Illustration of Safety Razor Parameters (Blade Exposure, Guard Span, Blade Gap, Etc.)

Discussion in 'General Shaving Discussion' started by ShavingByTheNumbers, Oct 17, 2017.

    :thumbup1: @Ad Astra should like that. :001_smile
  1. Ad Astra

    Ad Astra Ambassador

    Well, yeah! How else did you think I got here in space- chasing after a lost razor?

  2. :laugh:
  3. August West

    August West Moderator Emeritus

  4. @mozartman: I forgot to mention something. Months ago or last year, I seriously considered a curved reference surface for negative blade exposure, and I still consider it a good idea, but only in addition to the standard analysis with a flat reference surface. How does that sound?
  5. Sounds good. In fact, I think all of your analysis is impressive, and though you modestly say it has shortcomings and I guess I'll have to take your word on that, it is more than accurate enough to be very useful. I look forward to your future posts.
  6. Thanks! :thumbup1:
  7. I was thinking sticky because newbies are not familiar with the intricacies of a wiki. Keeping it at top of the very forum they are seeking assistance in would help them immediately understand the language and metrics needed to convey questions and interpret the feedback they will be getting without ever leaving the page. Confusion leads to fight or flight response resulting in paralysis when they are most desperate.
  8. Good work Grant! Are you interested in making a data set for known razors according to the parameters you've outlined in the diagram? I can contribute the following:

    Feather AS-D2
    Rockwell 6S (plates 1-6)
    Timeless .68 SB Stainless
    Gillette Tech British '73
    Gillette No.88 OC British '34

    I've always had a mind to work out why some razors work better than other and for different people, perhaps we might be able to finally attribute functionality to hard data?
  9. Wow! I would love to analyze the first three, and I was always planning on getting to some vintage, so the last two would be good, too. I'm not up for it right now, but please allow me to get back to you in the future, okay? We can absolutely attribute functionality to hard data. That's been something that I've been working on since my first post here on my photo analysis of the PAA DOC Satin. I actually have an empirical model for aggressiveness as a function of geometric parameters, but I haven't posted it because of a lack of validation data. Someday, I should have enough validation data to further refine the model and feel confident enough to publish it here. However, what matters more, I think, is getting us used to finding what guard span, blade exposure, and blade angle we each like, finding the optimum that works best for each of us. OneBlade claims to have that optimum, and maybe what they've found is the overall optimum across all guys, but that doesn't mean that it's the best for me or you, and it certainly doesn't mean that I'm willing to pay $400 for it when I might be able to find a relatively inexpensive DE razor with similar geometry.
  10. Happy to contribute, though I will need some time to work out how to get a decent macro shot working. The FF camera can't manage it with any depth of field. Maybe focus stacking...
  11. If I can use an old little Canon PowerShot for my photo analysis, I know that others can figure out how to do better with their better cameras. The setup takes time and is tricky for really good pictures. Then comes the analysis, which takes time and you have to know what you're doing there, too. I used to take a photo analysis picture, add lines in PowerPoint, print out the lines, take physical measurements, and then scale those measurements to get the true safety razor parameters. Now, I use a free scalable vector graphics (SVG) program to digitally scale down the picture, add lines to it, and digitally make measurements. It's faster, easier, and a little bit more accurate.
  12. I’ll contribute BBS1, Timeless ,68 and ,95 OC snd Merkur travel razor 34c
  13. The technical bits I can handle it's finding the time that I'll struggle with. Also, getting the higher res APS-C camera configured for macro might take practice too.

    @danlaw Ooo, BBS1! Maybe we can work out if any of the expensive razors are worth it!? :p
  14. Thanks! Like I told @TheKman, I can't deal with all of this now, but I might get back to you in the future. :001_smile
  15. Update with Neutral-, Steep-, and Shallow-Angle Shaving

    Below is a greatly improved illustration for the safety razor parameters around the blade cutting edge. Notes have been improved, and the demonstration of blade angle between the blade and shave planes is better than before, but the major improvement is the inclusion of steep- and shallow-angle shaving with color delineation versus neutral-angle shaving. Steep- and shallow-angle shaving are common terms, but based on my Internet search, it appears that I am the first to use the term "neutral-angle shaving" and, within the context of shaving, the term "neutral blade angle". Neutral-angle shaving neither favors 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.


    I would be remiss to not mention the wonderful help of @Cal. In updating the illustration, I reached out to my friend here, and as expected, Cal didn't disappoint. We ended up going back and forth on many details, and due to Cal's feedback and suggestions, this update is definitely better for it. Thanks for the help, buddy! :thumbup1:

    The illustration might be updated in the future, and if that happens, I will update this thread accordingly. Regardless, it is hoped that this new picture or an updated version will become the standard reference illustration for safety razor parameters with respect to neutral-, steep-, and shallow-angle shaving.
  16. I must say that your analysis is also very
    Relavent to this thread as well as very
    Important to the overall data of the OP
    My understanding is also
    That greater "contact angle range" is what I think of as more aggressive.
  17. Yes, I think ShavingByThe Numbers has the right idea by looking at the range between shallow and steep blade angle. Neutral blade angle is interesting too, as is blade exposure of course, but as you say the range from shallow to steep seems especially important.
  18. The range from shallow to steep blade angles is important, but it can be deceiving. You can get the same range with more or less aggression. Scaling down the razor profile size makes smaller spans and exposure while maintaining the same angles, so the blade angle range would stay the same, but razor aggressiveness would go down.
  19. If such a page dosen't exist then there
    Must be some simple way to create one.
    You are putting forth some very interesting
    And no doubt important info/analysis.

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