|Project by hingeman||posted 08-19-2011 11:23 PM||8855 views||16 times favorited||6 comments|
This is here becasue of a query about sharpening corner chisels – this was in a review of a jig I’ve developed which was kindly posted by Roger Bean. I have partially answered the query in the context of that article but thought that I would show the jig I use as a full project here.
It takes a little effort to make, but once you have it it’s worth its weight … assuming you use one of the Veritas chisels regularly, either with the Veritas guide or with my corner trimming jig. And the principal could be adapted for larger, handled versions.
This is really only a prototype – an attempt to hold the chisel absolutely firm and in the right orientation so that a slightly doctored diamond stone can be used with complete confidence to do this otherwise tricky job. The adjustments are fairly basic – the ‘rosewood and brass’ version will, of course, have all sorts of fine adjusting screws, an integral chisel clamp, spirit level and all sorts. In the next life, maybe.
The assembly that holds the chisel is held in place by a wing nut in a slot in its base – this allows it easily to swivel left and right, and slide forwards and backwards in order to register the chisel in exactly the correct position relative to the diamond stone. The angled sections that the chisel rests on can also have their angles adjusted.
The height of the groove that supports the diamond stone is important – it should be exactly level – and parallel – with whichever bevel of the chisel is uppermost.
I originally wanted to use a piece of tufnol with strips of wet & dry stuck to the underside – but the steel that the chisel is made from is so *&^ hard that I was having to replace it far too often in order to do the job efficiently. So, instead, I now use an old diamond stone ground off along one edge as shown, undercut very slightly away from the top. This ensures a sharp but ‘safe’ edge with which to get right into where the two bevels meet. I’ve put a piece of tape along the edge of the stone that runs along the support to stop it cutting/clogging/wearing.
It is important that the stone rubs absolutely flat on the bevel. After a few strokes you will see where you’re having an effect – if it’s hard to see, use some pencil or engineer’s blue to mark the face. Any slight adjustments needed can usually be made by adding scraps of tape and/or card to the underside of the stone to bring it into perfect alignment.
Once you can see the whole bevel is clean, repeat for the other side. Then after a single, gentle [push] stroke on each of the outside faces to remove the burrs … you’re done. Don’t be tempted to do more strokes on the outside, there’s alway the danger of compromising the squareness. And don’t be tempted to try to speed things up by having a secondary bevel, it simply doesn’t work because it causes mayhem in the corner!
For a swift freshen up I have posted a quick method as a comment at the end of Roger’s review here.
-- Andrew Crawford, Shropshire, UK http://www.box-making.com