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Why the curve?

Why are the heads/caps of safety razors curved? Bearing in mind it only cuts perfectly close at one angle...

Thanks
 
Probably a couple reasons... The curve should make the blade stiffer. And bending the edge down allows you to have the handle closer to your face so you can pull it through the whiskers easier than if the handle were perpendicular to your face.

That's my 2 cents anyway.
 
If you are asking about the curved surface shape of the head, it is the result of designing a multi-purpose tool that interfaces with concave, convex and flat surfaces in two directions.

The world is not flat like some SE folks might have you think.....Ooops, sorry Tony. Did not see you standing there.:blush:
 
The tops are curved because the bottoms are curved, and adding metal to make them anything but curved would be essentially a waste unless it served a purpose. And, as James said, the curve itself serves to stiffen the wafer thin blade -- very much the same way that it does the slats in Venetian blinds.

Incidentally, not all razors are curved on top. The Apollo Mikron, for example, has a flat top:

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And the Walbusch adjustable slant had a cap designed to balance the slanted head:

$walbuschb54sc2kiyznj.jpg
 
Try this simple experiment with a thin piece of any material that has some stiffness. Bend it. Now try bending it in the right angle direction at the same time. You can't. The same principle applies to razor blades. Bending the blade crosswise makes the edge more rigid.
 
Gives the blade the cutting angle. If you look inside, you'll see that the razor actually bends the blade at the center point to give a user friendly cutting angle. If there was no bend, it would be very awkward to shave with.
 
Thanks for everyone's input... I understand the that the curving of the blade increases rigidity but the internal of the cap could still allow this even if the outer is more angular... I am just interested at why the razor casing shape doesn't reflect the correct cutting angle for the user... I don't know if that makes sense to you...

That Mikron is kind of what I mean... that angular plane looks like when you run your skin against that surface... the blade angle is at the correct 30 degree angle to the skin.

Thanks again.
 
^That's what I thought you were asking, and I couldn't figure out what I missed that most other posts were answering.

If that Mikron would cause the proper angle then I've been using the wrong angle, with the blade more parallel to my skin and the handle more perpendicular.
 
Thanks for everyone's input... I understand the that the curving of the blade increases rigidity but the internal of the cap could still allow this even if the outer is more angular... I am just interested at why the razor casing shape doesn't reflect the correct cutting angle for the user... I don't know if that makes sense to you...

That Mikron is kind of what I mean... that angular plane looks like when you run your skin against that surface... the blade angle is at the correct 30 degree angle to the skin.

Thanks again.

Well, I'm glad they are curved in most cases, because it allows me to use them at a shallower blade angle than 30 degrees. If it was flat (and was so any significant distance from the blade), it would enforce only one angle. I wouldn't like that. 30 degrees is just a guideline - it's not the perfect angle for every situation (or necessarily any). The blade can cut at angles shallower and steeper than that. I prefer as shallow an angle as the razor will allow for most of my face - 25 degrees or less.
 
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jb91, obviously I missed it and am still not confident that I understand your question. Does it have to do with the arc of the top of the cap not being parallel to the curvature of the blade? If so, I would speculate that aesthetics, and configuring the head to enable it to get into tight spots -- say, under the nose -- might be considerations.
 
I'll venture this guess: It is necessary to have a decent thickness of the cap to keep everything stiff, but you can't have it thick at the edge or the blade would never touch your face. Therefore, it must be thick in the middle and tapered to the edges. Given those specifications, there are only a few shapes that fit, and the curve allows the user to fine-tune angle more effectively than flat surfaces that meet in angles.
 
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Bearing in mind it only cuts perfectly close at one angle...
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I don't think your assumption here is true. Razors cut well in a range of angles.

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the blade angle is at the correct 30 degree angle to the skin.
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People's faces are different and razors are different. With so many variables, 30 degrees can't possibly be the only correct and perfect shaving angle. Have you tried shaving with the Muhle 2011 R41 at 30 degrees?
 
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Originally Posted by jb91
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"Bearing in mind it only cuts perfectly close at one angle... "

Actually, I use different angles in differrent areas of my face and neck.


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I suspect the curved cap allows more angles to be used. With a straight razor, you use a more upright angle for WTG, and a more flat angle for ATG, and an intermediate angle for XTG. You also vary the angle based on the swirling grain and skin sensitivity in different areas. I bet the same things work well for DEs, but only if there is enough blade exposure to vary the angle.
 
Thanks everyone... I think what I meant about the perfectly close was misinterpreted... by perfectly close I mean the following... please correct me if I am misinformed.... (Also please disregard my terrible excuse of a drawing!

$IMG_1753.jpg

The use of the curved cap makes sense to allow you to get into tight spaces e.g. the upper lip/under nose area but to me it seems that if you hold the razor either too steep or too shallow it cuts hair, but away from the skin preventing a perfectly close shave no?
 
I think the blade may stick out more than that, at least in some razors, so that you have a few degrees of movement to play with where the guard or cap helps change the pressure that the blade applies while still allowing the blade to touch.
 
I think the blade may stick out more than that, at least in some razors, so that you have a few degrees of movement to play with where the guard or cap helps change the pressure that the blade applies while still allowing the blade to touch.


Oh really? How much are we talking?... anyone know a specific figure... something like the 34c?

Thanks.
 
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