Bevel grinding, what am I doing wrong?

Discussion in 'New to Knifemaking' started by PetrifiedWood, Jul 25, 2011.

  1. PetrifiedWood

    PetrifiedWood Well-Known Member

    I started work on my third knife today. I was trying for a half-height flat grind. On all of my previous knives I have tried for a flat grind, or a scandi grind first. These never seem to come out even. I wind up going with a full height convex grind because it covers the mistakes pretty well.

    I've seen what I can only describe as exquisite scandi grinds accomplished on a harbor freight 1X30 sander.

    So I'd like to know specifically how to get these super even, perfect flat and scandi grinds.

    I'm using a Grizzly 2X72" grinder, and have added a ceramic glass liner to the platen.

    What grit do you start with for grinding bevels?

    Are these grinds established with a single pass on each side?

    Are they done freehand?

    What devices are used beside the bubble jig to aid in achieving even grinds?

    I want to be able to get a good grind without trashing expensive steel. I also don't have a band saw so cutting out my profiles is a time consuming process involving drilling hundreds of little holes around the profile and "connecting the dots" to cut them out. This means I've already spent the better part of an hour cutting out my profiles.

    Another question would be: If there was a single moment in your knifemaking experience where you "got it" and your bevels were way better than ever before, what moment was it? Was it a change in technique, or a new tool?

    Thanks for your hep. This forum has been a great resource so far and although I'm having a little trouble here and there I think I am way farther along than I would be without it.
     
  2. ARCustomKnives

    ARCustomKnives Well-Known Member

    If you're starting off with a 2x72, than you've already substantially reduced the learning curve.

    To answer your "starting grit" question, I've seen guys use anything from a 36 grit belt to a 120 grit belt. I personally start with a 60 or 80 grit and take it up to 120 or so before HT.

    As far as the grinding process itself, I freehand mine and it typically takes many many passes per side.

    To give a short explanation, I scribe two center lines in the middle and flat grind each side to the closest line. I'll start at a 45 degree bevel, grind into my center line, then tilt the blade back to about 50 degrees and grind into the scribe line again. I keep tilting the blade back until I reach my desired depth on the flat grind, or until I reach a full flat.

    How flat and straight it comes out depends a lot on practice and experience, but the best advice I can give for starting out is to keep your angles as consistent as you can during the grind, and make deliberate movements. A work rest isn't a bad idea either. Helps keeps things stable.
     
  3. ARCustomKnives

    ARCustomKnives Well-Known Member

    by the way, there's a thread in this forum called "flat grinding help" started by pedro G. you might look at. Lots of good advice there.
     
  4. Sticks

    Sticks Well-Known Member

    I wouldn't be able to give any better advice than Andrew. I follow the advice in Richard Barney/Bob Loveless' book, "How to Make Knives. I'm still at the point where each blade is sort of trial and error. I take many passes to complete a grind. I try to start a grind at the plunge line and keep it going to the point. I usually do hollow grinds, so I'm not sure that the following will apply to flat grinds.

    If as you are making your grind you put more pressure as you get closer to the point, the grind line will follow the profile of point. In other words, curve up from the edge. You don't need to rotate the blade as you grind. Here's one I ground that way (not the insert that was my "plan").

    Remi%20'58%20almost%20finished-%20Orig%20concept%20and%20Inspiration[1].jpg
     
  5. Rob Nelson

    Rob Nelson Well-Known Member

    I just ground knives #4-7 for preHT, so I'm with you. Whatever confidence I felt on 1-3 is on vacation. Here's what's helping me:
    - Bubble Jig, I love it!
    - Scribe lines; got a knife scribe in a GAW here, and its the bomb. I use it to scribe my lines for a half-height
    - The grind angle chart; Fred Rowe posted it up last week on one of the threads here. You look up the material thickness,
    and how wide you want the bevel, and it tells you the correct grind angle. So I set the bubble jig for that, and grind on.

    I like a convex edge myself, so I put my secondary bevels on with a slack belt (no platen) and sharpen it up.
     
  6. PetrifiedWood

    PetrifiedWood Well-Known Member

    Thanks for the replies so far!

    It seems I have been applying WAY too much pressure and trying to remove too much with each pass. I was thinking a grind would happen in maybe 3-5 passes per side.

    I think part of my problem is the grinder moves fast and I probably need to go to a finer grit to compensate for the excessive belt speed. I also think I need to rig some kind of system to stop the belt from riding up over the plunge line onto the ricasso. This isn't so much a problem when I gring against the platen, but when I have been changing over to a convex to fix my mistakes, I'm grinding on the slack part of the belt between the idle wheel and the top of the platen and there is really nothing to brace against to prevent this. Perhaps I'll cut out some stock and drill and tap it for screws to make a clamp for the blade.
     
  7. Sticks

    Sticks Well-Known Member

    I think the less you remove with each pass the greater the opportunity to make adjustments until you are satisfied. The speed of the Grizzly is an issue but I'm sure that you'll get used to it. The blade clamp you describe is a good idea. I'm pretty sure they are commercially available in carbide. I mentioned Loveless before. He advised to use a "used" 60 grit belt for the initial 45 degree grind the Andrew describes. (Because that grind is really hard on the belts.) Then he says to use a new 60 grit belt for each blade.
     
  8. Doug Lester

    Doug Lester Well-Known Member

    I use a file guide to keep the plunge lines even and straight when I grind my bevels. The one I got is made of hardened A2 but I'm not sure where I got it from though I think it was probably under $40. I did see one that is made from a carbide steel that was a little on the pricy side but it would resist just about any belt. However, I don't have problems with any of my belts cutting into the file guide that I have.

    Doug
     
  9. RodneyJ

    RodneyJ Well-Known Member

    Please don't take this the wrong way but if you don't want to trash exspensive steel don't use it. You are getting some good advise but it takes lots of practice. I know how it feels to have a picture in your head of a beautiful knife with perfectly even lines and then produceing something less. We all have experienced it. For now stay with an inexpensive steel like 1080 or 1084 once you can consistently produce grinds you are happy with then switch to a more expensive steel. The blades you make with the inexpensive steel will make good knives. Your just not out as much if you mess them up
     
  10. Rob Nelson

    Rob Nelson Well-Known Member

    File guide is a good idea - forgot to mention, I use the one that comes with Fred's Bubble Jig system, and it works great! Much better than the pair of vice grips I was using before. I've also found a welder's magnet is handy - put a piece of tape on where it contacts the blade so it doesn't scratch. Gives me a better handle on the blade for a good angle.

    I only have a 2x42, and its really fast, so I can't use the orange belts for rough grit, but I have found a used Gator 60 belt works great for initial angle. Then I switch to a new 60 for the last couple passes, then 120, and 240.
     
  11. Justin King

    Justin King Well-Known Member

    I have to remind myself sometimes to keep my mind in the hand that is holding the tang, I have a tendency to want to grind aggressively and without realizing it I will start increasing the pressure I am applying with my off hand over the belt itself, and end up paying more attention to that hand than the one that is actually controlling the operation. This screws my grinds up every time.
    Have to keep the pressure relatively light and make each pass as smooth as you can. It actually helped me at one point to take a small blade to the grinder and try grinding without the free hand applying pressure on the blade, to focus on controlling it from the handle end. If you get that part right the belt will take care of the rest.
     
  12. baddog

    baddog Well-Known Member

    I also use a Grizzly. The belt speed is very fast. It took me a while to develop a lighter touch when grinding. I start with 80 grit belts. I take a couple of passes on one side then a couple on the other side. Then I move to 120 or 150 grit, then 220 grit before heat treat. I'm working with 01 tool steel.

    One thing I find helpful is to coat the blade with layout dye (or sharpie) this helps me to see how the grind lines are progressing. Have you tried grinding bevel side up? It makes it easier to see where you are grinding, just don't grind down your forehead like I did. Now I wear an old baseball cap when using the Grizz.

    You can also practice on some wood. I've made several, just to practice bevels. My kids love to play with them. I just use some scrap. A few of them I actually put handles on them and shaped them just to get an idea how to shape the handles on the grizz. If you use plywood, the layers will give you an indication of how even your grinds are.

    Keep making those knives, your bevels will get better!

    Ric
     
  13. PetrifiedWood

    PetrifiedWood Well-Known Member

    Thanks again for all the advice. I think I might get one of the carbide guides if the price isn't too high. One thing I did figure out is that it's perhaps a lot easier to fix minor grit scratches and so forth by hand rather than trying to use my grinder. I clamped this last blade to a board in my vise and used a hand sanding block to fix a few things and it went relatively quick, rather than trying to use a maul on a thumb tack and fix it with the grinder. I'm still waiting on a sanding drum I ordered for my drill press to get the inside curves. I bought one that can be loaded with regular sandpaper cut from sheets so I can change grits if I want and won't have to worry about availability of refills for it.

    When it comes out of the 2nd tempering cycle I'll probably hand finish it except for the final edge bevel. I think my best bet for now is going to be using the grinder for profiling, rough bevel grinding, and sanding the handles but I'll do the detail work by hand for more precise control.

    Here's a picture of the one I'm working on now.

    [​IMG]

    You can see some vertical scratches on the ricasso where I slipped and the belt rode up over the plunge line. I turned the blank over and did the same thing on the other side to make it symmetrical and I'm going to hand polish it out.
     
    Last edited: Jul 26, 2011
  14. Mike Martinez

    Mike Martinez Well-Known Member

    Same thing happens to me on that damn grinder. I've since junked it and use it only to do sand wood with a 60 grit belt and am using a friend's Wilton which is just as fast but tracks better and has phenomenal tracking and stability. By the end of next week I'm looking forward to completing my EERF type grinder.
     
  15. Fred Rowe

    Fred Rowe Well-Known Member

    After you have gained some experience you will look for ways to increase belt speed. The fewer passes you make, the fewer chances for poor passes.
    With experience you will grind with a lot more pressure and therefore more stock removed per pass.
    Most experienced grinders move to ceramic belts especially for rough grinds. Ceramic belts work best with speed and pressure. They are made for this and last much longer when worked in this manner.
    The owner of Pop's knife supply, who sells a lot of belts, told me there are people who grind with ceramics using a mechanical arm for pressure who grind a hundred blades on one belt. They are applying a lot of pressure with a belt speed of 7,000 surface feet a minute. These are commercial operations.

    A grinding clamp to position the plunge lines and keep them even is a real plus. The one I make is made of 01 with hardened jaws.

    Using an angle of 45 degrees to develop the edge, I believe, is a bit steep. Ten degrees is plenty, five degrees, even better. When you place the blade to the belt you want to remove as much metal as possible at one time.
    If you get a chance take a look at the progressive grinding thread in the main forum. You might find it useful.

    Have fun, Fred
     
  16. PetrifiedWood

    PetrifiedWood Well-Known Member

    I recently watched a video of the Anza Knives guy grinding bevels using a jig to hold the blade, and some kind of lever device attached to the grinder table that had what looked like a giant ball bearing the back of the jig would ride against. He would push forward on the lever and grind with what looked like a lot of pressure. Seemed like the entire grind was done in just a couple of passes.

    I also just read an 8 page thread on another forum (not sure if it's ok to mention here) about a simple jig that can be made from 2" aluminum angle to grind perfect scandi bevels. I think I'm going to go that route. I don't see the merit in spending hours and hours trying to learn to grind freehand when a simple jig like that has allowed first time knife makers to get professional looking results.

    I have only ground three blades so far and they all had to be made into full height convex grinds. But I think this jig will make flat and scandi grinds a LOT easier, and when used in combination with a file guide it will probably make for better convex grinds as well.

    It has really opened my eyes about the grinder I have too. I need to figure something out to make a much bigger and sturdier table for it.
     
  17. ARCustomKnives

    ARCustomKnives Well-Known Member

    I'm not gonna tell you not to try out a jig, as most (if not all of us) probably have tried out some kind of jig at some point.

    That being said, I believe there is all the merit in the world to learning how to free hand grind. This will become all the more evident to you when you have to grind or make repairs to a blade that doesn't fit in your jig.

    If you want to make the same exact types of knives, then a jig works great. If you want to expand and try new things, then don't box yourself in. I doubt you'll ever find a freehand knife maker who regrets the hours of practice and 100's of pounds of steel that it took him to get to where he is. Mistakes included.
     
  18. Fred Rowe

    Fred Rowe Well-Known Member

    It was the folks at Anza knives that he was referring to.Thats quite a set up they have.

    I believe you are correct. Learning everything you can about the machines you use and all the ways they can be put to use, makes a lot of seance.
    Sled type jigs even if adjustable have their limitations. They do a few things well, but not everything.
    The Bubble Jig is not really a jig at all; it is a reference. You can set any angle you want to reference and grind away. There is no guessing at the angles when you use this little reference tool. If you want to grind at 30 degrees, set it. If you want to sharpen at 10 degrees, set it and sharpen away.
    When you "free hand" grind you are referencing the spacing at the developed edge and make a judgment call at the angle. When I "free hand grind" I set the desired angle in the bubble, stick that on the blade and watch the bubble instead of the edge. The only real differences in what you are doing and what I do is what you use to reference your grinding angle.
    You watch the edge, I watch the bubble; you make a judgment call based on your experience where I know what the angle is when I center the bubble.
    I do a lot of regrinds on swords and other blades. Last week I reground the tips on two Japanese long swords. Someone had ruined the tips on both blades. I placed the tip of one sword against the platen to find the original angle, placed the bubble on the blade and adjusted the bubble to center.
    Started the machine, centered the bubble ground one side flipped the blade over placed the bubble on the blade and ground an exact matching bevel on that side.

    I am with you when you say don't box yourself in; you can't advance.

    On the wall above my layout bench is this quote:
    Without deviation from the norm progress is not possible

    Happy grinding, Fred
     
  19. PetrifiedWood

    PetrifiedWood Well-Known Member

    All very good points to consider. My line of thinking is that I'd like to make a few good looking knives to start out and build my confidence. I know a lot of guys start out building kit knives from blanks that already have the bevels ground. They learn how to attach handles and finish the knives first before they move on to learning bevel grinding. I think of a jig as an intermediate step. I'll be able to make my own "kits" to assemble with even grinds on them, and get some practice handling and finishing the knives without the frustration and disappointment of a bad grind. When I'm ready to try more challenging blade shapes and styles, then I can begin learning to grind bevels without the aid of a jig.

    I have to say that when I got to my third blade and was having horrible uneven grinds I was getting seriously discouraged and thought that I was in way over my head, trying to take on too much at once, etc. When I read about the jig is was a tremendous relief!

    I'm going to incorporate as much of the advice you all have given me into my technique like taking more passes with less pressure to start with. I do have a self centering edge scribe and a half pint of layout dye I've been using to trace my profiles and so forth, and I have been putting it on both of the flats to watch the grind.

    Thanks for all the help and input so far! :)
     
  20. clancy

    clancy Well-Known Member

    I was told that I would start to understand the grinding process by the time I made 100 knives, so I started making one a week and giving them away. I found that it was much easier to grind smaller blades using a welding magnet to hold the steel.

    ernie
     

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