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.

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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 ......

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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.

Quote:

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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....

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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...

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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...

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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

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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...

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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.

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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....

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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...:soapbox:


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.

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Originally Posted by gssixgun

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....

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That's very easy to do, but I don't see how it is useful. It seems a math trivia to me with no bearing on shaving unless we have some data that correlate the angle with the shaving.

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Originally Posted by gugi

That's very easy to do, but I don't see how it is useful. It seems a math trivia to me with no bearing on shaving unless we have some data that correlate the angle with the shaving.

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See above, I agree with you, it has no basis on shaving...

Glen how big would you say the range of working angles for shaving could be?

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Originally Posted by 0livia

Glen how big would you say the range of working angles for shaving could be?

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If you actually go back into the archives there were multiple tests done, I remember from 8-22 degrees were found to be shavable... But I have never had the time nor inclination to test it...

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Originally Posted by gssixgun

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....

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Happy to help, HOWEVER, with a great number of caveats. First, I agree with all above posters who mentioned that there's nothing conclusive to be stated about the meaningfulness of the bevel angle, in terms of shaving, at this juncture. Second, we can easily make calculations for, say, a 5/8" razor, but this takes very little into consideration; for example, with each successive honing, that measurement decreases slightly - and we're dealing in the realm of very small numbers where shaving off a few mils of metal will substantively change these calculations to such an extent as to make the calculations I've posted below meaningless. Furthermore, razors are often not completely even along their length -- curves, smiles, etc. change the blade width at various points -- so again the 5/8" basis for calculations becomes not useful. Lastly, the notion of "a layer of electrical tape" isn't especially useful as there is a wide margin of variety of thickness of electrical tapes on the market. Even confining calculations to "3M Electrical Tape" doesn't help, as that company has multiple products matching that description, which vary in thickness from 7 mil to 10 mil, and even up to 30 mil for certain varieties.

All that said, since you asked, here are the actual numbers. These assume that the blades are completely pristine (no metal has ever been shaved off), and that the blade edge is a perfectly straight line. Lastly, I've based this on the most common 3M electrical tape products, which are 7 mil in thickness.

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5/8" blade: Each layer of 7 mil tape lifts the spine .642 degrees above the hone
(Note: If 10 mil tape is used, the amount becomes .917 degrees, which is a 43% increase -- thus showing why these calculations are not at all useful unless an absolute standard is established for the type of tape used. As 3M manufactures literally dozens of different lines of "electrical tape", this really becomes especially specious.)

6/8" blade: Each layer of 7 mil tape lifts the spine .535 degrees above the hone

7/8" blade: Each layer of 7 mil tape lifts the spine .458 degrees above the hone

If there really is a +/- 3 degrees of error around an ideal angle for a comfortable shave, then even multiple layers of tape should have no ill effect.

- M.

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Originally Posted by gssixgun

If you actually go back into the archives there were multiple tests done, I remember from 8-22 degrees were found to be shavable... But I have never had the time nor inclination to test it...

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What archive? I don't remember ever seeing anything outside of 15 to 21 for shaving razors

I wonder if the 8 you're referring to is actually 8*2 = 16 :hmmm:

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Originally Posted by mrgad

Lastly, the notion of "a layer of electrical tape" isn't especially useful

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0.3mm, as stated in my initial post, and in the spreadsheet itself.

LOL ok, 8 sounded a bit thin anyway.
What benchmark does the industry set - with DE blades - for the angle?
Usually they max things out and play them safe.

The sheet seems pretty useful in several aspects.
Imagine you wanting to buy a razor for quite a chunk of money.
You could ask for the exact measurements and find out whether the blade was shortened or not. :idea:
Apart from having to use verniers calipers (which I hate) I think I'll give it a shot.
At least it does give a clue. Finetuning aside.

Why isn't it possible to give Bart a Rep, btw?
There is no button.

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.3mm, as stated in my initial post, and in the spreadsheet itself.

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Sorry, I was just responding to the question about what the math would be, rather than replying to the calculations in the OP.

But, for the record, mil and mm are different units of measurement. .3mm is the equivalent of 12 mil, and thus almost twice as thick as most of the electrical tape sold in the U.S.

Again, I wasn't criticizing the OP's calculations or methods. I was just giving an answer to the question of how much one layer of tape would increase the angle for a specific blade width.

Cheers,
M.

Every vintage wedge that I have ever seen has wear on the spine.

If +/- 2 degrees doesn't make much difference, then the estimate of: 1 layer of tape = an increase of 1 degree included angle; should be more than accurate enough.

IIRC Tim Zowada made an angle measuring device from Verhoeven's description, and measured the final bevel on Feathers to be 25 degrees.

Armed with this I got with Josh Earl and had him make me a wedge with a 25 degree honing angle (the final razor came out to about 24 degrees, 25 degrees with a couple layers of tape) and it shaves just fine.

My NOS-when-I-got-it Wonderedge has a pretty steep honing angle as well, it's about 18.7 degrees IIRC.

Oh I see, thank you.

Now is there a way to adjust the spreadsheet to german tape thickness?

After measuring several NOS razors in my collection, and having a friend run the angles, done rather quickly, and not accurately at all, we found that they are all over the place, we will each measure some more to make sure of this complete non-compliance of any semblance of order...... We will both use calipers on the next batch of measurements, also and see if in fact these angles truly are all over the place...

Although the the fact that I have a few that have the same spine width and vary from 6/8 to 4/8 on blade widths kinda tells me that my initial thought was correct.. and the angles are all over the place....

Oh BTW these all shave,,, regardless that the angles are all over the place....




BTW electrical tape thickness is determind by the protection factor it has,,,, thicker tape more resistance to electricity.... I have seen it from 3 mil -10 mil 3m is 7 mill though

Quote:

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Originally Posted by gssixgun

After measuring several NOS razors in my collection, and having a friend run the angles, done rather quickly, and not accurately at all, we found that they are all over the place

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I suspect that this is a major contributing factor to the fact that, in my limited experience, each different razor has a very different feel and level of effectiveness. Of course, as you said, there doesn't seem to be any real consensus on what the "best" is, as we all have our preferences.

The ideal bevel angle for me, and the ideal bevel angle for you may be quite different. I still hope we can distill something universally useful out of this. It's too interesting of a topic to go to waste. :)

For anyone following this thread who might be confused:

3M = company that makes tape
.3mm = 3/10 of a millimeter
3 mil = 3/1000 of an inch

1 mm = 39.4 mil

So after some math lessons from Lee we started dialing up razors, we did about 8 each ranging from brand new to slight hone wear....

We found that all the ones we did tonight fell between 13 and 19 degrees

We had mostly hollow grinds to check and there was no correlation between blade size and angle that I found....

Look forward to hearing of everyone else's measurements...

Also.... what about smiling razors????
the big choppers???? that vary on blade width???
That we just measured, and found to be 14 degrees at one end, and 18 degrees at the other, but we use a rolling stroke and we make this an even bevel ?????

So many thoughts.... so many mysteries to solve... I think I'll go hone some razors instead....

We old guys always thought that the manufacturer designed the spine thickness to allow the correct bevel angle to occur naturally, simply by keeping the edge and the spine flat on the hone while honing. If this is true, it should also be true for wedges. Why would a razor manufacturer design an incorrect spine thickness into razors that are his bread & butter? We have a basic issue here; the ratio/proportion of the spine thickness to the blade width. This issue should be resolved at the time of manufacture.

Someone should check with a manufacturer on this point. How about Tim Zowada or one of the other razor makers. They should be in the know on this issue. It seems to me there is a bit too much conjecture here. Are there any books on the subject of razor design and/or design theory?? I have always relied on the spine thickness and one or two layers of " sparkafication " tape for a decent shaving edge. K.I.S.S.............. JERRY :):hmmm::thinking:
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I gotta say I wouldn't know how to tell from the quality of a shave whether or not any of the razors I shave with are being negatively affected by a less than perfect bevel angle. I'm just not that good. If a shave is subpar, I check three things: beard prep, razor sharpness, and technique. If it comes down to razor sharpness, I check for a good stroke on the hone. Then I hone it sharp. Always. There are a few I haven't been able to get sharp yet, but their bevel angles fall within these same ranges.

Anyway, here are some bevel angles from razors I shave with, just for fun :)

A Glen-honed Hess 99 6/8 full hollow
15.38 degrees a half inch in from the toe
15.38 degrees a half inch in from the heel

A Lee-honed Hess 99 5/8 full hollow
16.37 / toe
17.08 / heel

A Lee-honed Rodgers wedge, 7/8+ at the toe, 5/8 at the heel *
13.82 / toe
17.11 / heel

A Lee's brother-honed 559 Wedge 4/8 wedge
17.84

A Lee-honed stamped Wapi (5/8 quarter hollow)
17.51

A Lee-honed Heljestrand 6/8 extra hollow
16.96

A Lee-honed Webster & Johnson 6/8 wedge
16.09

And lastly, a Joe Chandler honed Rodgers 9/8 half hollow (shave readiness not yet verified - anyone got any scales they want to loan me? :))
15.78

I also measured two other razors I am currently attempting to sharpen but am not quite there yet with either of them:

A Waterville 4/8 full hollow, thinnest spine on any razor I own
14.18

A two hundred year old Wostenholm 5/8 wedge - probably the wedgiest razor I own as the spine wear very nearly meets the bevel at the toe
18.46 / toe
18.38 / heel

I have no idea what these numbers mean, but it was fun getting them :)

I used analog calipers good to 1/1000" and measured spine width against blade width (from cutting edge to back of spine wear, letting one point of the caliper touch the cutting edge and one point touch the back of the spine wear) at the same points along the razors, halved the spine width, and then I found the inverse sine of the quotient and doubled the result.

*

Quote:

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Originally Posted by gssixgun

Also.... what about smiling razors????
the big choppers???? that vary on blade width???
That we just measured, and found to be 14 degrees at one end, and 18 degrees at the other, but we use a rolling stroke annd we make this an even bevel ?????

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Glen is referring to the Rodgers wedge I measured that is almost 15/16 at the toe, and about 6/8 at the heel. The spine was the same thickness near the toe as it was near the heel so the bevel at the toe is actually much steeper than the bevel at the heel. What does this imply? does it matter? beats me

Like I said, how do I know the bevel angles aren't falling out of an optimum range? I don't. If I am having trouble honing or shaving, bevel angle is just the last thing I think of. If I use tape, it's so I can make better contact with the hone, not so I can pull the bevel angle into a more acceptable range. If all else can be held equal, I would love to know what difference bevel angle makes to a shave, but I'd have to be convinced in any such proof that other factors introduced when creating and refining that bevel such as steel type, tempering process, honing technique, depth of striations, grind type, hone type, left hand, right hand, type of lube on the hone, type of tool used to lap the hone, how many strokes were used, consistency and constancy of various in-hone tests being performed, etc etc etc were held constant throughout the entire process. And then stropped the same way on the same strops in the same humidity after the same strop warm up, yada yada yada. And then shave tested on the same skin, same shaving technique, lather quality, etc etc etc. Otherwise I will probably always view it as just a cool bit of trivia and not really worth looking at unless perhaps a razor has been severely damaged and the edge has receded significantly into the blade or the razor was mishoned with the spine lifted way up :shrug:

In truth, it's actaully more complicated with that.

On a basic level, I agree with you. The spine thickness IS set to help keep a consistent bevel angle, and if a razor needs no correction, honing without tape would seem best to me. (True wedges may be a different story, and may differe from one manufacturer to another)

On the other hand, if a razor has been honed many times, especially by an ameteur, the spine may have thinned faster than the edge, due to the placement of the tang relative to the width of the blade.

If that's the case, you would need to hone with tape until you had returned to the "proper" angle.

Or, the edge might have warn faster, in which case only regrinding the razor could correct it.

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Originally Posted by mrsell63

Someone should check with a manufacturer on this point. How about Tim Zowada or one of the other razor makers. They should be in the know on this issue. It seems to me there is a bit too much conjecture here.

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I agree! Robin, could you check on that for us?

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Originally Posted by BeBerlin

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

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Thanks buddy :)

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Originally Posted by hoglahoo

I agree! Robin, could you check on that for us?
[...]
Thanks buddy :)

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Incidentally, he recommends 3 layers of tape to produce the final cutting bevel. So the final angle would be approximately 17 degrees. :confused:

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Originally Posted by 0livia

Now is there a way to adjust the spreadsheet to german tape thickness?

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Just replace .3 in G4-J7 with the desired thickness.

Here's a bit of background, taken from Schmidt, Max: Das Rasiermesser, sein Werdegang, seine Pflege, Radebeul, 1939, via Bayerische Staatsbibliothek (full text here: Digitale Bibliothek - Münchener Digitalisierungszentrum, thanks mh!). So we are looking at 15°.http://tohserver.com/%7Erobin/SRP/ga...8945_00025.jpg

Having done a bit more research, I am pleased to announce that I have found a solution to our problem, at least as far as sharpness is concerned: Sharpness testing machine - Patent 4178797. Now, we just need to build this thing. Failing that, we should do a little fundraiser and rent a Sharpness tester.

15° seems very rare in my fundus.

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Originally Posted by 0livia

15° seems very rare in my fundus.

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A moderator of a German forum kindly contributed measurements of 20 new razors. The edge angles are all between 15° and 20°, the majority being around 17°.

He also added that the main problem with old razors is honewear caused by bad honing, i.e. too much pressure on the spine, thus making the edge angle too steep unless you counteract the narrow spine with tape.

Another comment: Modern razors come with barely visible edges, caused by the production process, in which the edge is put on the razor without the spine touching the hone. Therefore, taping the razor is called for, although the results from the spreadsheet would suggest otherwise.

17 to 18° over here rather.
Old ones. Even the ones with heavy hone wear have more than 17°
That won't make the angle steeper.
Must admit that I don't have verniers calipers, so its not 100% accurate.

The bevel being very narrow can happen to an older blade with a spine down flat as well btw. Here's one. I've honed it some more after having taken those pics and still got only 0.3 millimeter at max. I'd recommend not to hone it taped though. The new owner also wanted it like that.
As far as the new ones - I'd say they are not much worth when not honed by hand.

Usually I look at the razors and then decide what to do.
Amazingly enough its almost the same then what the spreadsheet suggests.

I have no calipers, but I can measure the spines and the widths to within 1/64" using a ruler, which translates to about 0.5degree error in the angle so that's what I did.

I used several vintage razors which have virtually zero hone wear and they have not been reground, and the angles were
18.5 old sheffield wedge
19.0 old sheffield wedge
12.5 wostenholm 'celebrated hollow ground'
15.0 Thiers-Issard hollow ground
20.0 Thiers-Issard frameback
20.5 W&B frameback
16.5 Dovo "Diamond Steel"
15.5 SRD

If 17 degrees is optimal, clearly the first two and the framebacks cannot be made to shave 'optimally' by adding tape to the spine or honing with spine lifted (which only increases the angle).

The one with 12.5 degree angle is not a fluke, I have two of them, which are exactly the same razor, although with sligthtly different markings for different markets.

And all these are large companies, so they pretty much set the standards.

So, as far as I'm concerned the razor manufacturers didn't consider 17 as some sort of a magical number.

Again, unless somebody runs a test that demonstrates that razors shave better with a 17 degree bevel compared to 14 degree or 20 degree bevel, all this is just useless trivia that should have no bearing on how a razor must be honed.

//irony on
Something relatively simple made way too complicated. You don't need a vernier, dial, or digital caliper to math out how much tape to put on a spine... Once someone figures out what the perfect bevel angle is:

• just get one of these dial protractors and avoid the math entirely. :borg:

//irony off

The "perfect" bevel for a razor is the same as the perfect angle for any other knife: too many variables for one answer.

Best bevel angle?