The Great Rigid Blade Experiment

[Rosseforp]

Thus a piece of very rigid and light material should be placed between
the whole length of the very edge and
the tip of the fiddlestick ,
in order to distribute the force evenly
to the whole length of blade’s edge.

That would defeat the purpose of finding where the blade is least supported. How would you propose to do this on a slant? Pictures, drawings?

I get repeat readings from my setup.

My method of contacting the blades edge in a specific point lets me see where the flex is at the greatest area. The Fiddlestick is set at the angle the blade is at, to prevent deflection.

An example would be the Fatip FOCS, the blade is rigid as a rock in the center, but at the edges it flexes just like an R41, but not to the same extent, about twice the force is required to see the same amount of flex.
On the other hand, on a New SC, a RR GC OC 84, a Fatip Grande, and a Gillette Heritage the blade is is supported equally across the entire length of the blade.

 

[Dovo1695]

If one was so inclined, I'm not but it has crossed my mind, one could carefully polish the comb on a razor and increase blade exposure while maintaining free end distance. Why none of the razor designers other than Wolfman have thought of that I dont know, maybe they have and discarded the idea but it still has merit to me.

RazoRock does this. I was "nearly shopping" yesterday, (thanks @AimlessWanderer) and I put an RR Gamechanger .84 baseplate in my shopping cart after I noticed that they changed not just the gap, but also the blade exposure (albeit modestly at only .0508mm).

I think it's quite possible that other razor makers like Karve and Charcoal Goods do this as well, they just don't disclose it. This is a bit odd to me because gap is barely even relevant compared to gap. A razor with a 2mm gap and 0mm exposure is probably a bit less efficient than a razor with 0mm gap and 2mm blade exposure...

 

[Dovo1695]

Which is why I've never referred to the R41 as efficient. Yes, it can give me the same 12 hour BBS as my Grande but it takes me 15-20 minutes to achieve it and I need to pay close attention to direction of stroke in all three directions of passes, and, I can only use a fresh Feather blade.

Something not taken into consideration is the direction of cut. On a WTG pass, the blade can slip minutely along the hair shaft as it cuts which would impart less resistance to the blades edge. Shaving ATG however would offer far more resistance. My first shave with an R41 I used a Derby Extra, my go to blade for a new razor. Its a top 3 blade in my Grande. In the R41, my first shave below.

The R41 tugs my beard worse than any other razor I've ever used. @SCh5 cast some light on that though that was really interesting to me. He suggested that the R41 works better when moved very slowly. I tried it yesterday morning, and moved the razor at a glacially slow 1cm/sec, and it actually did tug noticeably less (though still more than any other razor I own).

The Importance of a Rigid Blade (or not)

A force probe/gauge could prove it. More force needed to deflect the edge equals more rigidity. Exactly! Interestingly, this is pretty similar problem to determining the durometer of croaps. I talked about this a bit in post #49 of my croap durometer experiment but I haven't figured out...

www.badgerandblade.com

My biggest takeaway was the following chart. The force exerted on the blade increases as razor speed increases. It increases by ~5g of cutting force for each increase of 50mm/s. Personally, I shave at about 10x this speed which means the forces are ~10x this. A blade that's not being held rigidly doesn't do well in this situation. I know you take long, extremely fast moving strokes too. Maybe that's why rigid blades work better for our style of shaving. At any rate, I thought it was interesting.

 

[Esox]

Tatara is one of the few (only?) who specs exposure on their plate and cap combinations.

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Thats good to know.

 

[Esox]

The R41 tugs my beard worse than any other razor I've ever used. @SCh5 cast some light on that though that was really interesting to me. He suggested that the R41 works better when moved very slowly.

Put a fresh Feather in it, it helps but you'll still shave slowly. Same blade in my Grande, one less pass, one less clean up and done in under 5 minutes, easily. Which is the more efficient razor? The Grande, by leaps and bounds. The difference? Blade rigidity, or more accurately, blade stability. The R41 is unpredictable. I prefer predictable. At least when I screw up I know its my fault lol.

Personally, I shave at about 10x this speed which means the forces are ~10x this. A blade that's not being held rigidly doesn't do well in this situation. I know you take long, extremely fast moving strokes too. Maybe that's why rigid blades work better for our style of shaving.

Full length strokes too, top of my cheek to the base of my neck in one stroke. Speed is a constant, the only thing that changes is the angle at and below my jawline. I use my Grande as fast as I do Schick 3 blade disposables and it shaves a lot closer and more comfortably too.

 

[Dovo1695]

Put a fresh Feather in it, it helps but you'll still shave slowly. Same blade in my Grande, one less pass, one less clean up and done in under 5 minutes, easily. Which is the more efficient razor? The Grande, by leaps and bounds. The difference? Blade rigidity, or more accurately, blade stability. The R41 is unpredictable. I prefer predictable. At least when I screw up I know its my fault lol.

That was with a Feather, which is my preferred blade with the R41 too. If all I had was Derby blades, I use tweezers rather than an R41; it would tug less.

I found that the combination of a glacially slow pace, short strokes, a Feather blade, and cap riding transforms the R41 from a beard tugging beast, to a merely an uncomfortable and unpleasant shave. It's only virtue is that is shaves as closely as a Grande (albeit in 4x the time and 1/4 the comfort). I only keep it around because I usually shave with mild razors, and using it periodically helps keep me from falling into bad habits like using too much pressure. It's unpredictable and unforgiving, so it makes for a good "training" razor. It's also handy for evaluating residual slickness when I'm testing out new soaps.

 

[jeffmudrick]

That was with a Feather, which is my preferred blade with the R41 too. If all I had was Derby blades, I use tweezers rather than an R41; it would tug less. [emoji39]

I found that the combination of a glacially slow pace, short strokes, a Feather blade, and cap riding transforms the R41 from a beard tugging beast, to a merely an uncomfortable and unpleasant shave. It's only virtue is that is shaves as closely as a Grande (albeit in 4x the time and 1/4 the comfort). I only keep it around because I usually shave with mild razors, and using it periodically helps keep me from falling into bad habits like using too much pressure. It's unpredictable and unforgiving, so it makes for a good "training" razor. It's also handy for evaluating residual slickness when I'm testing out new soaps.

I have the same rationale for keeping my mostly unused R41.

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[Cal]

Tatara is one of the few (only?) who specs exposure on their plate and cap combinations.

Thats good to know.

Karve too, HERE.

 

[jeffmudrick]

Karve too, HERE.

Right. Here's Tatara.

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[Esox]

If all I had was Derby blades, I use tweezers rather than an R41; it would tug less.

Waxing would be more efficient lol.

 

[SCh5]

I wonder ...
Since there are quite a few different
martensitic and ferritic grades of
stainless steel used in today’s DE/SE
razor blades production ...
And since each factory may apply
different heat treatments for hardening...
Or even different models from the same factory maybe differently heat treated ...
And since there are different blade
thicknesses ( thick 0.125 mm , medium : 0.1 mm ,thin : 0.075 mm ) ...

Maybe the apparatus can be used
to measure the rigidity of various different blades .
Quite useful to know which blades
have higher rigidity than the rest.

Side note : I bet that Nacets and GSBs will
definitely be amongst the most rigid ones!

 

[Rosseforp]

Maybe the apparatus can be used
to measure the rigidity of various different blades .
Quite useful to know which blades
have higher rigidity than the rest.

Good point, I have been using Derby Extra blades in all of my testing for consistency.

 

[thombrogan]

@Rosseforp - I was surprised that your fiddle test and @Esox ’s pen test revealed the rigid-ish part of the the blade was towards the center as it looks like the blade would have more baseplate support on the edges.

Would there be any value in measuring force needed for flexion towards the cap?

My assumption is most people don’t cram their razor’s cap against their face and slide waves of flesh beneath their blades to shave (though the month is early), but tend towards neutral or even steep angles - especially with razors that mix generous blade exposure and blade gap with miserly amounts of base support - so their whiskers would usually push against the blade in the opposite direction.

 

[thombrogan]

@SCh5 - wouldn’t the hardness of a martensitic steel only affect plastic deformation with force needed to flex the blade be reliant on width and temperature? Or am I misunderstanding that?

 

[SCh5]

Heat hardening martensitic steel usually does
not affect it’s rigidity -flexibility ,because
the heat-treated section is just a fraction
of the overall thickness of a knife,
for example
( i.e. 0.02 mm total thickness of
heat treated steel is 0.5% of a 4 mm thick knife blade).

But in case of the razor blades
( av. thickness 0.1 mm = 100 microns )
if the layer affected by heat treatment
is 10 microns on each side οf the blade,then 20% of the thickness is
hardened.20% is a quite large figure and may be affecting drastically
the elastic properties of the blade.

 

[Esox]

I was surprised that your fiddle test and @Esox ’s pen test revealed the rigid-ish part of the the blade was towards the center as it looks like the blade would have more baseplate support on the edges.

Mine doesnt, but then again, a normal person might not notice. I however, did lol.

 

[thombrogan]

Thank you, @SCh5. So are you looking to see whether different DE blades are reaching plastic failure and losing their ability to provide a smooth, clean shave as a result of low hardness martensite and the presence of pearlite and austenite?

a normal person might not notice.

You’re witnessing two d00ds use a cross-continental information exchange portal to speculate on the behavior of disposable razor blades based on their crystal configuration. Normal people don’t venture here.

 

[Esox]

Normal people don’t venture here.

 

[SCh5]

@thombrogan Good point there !
A just few μmeters keen edge ,
indeed might be subject to plastic deformation ,depending on the heat-treatment .

 

[thombrogan]

The great part about testing double edge razor blades is they’re inexpensive enough to obtain a decent sample size.

The bad part about testing double edge razors blades is it’s difficult to know whether one’s sample size is large enough to draw meaningful conclusions.