Work Sharp 3000/diamond discs/establishing chisel surfaces...

[ian maybury]

Just an update. Some of the 100 and 500 grit diamond lapidary discs bought on E Bay for the WorkSharp 3000 ( by http://www.thk.hk ) arrived from Hong Kong and have had a test run - on the remaining few Japanese chisels, and on a bunch of old Marples and blue Irwins (same blades) i've had for years and which have been used for everything. (including opening paint tins)

Stuck them down on to the WorkSharp glass discs using double sided adhesive film. It works very nicely. Just take care to use a 1/2 in drill or something in the hole in the glass to guide the diamond disc into place as they need to be accurately centred.

The diamond works well. It cuts very aggressively when new, but pretty rapidly loses a lot of its bite - but seems to be holding very well at a level very similar to the equivalent 'run in' aluminium oxide disc from WorkSharp and to be lasting much better. Another positive is that it seems to put notably less heat into the metal than the AlOx paper. An 80 grit diamond disc would probably be better for flattening the backs of western chisels of this sort than the above - but work the backs up through successively finer discs (to at least 500) before shifting to the waterstones.

The Marples (which presumably are the usual commercial grade alloy steel) are a very different ball game to hone than the Japanese white steel chisels. It cuts well on the (Shapton professional) waterstones judging by the amounts of metal coming off, but feels different. Especially when flattening the (relatively much larger area/not hollowed) backs - a much greater tendency to suck down, and takes more time. It underlines just how smart the Japanese design is.

The alloy steel cuts differently to the white/carbon steel. It's a bit draggy, and the surface doesn't polish (maintains quite a dark tone) until the 12,000 grit right at the end - and even then it's not as bright. It's harder to remove scratches between grits too - probably just slower metal removal caused by the larger area. The widest chisel was really hard work, without a lot of pressure it was inclined to skid on the stone. It worked out fine, but the grade of steel and the area being worked can clearly make a very big difference to how/how well a given waterstone works.....

They do take an arm shaving sharp edge (in this case using a micro bevel), but it takes a bit more care. Soem complain of problems. One issue may (?) be that the alloy steel tends to form an obviously much thicker and larger wire edge on the coarser grits. It eventually hones off properly to leave an intact cutting edge, but for this to happen it's necessary to sneak gently up on it with controlled movements on successively finer grits (using a honing guide probably helps quite a bit too) - while resisting the temptation to tear/knock it off and probably take a chunk out of the edge. Quite how they will hold up in use is another matter.

Light dry stropping (?) on a buffing pad mounted on the WorkSharp (taking care to match the angles) definitely brings them up a little more.

Next up is to try the suggested honing on hard leather or on MDF discs (will try both) for re-sharpening….