Measuring DE Blade Width with Digital Caliper and Homemade Cardstock Fixture

Discussion in 'Safety Razor Blades' started by ShavingByTheNumbers, Aug 25, 2016.

  1. In order to measure DE razor blade width and other parameters, I purchased a digital caliper, specifically the iGAGING OriginCal 0--6 in. Absolute Origin IP54 Digital Caliper, as shown below. The digital caliper has a resolution of 0.01 mm and a reported accuracy of 0.02 mm, which is plenty accurate for its purpose here.

    One can hold a DE blade in one hand and use the other hand to hold the caliper and move the slider to make the two outside measuring faces close onto the blade, but measuring blade width in this manner does not guarantee an accurate result since the blade might not be horizontal between the measuring faces and might not be flat, but have a little undesired bend to it. Further, measuring blade width with just one's hands and the caliper has an element of danger, sounds bad from the blade edges unintentionally scraping against the measuring faces when trying to hold the blade steady and in position, and can be frustrating. To resolve these issues, I made a fixture for holding the blade firmly flat and in the desired horizontal position between the caliper's measuring faces so that measuring blade width is quick, safe, and accurate.

    The fixture was basically made with cardstock and glue sticks. I first laminated cardstock pieces together using glue sticks, and then, using an X-ACTO-like knife, I cut out the shapes that I had designed and glued them together to form the top and bottom pieces of the fixture, as shown below. Sanding with 600-grit sandpaper happened during assembly and finalizing for fine tuning. It took time to make the fixture, from the preliminary design, to the prototype, to the final construction, but it was worth it. I now have a simple device to use with the digital caliper to make easy, accurate blade width measurements.

    The measuring process starts by cleaning the blade with rubbing (isopropyl) alcohol on clean white paper and allowing the blade to dry. This removes any excess film and debris that could affect the measurement. After this point, the blade is directly handled by only touching the blade tabs. The caliper measuring faces are also cleaned with rubbing alcohol on clean white paper by clamping the jaws onto the paper and sliding the jaws and paper apart. With everything clean and dry, the blade is ready to be loaded into the fixture. As indicated by the photos below, I simply place the blade on top of the bottom fixture piece and then press the top fixture piece into place. The blade is then securely held flat inside the fixture. (Don't mind the bit of photographic distortion that makes most straight lines and surfaces looked curved in the photos that are taken up close.)

    The loaded fixture is then held into place around the left caliper jaw using my left hand while I move the slider over with my right hand and get the right caliper jaw into the fixture. The slider stops when the blade edges fully contact the measuring surfaces. The blade edges are exposed just enough inside the fixture such that they are the only things that contact the caliper measuring faces, and the outermost layers of laminated cardstock on the fixture surround the caliper jaws with just enough space to allow free movement of the jaws while keeping the blade horizontal during the measuring process. After the slider has moved into place, an accurate measurement can then be read from the caliper's LCD display. The slider force seems reasonable such that there does not seem to be any damage to the blade or the measuring surfaces. To remove the blade when measuring is finished, I move the slider back out, take off the top fixture piece, and grab the blade by the blade tabs, which are exposed enough to allow for easy removal.

    The last two pictures show a used Wilkinson Sword blade being measured as having a 22.00 mm blade width. Since I only have two hands, I couldn't take a good picture showing the normal process of my left hand pinching the top and bottom of the fixture while my right hand holds the caliper and moves the slider into place, so I performed the measurement, put down the caliper, and took the pictures, which didn't change the 22.00 mm measurement.

    The Wilkinson Sword blade used here is the exact same one that I previously used in my photo analysis for dimensions (blade angle, exposure, etc.) of the PAA DOC. Based on available information and my own crude measurement, it appeared that the blade had a precise 22 mm width, which is why I chose it. Thankfully, this particular blade really does have a precise 22 mm width! This means that I do not need to calculate blade exposure and guard span for a 22 mm width using measurements made with a non-22-mm-wide blade. Ultimately, as I do more photo analysis and collect more data, the dimensions of blade exposure and guard span will be normalized for a precise 22 mm blade width, which was always the intent, but now that I have a way to accurately measure blade width, I can now accomplish this goal. Also, from now on, I will be collecting blade width data for various blades. Badger & Blade will someday have a comprehensive blade dimensions table in the ShaveWiki, I hope.

    Photo album:







  2. troy

    troy Steward

    Interesting. I've always assumed all blades were the same width. How many blades have you measured, and how much of a difference are you finding?
  3. troy

    troy Steward

    I wonder if Feathers are wider? It might explain why some people find them more aggressive.
  4. Blades do not have the same width, which is a big factor in why some blades work better in some razors while other blades work better in other razors, since blade width affects blade exposure. I just got the caliper, and I didn't want to bother taking measurements until I had a reliable, easy, safe, and accurate method for measuring blade width, which I now have. I have measured a used KAI blade when I was developing the fixture. I measured its width as 22.15 mm, I believe. I also measured a Feather blade, out of curiosity. I think that it came out to 21.94 mm. Those measurements aren't official, though. In time, I will collect measurements for multiple samples of the same blades to yield means and standard deviations of blade width. Blades widths should vary a bit from sample to sample, but some blades might vary more than others.
  5. troy

    troy Steward

    Thanks for doing these threads, that you've been doing. I will be very interested in your findings on blades and razors and see how the compare to my (and others) thoughts on them.
  6. You're welcome, troy. I'm glad that you like my threads. I still haven't gotten around to making the measurements for the Dorco PL602, but I'll get there. I plan on starting a blade dimensions table in the ShaveWiki sometime in the future for accurate measurements by me and others. The table would include blade width and thickness. When I bought the caliper, I also bought a micrometer. Even though the micrometer is more accurate than the caliper, it isn't friendly for measuring blade width because it exerts more force over a smaller area, resulting in unwanted blade deflection. A more complicated fixture could be made to use the micrometer compared to the caliper, though. Maybe I'll work on that. I didn't know whether I'd like the micrometer better for measuring blade width when I bought it, but I knew that it would be necessary for accurately measuring blade thickness. The caliper is not accurate enough for good thickness measurements, but the micrometer can handle it with a resolution of 0.001 mm and an accuracy of 0.003 mm relative to the nominal 0.100 mm blade thickness. Cleaning the surfaces with rubbing alcohol is not really important when measuring blade width with a caliper, but it is definitely important when measuring blade thickness with a micrometer. Film on the surface is picked up by the micrometer. I learned about that in a YouTube video and I've already seen it for myself.
  7. 1Cal

    1Cal Contributor

    View attachment 684083

    Like [MENTION=102704]troy[/MENTION] said, I always thought that all DE blades were 22mm wide. Of course, what individual manufacturers' permissible tolerances are... would be another story I guess.

    The only manufacturer I can find who publish their DE shaving blade size is Feather:
    $Feather Blade Dimensions.jpg
    I'm talking only about DE blades used for shaving. (Many manufacturers who make DE blades for industrial purposes publish their dimensions [and out of around three that I've seen, all have been 22mm wide and 0.1mm thick].)

    I'm looking forward to your discoveries. :thumbup1:
  8. Hey 1Cal,

    KAI also publishes official dimensions for their blades:

    KAI gives the width as 22.2 mm, the length as 43.0 mm, and the thickness as 0.10 mm. I measured one new KAI blade as having a width of 22.16 mm, a length of 43.11 mm, and a thickness of 0.100 mm. Rounded to their decimal places, the only difference that I measured was with the length being 43.1 mm instead of 43.0 mm, but the length doesn't really matter compared to width and thickness. Also, maybe these values vary a bit from box to box, blade to blade.

    You must be right about who publishes blade dimensions. When I looked in the past for official numbers, the only ones that I found were from Feather and KAI. Yes, 22 mm is the standard width and 0.1 mm is the standard thickness, but values vary from brand to brand, and probably a little from blade to blade. I measured the thickness of one new Derby Extra blade as 0.105 mm, for example. I thought that I'd read that KAI blades were thicker than other blades, but it's not true. That one Derby blade was thicker than that one KAI blade, and I'll probably find this to be true in time after measuring more Derby and KAI blades.

    Should I bother measuring that blade edge distance, or whatever you might call it, that is typically 37 mm? KAI doesn't even report that distance, but Feather does. Length doesn't really matter for blade analysis, but I'm measuring it because it is easy enough to do. I probably would measure the blade edge distance or whatever if I were set up to do that, but I'm not right now. I'd have to make another fixture.
  9. matwho

    matwho Steward Contributor

    Your findings will be a great resource for the community.
  10. Thanks. I think so, too. Measurements of blade width have been done for some blades in the past...

    ...and I've seen a table with some blades at an Australian website, but there does not appear to be a comprehensive database of width data taken using a reliable methodology, as I am doing with an absolute origin caliper and an appropriate fixture. Plus, very little data is available on blade thickness. I have not seen any documentation for means and standard deviations that show whether some blades are more consistent or if other blades are inconsistent, which could explain shaving differences that someone experiences with the "same" blade. Little by little, I will collect data. I already have an Excel spreadsheet started.
  11. Interesting, indeed.
  12. 1Cal

    1Cal Contributor

    Hey ShavingByTheNumbers, a first name would be nice (if you don't mind that sort of thing on a forum). :wink2:

    Thank you for that link, appreciated. :thumbup1:

    I would like to see the "blade length" (blade edge distance) as well as the "complete unit including tabs length." When trimming facial hair features like mustaches etc (along the edge lengthways [Vs from/to]) I like to know exactly where the blade ends. So if "blade lengths" aren't standard, I'd like to know.

    Here's an alignment (or should that be misalignment?) pic of my Mk1 Fatip Piccolo:


    It will align itself anywhere between perfect and the above pic. I used ONLY this razor for six months and always accepted the blade whichever way it landed. I didn't even know it was doing this till someone mentioned the alignment issue in my "Fatip Piccolo. I'm in love." thread.
    I now have the latest (MK2) Piccolo which has no alignment issues whatever. If you're interested, here's a link to another thread: Fatip Piccolo Mk1 & Mk2 differences.

    Considering the above, specially for me with my relatively tough skin, the fractions of millimeters being discussed here probably ain't going to make any difference whatever. BUT, being the incorrigible detail freak that I am, I will be watching this thread with great interest.

    The devil's in the detail. :devil:
  13. Cal,
    Thanks for the detailed response. I was leaning towards measuring the smaller length, too, simply because its hard for me not to measure it when I'm measuring everything else. (I'm not sure what to call it. "Blade edge length" isn't accurate because it is technically longer than the blade edge. Maybe "blade edge tab length" would be best to describe the length of the tab with the edge on it?) Measuring is quick and easy with the right tools. I already have the fixture for measuring width, and even though I'm currently using it for measuring total length, it wasn't designed for that and is frustrating when using it that way. I have designed a fixture for measuring total length and edge tab length. I will make it and post an update. The four measurements of width, thickness, total length, and edge tab length should cover it, right? Measuring a true edge length is difficult because of the curvature at the ends, and I don't think anyone reports that. What about "tab length"? It is around 13 mm. No one reports that, either, right?
  14. 1Cal

    1Cal Contributor

    "Blade edge length" is accurate because the cutting edge goes right to the end of the tab, even if it is rounded. Interestingly, there's a thread (How to take corner edges off off DE razors!) about removing the sharp edges from the blades' rounded corners, as some people were being nicked by them.

    As we call that whole piece of metal "the blade," rather than just the two sharp edges, I propose that we call the two "blades" the "cutting edges." So for the complete metal strip (that we call the blade) we would have the "length," and for the blade parts we would have "cutting edge length" like this:
    $Feather Blade Dimensions_X.jpg
    What do you think?

    Being the awkward kind of git that I am I would still like to see the "cutting edge length." That would then give five measurements which I would call:
    Cutting edge length, and
    Tab width (Vs. length [to eliminate reader orientation confusion]).

    Again, what do you think? The above are just my proposals and two cents worth. It's your party, and you're the guy who's doing all the work,
    which I very much appreciate. :thumbup:
  15. That's very interesting about people taking off the edge corners! I haven't had a problem, but I can see the benefit.

    Yes, the blade edge does run from tab to tab, but because of the curvature near the corners, the true edge length is longer than the straight distance along the edge tab. Nevertheless, I think that you might be right about the label. I'm probably being too technical. "Blade edge length" is a good label. If we were to have different measurements for "blade edge length" and "blade edge tab length", then there would be a reason for the different labels, but since we aren't making different measurements, we might as well use "blade edge length", which is appropriate. I don't think that it is necessary to use "cutting edge" instead of "edge", which is commonly used for the cutting edge. We don't say "double cutting edge", but "double edge", you know?

    I think that whatever labels are used, they should work with or without "blade" at the beginning. Do you agree? (You might already have considered that because your list doesn't have "blade" in it.) Your list is good. Your point is valid about "tab width" versus "tab length". I considered "width", but I just went with "length" without much thought because we usually think of length as longer than width, but "width" should be used. Here is the list without "cutting":

    Edge Length
    Tab Width

    How does that sound? I really appreciate your feedback, Cal! It's great to have someone to bounce this off of and work out the kinks.

    Instead of making another fixture out of laminated cardstock, I am now planning to spend a few bucks and get some clear polycarbonate to make new fixtures for the width and length measurements. Clear polycarbonate is way better to use than laminated cardstock. I used materials that I had on hand, and it worked as well as expected, but I now consider my cardstock fixture to be a working prototype. It will be easier to make fixtures with polycarbonate, since I have the necessary tools to cut and sand it. I'll use epoxy or superglue to adhere the pieces together. In the end, the polycarbonate fixtures will be flatter and stronger and not wear like the cardstock fixture is expected to do. The transparency of a polycarbonate fixture will be cool with a blade loaded, but I'm hoping that I'll be able to see the blade contact with the measuring faces of the caliper just in case there is some issue of imperfect contact that I wouldn't otherwise feel or see.

    By the way, you can call me Grant if you prefer. That is my name. I just really like my username because it is unique and I don't want to cause confusion. Maybe someday I'll put my name in the signature line like you do.
  16. 1Cal

    1Cal Contributor

    For me the shorter the description the better... except in this case. Sorry to be a pain, it's just the way I am. :001_rolle

    For everyone that uses DE blades I'm sure the other four will be obvious. But if I'm talking about blades to someone and use the term "edge length" I would expect:
    "Say what?" ("Edge, which edge?") Whereas if you add "cutting" they'll know exactly which "edge" you're talking about.

    That sounds great! :thumbup1:

    And yay Grant, a good Scottish name! :001_cool: Being a Scot I like Scottish things (barring the weather, I live in England :blushing:).
  17. ouch

    ouch Moderator Contributor

    I use blades so thin they only have one side.
  18. :lol:
  19. But "double edge" and "single edge" do not have "cutting" in them and we know which edges they are. Who would ask which edge of a "double edge" razor blade we are talking about with respect to "edge length"? You are right that adding "cutting" makes it clearer, but even then, the true cutting edge, which has some curvature at the ends, is longer than what we define. I think that the key to clearing up any possible confusion is the drawing with the dimensions labeled, right? The diagram would be included above the table of blade dimensions.

    By the way, there is Scottish, English, etc., on my mother's side, but German on my dad's side. :001_smile
  20. 1Cal

    1Cal Contributor

    Hey G, I'm only commenting and giving my opinion. You're running the show.

    It's your prerogative to do it exactly how you like, and that's as it should be. :thumbup1:
    And yes, we always love pictures. :001_wub:

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