Scary Sharp is a myth

I’m sure you’ve heard it before, and particularly associated with the method of sharpening chisels with increasing sandpaper grades: “So sharp, it is scary”

But can something be too sharp (which is almost the implication here)?  Should something sharp be regarded as scary, or rather more safe?

A blunt tool can still cut (you) easily.  What is too blunt to carve timber is still plenty sharp enough to do significant damage to your person.  It is a mistake to think a blunt tool is safer than a sharp one, and in fact the opposite is true.  Where a blunt tool takes effort to make it work, to the point that you find yourself using excessive force, and that risks slips, mistakes, and coming into contact with the working edge of the tool.

A sharp tool on the other hand cuts with ease, cuts with surprisingly little effort, produces a better result and is a pleasure to use to boot.

This is equally true for a chisel, a circular saw blade, a bandsaw blade, a drill bit, a kitchen knife etc.

Sharpness as a safety feature!

Taking that process on a step, and think about tools that require you to either feed material over a surface to make contact with the cutting edge (eg tablesaw, router table, jointer, thicknesser, tool fence etc) or have a working surface that runs over the material.  The simple step of lubricating that surface means less force is required, and therefore less chance of a slip and accident.

Lubrication as a safety feature!

9 Responses

  1. I liked your piece, but I am not sure if people who use the term ‘scary’ sharp are using it to indicate that it is in fact frightening. I would say that in the context with which it is being used, it is more akin to ‘scary as in wow’. Or perhaps that is just how I interpreted it. I may be wrong, I often am. Still, you made very good points, so I give it 5 stars.

  2. Scary in this context is slang that probably didn’t make its way to Australia. 🙂

    • Ah well, that was how it was presented to me when I first came across it – and so the title may not be as fitting for the US audience, it still is valid down under!

      Anyway – the title achieved one objective – made you look! 🙂

  3. This article is Scary Good! See what i did there? 🙂 Great points Stu. A sharp tool is a safe(er) tool.

  4. I’ve found that if you sharpen something too sharp (too fine an edge), the edge will not be durable enough to do much real work. Picture whittling with a straight razor vs a real whittling knife. I notice this particularly with my machete.

    • Sorry, but have to contradict you on that – you cannot have too sharp an edge where it comes to durability, but you can have too fine a bevel angle.

      What is happening is there is not enough material backing up the edge, so it is falling apart under load.

      Think about a pane of glass. It is SHARP, yet the bevel angle is 90 degrees! Now glass isn’t the best example because it is such a brittle material in the first place.

      Sharpness is how close to a zero radius corner you have on the junction between two surfaces. A zero radius is ideal (and impossible), so from there on you want the minimum radius possible.

      Depending on the tool, its purpose, and the brittleness of the material you choose a bevel angle accordingly.

  5. Re:Sharpness is how close to a zero radius corner you have.

    Zero radius equals flat.

    Flat no cut, flat smash, said in a cavemans voice. 🙂

    Wouldn’t this be more accurately described as having an angle (bevel) as close to 360 degrees as possible? With a back up bevel to support the finer bevel?

    Glass cuts by being like a very fine saw blade composed of microscopic peaks and valley very much like the edge of a knapped flint arrowhead.

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