Razor Design

So I was wondering, when designing scales people often talk about balancing the razor. I'm assuming the balance point would be the tang where you hold it as this is where you're manuevring it and you would have most control at the COM (balance point). By this logic, I ASSUME its better to balace the razor with the scales in the "open" or "shaving" or "in use" position, aka, 90 deg to the blade. Is this correct? How should/where should the razor be balanced?

On a further note, obviously things like the shoulder and belly and stuff serve to stiffen the razor, and hollow grinding makes it easier to hone, but how much of a razors shape is form and how much is function? Like, points are all mostly personal preference. Is this true of the width, length, etc? Obviously the spine width to thickness ration determines the bevel, but other than that do the dimensions actually matter all that much?

Finally, on two razors the same "size", but different point styles, will the length of the steel from tip of tang to longest point be constant, or will the distance between pins be constant, or will the cutting edge be the same length, or does it not matter and thereby vary based on personal preference?

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Originally Posted by khaos

By this logic, I ASSUME its better to balace the razor with the scales in the "open" or "shaving" or "in use" position, aka, 90 deg to the blade. Is this correct? How should/where should the razor be balanced?

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The balance is usually checked with the blade 180 degrees to the scale. From what the debate says it's more of a coolness factor than a function.

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Originally Posted by khaos

....but how much of a razors shape is form and how much is function? Like, points are all mostly personal preference. Is this true of the width, length, etc?

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Length and width can factor in maneuverability. That's why moustache razors tended to be smaller because it may be a harder task to shave your upper lip with a 10/8 meat chopper. Also, I would think, thicker blade (spine to edge), more metal, longer live span.

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Originally Posted by khaos

or will the cutting edge be the same length, or does it not matter and thereby vary based on personal preference?

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I'm a bit confused by this question. Are you asking if I take the same two blade styles, but have a different point, will the size be different at certain points? I think it's the Spanish point (has a slightly larger edge toe than the spine) that would not be the same as a square point.

Hope that helped.

Regarding your last question... it all varies but within small amounts. An example would be that the length of the cutting edge would be between 2.5" - 3" with some exceptions. The length of the monkey tail and its shape will vary as will the distance between the pivot pin hole and the heel of the razor.

Hope this helps,:)

I have some razors that balance nicely on the tang, and others that do not.

The ones that do, tend to be more comfortable and maneuverable on my face.

It's not 1:1, but there seems to be strong correlation.


As claytor said, it's usually done with the razor completely open to 180 degrees, not in a shaving position. The reason is that there is no practical way to test the balance with the razor opened to 270 degrees.

As far as the debate saying it's about coolness factor, that's a bit like saying the debate over health care going on in the US says that government sponsored health insurance would be good for the country. One side says that, the other side says the opposite.

I will say that balancing a razor on the tang with your finger as a fulcrum is a silly parlor trick because you can manage that with virtually any razor. However, balancing it on something hard and round that it can easily roll off of can be enlightening.

Because we spend very little time using the razor with the scales at 180 degrees, and the enormous number of variables in terms of blade geometry, scales geometry, preferred scale position while shaving and all the rest; it's virtually impossible to truly test the balance of a razor any way but to use it and see how it feels. However, if you're making scales (or grinding razors) balancing to the tang will at least give you a starting point, and get you into the ball park of a balanced razor.

Khaos;

Here is my take on your questions :)

Regarding the balance of a straight razor: The scales should be of an appropriate size and mass to counterbalance the blade.

An informal 'center of balance point' would be at the rear pinning point or very slightly forward of it. In practical terms, imagine an invisible line running from your elbow down through to where your wrist rotates and beyond. If the balance point of the razor lies on this line, then the razor will be found to be easier to maneuver and rotate. Razors that are either very nose or tail heavy do not feel as good in the hand.

With regard to your second question, my personal opnion is that a lot of the differences of size, width and so forth have to do with differing outlooks on what constitutes best form or style. For a barber, involved in daily shaving of customers, a slightly wider blade would have represented the best economy in terms of working life before the razor was chucked out as unsharpenable (became too narrow). On the other hand, to the traveller, a smaller lighter blade might have represented a real advantage in lightening the wieght of one's baggage as opposed to a wider, heavier blade intended for home use. Very narrow blades in the 3/8 width are really much better for hair trimming and stylist use rather than shaving of facial hair.

As to your last question, if one is starting with a forged blank of fixed proporations, then it seems logical that choice of point form will inevitably have a small effect upon the available length of cutting edge. Of course, this is no real problem, one way or the other, as the difference(s) would be minimal. IMO length of cutting edge, unless extremely long or short, isn't the greatest determinant of the quality of the shave.

- Ignatz

ah, the balance question....

some guys with 20-30 years of experience think the shaving balance is pure magic and only the most skilled makers can produce really well balanced razor razor after decades of failed attempt.

me - i think we've progressed a lot since the middle ages. take one of the intro physics courses and you'll be able to calculate the center of mass of any razor.
It depends on how the scales are positioned, but as you rotate them it goes around a circle. A razor is easiest to handle when the center of mass is right in the middle between your fingers whatever way you grip it. So, if you don't use only one configuration of the scales, you'll probably have to do some trade-offs. Unless the scales are really light (e.g. thin ivory) and the razor is fairly heavy, in which case the radius of that circle can be very small, small enogh that the center of mass is always within the shank. Otherwise it's good to be mindful of the direction of gravity as stable and unstable equilibriums are rather different.... but in practical terms it means that too light scales are much better than too heavy.


it works exactly like this:
http://themonkeycrew.typepad.com/pho...ess/imacg4.jpg

everything else is a matter of personal preference.

I have indeed taken intro Physics. And PHYS II. And mechanics of solids. And DE. And multivar. So I can calculate the COM (or at least approximate it very well). And I get what you're saying about the different positions of the scale- at 180 deg you have to integrate along its length to find the moment about the COM, whereas 270deg (standard grip) its simply the total weight of the scales times the distance the pin is from the COM, correct? And every position inbetween is basically ((Mass of scales)*gravity)x(vector from COM to COM (scales), right?

However... You kind of touched on the fact that it moves depending on the scales. This is what I was trying to get at where it should balance around. From what you said about the perfectly balanced in one position, would you recommend say, balancing them for a standard grip, and find a way to minimize the radius that the COM moves around in?

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Originally Posted by khaos

I have indeed taken intro Physics. And PHYS II. And mechanics of solids. And DE. And multivar. So I can calculate the COM (or at least approximate it very well). And I get what you're saying about the different positions of the scale- at 180 deg you have to integrate along its length to find the moment about the COM, whereas 270deg (standard grip) its simply the total weight of the scales times the distance the pin is from the COM, correct? And every position inbetween is basically ((Mass of scales)*gravity)x(vector from COM to COM (scales), right?

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Not really, no need of integration at all

Code:

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R= (Mb*Rb+Ms*Rs)/(Mb+Ms)

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M and R are mass and the coordinate of the center of mass, the b and s refers to the blade only and scales only.
So when the scales are rotated around the pivot and their center of mass makes a circle, the same happens with the center of mass of the razor just smaller radius.

Quote:

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Originally Posted by khaos

However... You kind of touched on the fact that it moves depending on the scales. This is what I was trying to get at where it should balance around. From what you said about the perfectly balanced in one position, would you recommend say, balancing them for a standard grip, and find a way to minimize the radius that the COM moves around in?

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I think i more than touched on where the balance point should be :) The best position for the center of mass is right in the middle of your fingers however you grip it. And if you use more than one position of the scales you'll have to prioritize.
As far as minimizing the radius of that circle well, the equation is right up - I think it's clear how to do this.... light scales, light wedge, scales weight shifted towards the pivot...

Didn't think of doing it in vectors. Thanks. Anyway. Considering the fact most people balance it scales at 180 just goes to show its not as critical as I thought (as you and I agree, rotating the scales up to 270 would then unbalance it, or at least change teh balance point.)