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Guard Span vs Gap | Is This A Missing Piece In Our Discussions?

Good photos are crucial and very hard to take. I have failed many many times to achieve the accuracy this sort of project requires. I'm glad you gentlemen are on it and figuring it out.
100% this. I've taken enough photos at this point to know that mine are junk. It's definitely the hardest part of the whole undertaking. Taking the measurements like I did is pretty trivial once you have a great photo with something in it for scale.

I'm going to buy a USB Pluggable 2.0, but I'm pretty sure it's going to be a while before my pics are up to @Rosseforp's level.
 
If the photos taken are level and
perpendicular to the profile of
the blade loaded razor head and
then well adjusted and corrected
( regarding possible lens distortion,for example ) ,then the precision
of measurements will be increased.

But even then the standard CNC machining tolerances (+\- 0.02 mm )
have to be taken into account .
Furthermore if sandblasting or any
other abrasive finishing is applied ,
more tolerances to be accounted
come into play.

Taking things to the extreme ,
if manual mirror polishing is applied
then due to randomness regarding
the material removed ,things might
get really complicated.

For example: I seriously doubt that
two mirror-polished Wolfman razors,both of same comb/bar type and of same declared blade gap and exposure,will actually have the exact
same measurements ,even if taken
with ultra high-precision 3D laser scanning.Hand polishing ,especially
if brought to mirror finish ,is rather harsh to precision’s integrity .

So ,in that case a single specimen
would not represent an “average” for
the rest of it’s kind/type ,
regarding the measurements taken.
 

Chan Eil Whiskers

Fumbling about.
If the photos taken are level and
perpendicular to the profile of
the blade loaded razor head and
then well adjusted and corrected
( regarding possible lens distortion,for example ) ,then the precision
of measurements will be increased.

But even then the standard CNC machining tolerances (+\- 0.02 mm )
have to be taken into account .
Furthermore if sandblasting or any
other abrasive finishing is applied ,
more tolerances to be accounted
come into play.

Taking things to the extreme ,
if manual mirror polishing is applied
then due to randomness regarding
the material removed ,things might
get really complicated.

For example: I seriously doubt that
two mirror-polished Wolfman razors,both of same comb/bar type and of same declared blade gap and exposure,will actually have the exact
same measurements ,even if taken
with ultra high-precision 3D laser scanning.Hand polishing ,especially
if brought to mirror finish ,is rather harsh to precision’s integrity .

So ,in that case a single specimen
would not represent an “average” for
the rest of it’s kind/type ,
regarding the measurements taken.

Very good points.
 
For example: I seriously doubt that
two mirror-polished Wolfman razors,both of same comb/bar type and of same declared blade gap and exposure,will actually have the exact
same measurements ,even if taken
with ultra high-precision 3D laser scanning.
Anything hand-made will suffer from this issue. Multiple measurements are inevitable to increase reproducibility of measurement whereby everything except the razor must be fixed for each experiment, e.g. blade, microscope/camera, etc.
Either someone in the forum attempts to do the measurement using off-the-shelf equipment (too pricey for most folks, me included) and we accept an inevitable error, or we hope that some day all existing manufacturers will copy the forum's illustration and substitute all terms for figures - and then believe the manufacturer measurements are correct. I think the former is more realistic.

Back to the question of the thread topic, I don't think so, at least if we compare all possible DE designs. The guard span and the blade gap of my FOCS are both lower than that of my Rockwell 6S, but FOCS = Rockwell 6SR5 for me (if I keep everything else the same, esp. blade). If we constrict the discussion to merely closed comb, straight bar razors, then yes - I agree that a wider guard can better flatten the skin prior to cutting the stubble.
 
"Guard span"...this is the term which definitely determines whether I like a razor or not.

I wasn't aware of this term before today but in my usage of many dozen razors, all else being similar, I have always disliked razors where the guard span is short and the cutting edge is closer to the guard.

I like razors where the blade is further back from the guard because my skin is naturally quite soft so a longer guard span prevents a razor being bitey for my skin.
 
This is a very interesting topic and didn't even cross my mind about the Guard Span on all the various razors I have in my den, I've been riding the top cap for a very long time.
 
Last edited:
Great topic and thread. I agree, I think the guard span is an interesting measurement. It almost seems like the guard span is a hybrid measurement of gap and exposure. Of course, all three measurements are ideal, but in the absence of all the measurements, guard span may better predict the behaviour of the razor. Also, the guard span gets after the gap, exposure, but also the shave plane. I need to think about this a bit more...

For discussion, one thing I have noticed that is very rarely noted, is the blade angle. To me it's a fairly straightforward parameter but is rarely discussed for a razor or for how a razor performs. I'm curious why that is? I prefer a steep angle (riding the guard). Therefore, razors with a smaller blade angle suits my preferences better. I typically like blade feel and not afraid of a large gapped razor. I've had some with lots of blade feel and gap, but didn't work, but I realized they have a higher blade angle that is better suited to riding the cap. Why don't we speak of blade angle as often?
 

Chan Eil Whiskers

Fumbling about.
Great topic and thread. I agree, I think the guard span is an interesting measurement. It almost seems like the guard span is a hybrid measurement of gap and exposure. Of course, all three measurements are ideal, but in the absence of all the measurements, guard span may better predict the behaviour of the razor. Also, the guard span gets after the gap, exposure, but also the shave plane. I need to think about this a bit more...

For discussion, one thing I have noticed that is very rarely noted, is the blade angle. To me it's a fairly straightforward parameter but is rarely discussed for a razor or for how a razor performs. I'm curious why that is? I prefer a steep angle (riding the guard). Therefore, razors with a smaller blade angle suits my preferences better. I typically like blade feel and not afraid of a large gapped razor. I've had some with lots of blade feel and gap, but didn't work, but I realized they have a higher blade angle that is better suited to riding the cap. Why don't we speak of blade angle as often?

Excellent question.

I have very little understanding of anything in the razor engineering and design arena. Perhaps blade angle is my strongest area of lackluster insight (meaning I know less than nothing about it).

Happy shaves,

Jim
 
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