Why is a Guillotine blade diagonal? | Hacker News Reader

Why is a Guillotine blade diagonal?

pepijndevos.nl

46 pointsjandeboevrie50 comments

One explanation is missing: the angle of the edge.

If the blade edge has been sharpened to 20 degree angle, it has the same 20 degree cutting angle when used diagonally. The effective cutting angle decreases in the direction of the cut when you rotate it. The smaller the angle, the sharper the knife.

this creates shear, lengthens the amount of blade edge, and directs force to a smaller contact surface than a perpedicular edge.

[But the story goes that the real reason the blade is diagonal is that the king suggested it might help with people with fat necks]

thus proclaimation was the lead contributor.

Cause someone thought the sound of SHIIINK was some terrifying original sound as opposed to clever chopping carrot

Guillotine proposed his device as a more humane alternative to traditional modes of execution like being drawn and quartered.

And contrary to legend he did not die by his own device.

Her device?

The namesake is Joseph-Ignace Guillotin and the prototype by Antoine Louis. Is there something else leading to your comment?

Digging me for putting an E on the end of a masculine name.

Basically a joke only Francophones would get and I’m a lapsed one. I think it’s only first names anyway, so the joke is probably still broken.

Slant razors, like the Merkur slant, are also slightly angled for an easier shave.

I have one and can vouch for it.

One colloquial term for the guillotine was (is?) "le rasoir national" = "the national razor."

Other colorful terms include "the regretful climb", "the silence mill", "Capet's necktie", "the patriotic shortener", "half-moon", "timbers of justice", and "Charlot's rocking-chair".

https://en.wikipedia.org/wiki/Guillotine#Names_for_the_guill...

Run that with a Feather blade, and buddy, you will be facesturbating all day.

I’ve used Feather, worked out OK for me. I have a couple of other blades I prefer though.

Quite the fascinating story, I dig up a bit more: https://archive.org/details/memoirsofsansons00sansuoft/page/...

Does being pushed sideways matter? If the knowArt test was on a small scale it might not have had the inertia of the full size.

Reminded me of this "La Révolution française" scene https://youtu.be/YPiiAHSi_48?t=5236

I'm sure diagonal blades are more practical, but style must be part of it right? It was a theatrical method of execution after all, done for crowds.

Less likely to bounce off a bone would be my guess? A diagonal blade will push obstacles out of the way.

Mainly because the slicing motion separates fibers in the fresh, it's more effective than blunt force. Same with a knife.

It's interesting, however, that this post is much higher on the front page than the post about Durov's arrest by the French ever was, despite having 1/10th the number of comments during a similar time period.

Which begs the question: why wasn’t it shaped like a ^

It'd be tough to keep that inside corner sharp...

Two overlapping triangles would work. A little work in disassembly reassembly, but not much.

Just make it a V.

You then have to ensure the flat side of the blade pair meets without a gap. The gap, at least when I’m sharpening wood planes with a chip breaker, allows material to get stuck which will prevent a good cut. I would imagine getting some spine caught in a gap there would cause issues. With a single blade you don’t need to worry about the back flatness as much.

"to beg the question" means "to dodge the question". You mean "prompts the question".

Dictionaries now seem to give both the definitions. Such is the fate of us victims of the dynamic English language.

When the people speaking standard English are outnumbered by the people using other forms dynamicity is to be expected. The curse of lingua franca.

We (Americans) stole it in the first place, so it is only fair that we’re happy to share.

True. But it may lead to some amusing situations - like when you are having a zoom call with people from all over the world to be at a disadvantage because you are native speaker or have C2 Proficiency in English.

Unlike cigar cutter on which you apply a constant force, a ^ guillotine has fixed potential energy. It will get to the toughest part of the neck when bigger portion of it is spent, so it may or may not be enough to cut trough.

Same Reason a Katana is curved, while the temp causes this, it augments the blades cutting angle, length, draw.

It's too soon to say

Without reading the article, my guess would be because it allows the force to be focused on a smaller area at the start of the cut.

Wouldn’t everything that is a blade be designed this way then?

Almost everything that is a blade is designed to be curved or slanted, yes.

Many are. Scissors, drill bits, even the way most people use a kitchen knife, they put as much force onto as small of area as possible. At certain differences in scale it won't matter (razor blade vs a single hair), but how a cut is performed is definitely part of the design process.

Like a mandolin slicer?

They are. Except for Japanese style knives, all knives have a slant.

The Japanese knives are only sharpened with a single edge, however. So they in a profile view look like a tiny guillotine.

chopping vegetables with a chef's knife applies the same principle

Only those that go in frames. The angle is applied while using proper cutting technique for knives. A flat blade would also go dull rather quickly, as only one portion of the blade would be doing all the cutting (well, tearing, a straight drop with a flat blade would be like trying to chop a tomato rather than slicing it).

> it allows the force to be focused on a smaller area at the start of the cut

Is this really true when the object to be cut, a neck, is approximately spherical?

I can see the truth of the statement for a straight horizontal rectangular object, but for a cylinder-like shape?

Cylindrical not spherical.

Approximately spherical after the fact.

Unreadable in dark mode :(

Looks fine to me

It is white text on black background by default. Do you have some browser plugins that mess with the website content?

I thought this would be about paper guillotines.

what paper guillotine has a diagonal blade? all of the ones I've ever used were curved

But thats because the cutting angle changes when depressing the lever. The curvature is meant to counter that to some extent.

A printer’s guillotine that cuts hundreds of sheets at once has a diagonal blade.

The point is that they cut at an angle.

What should we take away from this comment?

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