Thread: Convexed bevel, Good thing?

“One of my pet theories has been that using Slurry actually adds to the Convexity of the edge, making for a longerlasting and smoother feeling edge.”

I agree, here is what I think happens. Convexing a bevel is a good thing.

No matter how hard we try to grind flat, momentum forces the pressure to the edge, in the direction of travel, edge leading. On a stone without slurry that is not as big deal.

But with slurry, picture a bunch of balls under the bevel, as the pressure moves forward towards the edge, (the direction of travel) the edge dives down into the grit and contact the stone, the more slurry the more aggression, convexing. The balls/grit assist that momentum by reducing friction. Both the grit and the stone are aggressive, so cutting is multiplied and concentrated toward the direction of travel. Which is also why incrementally thinning slurry produces better results for finishing and polishes more that it cuts. Grinding vs Polishing.

All of this is microscopic, and the weight/pressure transfer is almost imperceptible, but it happens, and we, (razor honers) are talking about removing microns of steel.

A simple example of how little force is needed to make a change, is the X stroke. That little bit of centrifugal force concentrates the pressure on the edge, add a rolling action and the pressure is magnified on a small spot at a time as the pressure shifts along the edge.

Slurry is a remarkably interesting thing, that is not studied much in honing other than how to, and probably why it is difficult for new guys to understand and master. Thicker is not always better.
Add to the pressure shift the fact that some slurry is friable and crushes to a finer consistency and fresh cutting edge, but not necessarily uniformly, (natural stone), and the process is magnified, (one of the goals of finishing on slurry). The balls or bits of grit become smaller and multiply in number and abrades the steel.

Paste on a strop works much the same with added aggression from the grit. Add to the pressure shift and rolling grit, the strop flexes at the edge to the highest point or the most pressure and it too becomes more aggressive. The paste grit is not fixed, It will convex a bevel, but if your attention wanders one can easily roll an edge.

It is also why, when lapping a precision granite plate, they use a cast iron lapping plate, that imbeds the grit to prevent it from rolling around under the plate and cutting a more uniform surface. They also routinely clean the plate to remove the swarf and get a more uniform surface.