Scissors design

Pamela used his keyboard to write :

I can understand that the curve would help, but the torque available at the point of cut, is still bound to reduce dramatically further away from the pivot the cut proceeds. Making the curve rather a waste of time.

The difference in torque is plotted on fig.8. It's not a very well labelled set of curves - I assume the vertical axis is torque; which for straight edge scissors goes up to 1500 muot (mystery units of torque), the SC175 goes up to 800 muot, whereas their PA ones max out at 280 muot. Assuming[1] the muots are all the same, the advantage in lower torque is clear, as is the more gradual increase required.

I'm sure their scissors are very nice, but they really could have done with some proof reading. And perhaps some experimental measurements as well.

#Paul

On 20:54 23 Jan 2019, snipped-for-privacy@moo.uklinux.net wrote in news: snipped-for-privacy@moo.uklinux.net:

Those scissors they created after all the pondering are hardly any different to any ordinary pair. I bet no user can tell the difference.

There are other research papers like that.

Back to reality, it turns out my scissors need more than having the set (bend) restored but they need the inside ride line to be true.

I watched a few Youtube videos of youngsters assuring viewers all you need is to cut sandpaper or sharpen as if you were dealing with two knives or some other simplistic stuff noneof which worked for me.

I still can't get the scissors right, so maybe I'll just buy a new pair as they are cheap enough nowadays but I can't go throwing scissors away every time a pair develops a dead spot

As an aside, I came across this true enthusiast who seems to know what he's doing but I don't have like enough enthusiasm to try it. :)

Scissor blades are twisted, curved and bent. Or at least they are on properly made ones. There is only one point of contact between the blades.

The two blades BTW are not Left and right hand, they are identical.

I once read an article saying that you could exceed the speed of light with scissors if the blades are long enough. It was referring to the point of intersection of the blades so didn't contradict Einstein.

I think things can exceed the speed of light relative to each other (for example, if they're on opposite 'sides' of an expanding universe) - they just can't pass any information between each other. Or something like that.

On 07:24 24 Jan 2019, harry snipped-for-privacy@btinternet.com wrote in news: snipped-for-privacy@googlegroups.com:

In my quest, I learnt there's a distinction between handles on "scissors" and "shears".

This turns out not to be the case - at least, not always.

See for example

Andy

I took his assertion to mean that the sharpening angles are the same. I you seperate the blades and put the cutting edges side by side they are the same.

I once made some scissors as an apprentice project.

Not on my scissors they're not.

The intersection point of the two blades can move faster than the speed of light, but only because it's not actually a physical thing. All the physical objects (the blades) are moving slower.

#Paul

How about the intersection of radio waves from two separated sources?

The old traditional edges are, IIRC, 80 deg. each; I've seen a few 'modern' ones with one 80 deg. edge and one edge that seems to be almost knife-like. I was referring to just the sharpened 'corner'. So yes, they're not all the same!

On 09:34 27 Jan 2019, PeterC snipped-for-privacy@homecall.co.uk> wrote in news: snipped-for-privacy@40tude.net:

Several scissor sharpening videos I have seen mention 45 degrees.