tobytools":2iegybae said:
Sorry Jacob U may of misunderstood me I will flatten the old chisels and hone them! The new ones when I get them I will still do a few passes on the backs and bevel of them just to make sure they are at 100%, im no pro but im sure that an edge is made from two straights meeting (still learning terminology)
I may be wrong but it the backs arnt straight the chisel should either be sorted or uses to open tins lol.
Any help on this would be great.
Ps. I'm sure I've even seen people flatter LN irons fresh from the box
Toby, you've got the general idea spot on. A sharp edge is the meeting of two smooth and polished surfaces.
About 18 months ago, the family bought me a selection of Ashley Isles b/e chisels for a 'significant' birthday (following my dropping a broad hint or three and directing them to the Workshop Heaven website). They are absolutely superb, and I wouldn't part with them for a big gold clock. Flattening the backs (well, more just polishing the back right behind the cutting edge) using the finest sharpening stone you have, and a similar lick of two on the bevel, was very quick and easy. The set of eight took me about half-an-hour to prepare in total. As Jacob says, good chisels are made with a very slight hollow in length (about 3 thousands of an inch, so very slight indeed), so it's easy to just polish right by the edge.
The technique I used was to place the back of the chisel on the edge of the sharpening stone, with the edge up in the air and the handle below the stone, then bring the handle up so that the back laid on the stone, then with finger pressure directly downwards on the chisel blade, draw it back. Repeat several times, and check for a polish across the whole cutting edge for about a milimetre or two behind the edge. Once you've got that, polish the bevel as in normal sharpening, turn over again and put the flat side to the stone, and draw back to turn the wire-edge. You may need to go bevel-back-bevel-back a few times to completely remove the wire edge, or draw the edge through the endgrain of a piece of softwood. Once that's done, your chisel as about as sharp as you will ever get it from that stone.
Be careful with narrower chisels when preparing and sharpening them. Keep finger pressure directly down - it's quite easy for a narrow chisel to tilt and allow you to dub off a corner if you aren't careful enough.
Once the flat side has it's initial polish, you never need to repeat. The act of removing the wire edge during normal sharpening will maintain (and gradually improve) the polish on the flat. Just be sure NEVER to allow the cutting edge on the flat side to contact the stone before the rest of the back does - get into the habit of lowering the handle before putting the flat side to the stone so that a point a couple of inches back from the edge contacts the stone first. That way, you'll never dub over the cutting edge on the flat side.
Enjoy you new AI chisels. Keep them for 'best' work, and they'll serve you well for the rest of your woodworking days!
Edit to add - with the older chisels, if you keep a few for 'rough' work, it isn't essential that the flat sides are absolutely dead flat. Chisels used for heavy chopping and removal of 'bulk' waste just need a sharpish edge, and provided you can 'draw off' the wire edge when sharpening them, a few minor hollows or bumps won't hurt much. Dead flat chisels are only really needed for very fine work, fitting tight cabinetmaking joints and the like.