I suspect writers who, after describing how to sharpen a plane blade for final finishing cuts, say "and if you want a proper job you can crown the cap iron to match", have not actually tried this. To show why, just tilt a 2p piece resting on the table - a crowned cap iron only touches the blade in the centre!
Now all those bevel up smoother (no cap irons) folk may say why bother. Indeed, they have a point as most past writers have suggested positioning the cap iron too far from the blade for it to have any useful effect on cutting quality. Explore:
http://planetuning.infillplane.com/html ... aking.html
Here's one way to arrange a crowned cap iron that doesn't trap shavings, and can be set sufficiently close all across the crowned blade. Grind the back of a LN cap iron (chipbreaker) flat to remove the lip at the 'sharp' end, 'sharpen' the cap iron to match the blade crown, and turn over a burr, scraper plane style. A couple of gentle passes over 600 grit evens out the burr. The burnishing angle sets the 'chipbreaking' angle, so don't over do it. The chipbreaker sits virtually flat on the blade, so the curved burr still touches over the full width.
The idea came from a turn of the century book, though in this case the writer suggested burnishing a standard cap iron in situ if it still trapped shavings after fettling.
Now all those bevel up smoother (no cap irons) folk may say why bother. Indeed, they have a point as most past writers have suggested positioning the cap iron too far from the blade for it to have any useful effect on cutting quality. Explore:
http://planetuning.infillplane.com/html ... aking.html
Here's one way to arrange a crowned cap iron that doesn't trap shavings, and can be set sufficiently close all across the crowned blade. Grind the back of a LN cap iron (chipbreaker) flat to remove the lip at the 'sharp' end, 'sharpen' the cap iron to match the blade crown, and turn over a burr, scraper plane style. A couple of gentle passes over 600 grit evens out the burr. The burnishing angle sets the 'chipbreaking' angle, so don't over do it. The chipbreaker sits virtually flat on the blade, so the curved burr still touches over the full width.
The idea came from a turn of the century book, though in this case the writer suggested burnishing a standard cap iron in situ if it still trapped shavings after fettling.
