09-07-2020, 07:47 PM
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Some inventions are solutions in search of problems. The double double edged blade is a prime example, double so in J O Plesch’s itteration of the idea. Not just a double double edged blade, but attempting to be a slant at the same time. And likely prone to blade chatter. However, as the patent explains, his intentions were good:

Quote:Various constructions of safety razor are known which are adapted to operate with two or more razor blades arranged in tandem so as to give a closer and better shave than is obtainable when using a razor fitted with only one blade. A disadvantage of these known safety razor constructions is that they are more complicated than razors designed to operate with a single blade and take longer to assemble and dismantle.
It is an object of the present invention to enable the better shaving properties of a multi-bladed razor to be achieved, while at the same time avoiding the above mentioned disadvantages.
A further object is to enable two or more blades to be used in suitably spaced relationship in most conventional safety razors.

So far, so good. There was blades that fit that description. The double double edged blade that Mr Plesch came up with was… different. And different dont always mean good. Let us continue with the text of the patent:

Quote:Yet another object is to make provision for the cutting edges of two or more safety razor blades to operate closely spaced one behind the other, by a spacing which varies from one end of the blade to the other, and to arrange the cutting edges of the two blades at different angles so that at least one cutting edge will have a slicing action.

So… variable spacing and non-parallel? That would mean that the blade gap and exposure will be different from one end of the razor to the other. Perhaps the patent drawing will clear up any confusion and show that the idea isn’t insane:
[Image: US2794252-drawings-page-1-697x1024.png]
Patent drawing for US patent 2,794,252

No… it looks even more insane in the drawing. Not only does the top blade in the drawing have uneven exposure, but the fact that one end of the blade is thicker* means that the other end will not be clamped down as tight. Say hello to blade chatter, which is not a good thing to have.

Mr Plesch might have had good intentions. Looking at his patent though… I can see why this didn’t take off. It’s just not a great idea, and certainly not a useful improvement on other blades.
The full patent text is available on Google Patents, for those curious. And if you want more patent madness, I got a page full.

*) The patent text suggest the use of a india rubber spacer as an alternative to metal or polymer. This would – perhaps – enable enough compression to get rid of the chatter. That would also get rid of any potential benefit of having an progressively increasing spacing.

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