Sharpening scissors

[Jan]

Recently I have sharpened my hair-cutting (not thinning) scissors. I set the sharpening angle to the existing edge angle. The edge angle was between 75 and 80 degrees, i.e. slightly beyond the range of the AngleMaster. The scissors jig worked fine, despite some vibrations and squealing. I was not able to sharpen the end of the bevel near the pivot (some 1/8"). The scissors cut fine.
Regards Jan

[Herman Trivilino]

The bevel angle is usually more blunt near the hinge. On some scissors it's more pronounced than on others. I have seen scissors that don't do this, but most do.

[Jan]

Thank you Herman for your important comment! You are correct.

The sharpest part of the scissors edge is called "knife edge" and has an angle approx. 45 degrees. It is followed by the middle part of the edge with some 60 degrees. The final part of the edge near the hinge may approach 90 degrees.

From the mechanical point of view it is fully justified. Scissors, as a typical double-lever, have much larger mechanical advantage near the hinge than near the tip.

In my understanding this concerns mainly high-quality scissors.
Regards Jan

[Rhino]

Scissors are some of the most poorly made things that I have ever sharpened.  The blades don't have the same angle.  The same blade has different angles and most of them are not made with hardened material.  Any sharpening will improve them.  While the Tormek is not good for removing large amounts of materials, I have removed lots of material from abused scissors without difficulties.

I find sometimes they are more like the old paper cutters.  On blade has a 90 degree angle and one blade has more of a cutting angle.

On the other hand, taking an old pair of scissors that has been abused and bringing them back to functional shape, even better than new, is very satisfying.  I have taken so much material off of abused scissors that the tip would no longer close.  I have to grind the tip down too. 

[Ken S]

Interesting posts. One of my jobs along the way at the telephone company was a cable splicer. The easiest way to spot a splicer in a crowd is to look for a small leather pouch threaded into his belt. The pouch holds a pair of snips (scissors to the rest of the world) and a "blue knife". These knives have a blade about an inch and a half long and,traditionally, a blue handle. ("civilian" versions are now available with orange handles.) The knives are also called skinnin knives. They are used for skinning the outer insulation from cables.

These are often very abused tools. They are well made, but get industrial use. I have several very used ones of both. I enjoy bringing them back to life with my Tormek. I would not quite call them restored. They are sharp again and work well, however, they are far from pristine. They are useful.

I believe one of the satisfactions of working with a Tormek is restoring tools to usefulness.

Ken

[Jan]

On the other hand, taking an old pair of scissors that has been abused and bringing them back to functional shape, even better than new, is very satisfying.  I have taken so much material off of abused scissors that the tip would no longer close.  I have to grind the tip down too. 

Before grinding down the scissors tips, I always consider whether the problem can be solved by grinding down the inside of the finger rings. Some scissors have here a bumper or stopper.

[Jan]

The easiest way to spot a splicer in a crowd is to look for a small leather pouch threaded into his belt. The pouch holds a pair of snips (scissors to the rest of the world) and a "blue knife".

As a non native speaker I have sometimes to look up the meaning of words. What are the differences between "snips", "shears" and "scissors"?

I got the following answers:
1) Snips are shears used to cut metal.

2) The word "scissor" comes from the Latin word "cisoria" meaning a cutting instrument. The verb "scinder" means to cut or separate. The word appears in Old French between 842-1300 A.D. as "Cisoires," from which the Modern French word "Ciseaux" derives. In late Middle English, about 1400 A.D., there is found reference to "sisours" and "cysowres. "
   
The word "shears" has a different derivation, originating from the Germanic/Teutonic root "Sker, " which later changed to "Skeresa. " In Old English, the word became "Scear." The word in German is today "Schere. "

Today both words, shear and scissor, are used interchangeably in the English language. One definition is that a scissor is up to 6" in length. Anything longer than 6" is generally considered a shear. Another definition is that even sized fingerings are a scissor and uneven ones a shear.
http://www.chrissystems.com/customer-support-center/grooming-scissors-education.aspx

English is a very difficult, irregular language.
Be happy you are native speakers.

[Herman Trivilino]

Engineers also use the word shear to describe the direction of the force applied to the material being cut. As in the comparison of shear waves (transverse waves) to pressure waves (longitudinal waves) occurring during an earthquake. Or as in the shear force versus the tensile force applied to a bolt. The shear force is the force you'd apply if you tried to cut the bolt with a pair of shears whereas the tensile force is the force you'd apply to stretch the bolt. Then there is the shear force versus the bending moment applied to a beam under a load.
 

[Jan]

Good comment, Herman. From the mechanical point of view the scissors cut material, when the shear stress at the point where the blades meet is larger then the shear strength of the material.

[breid]

 
Replying to all of the above -- I came here to learn more about sharpening knives and scissors and am amazed at the depth of knowledge many of you have on all things related to tools, cutting, sharpening, etc. I appreciate it all and thank you for taking the time to share it.

The true razor edge eluded me for decades. I've been able to reach only "sorta sharp" on the many handstones I've worn down in trying. My Tormek fixed that; Now I know what it means to truly slice a tomato.

[Elden]

   Welcome to the forum, Bob. Glad to have you a board. You are correct. There is a lot of good information posted here. I learn different things quite regularly. Feel free to post questions or information to be added. Glad to hear the Tormek is working well for you.

[stevebot]

Many scissor/shear designs combine the cutting action of a knife with the shearing action of scissors. The most straight forward example is the dressmaker "knife-edge" scissor. The thumb or base (lower) blade is sharpened at about 15 deg (75 deg) while the finger blade is sharpened at 45 deg (45)  Since a knife sharpened at 22.5 would have a total included angle of 45 deg, this blade is potentially as sharp as a knife, allowing it to cut through thick material up until the final shearing moment. In my practice I leave the thumb blade rough at 120 grit and hone to finger blade to 400 grit or better.

Salon shears are knife or razor sharp on both blades. They shear when being closed but slice cut when used for slide cuts.

In more extreme cases the base blade is corrugated to prevent slipping. Examples are kitchen shears and some metal snips.

An oddity - beauticians and barbers hold their shears opposite the paper cutting/dress making hold, so the base blade is the finger blade, and it is sometimes corrugated.

[Jan]

Steve, thanks for sharing your experience with asymmetrically sharpened scissors blades.  It is very important to know about it in advance and not be surprised by that during the actual grinding.

Having a concept is especially important when sharpening ancient scissors, where the initial edge angles are no more easy recognizable.


Tailor's shears made by A. Wingen Jr., Solingen/Germany, about 1910.

Jan

[jeffs55]

If only those scissors could talk, a lot has happened in your country since 1938.

[Jan]

Jeff, I inherited the shears from my grandmother, who was a dressmaker.

I hope that after the next hundred years the shears will tell my grand-grand-grandchildren how carefully I sharpened them on the great Swedish water cooled grinder.
I wish so much the shears will not have to experience another world war. 

Jan