richarddownunder":3f5et18l said:
So, your reference to cap iron means setting it close and having it seating well?
Yes having it seated properly is a must regardless of usage, but it shouldn't always be set close. Adjustment of the cap iron's position relative to the cutting edge is what gives the easy adjustability of any double-iron plane that is rightly valued, set it back for easy working where appropriate and moving it closer and closer to provide control over tearout as needed (at the cost of increasing resistance, hence why you don't want to leave it well forward all the time if it's not required). You set it well back for rougher work where you basically want the cap iron to get out of the way, closer than this for flattening/smoothing operations in easy-planing woods, closer still where the wood is proving challenging, and "as close as you dare" for wood that's really troublesome. Some numbers on this if you need them: 2-3mm, 1-2mm, 0.5-1mm, >0.3mm.
We all know seating is a must with cap irons and virtually every modern guide will show how to get it right so that not even a sliver of light is visible underneath, what's far less commonly included in these fettling guides is doing anything more than polishing the front of the curve. To work right as a means of controlling tearout the leading edge usually needs to be worked on, not merely smoothed and polished but giving it a small steep bevel. It should be well north of 45° but not so steep as to get closer to perpendicular; approximately 60° is a good sweet spot to aim for because if you're off in either direction it'll still work. This is, incidentally, why modern flatter cap irons (
case in point) aren't working as well for some users compared to a bog-standard thin cap in a Bailey-pattern plane, because what angle is that?