The View Up Here

Random scribblings about kites, photography, machining, and anything else

Putting An Edge On Scissors

Posted by Tom Benedict on 27/05/2011

Back in October I volunteered some knife sharpening to an auction to raise money for cancer research. The previous year someone brought in a lawn mower blade, so this year I figured I’d be all-inclusive and offer to do anything with an edge.

So someone dropped off a pair of sewing scissors.

If your total exposure to putting an edge on a thing is using the sharpener on the back of an electric can opener, this probably doesn’t raise the sort of panic I felt. If you regularly put edges on fine woodworking tools, you probably have a better idea how I felt, but you’re probably thinking, “No problem!  Use your scissor jig.  I use my chisel jig for my chisels!”  Yeah…  I don’t own a scissor jig, and the thought of free-handing an edge on these things panicked me.

My adrenaline shot up again when the owner said the other pair they wanted me to sharpen were Ginghers.  I own a pair of left-handed 7″ dressmaker’s Ginghers. The thought of botching an edge on my own Ginghers makes me want to curl up and die. The thought of doing it to someone else’s makes me want to do my curling up and dying somewhere really private so I don’t have to bring shame upon my friends and family.

This was back in October. It’s now May of the following year.  It took this long to figure out how simple the answer really was.  When it finally came to me I almost laughed.  Then I almost strangled myself for being so dense!  Here’s how I did it:

Lansky Scissor Accessory

I built an extension to my Lansky sharpener that gave me the angles I needed. It’s a simple length of hardware store extruded aluminum with the same pattern of slots milled in it, and a set of threaded holes to make it easy to attach to the Lansky clamp. I used a bending brake to bend it up at about a 45 degree angle, but this stuff is soft. The same could have been done with a vise and a 2×4.

The slots are 10/32″ apart, center-to-center. Weird number, but that’s what I got. I used a 3/16″ diameter mill to cut them, and jogged it +/- 0.100″ off center to make the slot. It took less than thirty minutes to make, including tapping the holes that let me mount it to the Lansky clamp.

But the proof is in the pudding.  The real question is would it work?

The first pair of scissors had a terrible edge on them. In the past someone had used something that ground the metal at the wrong angle, and chattered enough that the edge on one side was almost serrated. At a guess it was a pre-packaged scissor sharpener.  I own one of these, but I never use it any more.  It works, but it takes a toll on the scissors.  Eventually the angles on the blades are so messed up the scissors won’t cut any more, and the sharpener won’t do its job.  Given the choice, it’s always better to put a precise angle on a cutting edge and maintain that angle throughout the tool’s life.  These scissors were trashed.  It took close to an hour to clean everything back up and get it back to the factory original angle.

I’ve got three stones with my Lansky.  I didn’t go all the way to the finest stone, but I don’t think it was necessary to. The original grind on the scissors was fairly coarse. (Most are, compared to the grinding on a chef’s knife.)  Most of the work was done with my coarsest stone, and involved about as much finesse as sharpening a stick by rubbing it on a sidewalk.  I checked the edge under a loupe until I started to get close.  The last tenth of a millimeter of edge was done using proper sharpening technique.  The second stone just cleaned up the scratches left from the first.  At that point I called it quits.

One step that’s worth mentioning:  When removing that much metal from an edge, you will always always raise a burr on the opposite side of the edge.  If you close the scissors with this burr present, it tears up the edge of the opposing blade.  It’s tempting to run a stone across the flat of the blade to remove the burr.  If you’re good, this works.  If you’re bad you just destroyed your scissors.  I might do this on my kids’ paper scissors, but not on someone else’s sewing scissors.  I used the end grain of a chunk of wood to remove the small burrs, but had to go after the heavier stuff with a razor blade to get it clean.  Then I put a new edge on because while the razor blade trick is kind to the back side of the blade, it’s not all that kind to the edge itself.  In the end the scissors were sharp enough to shave with either blade.

The real prize for me was testing them on a scrap piece of cloth.  It was cotton duck, but the stuff cut like silk.  Good to go.

– Tom

P.S. For what it’s worth this kind of thing can be applied to just about any knife sharpening jig that’s built along the same lines as the Lansky. But check your hole spacings and sizes before making the tapped holes.

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One Response to “Putting An Edge On Scissors”

  1. Eben Fourie said

    Tom, fantastic idea, thanks for posting.

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