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Thread: How Bevel is Affected by Taping

  1. #1
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    Default How Bevel is Affected by Taping

    Okay, this may not be news for some. I wanted to know how much the application of a single layer of electrical tape to the spine of a razor you are honing affects the angle of the bevel (as compared to no tape). So I took two measurements on the nine (9) razors I currently own:
    1. blade width from the thickest part of the spine(which is what contacts the hone) to the edge
    2. thickness of the spine
    Then I used the following formula to calculate the theoretical bevel angle (I'm not smart enough to work these computers so I am showing a photo of the formula):

    Where (still not smart enough, I insert yet another picture of a picture):

    Note: I divided the spine width by two to get the actual bevel angle. Otherwise I would have calculated the included angle of both sides of the blade.

    I then ran the calculations as above and added 0.007" (the typical tape thickness or TTT for those that dig abbreviations) to O to calculate the angle (theoretical) with tape.

    Here's the data Oh my God I'm so stupid! I have to put in another picture):


    Conclusions:
    • Yes, taping the spine will affect the geometry of the bevel (but DUH Icedog! we already knew that!)
    • The narrower the blade, the more it's bevel will be affected by taping.
    • I need more big razors
    • I really need to get back to work!
    So what do you think about that?
    Last edited by icedog; 05-22-2008 at 09:32 PM. Reason: My Excel knowledge is shamefully inadequate
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    Senior Member 0o.Mark.o0's Avatar
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    Its good to see a quantifiable description of what you can reason out for yourself. For things like this measurements are better than feeling. Thanks.

    Mark

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    I think that it proves a point.

    To be honest IMHO if a blade needs to be taped to be honed, sell the razor on E Bay, because it's got a basic design flaw

    I still say this even if the razor has pretty etchings or gold or diamonds or whatever.

    Razors are for shaving and a nothing else. They are an instrument and shouldn't require special treatment.

    I've said it before and Ill say it again, a new razor that needs to be taped to be honed is badly designed.

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    Senior Member jwoods's Avatar
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    people tape up their razors so they will not have spine wear, the pretty factor, for better resale value, i do it for that reason as i am rather new to honing ,and am learning light and easy is better

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    I'm kind of new at this myself but I have jumped in with both feet. I am acquiring a fair amount of razors. Some high end and some cheap vintage ebay specials and I am doing a lot of honing. Having posted a poll asking if you tape the spine and looking at the posts that opined on the topic I have decided that I will only tape a spine if I am working a large chip out of a blade. Once it is out I will set a new bevel and hone without tape. That is the conclusion I have come to based on all that I have read on the topic.
    Be careful how you treat people on your way up, you may meet them again on your way back down.

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    Quote Originally Posted by Slant-Fan View Post
    I'm kind of new at this myself but I have jumped in with both feet. I am acquiring a fair amount of razors. Some high end and some cheap vintage ebay specials and I am doing a lot of honing. Having posted a poll asking if you tape the spine and looking at the posts that opined on the topic I have decided that I will only tape a spine if I am working a large chip out of a blade. Once it is out I will set a new bevel and hone without tape. That is the conclusion I have come to based on all that I have read on the topic.

    Increasing the angle to get the chip out doesn't really save you anything except to give you the satisfaction of seeing the chip dissapear sooner.

    Since you will then have to re-set the bevel with the tape removed. In the end you have to remove the same amount of material, and in my opinion it will be easier to do that with a single bevel, as you know when to stop when the chip is gone.

    With a double bevel, re-setting the original bevel is more difficult, as it is hard to see if the very edge is still at the double bevel angle, or if you have finally got it back to the original angle. I know this, as I tried a double bevel, didn't much care for it, and had a long, uphill fight to regain my original edge.

    If you want to get rid of a chip, go to some really low grits to speed the work (600 is fine), rather than changing angles. But that is just my experience.

    Other than that, taping the spine to protect a gilded gold spine or something seems reasonable, but I don't go for that kind of thing anyhow.

    P.S.- thanks Icedog for your calculations! When I did my double bevel experiment I used my CAD software at work to determine the angular changes.
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    Senior Member blabbermouth
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    Quote Originally Posted by icedog View Post
    Okay, this may not be news for some. I wanted to know how much the application of a single layer of electrical tape to the spine of a razor you are honing affects the angle of the bevel (as compared to no tape). So I took two measurements on the nine (9) razors I currently own:
    1. blade width from the thickest part of the spine(which is what contacts the hone) to the edge
    2. thickness of the spine
    Then I used the following formula to calculate the theoretical bevel angle (I'm not smart enough to work these computers so I am showing a photo of the formula):

    Where (still not smart enough, I insert yet another picture of a picture):

    Note: I divided the spine width by two to get the actual bevel angle. Otherwise I would have calculated the included angle of both sides of the blade.

    I then ran the calculations as above and added 0.007" (the typical tape thickness or TTT for those that dig abbreviating shit) to O to calculate the angle (theoretical) with tape.

    Here's the data Oh my God I'm so stupid! I have to put in another picture):



    Conclusions:
    • Yes, taping the spine will affect the geometry of the bevel (but DUH Icedog! we already knew that!)
    • The narrower the blade, the more it's bevel will be affected by taping.
    • I need more big razors
    • I really need to get back to work!
    So what do you think about that?
    Icedog, this is what I think: you're an animal! Kinda crazy too - to go through all that, but a great idea.

    I also believe that as the spine wears down, coincidentally with the edge (under normal honing) that the angle remains constant for a correct shaving edge. Can you figure a formula for that? Eh?

    Or how about this: (and maybe your above data aready has some of what I'm about to suggest)

    Assuming a brand new straight razor, the spine has a certain thickness, blade certain width, equals a bevel of X. That bevel would be the intended thickness for shaving for that razor. Yes? Now add the tape. How far off is the bevel with the tape (I guess that is your Delta above), and how would that affect shaving?

    Also a rate equation: under normal honing (define) how long will a straight razor blade last before the edge/spine wear will no longer produce a shaving edge?

    All in fun, of course.




    Scott
    Last edited by honedright; 05-22-2008 at 07:33 PM.

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    My point is if you can not see the true hone ware you can not tell the usage including over honing by previous users. This includes learners and the inexperienced.

    As I have said before taping a spine is hiding the truth. I don't say it's done with intentional bad intentions but the fact is the hone ware on a taped spine means the spine and blade ware don't match.

    That for me is cheating and the razor becomes untrue.

    Last time I said this some members went up the wall trying to justify why I was wrong in my view.

    Inexperienced honers, taping spines while they learn how to hone is not the way forward.

    The general message I would put out is that taping a spine by an inexperienced honer is likely to corrupt the original geometry of the razor to such an extent that it will probably impact the quality of the shave.

    But of course if you buy a razor, you can do what you like with it.

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    Default Save razors tape the spine......

    OK..... Time for another wrinkle in the tape that spine arguement....
    If the spine is taped we all agree that a slightly sharper angle is achieved on the bevel... So armed with that assumption we have also found that this slightly smaller bevel could be viewed as a slightly stronger bevel.... Therefore I assert that taping the bevel creates a longer lasting edge..... Hmmmmmmm something else to think about because if I am right then taping the spine makes razors last longer...... I would draw this out but I dont know how to do that on the computer

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    Quote Originally Posted by honedright View Post
    Icedog, this is what I think: you're an animal! Kinda crazy too - to go through all that, but a great idea.

    I also believe that as the spine wears down, coincidentally with the edge (under normal honing) that the angle remains constant for a correct shaving edge. Can you figure a formula for that? Eh?

    Or how about this: (and maybe your above data aready has some of what I'm about to suggest)

    Assuming a brand new straight razor, the spine has a certain thickness, blade certain width, equals a bevel of X. That bevel would be the intended thickness for shaving for that razor. Yes? Now add the tape. How far off is the bevel with the tape (I guess that is your Delta above), and how would that affect shaving?

    Also a rate equation: under normal honing (define) how long will a straight razor blade last before the edge/spine wear will no longer produce a shaving edge?

    All in fun, of course.




    Scott


    tan A= opposite/adjacent=a/b

    If the cutting edge is angle A. As hone wear reduces the spine thickness (side "a"), the edge honing also reduces total blade width (side "b"), thus maintaining edge geometry "A".


    I think?

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