Thursday, June 19, 2008

Wicked Edge on a Chisel

This has been a long time coming, I know. Wasn't my intent to leave this alone for so long. Well anyway, on with the info.
This is actually an add-on to the previous post of Sharping Perfection. I am still
working on gouges, they of course are a little tougher given their curve. But at this point that isn't a big issue since I don't do much carving. I do a bit of turning but turning chisels don't require the highly polished bevels that are required in carving, finishing, mortise, and other works.
This is by far the best honing process that I have found so far for not so curved blades. It will bringing two edges to a brightly mirrored polish without reverting to buffing wheels which, if you follow the physics of how a buffing wheel works, tends to round over the cutting edge while it polishes the bevels.

(I use the term "blade" to cover all pieces of metal to be honed and polished whether they be plane irons, chisels, gouges, etc.....)

The Strop:

First, start with a flat piece of plywood, a scrap piece of cabinet grade of course works best. Cut the 3/4" ply into a decent sized rectangle, the size of course going to vary with the next item, a square edged belt. You know the type I am thinking of, think 1950's Levi's black belt. Belts with tapered edges aren't going to work too well and belts that have edge stitching aren't going to work at all. Used belts work fine as long as they can be made to lay perfectly flat. NOTE: You are going to cut the belt into at least two pieces; so if your belt has that little section in the back that curls you can cut that piece out. The way I cut my belt was in thirds. I used the piece with the holes as well but cut that section in roughing half to avoid the hole indentations.
Next I put a double coating of spray adhesive onto the face of the plywood following the directions on the spray can for additional adhesion. I then sprayed a double coat on the belt sections on the rough side being careful not to over spray onto the edges of the leather, important you want the smooth side of the leather to be the stropping side. Carefully place the leather onto the plywood being sure to fit it right the first time, if you have to reposition the leather it may weaken the bond to the plywood. Press it into place and apply pressure until it sets up. The Strop is done.

The Honing Compound:

I have used black (or gray) honing compound also known as Emery. This stuff is the course stuff. If there was a honing compound for power stripping varnish off a foot locker, this would be it. This stuff in like Lava hand soap for hands. In fact I wouldn't be surprised if it was made with lava. It is good rough honing or light metal removal, but NOT for polishing or final honing.

Red honing compound, this is more for jewelry, silver, gold, platinum, etc..... It is the finest of the honing compounds but it doesn't have the cutting power to deal with steel, especially tool, hardened, and high carbon steels.

Tripoli Brown Rouge, can be used on a lot of things aluminum, plastics, copper, zinc, and even wood. I don't really get the buffing wood part, well maybe exotic oily woods. But again, not for wood working tools.

This brings me to Green. This is the most widely used for tools. The particles are in the .5 to .7 micron range (1 micron = 1 micrometer or 1 millionth of a meter). This is great for almost all tool applications.

Then there is my new favorite, White honing compound. These particles are less than .5 microns.

The process is simple. Once you run the blade through the stones (even up to 8000 grit) or sandpaper higher polishing can be attained by the use of honing compounds, like diamond paste but much less expensive. The honing compound is rubbed into the leather and adheres partly due to the wax, or sometimes grease. The particles embed into the leather and are instantly ready to polish the two sides of the edge.

The polishing can take an edge like this (which is a LN blade only slightly used):

And turn it into something like this:

The idea is to first use a high grit, to remove nicks and square up the blade. Then to work up the grits, higher and higher removing only the scratches the previous grit left. You can go a little over board on the number of stones you go through. Generally a 220, 400, 1000, and then 8000 can be sufficient, but some, like me, have a more varied set that really isn't required. After the 8000 grit most would consider things done, and they would generally be correct. But there is something I get from the feel of a plane or chisels sliding and slicing through wood and lifting shaving off like this:

The bottom shaving is from my Lie Nielsen #7 right out of the box. The one on top is after sharpening the blade and chip breaker to the picture above. SWEEEEEET. Like mosquito wings.