Thread: Fun with Verniers calipers and tape

Greetings,

I recently sent of a number of razors to Bart. He mentioned that he uses Verniers calipers to calculate the amount of tape needed for razors, wedges in particular. I turned this into the following spreadsheet in the hope that you'll find it useful.

The spreadsheet makes two assumptions:

1. You will be using regular electric tape, not something 5m thick (hence the formula Bart came up with: =DEGREES(2*ASIN((B4+0.3)/2/C4))).
2. The ideal angle for a bevel is 17°: "I believe that most of these old wedges were not designed to lay flat on the hone for sharpening. I believe they were usually honed knife-style (with the spine lifted above the hone). A razor shaves best with a bevel angle of approximately 17 degrees, +/- 2 degrees. Lower than 15 degrees and the edge becomes too weak, over 20 degrees gives a horrendous shave."

I'd greatly appreciate your comments and suggestions, because I would like to put this spreadsheet into the Wiki if you find that it makes sense: Honing_Angles_Matrix.xls

Thanks in advance,
Robin

I think that the ideal angle is a bit presumutous..... there are other tests that have been done on here, that show razor angle from 8 degrees out to 22 degrees.... I also understand that you are talking wedges here, but to call any angle the best, is asking for trouble ......

Now if you were to clarify that, and call 17 degrees the best on that razor, on your face, in your hands, that would be different, but to arbitrarily call 17 degrees the best angle, I have a problem with that going in the Wiki, as that would automatically give it credence....

I have to wait until I get to work to open the spread sheet....

I am with Glen on this one. Bart is a great guy and very knowledgeable. He is of a scientific bent and I always appreciated his numerous experiments. OTOH, I have seen a lot of speculation on how the old wedges were honed back in the old days but from the wear I have seen on the spines of many of them I don't think that they were honed with the spine off of the stone knife style.

In the old books and instructions on hone labels that I have seen I haven't seen any reference to honing razors that didn't instruct the honer to keep the blade flat on the hone. To me using multiple layers of tape is short cutting it. I have honed those old Sheffield wedges with one layer and it was a lot of work but I have gotten them to shave well with the one layer. FWIW, I believe Lynn hones them without any tape.

It's a good place to start when determining the number of layers. I use 3 on my 7/8 Friodur, which i concede right now, is not a wedge. I've found that on my particular blade it gives the best balance between keenness, smoothness, & a durable edge. I had to get there through trial & error though.

Has the table taken into account that the point of the spine resting on the hone is not the back? As it varies with each razor, ought we be measuring the blade width from the point that the spine rests on the hone, to the edge, rather than the full width?

As a result of this thread i have only now notice that the Friodur has a spine of tapering thickness. It's thicker at the heel end than at the toe. I'm not going to let it bother me, as the shaves it gives are great. It's just an observation i made that surprised me.

Originally Posted by gssixgun

I think that the ideal angle is a bit presumutous..... there are other tests that have been done on here, that show razor angle from 8 degrees out to 22 degrees.... I also understand that you are talking wedges here, but to call any angle the best, is asking for trouble ......

8 degrees seems extremely steep. Wouldn't that result in a spine width of about 2.2mm on a typical razor of 5/8" blade width? That occurs to me as very thin. I performed a few searches, but am not sure I found the right thread. Could those 8 degrees come out of this thread: How Bevel is Affected by Taping - Straight Razor Place Forums That one started off using a formula that only calculated the half bevel angle. AfDavis did some measuring too, using another formula for calculating the same: http://straightrazorpalace.com/101962-post13.html

I checked with Bart, and he said that 17 degrees seems to be the angle that most decent blades conform with, give or take 2 degrees, as outlined above. He said he likes to use 2 or 3 layers tape for honing a wedge, but only if it checks out not to put the bevel angle out of range. That makes sense to me.

I also checked Tim Zowada's site, and his razors sport a 15° angle.

Originally Posted by gssixgun

Now if you were to clarify that, and call 17 degrees the best on that razor, on your face, in your hands, that would be different, but to arbitrarily call 17 degrees the best angle, I have a problem with that going in the Wiki, as that would automatically give it credence....

I wonder if we could do a field test, thus finding out what the angles on well shaving razors actually are. Will go shopping for Verniers calipers on Monday...

Originally Posted by BeBerlin

I wonder if we could do a field test, thus finding out what the angles on well shaving razors actually are. Will go shopping for Verniers calipers on Monday...

I purchased a set from amazon today and should be here in a week. I wanted to find out the angle on all my best shavers and see how they compare to the ones I can't seem to get quite right.

I think there may be some merit to this...

Dave

Originally Posted by BeBerlin

8 degrees seems extremely steep. Wouldn't that result in a spine width of about 2.2mm on a typical razor of 5/8" blade width? That occurs to me as very thin.
Measure some Genco and other American full hollows I bet they are close, again as I keep saying over and over and over when you try and make an absolute statment about this hobby it is going to come back to haunt you....


I performed a few searches, but am not sure I found the right thread. Could those 8 degrees come out of this thread: How Bevel is Affected by Taping - Straight Razor Place Forums That one started off using a formula that only calculated the half bevel angle. AfDavis did some measuring too, using another formula for calculating the same: http://straightrazorpalace.com/101962-post13.html

I checked with Bart, and he said that 17 degrees seems to be the angle that most decent blades conform with, give or take 2 degrees, as outlined above.
That is one person's opinion, that has no basis in any proof, in fact you made it even more ambiguous by saying "any decent blade"...

He said he likes to use 2 or 3 layers tape for honing a wedge, but only if it checks out not to put the bevel angle out of range. That makes sense to me.
I have never ever needed more than one layer of tape on even the heaviest wedges so what does that say???? I don't even think Lynn uses any. at all and as Jimmy just said he uses one layer so now where does that put this theory????

I also checked Tim Zowada's site, and his razors sport a 15° angle.

Great!!! good for Tim, doesn't mean a thing other than he uses 15 degress... and he has found that for his designs that works the best...



I wonder if we could do a field test, thus finding out what the angles on well shaving razors actually are. Will go shopping for Verniers calipers on Monday...

Have fun !! as Lynn so fondly says...


This is what happens every time somebody tries to nail something down and set it in stone... way to little of razordom fits neatly into a little scientific box, and maybe that has it's own appeal... The romantasium and small mysteries that keep popping up that need solving.....



EDIT: FWIW I too agree with TZ and Bart that the perfect angle is close to 16 degrees but my opinion doesn't matter either....

I think we can still find some real usefullness to this in the wiki. Perhaps without the absolute statements, but there is some really sound theory here.

Each layer of tape on a razor of a given width will change the bevel by a given degree. For people who are either very advanced in honing, or people like me who are all into geometry and mathematics (it was my major in college after all) it could be turned into something really useful.

Perhaps it could even include an in depth explanation of the effect of bevel angle, and the way it effects durability and sharpness.

Originally Posted by VeeDubb65

I think we can still find some real usefullness to this in the wiki. Perhaps without the absolute statements, but there is some really sound theory here.

Each layer of tape on a razor of a given width will change the bevel by a given degree.
On a given spine thickness and don't forget that is not necessarily a constant along the spine itself and don't forget that all tape is not of equal thickness in fact there is quite a bit of variation in that alone....

For people who are either very advanced in honing, or people like me who are all into geometry and mathematics (it was my major in college after all) it could be turned into something really useful.

Perhaps it could even include an in depth explanation of the effect of bevel angle, and the way it effects durability and sharpness.

On a given razor honed on a given stone stropped on a given strop shaved on a given face....

Do you see where I am heading here, Honing in itself is just not a science,
unfortuantly it just doesn't work that way... heck we can't even all agree on what is meant by light pressure... Nor can we quantify it...


Now if one of you math whizzes could figure out exactly how much each layer of 3m tape (the most used that I know of) changes the degree of angle on the 3 major sizes of spines, on the most common widths of razors that would be useful information....

Example: on a 3/16 spine width, 6/8 size razor the degree of bevel change is .64 degrees now that would be cool to have in the Wiki...

The angle is easy to compute. The problem is that so far I have not seen any evidence of how that angle correlates with the shaving.

Yes, I can see that the extremes won't work, but if 99% of the razors fit in 18+/-5 degrees do 3 or 5 degrees make a perceptable difference while shaving?

So, until few people run an experiment by honing 5 of the same razors at 5 different angles (on some adding tape on others wearing down the spine), we don't have any real evidence that it matters much.

To the guys who offer honing services, why don't you try this next time you have a 7-day set. It's a bit more work, but from my personal experience rehoning a razor with fewer layers of tape takes 10-20min, and you're likely much faster at honing too. So, the cost of running such an experiment is something like an extra hour of honing.