Ours was from the mid 1970's, but those models still command a bit of a price tag. This one just like ours, is going for $2500.
I'm looking at more of a desk model, and a much cheaper price tag. LOL
DE razor geometry. A system for measuring aggressive razors.
- Thread starter Slock
- Start date
I'm looking at more of a desk model, and a much cheaper price tag. LOL
I like this, but another option would be numbers. -1 for negative exposure, 0 for neutral, 1 for positive, 1+ for extremely positive. A similar thing could be done for blade support/rigidity: 0 for poor, 1 for moderate, and 2 for excellent support.
So, here would be a fairly simple concept. It could go Gap, Exposure, Blade Support. Say the razor has a gap of .70, neutral exposure, and excellent support. It would be listed as .7/0/2. A razor with a gap of 0.98, positive but not extreme exposure, and moderate support would be listed as 0.98/1/1.
I don't know, maybe it is still too complicated? But I think people would get the hang of it after a while. I do think there is value to simplifying exposure and support to relative values, or, in the case of exposure, just to negative, neutral, positive, and positive+.
Maybe get rid of the numbers and go to words? Gap would be a number. Exposure could then be Ng/Nt/P. Support could be Minimal (MIN), Good, or Exc (excellent). Using this system, the two razors I mentioned above would then be 0.7/Nt/exc and 0.98/P/good. (Side note: too bad that Negative and Neutral both start with the same letter!)
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That thing is pretty cool. I just checked the price tag for new one's and they're $12,000.
Here is my "poor man's comparator". I took the full sized jpg of the Karve SBD .98 photo of yours that I posted just previously and dropped it into Microsoft PowerPoint. We have a known measurement in the blade thickness, which is 0.1mm for pretty much all blades. I drew a line segment the same height as blade, which in the massively scaled up PowerPoint slide was .07" in length as shown by Pic 1 below. Now we have a scale in .1mm increments. (you can click on the photos below and they'll blow up in size for legibility).
Here is the picture I started with of the Karve SBD .98. Subsequent photos are just zooms of that photo:
Next, I drew a line segment the length of blade exposure from the edge of the green line to tip of the blade. On the massively scaled up PowerPoint slide, that measured .29", which is 4.1x the size of our 0.1mm line segment. Ergo, the exposure is ~0.4mm.
That's a huge exposure. Frankly I didn't know that exposure went that high. I wouldn't believe it, except for the fact that whatever razor you were taking a pic of with the J&L comparator showed an exposure just over 1 thousandth of an inch, which is 0.254mm. I guess blade exposures are bigger than I realized.
That makes me curious what Karve lists the exposure as; they're one of the only companies in the world that lists blade exposure on their website. It also makes me wonder what kind of blade was loaded, and what the width of the loaded blade was.
I'm not saying this is the "right" method; I'm just trying to brainstorm an easy, inexpensive, and relatively accurate way to measure blade exposure.
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Interestingly, the Karve website lists the SB-D plate as 0.13mm. That doesn't seem possible. The razor blade in the photo is 0.10mm thick (basically all razor blades are), and the exposure appears to be way more than that. Hmmm...
I tried measuring the gap with the exact same methodology to see if I got the .98mm that the Karve states is the gap. Using the exact same methodology (.7" per mm), I came up with .94mmas the measured blade gap in the photo. That's pretty damn close. Hmmmm...
I registered just to post this, sorry if it's crap:I tried measuring the gap with the exact same methodology to see if I got the .98mm that the Karve states is the gap. Using the exact same methodology (.7" per mm), I came up with .94mmas the measured blade gap in the photo. That's pretty damn close. Hmmmm...
SIN(x)=Opposite/Hypotenuse so
SIN(19)*.4=.13
Therefore, guessing, exposure is perpendicular to the plane of shaving
Aaron
Data Science, categorical vs numerical data:
With categorical data, you have an intuitive description of a sample (here sample = safety razor), but cannot compare. E.g. given categories mild and mild-to-aggressive, you cannot compare 2 samples from each category, provided that 1 sample has e.g. P/Exc/whatever and the other Nt/Min/whatever.
With numerical data, you can compare samples. Programming a classifier is trickier though, as noted by @Dovo1695. Also, I agree with you that the numbers can get overwhelming for new wet shavers.
I'm not sure whether @Slock wants to be able to compare razors or just label them "mild" vs "aggressive". I would prefer the former.
I don't think that's it but I'm also puzzled by the large difference between the .13mm exposure on Karve's website for this razor and the .4mm that it appears to be in photo, so it's not like I have a better explanation. Where did you get the 19 degree angle? I'm measuring about 28 degrees.
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It was either my Y2 Korean War Tech or my English Tech. You'd like my English Tech, Nick, shaves just like my GC68-P.
You guys make me look cool.
A bunch of math nerds!
When is chess club practice?
(Lol, sorry, I ALWAYS go for the low hanging fruit....)
A bunch of math nerds!
When is chess club practice?
(Lol, sorry, I ALWAYS go for the low hanging fruit....)
Did you not get the memo? Nerdy is cool now.
Great points here. I can definitely see value in having an ordinal scale for each of the 3 parameters. It would definitely help narrow things down. It would also definitely be easier to do.
I'm in the same boat. I appreciate the ordinal scale's virtue of simplicity and ease of measurement, but my own preference is definitely for an interval scale we're able to compare razors on a continuum. I'd definitely rather see "Exposure = .1mm" rather than "positive", but I'll be the first to acknowledge that it's a more difficult undertaking, and that increasing difficulty decreases the odds of anything getting done.
Are you telling me that I was actually COOL in High Skool?!?
I always was a day late and a dollar short...Absolutely not. Timing is everything...
Man! You all have seen my profile pic.... I can get this abuse at home!
That's at least part of the reason I 'forgot' to get married...
Sorry, I said I guessed! I played with plausible numbers until 19 gave almost exactly their .13.
Sorry, I said I guessed! I played with plausible numbers until 19 gave almost exactly their .13.
Lol. Don't be sorry, you were actually right. Blade exposure is measured perpendicular to the shave plane, which is not what I was doing.
The corrected blade exposure measurement I get is .157mm, which is bigger than the .13mm stated by the manufacturer, but I'm pretty happy with being within a few hundredths of a mm. The gap is only off by a few hundredths of mm too, which I'm pretty happy with. It looks like a reasonably accurate way to get measurements with $40 worth of equipment. Once you have the picture, it's about 5 minutes worth of work to get measurements.
I think ImageJ will probably do a better job than my proof-of-concept attempt with Powerpoint, especially if "focus stacking" can make the reference lines a bit crisper. Here are the updated measurements:
