Shear: Mechanics , Geology . to become fractured along a plane as a result of forces acting parallel to the plane.

Which is what they do when cutting the wood for plywood or veneer. Shearing is the correct term, but it is what is being done both in the crank and flat sharpener. The crank or rotary just does it in a single small area that is moving as the cutters revolve, verses the whole surface that the flat blade does.

 

Shearing is the correct term

Perhaps it might better describe what I'm saying by using the word "Skew".

 

You need to understand that the helical cutter in the crank type sharpener, is just the same flat cutter in the box sharpener that is wrapped into a helix. The same way that a screw thread is a inclined plane wrapped into a helix.

Skew relates to the cutting action with regards to the grain of the wood. A skew chisel is a tool used with a wood lathe and again it makes a single point of contact with the material being cut, like the helical cutter in the crank sharpener.

Not trying to be difficult, though it seems like I'm becoming, but like in electronics there are things in mechanics that have their own rules and laws. And for everyone to talk about the same thing, the terms need to be used in the same way. This stuff was taught in my early days of learning to be a machinist, back in my junior year of high school.

 

My thinking on the helical cutter is that it cuts across the pencil on an angle whereas the razor blade cuts across the pencil perpendicular to the grain. Semantics not withstanding, I still wonder why the TS wants to build a nuclear pencil sharpener.

 

See I thought he wanted to motor power an crank sharpener from the begining of this. Until he showed one like Max showed in post #20.

My thinking on the helical cutter is that it cuts across the pencil on an angle whereas the razor blade cuts across the pencil perpendicular to the grain.

They are both doing it the same just that the helical one is doing it with a much smaller point of contact. A point of conact that is moving up and down the angle as the cutter rotates.

 

My kids crayon sharpener consisted of three sharp edged plastic blades. Plastic because that was sufficient to cut through the wax. Maybe a pencil sharpener with a razor blade should (or could) have three blades. But since the single blade works well enough for many years - and ever since I was in elementary school - why reinvent the thing?

 

Get a cheap 30cent pencil sharpener from home depot; the one that chucks into a impact driver. Get one of those geared motors and drill a hole on the chuck shaft and insert the motors output shaft then mount it into a pvc pipe? Probably need some button cell batteries to keep the length down and drill holes in the pvc for shaving's to fall out.

Sincerely,
Mytwocents

 

Or get a mechanical pencil. One click sharpens quick.

 

My kids crayon sharpener consisted of three sharp edged plastic blades. Plastic because that was sufficient to cut through the wax. Maybe a pencil sharpener with a razor blade should (or could) have three blades.

I don't think it will work like that cutting the wood of a pencil. The surrounding plastic and one flat blade is to keep it from chattering and breaking the lead.

 

Or get a mechanical pencil. One click sharpens quick.

The old pencil sharpeners were more like spiral mills, i.e., not a single cutting edge:


One of the times I tested my mom was when I reversed the pencil sharpener mount we had in our pantry. I was left handed, and still am. She accepted that, even though it was more difficult for me to use too.

 

The problem that I have with sharpeners as pictured is that they seem to break the lead a whole lot of times. Hence my thinking that a much higher speed spinning cutter taking much less material at each cut, would be a better choice. Sorry if some could not visualize what I was describing, or at least trying to describe.

 

The problem that I have with sharpeners as pictured is that they seem to break the lead a whole lot of times. Hence my thinking that a much higher speed spinning cutter taking much less material at each cut, would be a better choice. Sorry if some could not visualize what I was describing, or at least trying to describe.

I agree in principle. If you have ever sharpened a pencil by hand, say with a box cutter, the smaller the cut, the better the point. Of course, concrete or sand paper do well for the final touch. But, it has been a very long time since students were told to bring several #2 sharpened lead pencils to class on Tuesday.

 

I agree in principle. If you have ever sharpened a pencil by hand, say with a box cutter, the smaller the cut, the better the point. Of course, concrete or sand paper do well for the final touch. But, it has been a very long time since students were told to bring several #2 sharpened lead pencils to class on Tuesday.

I can recall that although it was many decades ago.

 

The problem that I have with sharpeners as pictured is that they seem to break the lead a whole lot of times. Hence my thinking that a much higher speed spinning cutter taking much less material at each cut, would be a better choice. Sorry if some could not visualize what I was describing, or at least trying to describe.

I understand your thinking. Like a 60t vs a 40t saw blade. its not just the teeth but the speed as well to keep it from chipping.

 

I heard of these "artisan pencil sharpeners".
http://www.artisanalpencilsharpening.com/
lol

 

Time for you to write a book.

 

These guys do a Dam(n) fine job.

Max.

 

@MaxHeadRoom Already mentioned keeping a beaver in his pocket.

 

="Tonyr1084, Already mentioned keeping a beaver in his pocket.

A picture is worth a thousand words!
Max.

 

@MaxHeadRoom Already mentioned keeping a beaver in his pocket.

That was no beaver, he was just happy to see a dull pencil.