Slight Bow in Spine

Discussion in 'Hones/Honing' started by b0bp, Apr 6, 2011.

  1. I've been trying to hone a razor that has been giving me some trouble. Now, to be fair, I don't claim to be an expert. I'm working with a 5/8 full hollow.

    I reset the bevel and noticed that the bevel was slightly wider on the heel and tip of one side than it was in the center of the blade. The other side shows a much narrower bevel altogether. At first I thought it was poor technique. Then I took the razor and laid the spine on flat surface and that's when I noticed that the spine has a slight bow.

    I decided to try to work through a progression on a Norton 4k/8k and I was able to achieve spotty HHT results. Nothing better than HHT-2, but very inconsistent. So, I thought I'd use the pyramid method and results were pretty much the same. After doing this twice (and stropping) I thought that maybe someone here would have some ideas.

    I'm wondering if I should even bother to try to straighten the spine. The bow is somewhat slight but it is easily noticeable to the naked eye. I'm afraid I may ruin the blade if I try to bend it. Should I try it? Maybe I should go back to the beginning and consider setting a new bevel. Or, maybe this issue is not uncommon and I just need to sort out my technique so that I address the issue correctly. Any ideas or suggestions?
     
  2. This bow is an intentional part of the manufacturing process of this razor. Such geometry is extremely common, partly because it is believed to help prevent warping, as I understand it. You need to use an x-stroke with an ever so slight roll to hone it. As you honed it, the bulk of the hone wear may be at the middle of the blade, in which case you need to correct this.
     
    Last edited: Apr 6, 2011
  3. Hey there,

    Don't try to bend it, it will just break. It's not uncommon to have some small issues like this. As you mentioned you just have to find the sweet spot, try some slight rolling X motion on the bowed side to catch the whole blade on the stone.
     
  4. Zero chance of fixing it, non zero chance of breaking it if you try.

    Almost all my razors are warped to some degree.

    My fixes:

    1) Use a hone 30mm wide or less
    2) Rolling X stroke
     
  5. Wait, in which dimension is it bowed? My initial understanding was that the razor has a slight smile.
     
  6. Kentos

    Kentos Moderator Emeritus

    I think its bowed so it doesn't lay flat on a hone
     

  7. A smiling razor will not lay flat on a hone, but this deviance from flat should be the same on both sides.
     
  8. In this world, it is safe to assume that nothing is absolutely flat or straight. I think the razor in question is slightly bent, viewed from the top of the spine. The suggestions so far are spot-on. Learn to hone such razors so the edge is consistent, not totally straight or flat. A rolling X stroke on a narrow hone will keep a nice edge on a razor which is not geometrically perfect in shape.

    It's all relative (Einstein quote needed here).
     
  9. Without pictures, I agree, it does sound to have a 'bend' or kink along the length of the spine.

    As posted above, a narrow hone and carefully working an X stroke will easily address the 'convex' side if you like: the side which 'bends' upwards so to speak. You'll be able to do similar work on a conventional width hone, IME.

    The 'concave' side will be more challenging on a conventional width hone, and you will find yourself working the 'concave' area of the blade along, and off, the top face edge of your hone so that you 'get in' to the slight curvature. Again, a narrow hone will make this aspect easier.

    Hope this makes sense:blink::001_smile

    Get some pictures up for clarity: one side on, showing the current wear on the spine and bevel. One flat on something flat/straight:thumbup1:
     
  10. Just to confirm, it is a bow in the spine not a smile on the leading edge. If I lay the spine on a flat surface I can rock the blade up and down. Flipping it over and lying on a flat surface results in the heel and the tip making contact with a rise in the center.

    I took a fair amount of time with X strokes but haven't tried any sort of rolling. It sounds like I would need to roll the blade over the edge of the hone to make contact with the bow in the center. I can see where this would require some finesse and the chance of mishap on any one stroke could result in a set back.

    So, is it suggested that I start over; drop back to the Norton 1k and work all the through. Or, might it be worth giving this a shot on the 4k/8k?

    Thanks for the comments and advice.
     
  11. Sounds to me like the spine may be ~convex one side (left or right) and concave the opposite side, looking down on the spine from the top. Honed with the convex side up, the heel and toe would have more wear on the edge and a slightly wider bevel than the center section - for that one side. Flipped over convex side down, the bevel would theoretically be influenced more by your honing motion as the edge/spine may not be making uniform contact with the stone, especially at the ends.

    Yes - I've also read about using tape on the section on the section of one side of the spine that is not making contact with the hone to compensate. I've tried that myself with only limited success, but the stroke technique, narrow hone, and possibly selective taping sound good ways to approach it.
     
    Last edited: Apr 7, 2011
  12. Yes Steve, I've contemplated the selective taping in the past. I didn't get onto it, but my thoughts were to tape the 'dip' and a little either side; flat hone the spine only to feather out, repeat until a sufficient build up was there to compensate. I'm sure someone out there might LOL at this one, but it made sense to me at the time...I didn't do it:blink::001_smile

    Bobp, you got it: the roll though would be a'rolling X' stroke to get the upwards curvature, whereas the honing off the edge of the stone, would address the bow in the centre as you say. It's not really a roll, but literally moving the razor along the edge to get the spot where contact is needed.

    Have a practice with real light pressure to get a feel for it, you can't do much harm.

    Re 1,4,8K: If you haven't got a bevel in any particular area, it would be wise to establish one on the coarser stone you have for sure, then move on. I'd say you could be selective in the deficient areas with the 1K, as the higher grits are for refining. Depends how comfy you feel about localising efforts through the range of grits.
     
  13. I can see where this will be a challenge. I'm a little concerned about rolling the edge of the blade and really messing things up. What if I were to lead with heel or tip and run the edge almost perpendicular to the hone (or maybe this is what is meant by rolling)??
     
  14. It's been recommended and done by several honemeisters...:001_cool:...but like I said, it's been tough for me, probably because I did not compensate well enough with my stroke technique. I suspect that razors that don't lay perfectly flat on the hone are not that uncommon....
     
  15. The rolling refers to a slight change in position of your hand as the stroke proceeds so as to alter the pressure on the edge along its length. The idea is to put more pressure where the blade stands proud of the stone and less where it naturally, because of the curve, hits the stone. There are good write ups of the different strokes on the coticule.be website and probably others as well.

    But for me switching to a narrower hone made all the difference in the world. And holding the hone in my hand and letting it rock slightly in response to the change in pressure from the hand holding the blade. I had no luck learning the rolling stroke with the stone on the bench.

    Honing the convex side is pretty easy once you get the knack, but the concave side is the challenge and a narrower hone lets you get in there easier.
     
  16. Depending on the value of the razor, and the degree of sideways bend, you might consider taking it down on a coarse DMT until you have simply ground out the bend. If it is extreme, this won't work. You would be taking too much steel. This would work best if the amount of sideways bow is no more than the thickness of a couple sheets of paper. A matchbook cover or more would be too much to grind out. If the spine is bent, then the entire blade is probably bent, too. The side with the convex bow will end up with a wide bevel surface at the center of the bend, and narrow at the ends. The concave side will end up with a wider bevel at the ends and narrow at the bend.

    I HAVE straightened one razor with a sideways bow. You don't try to bend it back because it will very likely break or give you an "S" curve instead of a straight blade. You lay the spine on a large vise or other suitable anvil surface, concave down, and hammer on the center of the bend, spine only. A fairly flat hammer face and dead-on blows are essential. A soft face hammer like brass or copper might be better but I used an ordinary steelfaced one-pounder. Don't hammer on the thin part of the blade... just the spine. Straighten the spine, and the rest of the blade, in time, to a large degree, will follow. This may require more than one session at the anvil. Let the blade rest for a week or two afterwards, to give the edge time to follow the spine. Don't be surprised if you end up with a few dents or minor deformations, or a spine that appears slightly concave on both sides. A lot of hammering might actually thin the spine at the hammered area. The proof is in the puddin. If the blade will no longer rock longitudinally when flat against a flat surface, you are ready to reset your bevel and get on with your honing. A wide hone and only a small amount of "X" slide will help to give you a consistent flat bevel in spite of any minor deformation caused by your hammering.

    If the razor is a valuable one, you might try taping and using a rolling "X" as others have suggested, or just leaving it alone. If it is just a user grade shaver, then it is nearly worthless as it is and I suggest, literally, going for broke. Chances are, you can make a decent shaver out of it again. If you mess up, well, it was already messed up but at least you tried. I am sure many would be interested in your results, whether good or bad.
     

  17. This!

    This bold quote is where the magic happens for me! Great job of putting this into words brownbear. This is where small handsize coticules shine.
     
  18. I'm reluctant to try bending or hammering before trying some different honing techniques. If I can manage to capture a picture that shows the extent of the bow I'll post it but that may be difficult to accomplish.

    I guess the only other thought related to this would be that if I can put a descent edge on this razor, I wonder how it will shave.

    Thanks to all for the comments, insight and suggestions. I'm going to try getting a picture so folks can see the actual extent of the issue. It may lead to some useful commentary.
     
  19. I can't get a picture to capture meaningful detail. I'm planning to get back to the hone and practice some varying techniques. I don't have any small, narrow hones so it should be interesting. I'm thinking that if I can get some consistency on the blade using the Norton 8K I'll jump up another level to a finer hone and see if I can repeat the pattern. This assumes I can get some consistency on the blade to begin with.
     
  20. I don't blame you. There is no need to resort to brute force.

    What hones do you currently have besides the Nortons? I'm sure that we can come up with something creative to do to hone it. Ideally, you'd use a narrow hone. (Coticules come to mind since they've been used for centuries and are typically narrow, or cutting your Nortons in half, but I imagine you not feeling comfortable with that.) But, maybe be can figure something else out with what you have.
     

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