Flat grinding advice?

Discussion in 'Hammer & Tongs' started by Drew.Haynes, Apr 23, 2016.

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  1. Drew.Haynes

    Drew.Haynes

    37
    Oct 16, 2012
    Hi guys,

    New maker here.. I tried doing flat grinds my first two knives yesterday and had a couple challenges. Based on what I've seen people suggest I tried to first scribe two center lines, 20 thousandths apart. I ground roughly 45 degree bevels to those scribe lines. I then tried to "walk the grind" up the sides.

    Can anyone give me any additional fine detail tips? In the end both sides were fairly even, but I ended up with darn near a zero grind. I tried to keep pressure off the edge.. But still managed to slowly lose that 20 thou thickness I wanted. When you are bringing the grind up the knife.. When bringing the knife into contact with the belt, do you try to just make the whole bevel hit the belt flat instantly, and then shift pressure toward the spine? Or let the edge end of the grind make first contact? Drop the top of the grind against the belt and then lean into the bevel?

    Hope that makes sense.. Just looking for additional insight.

    Thanks,

    DH
     
  2. Fred.Rowe

    Fred.Rowe Dealer / Materials Provider Dealer / Materials Provider

    May 2, 2004
    Have you tried flattening out the angle used to develop the edge? I grind with a Bubble Jig but my beginning angle is 5 degrees and not 45. @ 45 degrees the edge happens in a hurry. With a five degree angle, on a smaller knife, you may grind clear to the spine using the same 5 degree setting. Once you establish a flat bevel Use it as the control and apply pressure either up or down depending on what is needed.

    Fred
     
  3. Redmeadow Knives

    Redmeadow Knives John Conner Moderator Knifemaker / Craftsman / Service Provider

    Aug 29, 2010
    I knock the edge of off of the profiled blade just to prevent it from skinning grit off the belt right off the bat and go from there.

    Are you starting with a 45 degree bevel on the edge as a marker to know when your close to the desired .02"? That's a good plan.

    But If I'm reading this correctly, are you saying that you're placing that 45 degree angle against the platen?? If so, you are at way too hard if an angle. That bevel should act as a guide so you know when you are at your thickness,not a guide for the angle to start walking up from.

    I might have misunderstood, certainly wouldn't be the first time!
     
  4. Rhinoknives1

    Rhinoknives1 Gold Member Gold Member

    Jul 1, 2013
    First,
    I grind my blades after HT,
    I Take about half the material away i want to to get to those center lines with a 36 grit ceramic belt.
    I take a little more than half again the material I want to remove with a 60 grit belt.
    I take the material I want removed to about a zero edge with a 120 Grit belt.

    Then I use a 220 grit Hermes Cork belt and clean her up.

    Then a Scotchbrite belt progression of Brown, Maroon & then Grey.

    Vola! Hope that helps some.
     
  5. Drew.Haynes

    Drew.Haynes

    37
    Oct 16, 2012
    So, you don't first grind to your line and then work the grind up? That's what I'm getting I think. That might work better for me!

    Also.. I am grinding after HT like you.. .098 AEBL
     
  6. Drew.Haynes

    Drew.Haynes

    37
    Oct 16, 2012
    Hey sorry, when I came here from my notification, I only saw the last response. I think what you guys are saying is to start "shallow" to begin with. Much different than I thought I understood from things I had read. I was grinding a 45 degree angle on the edge all the way to my scribe lines.. And then trying to steepen the angle to bring it toward the spine. My first knife turned out pretty decent but maybe just by luck.

    I may Photoshop some "cross section" images tomorrow of what I'm talking about vs what I THINK you guys are talking about.. Just to make sure we are on the same page!
     
  7. Redmeadow Knives

    Redmeadow Knives John Conner Moderator Knifemaker / Craftsman / Service Provider

    Aug 29, 2010
    I think we're on the same page now. The spine of the blade shouldn't be far from the belt when you start grinding, the angle that you're holding the blade shouldn't change much as your grind moves up.

    You're saying that when you start the edge, you make contact only with the bevel and kind of "roll up" as you go? So the spine is way off the belt at the start and as your grind moves up you're eating the edge to zero? You can correct that by taking the edge back down to the thickness you want. It will give you a slightly shorter blade, but a salvageable one.

    Check out YouTube and there should be some videos that will help you out. What kind of grinder are you using?
     
  8. Drew.Haynes

    Drew.Haynes

    37
    Oct 16, 2012
    I think I get what you are saying.. I have a wilmont lb1000.. Loving it so far. I have the flat platen, an 8" wheel, and a small wheel attachment with a 3/4" wheel. I'm going to try a new approach tomorrow based on what you guys have said
     
  9. Drew Riley

    Drew Riley Riley Knife and Tool Knifemaker / Craftsman / Service Provider

    Oct 17, 2007
    I start with the 45 degree to keep from scraping all the grit off as well. I also grind to my scribe lines (or pretty close to them), and start "walking" the grind down. I make sure to leave a little bit of space at the top though, or in other words, hold the scribe lines about .020 or so off the belt, until the bottom of my grind is almost done. THEN I'll tilt the top edge of the blade and and take it the rest of the way to my scribe line, while trying to keep a little pressure toward the bottom as well to finish the full grind.

    It just takes practice to get the feel for it and know how to look at it, but it will come after you grind a few.
     
  10. coldsteelburns

    coldsteelburns

    Aug 2, 2010
    This is something I actually learned from a thread that Fred Rowe posted a number a years ago and it can help you grind faster and also keep you off of the 0.020" that you established at the edge. It's called "progressive angle/bevel grinding" (or something like that ;) ). Here is a quick diagram I made a while back for another forum member asking about flat grinding.

    [​IMG]

    In addition to the diagram above, it can also be very helpful to NOT grind ALL the way down to your pre-established 45 degree bevel/.020" thick edge while you're progressing through the different angles and walking the bevel up closer to the spine. What I mean is, basically try to keep at least 1/16 to 1/8" inch of space between the original 45 degree bevel where it contacts the edge, and the bottom of where the last angle/bevel you ground at ends, thus keeping some of your original 45 degree grind on the blade. Then, when you are finally at your desired bevel height, just lay the bevel flat against the belt and push "into" the edge to take away that little bit of extra "safety meat" between the main flat grind and the edge to make it ONE flat bevel, as opposed to 2 separate flat planes.

    Those measurements obviously don't needs to be exact, but its just a way to help illustrate what I'm trying to describe ( which hopefully makes sense :D ). Just doing something along the same lines can help keep you from slowly grinding away the edge thickness which each pass if the belt is always making contact with the edge area.

    This technique can help guys have a better understanding for flat grinding when starting out as well as leaving some room for error. It is however, still a great technique to use even when you become quite good and efficient at grinding. Also, as Fred describes in his original thread, taking off the peaks of each new bevel also grinds the steel away faster, as there is less surface area making contact with the belt every time you begin a new angle to grind away the shoulders ("peaks") that were established from the previous flat grind angle, (as opposed to always laying the entire bevel flat against the belt and just pushing towards the spine). . :thumbup:

    ~Paul
    [HR][/HR]My YT Channel Lsubslimed
    ... (It's been a few years since my last upload)
     
    Last edited: Apr 24, 2016
  11. Fallbrook Forge

    Fallbrook Forge Gold Member Gold Member

    Jan 1, 2006
    I've only ground a handful of blades so take this for what it's worth.

    Just finished the ABS intro to bladesmithing with Greg Neely and Jason Knight, Jason grinds like you are describing, Greg does not.
    Greg taught us to bring the edge in toward the belt until it just kisses the belt, then pivot the spine toward the belt to get the bevels.
    This method worked much better for me, I will continue to experiment, but I got much cleaner grinds this way.
     
  12. Drew.Haynes

    Drew.Haynes

    37
    Oct 16, 2012
    I appreciate all the advice guys. I'm trying another one now. No screw ups yet, but it does feel craaaazy slow! I'm using an 80 grit ceramic.. Some passes get hot enough I have to quit pressing with my other thumb, yet you can't even hardly see any change to the bevel!
     
  13. Drew.Haynes

    Drew.Haynes

    37
    Oct 16, 2012
    Quick update. My right hand is better than my left. Slowly worked the grind up one side and looked almost exactly like I wanted. Switched to left hand.. Grind line kept looking like a two year old drew it. As I got near the right grind height but still uneven, I accidentally tilted the spine into the belt. I rage quit and tossed the knife across my workbench. :|
     
  14. Drew.Haynes

    Drew.Haynes

    37
    Oct 16, 2012
    [​IMG]

    [​IMG]
     
  15. Fallbrook Forge

    Fallbrook Forge Gold Member Gold Member

    Jan 1, 2006
    Maybe buy some mild steel bar stock and just practice?
     
  16. coldsteelburns

    coldsteelburns

    Aug 2, 2010
    Some great advice that I've read many times here is to grind the bevel on your off hand side first, then when you get something you're "happy" with, match it with your good side. Also don't worry, this is extremely common and it's just something that comes with practice. It's the same as learning to play any instrument that uses both hands equally, you know, like when you first pick up a guitar and you feel almost paralyzed with your non dominant hand? ;)

    A big part of grinding in general is learning how to adjust and fix your screw ups as you go. Also, proper grinding stance is very important and takes a lot of variables out of the equation, such as tucking your elbows into your waist so they don't move, locking your wrists into a fixed position and doing almost all of the grinding motion by shifting your weight between your legs along with a little bit of waist movement ("twisting") as well. Essentially you are trying to use your whole body as if you were one big fixture/jig that doesn't wobble this or that way etc.

    And FWIW, that bevel still has plenty of room to be fixed up. Just get it flat and then raise the good side to match it. It's very hard (as least it was for me) when starting out to grind short height bevels, especially on thinner stock. Try not to focus too much on getting the height of the grind just right and instead try to get them flat and even without cutting into the spine in the plunge. Hope some of this info helps :)

    Oh yes! Knifemaking is definitely great at forcing you to learn patience and perseverance! ;)

    ~Paul
    [HR][/HR]My YT Channel Lsubslimed
    ... (It's been a few years since my last upload)
     
  17. coldsteelburns

    coldsteelburns

    Aug 2, 2010
    And don't forget that you can always grind the flats of the blade (vertically on the platen using a strong magnet) by taking a bit of the blade thickness down to help clean up the top of your grind lines. The picture you just showed above is a perfect example of when cleaning up the flats comes in handy. A lot of guys do this, and no, it's not "cheating", in case somebody were to think that for some reason lol. :D

    ~Paul
    [HR][/HR]My YT Channel Lsubslimed
    ... (It's been a few years since my last upload)
     
  18. Drew.Haynes

    Drew.Haynes

    37
    Oct 16, 2012
    Really appreciate that advice. I had actually JUST said to my wife.. "Wonder if I could just throw this on a magnet and grind it flat". Also.. Stance could be an issue. My existing workbench puts my tool rest at about sternum height. I've been wanting to move the grinder so the rest is more "belly button" height.

    Hope many knives did you guys screw up? :) I have twenty back from heat treat.. 16 small and 4 8-10" knives. I'll sacrifice all 16 small ones in practice if I can just turn out the big ones clean!
     
  19. Rhinoknives1

    Rhinoknives1 Gold Member Gold Member

    Jul 1, 2013
    How many? Hah! Hah! Hah!

    Every maker have a bucket of em in his shop. If he doesn't? He hasn't made very many knives. :D

    Let me share something with you that any really great Artist will agree with. Your Style? Your styles comes from how you cover up your F-ups!

    So practice with that non dominate hand, and then match that work with the dominate. Keep those F-ups and some day as you improve they will become DM's That stands for Design Modifications.

    Well I was making a 9" Bowie and then had this brilliant idea to make this 5" Hunter. ;)
     
  20. josh81

    josh81

    435
    Jan 11, 2016
    I'm at about the same point as you as far as experience. I can't offer a lot of advice other than try and think things through before you try and fix mistakes. Things can compound quickly. I'll attach a picture of what was supposed to be my 5th knife. I was to the point of epoxying the scales on and decided I wanted to drill some holes for epoxy rivets. I overheated and bent the tang. Then, being frustrated, tried to over straighten it. Long story short knife number five started my scrap pile. If I would have thought things through calmly it probably wouldn't have happened. Good luck and know you're not the only one in the struggle lol
    [​IMG]
    Sent from my SM-G920V using Tapatalk
     
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