Understanding shear and scissors edge angles.

When is 90 degrees Zero degrees? When you switch from sharpening knives to sharpening beauty shears in the USA.

I trained a new shear sharpener yesterday who has copious experience in sharpening and making knives. He was left hopelessly confused with the crazy way we measure angles when sharpening beauty shears and scissors. I have run into this problem before with people I have trained from Asian countries who had some limited experience in sharpening hair scissors because over there, the angle on hair shears is measured in the same way that the angle on knives and other sharpened tools and instruments are measured throughout the world.

Here is a chart that will help in converting the angles. Understand on shears, the higher the angle, the more acute or sharper the edge.

So, things might be upside down in Australia, but shear angles are for sure backwards and wacked out here in the USA. Don’t expect this to change. We Americans continue to measure distance in miles instead of kilometers. Some things you don’t have to understand. You just go with what is accepted. Since the average age of the American shear sharpener is probably about 60, I don’t ever expect to see a budge in the USA shear sharpening scissor mechanics measure shear angles.

Please, Watch, LIKE and SUBSCRIBE to my Youtube videos. I think this one may explain the angle dilemma for sharpeners who sharpen for the beauty and hair industry.

For training in shear sharpening check out these classes. http://www.bonika.com/sharpener-events/

#shearsharpening #scissorsharpening 

What’s the deal with the 800 mm radius on Japanese Shears?

The 800 mm radius myth started a number of years ago. Larry Brooks, a well respected retired shear sharpener, wrote a book on how to sharpen beauty scissors. To my knowledge this is still the only book on how to sharpen beauty shears. I bought it and read it and found it had a lot of good information Larry noticed that shears from Japan have a curvature to the edge of the blade, a belly so to speak. He wanted to know what the curvature was and took several of the shears he had at that time and laid them on his barn floor and drew a circle from the shape of the edge of the blade. Lo and behold, all the shears he had an 800 mm radius. This piece of information was interesting but accurate for only the shears he picked up and measured. It is not accurate for all shears.

The best radius for a shear for the least push and the best cut is 800 mm. HOWEVER, just like there are specific paint brushes for specific purposes for painting there are different edges of shears that make them specifically better for slide cutting, point cutting, blunt cutting, texturizing and more. These will all have a different radius to make them more suitable for a particular purpose.




When sharpening, the sharpener should when possible maintain or reestablish the original radius. Sometimes due to damage to shear from previous sharpening, deep nicks or other issues it is not in the best interest of the longevity of the edge to restore the original radius. All of this means
that the sharpener and his or her equipment must be able to follow the edge of the blade and can create any radius that is on the market and be prepared for the shears of the future.

The Bonika Firefly Shear has a different radius on each of the blades. The top blade has a radius of approximately 1200 mm (almost straight) and the lower blade has a low radius of around 600 mm (curved). In addition, the edge angle of the two blades are different as well. This shear is one
example why a 800 mm radius would be inappropriate for this shear. Other shears like the
Bonika Fishbone has a low radius to slide cut and point cut better while most German type shears like the Kretzer have a high radius for straight line precise cutting.


For those who want to know more from the manufacturer’s point of view this is a video clip from a sharpening convention in which a USA scissor manufacturer answers to question of a sharpening concerning the 800 mm radius.
https://youtu.be/bmvMe6SfKco


If you are looking for sharpening equipment please be sure you purchase equipment like the
Scimech Scissor Flathone and others that can address all the different radii found on today’s shears from a 500mm to 1500mm as well as the 800mm. If you have equipment that will only sharpen a 800 mm radius my suggestion is to purchase another clamping system so that you have the flexibility to sharpen any type of shear or scissor on the market today and will appear on the market tomorrow.

Announcing California Shear Sharpening School

Learn to Sharpen Shears with Bonnie Megowan of Bonika Shears

Scissor Sharpening School

• 9Am - 1PM,
• January 28, 2011
• Clarion Hotel South Bay 888 E. Dominguez St, Carson, CA Between LAX and Long Beach
• Instructor: Bonnie Megowan and Gene MegowanAppropiate for beginner and intermediate sharpener.You will learn hands-on how to sharpen convex (Japanese style) beauty shears and bevel edge (barber style) shears.

• Includes
  Instruction on how to sharpen shears on a flathone type system
  DVD "Sharpen Faster and Easier" a $59 value
  Practice scissors
  Certificate of school completion
  Lifetime Membership in the International Scissor Sharpeners Association

• You will need to bring:
  Your sharpening equipment flathone style (if you do not have equipment it is available for purchase or you can arrange to borrow ours)
  Problem scissors you may have encountered
  Notepad, pen and a red Sharpie pen

This is an abbreviated class of the full one day class. Class size is limited to 4. Bring a companion to observe at no charge.This class is the day before the Long Beach International Salon and Spa Expo. If you would like to stop by and see us to shop, visit and get your questions answered there is no charge. Call us if you would like to make an appointment to see us while we are in California.

Call 1-888-290-3393 or email sales@bonika.com.Cost $300.00 plus shipping for the DVD to watch before the class.

See the website at http://www.bonika.com/sharpnshop.html for details or to register. Limited spaces. First come basis.