SE Razor Parameters DEFINED

Discussion in 'General Shaving Discussion' started by ShavingByTheNumbers, Oct 25, 2017.


    The illustration above was posted recently in the DE razors forum (B&B URL) and the general shaving discussion forum (B&B URL), but since the illustrated safety razor parameters and modes of shaving apply both to DE and SE safety razors, the illustration seems to belong here, too.

    The comprehensive illustration shows the blade and shave planes and the parameters that follow around the blade cutting edge for a blade loaded in a safety razor: blade angle, handle angle, blade exposure, guard span, cap span, blade gap, free-end distance, clamp distance. Free-end and clamp distances were measured for the first time with my photo analysis of the Edwin Jagger (EJ) DE89 head (B&B URL). Important details that could not be simply illustrated are included at the bottom of the picture. For example, I rigorously define blade gap based on personal experience in measuring the quantity with my accurate set of micrometer-measured feeler gauge blade combinations (B&B URL).

    Blade gap is commonly associated with razor aggressiveness, but, at best, blade gap only loosely relates to razor performance. Blade exposure, guard span, and blade angle, on the other hand, are very important performance parameters with respect to aggressiveness and efficiency. Unfortunately, these three parameters are not easily measured. Photo analysis is the primary method for measuring the illustrated parameters, but physical measurements, such as for blade gap, should be used when appropriate to complement or supersede digital measurements.

    Steep- and shallow-angle shaving are common terms (often employed without hyphens), but based on my Internet search, it appears that I am the first to use the term "neutral-angle shaving" (with or without the hyphen) and, within the context of shaving, the term "neutral blade angle". Neutral-angle shaving favors neither the guard nor the cap, justifying the use of the word "neutral", while steep-angle shaving favors the guard and shallow-angle shaving favors the cap. Accordingly, we have neutral, steep, and shallow blade angles. I encourage the use of these terms.

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

    Feedback is welcome. What do you think?
  1. Chan Eil Whiskers

    Chan Eil Whiskers Contributor

    I think this is fabulous.

    It needs a good bit more of my attention, and will get it.

    One comment. I've seen what you're calling neutral-angle shaving called the design angle. See this post and the post previous to it. I like that term, and yours, for different reasons.

    Another comment. It is a bit hard to see exactly what some parts of the photo and descriptions are talking about. It would be a lot more work for you, but it would be very helpful, I think, to have similarly labeled and marked photographs of another razor or two.

    This is, I think, extremely useful and good work. It will help facilitate meaningful discussion where people are on the same page and have a common reference point. Too often we use words and terms in ways which are not standard.

    Thanks so much for doing this.

    Happy shaves,

  2. Ron R

    Ron R Contributor

    Well to put it simply"Bravo" that is a great effort into the jargon of words that gets thrown around at times. Very nice.
    All the best
  3. :thumbup1:

    It's funny that you bring this up, because @Cal helped me refine my illustration and this was one of those things that we talked about. I gave credit to Cal in my original OP in the DE razors forum and in the repost in the general shaving discussion forum, but I failed to mention his help in this repost when I rewrote the introduction. (Sorry, Cal.) As I told Cal, I like "design angle", too, but it presumes that the neutral blade angle is the intended angle for use by the designer. Also, shallow and steep blade angles could have been designed, too. Language also helps explain why I settled on "neutral". Parallel language between "neutral", "steep", and "shallow" is attractive, and I can say "neutral blade angle" when I can't say "design blade angle" because "design" is not an adjective.

    I can't put more razors in the illustration, and I get what you're saying about the difficulty of seeing some parts of the photo, such as the area around the end of the clamp distance. I'd probably have the same problem with other razors, too, because of how dark the razors come out in the pictures. Nevertheless, what you are talking about with labeling and marking other photographs is what I've been doing and what should develop in time. I've done photo analyses for the PAA DOC Satin, the Dorco PL602, and the EJ Kelvin. In the photo-analysis pictures, the same parameters are illustrated with their values given. My most recent analysis of the EJ DE89 head is the most complete with free-end and clamp distances and steep- and shallow-angle values, too. Now, I can refer to the general illustration on safety razor parameters as a standard reference for those parameters. If something needs to be improved in the illustration, I'd like to fix it.

    Yes! Exactly! :thumbup:

    You're welcome, Jim. :001_smile
  4. Thanks, Ron! I appreciate that. :001_smile
  5. 3rd Version with Blade Reveal Added

    [Note: This was just posted in the DE razors forum (B&B URL) and the general shaving discussion 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.

  6. I've created a ShaveWiki page as a reliable location for the most up-to-date illustration and information about safety razor parameters:

    Safety Razor Parameters: Illustrated and Defined

    Please use the wiki page whenever referencing this material. Thanks.
  7. Ron R

    Ron R Contributor

    Very nice article and reference, if people get confused I know how this article will help all future discussions for now & future generations. Job well done!
  8. Thanks, Ron! :001_smile I think so, too. If you see anything that needs correction or clarification or if there's something that you think should be added, please let me know.
  9. This trips my engineering trigger. I was just thinking about investigating the correlation between blade gap and blade exposure on my Gillette Slim adjustable razor. I noticed last night that I dialed it back to 3 instead of my usual 4 and I had a much smoother shave. That got me thinking that by increasing the blade gap, I was also increasing the blade exposure. I'm tempted to bring it into work and experiment with our Keyence vision system in our lab to see if I can capture these measurements in an efficient fashion.
  10. Cool! Please post any pictures if you get to use that system. :001_smile As for blade gap and blade exposure, there really isn't much of a correlation, or at least there isn't much of a necessity for one. Guard span, on the other hand, generally correlates with blade gap, in that more blade gap generally means more guard span, but the correlation isn't strong, if I remember correctly from my measurements. Blade gap matters little compared to guard span and blade exposure, and also blade angle. Unfortunately, blade gap gets more attention because it's relatively easy to measure and easier to see, and manufacturers keep using it.
  11. Thanks for the updated diagram!!:a14::a14:
  12. naughtilus

    naughtilus Contributor

    One can consider an Open Comb guard as infinite blade gap.
  13. You're welcome :001_smile

    If you mean between the teeth of the OC guard, then maybe so at those points. Blade gap could possibly be measured in between the teeth, but the measurement would be meaningless. For modeling purposes, such as toward creating an effective blade gap for OC guards, tooth thickness and spacing would be used, along with the blade gap as defined using feeler gauges (which applies for the teeth, not the spaces).
  14. ajkel64

    ajkel64 Moderator

    Thanks for sharing, very interesting.
  15. You're welcome, Andrew. :001_smile
  16. Ad Astra

    Ad Astra Ambassador

    The engineering analysis is appreciated! and fascinating!

    If golf is a game of inches … shaving is a game of thousands of an inch!

  17. Thanks, Mike!

    True! :thumbup1:

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