Steep and Shallow Angle Shaving DEFINED

Discussion in 'General Shaving Discussion' started by ShavingByTheNumbers, Oct 23, 2017.

    Yes, the PL602 is light, like a disposable, but I'm still enjoying the shave I had using it
    today, and do not consider it a toy.
     
  1. Of course, it's not a toy. It cuts hair off your face. :001_tongu
     
  2. Excellent explanation. One picture is worth a thousand words, and we've needed a standard reference to show people.
     
  3. :thumbup1:
     
  4. I ride both cap and guard depending on where I am on the face. I am certain that I do not maintain a consistent relative approach angle throughout all my facial contours. However, the razors I have seem to be forgiving enough for my inconsistencies, and irrespective of approach angle, I will always get a little redness under the jaw unless I follow it over with a wet alum block after the final pass.
     
  5. Impressive and formidable work!

    This work deserves a sticky somewhere, to be used as a point of reference.

    Thank you ShavingByTheNumbers! :thumbsup:
     
  6. Thanks! :001_smile
     
  7. Excellent


    Sent from my iPhone using Tapatalk
     
  8. Much appreciated
     
  9. 3rd Version with Blade Reveal Added


    [Note: This was just posted in the DE razors forum (B&B URL).]

    Below is an updated version of the illustration for safety razor parameters around the blade cutting edge, which applies both for DE and SE razors. This third version involves two changes: (1) blade reveal has been added and (2) the bullet point on blade rigidity has been improved.

    For a given razor, an increase in blade width causes increases in blade reveal and blade exposure. However, when comparing different razors, more blade reveal does not mean more blade exposure. Blade reveal should not be confused with blade exposure. Blade rigidity may seem dependent on blade reveal, but blade rigidity actually depends on free-end and clamp distances, along with blade thickness and the elastic modulus of the blade material. Blade rigidity is, nevertheless, related to blade reveal in that free-end and clamp distances increase with increasing blade reveal.

    It is hoped that this updated version will become the standard reference illustration for safety razor parameters with respect to neutral-, steep-, and shallow-angle shaving.

    [​IMG]
     
  10. Great discussion! I especially appreciate the concept of 'neutral angle!'
     
  11. BDF

    BDF

    I have been working on the same thing- the angle of the blade in relationship with the angle formed by the contact points of the cap and the guard bar. There is very little mention, if any, of this and I too believe it is crucial in the performance of any safety razor.

    Gillette butterfly razors, especially the later adjustable types, seem particularly steep and in my experience, are terribly irritating razors while being very mild going by all classic parameters. Merkur razors, and the Progress in particular, seem to be on the opposite end of the scale and again, the major difference is the extremely shallow angle of the blade in relation to the line formed between the cap and guard.

    On a side note, I have also just finished testing the famously 'mild' Feather AS D2 and again found that while it was not aggressive at all regarding actual hair cutting, it did have a relatively steep angle resulting in a lot of razor burn. I was actually disappointing in the razor's overall performance and believe the irritation was entirely due to the much closer to perpendicular angle of the blade in relationship to the line formed between the cap and guard.

    Currently I am testing a Rockwell 6S razor set, and thinking about an Above The Tie razor for testing. One of the keys in a razor setting a shallow shaving angle, in relationship to the skin (the razor's angle is actually set by the line formed between the cap and guard, if this angle is not held correctly the razor blade's edge is actually held away from the skin) seems to be quite dependent on the height and radius of the top cap; the higher and rounder the cap, the shallower the blade's angle against the skin. Of course the blade angle could be shallow with a fairly flat razor top cap but the gap must be increased to allow that, and that itself would cause a razor to be more aggressive, if not when shaving relatively flat areas but certainly so when going around any convex curves; the larger gap would combine with the sharper curve of the skin to again produce a sharper blade angle as well as making it much more likely to have skin actually protrude into that gap, all of which would make for a very uncomfortable shave IMO.

    Brian

     
  12. Raven Koenes

    Raven Koenes Contributor

    :laugh:
     
  13. Excellent! :thumbup1:
     
  14. Blade angle isn't easy to measure with precision, but a good approximation can be made with the help of paper, tape, other material, pencil, straight edge, and protractor. (Prop the razor up on a piece of paper so the handle is horizontal and the side of the head is facing up. Use tape to fix the razor to the paper. Use the straight edge and pencil to make a line for the shave plane. Do the same for the blade plane and the handle direction. Carefully remove the tape and razor from the paper and use the protractor to measure the blade angle and handle angle.) More shavers should take a close look at the blade angle of their razors. It's cool that you're looking at it. :thumbup1:

    I've wondered about vintage Gillette TTOs. What are their blade angles? The blade angle that I measured for my EJ DE89 head is 30.5 degrees (B&B URL). Do you have any measurements for the Merkur 34C or Progress?

    Some love the Feather AS-D2, but I understand why you and others don't. Based on my estimates from pictures that others have taken, it seems that the AS-D2 has a blade angle around 30 degrees, negative blade exposure, and a normal or large guard span. Maybe I'm wrong and the blade angle is higher than normal, causing the irritation that you've experienced. The combination of blade exposure and guard span definitely makes the razor relatively less efficient compared to other razors, as you've experienced. Did you apply more pressure with the AS-D2, in order for it to cut hair, which may have caused more irritation?

    Those are nice looking razors! :001_smile Razor aggressiveness does increase with more guard span, which is generally correlated with more blade gap. According to OneBlade, the optimum blade angle is 31.3 deg. I'm skeptical, thinking that some guys might like more shallow blade angles while others might like steeper blade angles. Maybe the optimum that they found is an average of user preferences, or maybe they based it on the mechanics involved. They stuck with a Feather blade, so the optimum blade angle might be tuned for it, since it's very possible that optimum blade angles vary with the blade.
     
  15. BDF

    BDF

    It is easy with a precision X Y table with either a microscope or shadowgraph but most do not have access to those.

    The next 'best' way IMO is exactly what you did with a simple photograph and some layout lines draw over the key points of the razor and blade. Not precise but from what I have been finding, this is not a subtle thing at all; razor angles are hugely different and so separating the shallow ones from the more acute versions is not a matter of fractions of one degree but several degrees.

    I only began to look at this because I could not find any reason or rhyme as to why some razors shaved well, some shaved poorly, some produced razor burn and some (actually one- a Merkur Progress, slightly modified) that did not. The truly amazing thing for me was finding that Gillette adjustable could be adjusted so that they would NOT yield a BBS shave and yet still produce razor burn! After trying perhaps 15 razors, some new and some old types, I came to the conclusion that the blade angle against the skin, or the razor geometry that generates that angle specifically, was a big factor in how a razor performs. Again, it is easy to compare with a straight razor because a straight has infinite angle choices but no one would choose to make a primary pass, or even a later pass ATG with a straight. But we do this with safety razors all the time simply because we have to due to the mechanics of the razor.

    A truly amazing thing to me was finding that one side of my Merkur Progress shaved with no razor burn while the other side did not. After examining the razor, I found the top cap was biased toward one side by just under 0.010" (ten thousandths of an inch). The gap is very close to the same but because the cap edge is in a different position relative to the safety bar, it changes the angle formed between those two points and therefore changes the blade angle. This is what led me to believe that the actual razor- to- skin angle is not only important but critical.

    If you look at all the Gillette adjustable, and most of the line in fact, it is easy to see how flat the top cap- shape really is, especially when compared to a Merkur for example. The radius of the top cap seems to be the single most important factor in determining the razor blade edge angle w/in the razor's gap, so the high, more rounded razors seem to generally produce a shallower shaving angle on the blade.

    Unfortunately, no I do not have any actual blade angle measurements. At the time I was measuring them, my main concern was simple to compare two razors, usually the Merkur Progress and whatever razor was ripping my neck the day before. :)

    The Feather razor has a fairly steep angle on the blade and in addition, the blade is unsupported for quite some distance resulting in a lot of shaving noise as well as possible blade vibration. This ties in with some of the other discussions of blade stiffness, and I found the Feather left a great deal of blade edge unsupported or bearing on either the cap or lower plate. I also found it very difficult to 'ride the cap' on that razor; it seemed to jump from not cutting to causing irritation with the slightest change of angle (razor to skin angle).

    The Rockwell 6S is a little more difficult to examine because it has a unusual undercut in the lower plate just below the blade's edge. It appears to have a slightly steeper angle than the Progress, though still quite shallow but can be adjusted even milder than the Progress if using the #1 or #2 plates. I have used the first three and as #3 yielded a little burn I went back to #1 and will continue to use that. Plate #1 does not seem to quite get the absolute last of the hair though; the blade is actually recessed behind the plane formed between the cap and safety bar- this is truly a very mild razor.

    All my testing is done with Feather blades. I have not had much success with blades less sharp generally, regardless of razor, and the only real result is a worse shave with just as much razor burn. So I basically only use Feathers or the occasional Gillette 7 O'clock yellow, which is close to a Feather in sharpness.

    Brian

     
  16. I don't think that using a microscope would be easier or better than standard photographic methods. Also, a shadowgraph is really for flow visualization, so I don't know how that would come in handy here. My previous photo analyses were good, better each time, and actually, the improved techniques that I've used for the Bevel are excellent, allowing for even better measurements of angles and distances. I'll eventually get to publishing that material.

    Razors do vary a lot in the key parameters that affect aggressiveness and efficiency: blade exposure, guard span, and blade angle.

    Very good deduction with measurements! Excellent! :thumbup1:

    That makes sense. Good analysis.

    I get that. No problem.

    Yikes! I'd like to analyze the Feather AS-D2 someday, but I might not want to shave with it. :001_unsur

    The Rockwell 6S wouldn't be a problem to analyze. It would take time, as is true for every razor, but my analysis techniques would work. It certainly wouldn't be harder than analyzing the Bevel, which basically has everything covered from the side except for the tip of the blade sticking out from the shave plane. According to the high-resolution pictures that I've seen for the Rockwell 6S with different plates, the blade exposure is negative with all baseplates, just shrinking in size with increasing baseplate number. I haven't confirmed this with my own physical and photo analysis, though. The guard span increases with increasing baseplate number, even more so if we use a more appropriate curved shave plane instead of the standard flat shave plane.

    I like sharper blades, too. I've been primarily using the Kai blade lately, but I haven't used the Feather blade in a long time. Based on my testing with different razors, I've confirmed closer shaves with the Kai than with the Astra SP, even when the blade exposure was a little more with the Astra SP.
     
  17. BDF

    BDF

    A shadowgraph is a mechanical contraption that moves the 'target' in precise amounts in two dimensions while displaying the 'target' onto a frosted screen at great magnification. The 'target' is then moved and the graduations on the screen used to measure angles, the table used to measure distances and so forth. All very accurately. And the microscope I mention is again not just a microscope but an entire assembly that uses a microscope as the optical interface but the table holding the 'target' is again moved with micrometer heads or laser interferometry gauges and distances carefully recorded. These data points are then fed into a CAD program and a model of the 'target' is created, again with extreme accuracy.

    The Feather was a big disappointment to be because it is often held up on a very high pedestal. And the razor was absolutely top- shelf, extremely well made, precise and overall (even the packaging) it was nothing short of excellent. I just could not get my face, especially my neck, to 'play nice' with the thing. I am in no way knocking a Feather razor, merely stating that I did not find it worked for me, unfortunately. It was definately a better made razor regarding precision than the Rockwell, for example.

    The Rockwell is somewhat tough to simply look at and get a feel for the geometry because of the particular design. There is a large step below the blade that sets the position of the safety bar, while most razors just have the safety bar projecting out below the blade. Difficult to describe, and I agree that it would be easy enough to photograph and then overlay lines and dimensions but just using a Mark I eyeball, it is more elusive. I am getting to like it though and think it is going to be worth the time to find the right combination that I hope will work for me.

    We all have our methods I guess but I use the 'tree top' arm hair method, along with snagging single hairs of my (dry) beard to test both straights as well as DE blades. And I have not found anything as sharp as a Feather. I can approach that level of keeness with a straight using charged balsa strops but have not found any other DE blade that is as sharp. And Feathers always give my very best, least irritating shaves with a brand new edge; the second shave is also excellent but not as good as the first. So if I could find a sharper blade I would happily try it.

    Back to the DE thing: I will continue to work with the Rockwell and post what I find just to throw another opinion in the mix. And as I said, I am really considering an Above The Tie in a mild form. One of the things that I think contributes to the smoothness of a Progress is the scalloped safetly bar, which leaves some shaving cream behind for the blade itself. The Rockwell does not have this feature but the ATT's do, at least some of them, and I think that along with precise manufacture, might well make a wonderful shaving razor.

    Brian

     
  18. I looked up shadowgraph and Wikipedia said that it was mainly used for flow visualization, so there are definitely at least two different types of contraptions known as shadowgraphs. :001_smile I get what you're saying about using laser interferometers for capturing 3-D spatial coordinates. That's a fancy setup, and yes, it would be very accurate, but I can be very accurate with my physical and digital measurements, too, without any expensive or atypical equipment. We should be able to collect good data for razors at home using simple tools, right?

    I completely understand. It's a beautiful razor, but a higher price doesn't mean a better shave.

    That's great, Brian! Last year, I used some pictures of the Rockwell 6S in considering a refinement to my aggressiveness model. That's saved in a PowerPoint file, so I'm aware of the Rockwell's geometry. Most people seem to really like the razor. I'd like to try it someday. Good luck finding the right combination that works for you. :001_smile

    Apparently, there is no DE blade sharper than the Feather. It's reputation sounds well earned. I haven't used one in a long time and I really need to give it a try again now that I'm using a new razor and have more experience. In the past, I found it sharp, of course, but not as smooth as the Kai, which is why I leaned towards the Kai.

    I would love to get my hands on an ATT, especially a mild one like you're talking about, even if just to analyze it. What you said about a scalloped versus straight bar hits home for me. The Bevel is my first daily driver with a straight bar, and my initial impression is that slickness is a little bit better with a scalloped bar (as with my EJ Kelvin) because of precisely what you're saying about lather. However, I can't compare the same setup with two nearly identical razors in which one has a straight bar and the other has a scalloped bar, so I'm hesitant to draw the conclusion.
     
  19. BDF

    BDF

    Old school slang term I am using: try optical comparator and you will hit paydirt. Mitutoyo is a decent mfg. of them and would be a good example.

    The microscope looking at the X-Y plane is a more modern version and now is often digitalized. The way they are used is that the 'target' is placed on the table, and the microscope used to place the reticle onto the desired place, then the table's position recorded. Three points on one plane is a line, three points on an arc is a circle, etc. The data points are fed into piece of software capable of plotting them and a model or 3D CAD representation is created, displayed and if desired, turned into CNC code to 'make another one'.

    Yeah, decent results can be done at home, especially with today's inexpensive and excellent digital cameras and software readily available. One of those things where a little care in setting it up goes a LONG way to getting good results. Of course even using excellent commercial equiptment, the data gathered is only as good as the setup was. Or used to be, today's CMM's will actually compensate for bad (read: Atrocious) operator ability.

    Will continue with the Rockwell and will also probably give ATT a call and see what they think of the whole Merkur Progress thing (and why I think it works so well for me at least).

    Brian

     

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