Under the Choko Tree By Nevin Sweeney

Tool Sharpening - Part 3: Scissors

Thirty years ago an old friend of mine by the name of Bill Tarplee was operating a magazine out of Canberra and he wrote a series of articles on tools. Bill was a manual arts teacher at one stage, very skilful with his hands and knows all that there is to know about hand tools, their care and sharpening. I have been lucky enough to secure his permission to republish some of his original articles.

This one was first published in September 1981 and is the third in a series of three articles about tool sharpening.

Scissor sharpening is not difficult, once you understand the principle underlying the scissors’ cutting action. Scissors do not cut in the sense that a knife cuts or a saw cuts. Knives cut by a slicing action; saws cut by either a slicing action or a chiselling action (depending on whether the saw is a cross cut or rip saw). Scissors cut by shearing. In simple terms one blade moves against the other fixed blade and shears through the article between the two blades.

In this instance then, a pair of scissor blades are sharp at the touching edges. Sharpness is defined by the fact that the edges should be fine and not rounded over or gapped.

Moreover, scissor blades are slightly curved, so that the edges bear against each other over the length of the cut. In addition, the blades are hollow ground, so that the only point of contact is the sharing edge where two blades cross. To sharpen scissors properly, it is necessary that these factors should be fully understood. I would suggest that a new pair of scissors be inspected to observe this, so you can duplicate these points on the blunt blades.

To sharpen scissors you may use either an emery wheel or a file – whichever is to hand on the occasion.

Hold the scissor blade securely, preferably in a vise fitted with ‘soft jaws’ (two plates of aluminium or similar soft metal across the vise teeth to protect the scissor handle) and file lightly at an angle of 75⁰ to 80⁰ from the perpendicular, across the blade toward the cutting edge, until a fresh facet has been produced for the length of the blade.

If the scissors are badly worn on the inside of the blades (and this will be shown by a shin patch below the cutting edge) it will be necessary to dismantle the blades by removing the screw or rivet on which the blades pivot.

Next carefully run the blades, individually, across an emery wheel. You can’t do this step with a file. I guess you could do it with an oilstone slip if you had a lot of time. This will renew the hollow ground facet.

If there is a ragged edge left after grinding and filing, it should be left unless it is too coarse. Under those circumstances lightly file with a fine file. Don’t remove the burr with an oilstone as the cutting action is not as satisfactory. Scissors work best with a fine but ragged cutting edge.

Another point to check is that the screw (or rivet) is tight enough to maintain the contact between the cutting edges over the length of the blade. If the rivet is too tight the scissors will bind and they will be difficult to use. If too loose then they won’t cut. With riveted blades be careful and use a light hammer – preferably a ball pein hammer and use the ball. You will often find that just one light hammer blow will be the difference between too loose and just tight enough.

When the blades have been screwed together and the right degree of friction attained, the screw can be locked by punching with a centre-punch between the edge of the screw and the scissor.

Note: back a hundred years ago, itinerant travellers earnt a meagre living through scissor and knife sharpening. The time may come again when such a skill would once again provide a living. Especially in this age of getting someone else to do even basic jobs. You will find that sharpening is not difficult and it is worth learning, even if only to save yourself some money.

Finally, remember that the shearing action is not restricted to just scissors. The same action is utilised by shears, tin snips, guillotines, and metal shears. The sane principles apply , even though the tools may be much larger and rely more upon grinding than filing.

Part 1: Grinding and Sharpening Equipment

Part 2: Sharpening Plane Irons, Chisels and Knives

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