Thread: Jointing

Jointing is different from killing an edge on glass, though they may be used for the same reason.
Killing an edge on glass, take the edge and rolls it over so it will not cut. You must remember that the edge, the true edge cannot be seen even at 400 x. It is a thin, foil edge. Some kill an edge when starting to hone, just to ensure that they create a whole new edge.

I kill edges with a 1k diamond file, to remove the edge when working on a blade for safety, especially when buffing.

Jointing, is or can be used to remove a burr or flash when too much pressure has been use to hone, on low grit stones, or to remove steel that has micro-chipped. It can also be used, to get a straighter edge on a low grit stone, than is normally possible by edge forward honing.

You can joint an edge on the stone face, stone side, the stone face edge or vertical corner. I use the upper corner of the stone. The razor edge is dragged lightly on the stone to remove just a bit of steel, off the edge. It is not a sawing motion like a bread-knife, but a very light single stroke.

Often if the edge is ragged or has a small chip you can feel the it. Usually one or two strokes will straighten the edge and get to solid steel.

Once a bevel is flat, a jointed edge can be brought back to meeting with just a few strokes, depending on the grit of the stone.

I often joint after a 1k, especially if a lot of material has been removed or the edge was reshaped. Then bring the bevels to meeting on a 2 or 4k.

I also typically joint at the 8k and the last laps on the finish stone, to ensure the edge is as straight as can be and that there are no chips. I also strop on a Chrome Oxide pasted canvas strop before going to the finish stone, for the same reason.

It is not something that is needed all the time, but it also does not take a lot of time or remove a lot of steel. It is a good technique to use on chippy edges and I feel builds a stronger edge.

Try it on a 1k, set the bevel, look at the edge, it will be ragged, now joint it straight and reset it on the 1k, with very light laps, 10-20. Look at the edge again.

So, if the goal of honing is to get as straight an edge as possible for comfort, why not joint the edge straight, then hone to that edge?

Glass, corks and thumbnails do similar things, but jointing on a stone cuts off the edge cleanly, instead of tearing it off or rolling it over.

I would like to add one thing to what these very knowledgeable guys have stated as they have covered it quite well, however:

Not all blades need it, nor do you have to do it every time you are at the stones.