Would love to know gaps and blade exposures for classic vintage razors.....

[kingfisher]

With all the discussion about how modern razor makers are providing gaps and at least some are saying "negative/neutral/positive" for exposures (with some people wishing to hear actual exposure numbers), what I would love to know is the blade exposures of classic vintage razors, especially Gillettes.

Pretty sure there is already a table in the Wiki with gaps for these razors, but exposures are nowhere to be found. I wonder if one of our technically minded people could figure out a way to quantify gaps for, say, the various Superspeeds, Fatboy/Slim, Techs, LC and SC New, Old type, New Improved, etc. Personally I would love to have that information. I figure for somebody who is experienced with lots of vintage Gillettes, it might help if they decide to pick up a new razor. In other words, if they know what vintage razor works best for them, and they had gap/exposure information for said razor, they could choose a modern razor that would match their known preferences.

Has anybody made an attempt to quantify the blade exposures of classic vintage Gillette razors? If not, is there anybody who would be able to do it?

 

[Dovo1695]

With all the discussion about how modern razor makers are providing gaps and at least some are saying "negative/neutral/positive" for exposures (with some people wishing to hear actual exposure numbers), what I would love to know is the blade exposures of classic vintage razors, especially Gillettes.

Pretty sure there is already a table in the Wiki with gaps for these razors, but exposures are nowhere to be found. I wonder if one of our technically minded people could figure out a way to quantify gaps for, say, the various Superspeeds, Fatboy/Slim, Techs, LC and SC New, Old type, New Improved, etc. Personally I would love to have that information. I figure for somebody who is experienced with lots of vintage Gillettes, it might help if they decide to pick up a new razor. In other words, if they know what vintage razor works best for them, and they had gap/exposure information for said razor, they could choose a modern razor that would match their known preferences.

Has anybody made an attempt to quantify the blade exposures of classic vintage Gillette razors? If not, is there anybody who would be able to do it?

Gaps are well trod ground, but exposures are known for only a handful of razors (modern or vintage). The only way to really get that information as far as I can tell is a closeup photograph of a razor with a perfect blade loaded, with a known scale, and then measure the distance in the photo using a program like ImageJ.

There are two fundamental problems with this. The first problem is that photographing a closeup of a razor correctly in order to measure blade exposure is challenging. The second is that exposure is dependent upon the razor blade used, because essentially no blade is actually 22mm.

Problem 1: Photographing a razor correctly is hard.

Photographing a razor with a cell phone camera isn't really ideal. Cell phone camera's area miracle of modern engineering designed to take photos of objects from 1 foot away or 1000 feet away and nearly all have autofocus. Auto focus camera's have a hard time taking pictures of close up reflective surfaces in my experience. The other problem is that the photo needs to be taken directly above the object, otherwise the image is skewed and the measurement will not be correct. I don't know much about photography, but I do know a lot about trying (and failing!) to get a good picture of blade exposure with a cell phone camera.

https://www.amazon.com/Plugable-Microscope-Flexible-Observation-Magnification/dp/B00XNYXQHE/ref=sr_1_5?_encoding=UTF8&c=ts&dchild=1&keywords=Lab+Handheld+Digital+Microscopes&qid=1622843472&s=photo&sr=1-5&ts_id=2742273011

I'm thinking about upgrading my kit to a USB microscope that will allow me to manually focus and will give me 40x magnification. I'm thinking of this one. Maybe someone who knows about microscopes or photography can point me in a better direction. Once a photograph is taken correctly with a know scale, measuring the exposure is a little more straightforward. Here is a link to some open source software developed by the US National Institute of Health that's used by a lot of academics to take precise measurements of photos taken by microscopes.

Link to the NIH ImageJ software:

ImageJ

imagej.nih.gov

You'll want to mute this one but it's a concise demo:

Problem 2: No blade is actually 22mm

Blade exposure is determined in no small part by the width of a razor blade. A razor may have 0.05mm assuming a razor blade of precisely 22mm, but that's kind of meaningless if the razor blade you've just loaded is 22.18mm wide. Now you have a blade exposure of +0.14mm (0.05mm baseline exposure + 0.18mm/2 = 0.14mm). Is that a realistic scenario? It is if you've just loaded a KAI, which is in fact 22.18mm. Here is a table of DE blades measured by a micrometer a few years back by Giovanni Arbate. I'd link the blog, but it's against B&B policy, so I'll just insert a picture of the table. Put simply, you've got to get yourself a reference blade that you've measured with a micrometer with some certainty and repeatability that it's 22.00mm. This also assumes your micrometer is that accurate.

In short, getting blade exposure measurements isn't easy. It assumes a perfect photo, and a perfect reference blade. Or maybe not. Maybe there is an easier way. If so, I'd love to hear about it! I'd love to help work on a wiki page that creates a table of razor exposures, because I think exposure is 10x as important in determining razor aggressiveness/efficiency than gap.

 

[Blackland Razors]

Incredible answer above. Yes, measuring blade exposure is not easily done and when tenths of a mm matter, the system for measurement must be robust and repeatable.

 

[kingfisher]

Thanks, dovo1695; I figured it wouldn't be easy. What would be awesome is if somebody had the equipment and set up to do it so that the camera always stayed in the same place and they could use the same blade every time. Even if we didn't get exact measurements, at least we would get a RELATIVE idea about the exposure of different classic razors.

As an example, I am really enjoying the British flat-bottom long-comb New right now; I'd love to know if there is a modern razor that has similar parameters. Just for fun, if for no other reason. I like this razor so much I have half a mind to sell all my other DEs and just use this one (it won't happen, but I liked typing it out as if it were possible, lol). Or maybe I could get to where I just have one vintage open comb, one vintage safety bar, one modern open comb, and one modern safety bar razor; that way I could still have some variety but not have so danged many razors!

 

[Asland408]

Blade Gap Comparison

.001 inch millimeters Razor weight in grams 4 0.10 Above the Tie (ATT) G1 (v.1) Atlas = 94g / Kronos = 105g / Colossus = 120g / Bamboo = 90g 8 0.20 Rockwell R1 100g 10 0.25 Above the Tie (ATT) M1 & M2 Atlas = 94g / Bamboo = 94g / Calypso = 112g / Kronos = 109g 10 0.25 Above the Tie (ATT) SSM1 &...

www.abovethetie.com

Sent from my iPad using Tapatalk

 

[Dovo1695]

Thanks, dovo1695; I figured it wouldn't be easy. What would be awesome is if somebody had the equipment and set up to do it so that the camera always stayed in the same place and they could use the same blade every time. Even if we didn't get exact measurements, at least we would get a RELATIVE idea about the exposure of different classic razors.

I'm going to buy a Plug USB 2.0 microscope like the one above and give it a try. I've got a micrometer, but it's nothing special. Like you said, the measurements won't be perfect to .001mm, but even relative measurements of exposure is a step in the right direction.

If nothing else, it'll be good to lay out a methodology in some posts about how to set things up for accuracy and repeatability. I'm no expert in micro-measurements, but I have a wealth of experience in documenting screw-ups...

 

[Dovo1695]

With all the discussion about how modern razor makers are providing gaps and at least some are saying "negative/neutral/positive" for exposures (with some people wishing to hear actual exposure numbers), what I would love to know is the blade exposures of classic vintage razors, especially Gillettes.

Pretty sure there is already a table in the Wiki with gaps for these razors, but exposures are nowhere to be found. I wonder if one of our technically minded people could figure out a way to quantify gaps for, say, the various Superspeeds, Fatboy/Slim, Techs, LC and SC New, Old type, New Improved, etc. Personally I would love to have that information. I figure for somebody who is experienced with lots of vintage Gillettes, it might help if they decide to pick up a new razor. In other words, if they know what vintage razor works best for them, and they had gap/exposure information for said razor, they could choose a modern razor that would match their known preferences.

Has anybody made an attempt to quantify the blade exposures of classic vintage Gillette razors? If not, is there anybody who would be able to do it?

This might be of interest to you. It's the comparison of a vintage adjustable with a modern adjustable that focuses on the extent to which each relies on blade gap vs blade exposure to increase efficiency. The source for the Murumasa data is the company website and the blank data fields are there because it only has 5 settings not 9. The data for the Gillette adjustable comes from a purported internal Gillette memo from the era and is linked below. Rereading it, it doesn't explicitly say that it was a "slim" adjustable and I don't remember where I got that:

Why does my slim adjustable shave smoother on 7 than on 3?

I started out quite a while back with my slim adjustable set on 3 then 4. The shave wasn't that close or smooth. I hadn't used it for a while so I cranked it up to 7 and the last 2 shaves I've had with it were not only incredibly close but very smooth. I need further testing but it might be my...

www.badgerandblade.com

 

[Ron R]

Measuring blade exposure is the hardest to measure IMO. As for blade gap all you need are feeler gauges and that will get a person with in +/-.001 thousands of a inch or +/-.0254mm.
For checking whether a DE razor has positive blade exposure all I do first is check it with a modified blade I designed just for this to see if there is any positive or negative exposure. A magnifier loupe will help also if you have a know thickness to approximate how far up the (sharpe)blackened edge the blade edge it is. So if a known thickness of .020 thousands inch contact edge and blade edge is approximately 1/4 of the thickness up the contact edge you know the exposure is .005 approximately. Close enough for this retired machinist. I have very fine accurate dial indicators but is a lot harder to measure deflection accurately and is not as accurate with my crude setup I tried to test with dial indicator.

Have some great shaves!

 

[kingfisher]

Interesting that the slim or Fatboy has positive exposure at all settings.

 

[Dovo1695]

Interesting that the slim or Fatboy has positive exposure at all settings.

I thought so too. That said, I think that most stated "exposure estimates" assume a 22mm blade though. If so, given that vintage Gillette blades were about 21.95, you wouldn't actually get positive exposure in real life until you got to setting 3. I've definitely heard people say on the forum that a slim won't even shave on settings 1 or 2.

 

[Cesare]

Incredible answer above. Yes, measuring blade exposure is not easily done and when tenths of a mm matter, the system for measurement must be robust and repeatable.

Shane, how do you go about when designing a razor? Get the desired exposure using some CAD like program (this is probably way outdated), then prototype it and face test? Can you simulate the result (the combination of exposure and gap) with a computer? Can you simulate to “adjust” for different shaving angles?

 

[Dovo1695]

Measuring blade exposure is the hardest to measure IMO. As for blade gap all you need are feeler gauges and that will get a person with in +/-.001 thousands of a inch or +/-.0254mm.
For checking whether a DE razor has positive blade exposure all I do first is check it with a modified blade I designed just for this to see if there is any positive or negative exposure. A magnifier loupe will help also if you have a know thickness to approximate how far up the (sharpe)blackened edge the blade edge it is. So if a known thickness of .020 thousands inch contact edge and blade edge is approximately 1/4 of the thickness up the contact edge you know the exposure is .005 approximately. Close enough for this retired machinist. I have very fine accurate dial indicators but is a lot harder to measure deflection accurately and is not as accurate with my crude setup I tried to test with dial indicator.
View attachment 1277252 View attachment 1277251 View attachment 1277250
View attachment 1277253
Have some great shaves!

I like this idea. It gives a rough gauge of blade exposure without much fuss.

 

[Ron R]

I thought so too. That said, I think that most stated "exposure estimates" assume a 22mm blade though. If so, given that vintage Gillette blades were about 21.95, you wouldn't actually get positive exposure in real life until you got to setting 3. I've definitely heard people say on the forum that a slim won't even shave on settings 1 or 2.

One of the fellows had a Fatboy chart on gap and exposure setting according to dial settings, if my memory is correct for every # advanced = .001 thousands of inch blade exposure. I can not find that site where the discussion was on or the Gillette chart that was posted. It was Gillette chart and I should of copied it for this type of discussion.

 

[Dovo1695]

One of the fellows had a Fatboy chart on gap and exposure setting according to dial settings, if my memory is correct for every # advanced = .001 thousands of inch blade exposure. I can not find that site where the discussion was on or the Gillette chart that was posted. It was Gillette chart and I should of copied it for this type of discussion.

I'd love to see his data source. If you track it down, post it for sure. Increasing by exactly .001 sounds exactly what a 1950's American engineering team would be inclined to do. That lines up perfectly with the table I posted up above by the way. My data source was in thousands of and inch as well, and I just did the mm conversion.

Why does my slim adjustable shave smoother on 7 than on 3?

I started out quite a while back with my slim adjustable set on 3 then 4. The shave wasn't that close or smooth. I hadn't used it for a while so I cranked it up to 7 and the last 2 shaves I've had with it were not only incredibly close but very smooth. I need further testing but it might be my...

www.badgerandblade.com

 

[Steve K]

Had this book marked from this site.

Double-Edged Safety Razors Ranked by Blade Gap

Ranking by blade gap size

www.badgerandblade.com

 

[Ron R]

I'd love to see his data source. If you track it down, post it for sure. Increasing by exactly .001 sounds exactly what a 1950's American engineering team would be inclined to do. That lines up perfectly with the table I posted up above by the way. My data source was in thousands of and inch as well, and I just did the mm conversion.

Why does my slim adjustable shave smoother on 7 than on 3?

I started out quite a while back with my slim adjustable set on 3 then 4. The shave wasn't that close or smooth. I hadn't used it for a while so I cranked it up to 7 and the last 2 shaves I've had with it were not only incredibly close but very smooth. I need further testing but it might be my...

www.badgerandblade.com

If you look at the Gillette slim adjustable Vs Tatara adjustable blade exposure it works out from mm to inch = .001 thousands of a inch per # Example slim #7 setting is about .007 thousands of a inch.

Have some great shaves!

 

[Dovo1695]

If you look at the Gillette slim adjustable Vs Tatara adjustable blade exposure it works out from mm to inch = .001 thousands of a inch per # Example slim #7 setting is about .007 thousands of a inch.

Have some great shaves!

Correct. This is the data source. It goes up in .001" increments. I converted it to mm.

 

[Dovo1695]

Just a follow up. I did a proof-of-concept of the method described above and it works pretty well. I used a Karve SB-D .98. as a reference pic and I used a photo taken with the Pluggable USB 2.0 by profile pic pioneer @Rosseforp. Apparently he's been taking these amazing close-up pics of blade exposure for a while now!

The Karve website lists the gap as .98mm and the exposure as .13mm. Using the method I described in my first post up above, but substituting Microsoft PowerPoint for ImageJ, I came up with a gap of .94mm an exposure of .157mm. Not bad for a first try. I think 80% of the error can be eliminated with some pretty simple steps. At any rate, here are the results of the first attempt:

As far as error reduction goes, here are some things that I think might help with measurement accuracy:

1. Include a steel ruler on the same plane as the side of the razor in the photo for scaling.
2. 2 photos at two different focal lengths. One focused on the side of the razor, one on the blade itself. Image stacking in ImageJ combines the two photos for crisp focus at all points. That's what scientists do with photos taken by microscopes
3. For extra accuracy, it would help to flip to the razor 180 degrees and do it again. Average the results from the two sides of the razor. This will account for blade skew, especially on razors like the Fatip Grande.

 

[APBinNCA]

Problem 2: No blade is actually 22mm

Blade exposure is determined in no small part by the width of a razor blade. A razor may have 0.05mm assuming a razor blade of precisely 22mm, but that's kind of meaningless if the razor blade you've just loaded is 22.18mm wide. Now you have a blade exposure of +0.14mm (0.05mm baseline exposure + 0.18mm/2 = 0.14mm). Is that a realistic scenario? It is if you've just loaded a KAI, which is in fact 22.18mm. Here is a table of DE blades measured by a micrometer a few years back by Giovanni Arbate. I'd link the blog, but it's against B&B policy, so I'll just insert a picture of the table. Put simply, you've got to get yourself a reference blade that you've measured with a micrometer with some certainty and repeatability that it's 22.00mm. This also assumes your micrometer is that accurate.

In short, getting blade exposure measurements isn't easy. It assumes a perfect photo, and a perfect reference blade. Or maybe not. Maybe there is an easier way. If so, I'd love to hear about it! I'd love to help work on a wiki page that creates a table of razor exposures, because I think exposure is 10x as important in determining razor aggressiveness/efficiency than gap.

I didn't know where else to put this, but a wider blade will not give the increase in exposure that you are calculating. As per the manufacturers, the blade is bent downward at approximately 30 degrees per side. Obviously, razor dependent. The blade is describing an arc of a circle, but what you want is the straight distance edge to edge divided by two. This can be calculated with some difficulty, but even a pair of cheap calipers should suffice. Based on reading the technical section on Henson's website, I would doubt that the KAI blade increases the exposure more than .06. The more interesting question is comparing the American Personna to the Israeli. That might decrease exposure .05 and explain why many people find them comfortable in spite of their sharpness.

 

[Dovo1695]

I didn't know where else to put this, but a wider blade will not give the increase in exposure that you are calculating. As per the manufacturers, the blade is bent downward at approximately 30 degrees per side. Obviously, razor dependent. The blade is describing an arc of a circle, but what you want is the straight distance edge to edge divided by two. This can be calculated with some difficulty, but even a pair of cheap calipers should suffice. Based on reading the technical section on Henson's website, I would doubt that the KAI blade increases the exposure more than .06. The more interesting question is comparing the American Personna to the Israeli. That might decrease exposure .05 and explain why many people find them comfortable in spite of their sharpness.

Good point. The steeper the bend a razor puts on blade, the less additional exposure a wide blade is going to have.

Most razors don't blend blades very much though. I've seen more than one razor where the blade is actually 100% flat. The Henson razor bends the blade way more than any other razor I've ever seen. I'm guessing it's bent at double the angle compared to any other razor I've seen. That's part of what makes it such a great design. The change in exposure will affect a Henson razor much less than any other razor.

I talked about this a bit in the Great Rigid Blade experiment thread. The extent to which blades are bent vary widely among razors. I called this parameter "chord span" or bend radius. I don't know how much it would affect the marginal blade exposure of the Karve, but you're right that you're not getting the full 0.10mm.