel. If you lay the push stick flat against the tool rest and push against the edge of the blade, the ultimate height of the hollow grind will be determined by the height of the push stick contacting the blade. To raise the grind line, just grind off a touch of the end of the stick to make the contact area taller, and to lower, grind the angle to make the contact area shorter. This allows you to hollow grind up to the same height on both sides of the blade fairly easily.

This is NOT my original ideal, full credit for this technique goes to my teacher/friend Don Morgan. Any problems are probably caused by my description.
 
T.J.
Sorry, I didn't follow your explaination. Could you please send me expanded version. I am new to this hobby and am using a 4X36 belt sander (basic Craftman model). Either post or e-mail me at SVanderkolff@Spaenaur.com

Thanks
Steve
 
Thanks guys for the information so far, I’m getting a better handle on it. I had a feeling this is something that is better done than explained in writing. But, everyone is explaining it quite well, thanks! A few follow up questions though:

George: With the knife edge upwards on the 3:00 position, do I understand you take one deep plunge cut until I hit about 1/64” from the edge? Then take one pass (from the ricasso) to the tip. Would I need to overlap the belt over the wheel before I take the one pass? This would be with a 60 grit belt then maybe go to 220 or more to polish up?

Doug: I like the idea with the 45-degree bevel, make sense to me. It probably would have less tendency for the belt to grab the steel out of my hand. I do have a flat plate attachment so I’ll give flat grinding a shot. Thanks for the caution on flat grinding all the way to the spine first, that’s the direction I was originally heading. For a flat file do you recommend any type or grade (I know zero about files)?

T.J.: I think I understand where you’re coming from. In doing this type of grinding would the cutting edge/bevel be pointing down? After you grind the edge of the push stick, you would clamp this down to the tool rest and place the knife steel in-between the angled push stick and the belt?

Thanks everyone for your explanations. Keep’em coming.

Tom


[This message has been edited by Tmac (edited 16 September 1999).]
 
Ok, some clarifications. Yes, the final edge is facing down, so you have to stop and look at it from time to time to see if your getting near your center scribe mark. I grind with many passes across the belt instead of doing one deep pass, and hold the push stick in one hand and the tang in the other. This lets you change the pressure of the blade against the wheel. I find that if I use the same pressure the whole length of the blade the tip gets too thin too fast, so on each stroke, I ease off on the push stick about the same time that I start to lift up on the tang to make the hollow grind follow the shape of the tip. Dipping the stick in your quench water helps it slide better too.


 
Mr. Tichbourne's recommendation of practicing on mild steel should not be omitted. When I first started a few years ago, I practiced on wood. Some other folks have suggested aluminum. Doing this is invaluable. More than one beginning maker has ruined some really nice steel. It is very easy to do!
As far as the edge of the blade being down, I have never seen this technique. I only flat grind so maybe there are some folks that may grind this way. I am not saying that it can't be done, I just have never heard or seen this method.

C Wilkins
 
I`m just a beginer myself but I have something to add to the mild steel issue. I`m the kinda guy who hates to waste anything. The first few blades I ground were mild steel and I put pretty much time into em to get the grinds right. Then I had to toss em because they were useless,doh! I made the next few out of scrap leafspring steel (5160). Some came out pretty well ,some didn`t but I heat treated em all and now I have a bunch of work knives I can still use. This also let me practice heat treating techniques. I ended up really liking 5160 and now buy it in annealed stock but some of those old attempts made from rusty springs are still working hard for me instead of rusting in a scrap pile. Marcus
 
TMAC:

It's fun to read how others approch the problem. And no one has given you bad advice! You will develope your way and it will be great. You don't grind with enouph pressure that the grinder will take the steel from you. Go easy, approch the finished dimentions slowly. I put my bucket of water directly where the sparks go below the belt. Contains the mess better! I also put a little dish washing soap in the water bucket so the grindings will sink and not pollute your work.(Kills the serface tention!)

I grind edge up so I can see the edge lay out lines. Works for me!!

Breaking the edge of your barstock to a 45 degree, does two things. SAVES your belts! A piece of barstock presented to your belt with square, sharp edges will remove much of the grit on the belt pronto!

And if you break the edge all the way to you edge layout lines, they are much easer to see!

My grinder has two goose neck lamps mounted to it and I grind using magnafication. You have got to see what you are doing.

Buy two flat files, one fine and one corse about 12-14 inches long. Buy good ones made in USA, I like Nickelson (not sure of spelling) Put handles on them and this will give you a good start. While your at it, buy a "file card", it's a wire brush made expressly to clean you files. The suggestion to grind a wooden knife, I like and have suggested it to others. It goes fast and helps you to get the feel. Aluminum is hard on good belts. When you buy belts, buy the good ones as they last much longer and become more cost effective! I like John at Trugrit!

Let us know how you are doing!

Doug
bladesmithdoug@worldnet.att.net
 
Thanks everyone for the input, it’s much appreciated. I can’t wait to get started, I’ll be chomping at the bit until my steel (mild) gets here.

Tom
 
George, does your blade get hot from doing this grind in one pass. I usually take several passes to get the bevels where I want them.
 
Dan the blade does heat up but not excessively if I use a sharp belt. The sharp(new) belt removes material quickly and with that material goes most of the heat. Dull belts really heat up the workpiece.

Don't get me wrong, after the primary grind is finished I will go back and forth to get the grinds even on both sides before filing them flat.

I hold the blades by the handle and use a wooden push stick against the tip to ensure that I have even pressure across the width of the belt. This becomes even more necessary when grinding big bowies.

------------------
george
www.tichbourneknives.com
sales@tichbourneknives.com



[This message has been edited by george tichbourne (edited 17 September 1999).]
 
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