Thread: How Bevel is Affected by Taping

I was crap at trig in school, so I'm not even gonna think about challenging the methods. lol

Originally Posted by icedog

While you guys may argue the measurement is actually hypotenuse as opposed to adjacent, I think you'll find that with such a shallow triangle, that point is moot. Now I may be wrong but I believe, in this case, what is important is the delta.

Am I wrong?

Yes, you're wrong. I went through this same exact exercise in a thread about a year ago, making the same trig and handwaving errors before realizing the problems and correcting them, so I'm gonna be hard-assed about this. Even if you're just interested in the delta, you're calculating the wrong delta. The atan and asin curves are very different and diverging at different rates even at those small angles. If such errors don't bother you, then the small delta in thickness that the tape causes probably shouldn't bother you either. It doesn't bother me, though the reason I don't worry is I've found that it doesn't noticeably affect stropping, and there's such a wide range of angles found in razors out in the wild that anything in the range of 17.5 degrees +/- 3 will hone and shave perfectly fine, and adding a little tape isn't likely to push you out of the "normal" range of honing angles.

Originally Posted by jnich67

I'm certainly not into this as much as some of you guys, but if razors are such crude utilitarian tools, I can't imagine the thickness of a piece of electrical tape is going to make that much of a difference.


Jordan

I have to agree with this sentiment.

Considering the lengths gone to just to get accurate measurements here for these calculations, and the disagreement about what those calculations should be I'm getting the sense that this is not something Joe, Tim, Josh, or even Maestro Levi figures out before they start grinding away on a piece of soft steel. I for sure doubt that even Mike Blue could be knowledgeable enough to reach the fractional tolerances required by these calculations when predicting the size changes through the tempering process.

So in other words, the Spine angle predicting the honing angle is less a deliberate and accurate attempt to get the perfect edge and more a happy accident we take advantage of when trying for the finest edge possible, and sometimes we are willing to compromise the very finest of edges to preserve beauty or ease our task.

Originally Posted by Wildtim

... I'm getting the sense that this is not something Joe, Tim, Josh, or even Maestro Levi figures out before they start grinding away on a piece of soft steel.

I know that Josh has done this for at least one razor he's made. It's not that hard and only takes a few seconds. But yeah this just isn't that critical of a measurement - it's a pretty big ballpark.

Originally Posted by icedog

Lee,

Wow what a great diagram you made. I guess this is done with some CAD program? I am so ignorant I can barely function in this world. You and the other folks of this community are teaching me alot about alot.

Thanks! I used a NASA supercomputer. I just can't figure out how you posted such a perfectly hand-written using drawing. Did you use a scanner? I can never seem to get those things to work, but I've never owned one either. Just sticking to the NASA supercomputer for now

Originally Posted by icedog

I did not do this to get the actual angle of the razor's edge. Does anyone really care what that is? One has only to look at a full hollow to know it is a pretty shallow angle.

Which is why I added,

Originally Posted by hoglahoo

(although the angle is so small, the results should be very close either way - where's my calculator?)

I'm glad you performed this analysis. Maybe someday I will figure out how to draw a full hollow!
Shall we see if delta is different when the inverse sine function is used instead of inverse tangent?



The results are so close that it hardly even matters! I guess it's a good exercise for me to get the work day started at least

Originally Posted by mparker762

Yes, you're wrong. I went through this same exact exercise in a thread about a year ago, making the same trig and handwaving errors before realizing the problems and correcting them, so I'm gonna be hard-assed about this. Even if you're just interested in the delta, you're calculating the wrong delta. The atan and asin curves are very different and diverging at different rates even at those small angles. If such errors don't bother you, then the small delta in thickness that the tape causes probably shouldn't bother you either. It doesn't bother me, though the reason I don't worry is I've found that it doesn't noticeably affect stropping, and there's such a wide range of angles found in razors out in the wild that anything in the range of 17.5 degrees +/- 3 will hone and shave perfectly fine, and adding a little tape isn't likely to push you out of the "normal" range of honing angles.

I am having a hard time responding without sarcasm. I ran the numbers the other way and it is still what I consider a neglible difference. I think you agree with that statement. Sheesh, have a drink and chill out would ya?

Originally Posted by hoglahoo

Thanks! I used a NASA supercomputer. I just can't figure out how you posted such a perfectly hand-written using drawing. Did you use a scanner? I can never seem to get those things to work, but I've never owned one either. Just sticking to the NASA supercomputer for now


The results are so close that it hardly even matters! I guess it's a good exercise for me to get the work day started at least

Thanks Lee. I simply used a digital camera to shoot a picture of my sketches.

I think i need my boots ......

Originally Posted by icedog

I am having a hard time responding without sarcasm. I ran the numbers the other way and it is still what I consider a neglible difference. I think you agree with that statement. Sheesh, have a drink and chill out would ya?

Feel free to pile on the sarcasm, but I'm not backing down on this. It's one thing to use the correct equation to calculate the correct numbers then decide that it doesn't matter. It's quite another to decide that it doesn't matter based on incorrect data and incorrect reasoning. Pedagogy mean that the methodology matters - the odds are very good that somebody will come along in a few years and find this thread and attempt to use the incorrect atan-based equation to calculate something more significant than a single layer of tape and the difference may no longer be negligible. I recently had occasion to add many layers of tape (>10) to a couple of razors to attempt to hit some specific angles, and it definitely mattered that I used the right equation to calculate this.

Originally Posted by mparker762

Feel free to pile on the sarcasm, but I'm not backing down on this. It's one thing to use the correct equation to calculate the correct numbers then decide that it doesn't matter. It's quite another to decide that it doesn't matter based on incorrect data and incorrect reasoning. Pedagogy mean that the methodology matters - the odds are very good that somebody will come along in a few years and find this thread and attempt to use the incorrect atan-based equation to calculate something more significant than a single layer of tape and the difference may no longer be negligible. I recently had occasion to add many layers of tape (>10) to a couple of razors to attempt to hit some specific angles, and it definitely mattered that I used the right equation to calculate this.

Alrighty then. The measurements are there on the initial post. If being right about minutia is that important to you, run the calculations your way and prove me wrong. Show me that flipping the triangle over makes any appreciable difference. The odd thing is that I believe you are agreeing that regardless of which way it is done, an additional .007" on the side opposite the angle of the bevel will be negligible.

Maybe you don't need a drink. You just need to be right. I see you have posted 2614 times and have been thanked 7 times. I have posted 304 times and have been thanked 26 times. It looks like I am more popular with an approval rating of 8.55% vs your 0.27%. Of course my calculations could be wrong.

I have to go do a brake job on my car now. Would you please come over and make sure I do it right? Brakes are much more important.