Which smoothing plane to buy

[Pat Barry]

The tightest that I've both used successfully and measured was ~5 mils, but I would only go that low for a problematic workpiece. It's possible I've gone lower than that by now, but I haven't measured in a while as doing so is somewhat involved (I used a reflective/metallurgical microscope) and fairly pointless once you have the hang of things.

Steve Elliott has some 'scope shots on his page showing a 4-mil setback.

Like most people, when I need a close-set cap-iron I adjust it with a bright light reflecting from the iron, and advance the cap iron until a uniform (or symmetric if the blade is rounded) sliver shows all the way across. I used to do it under a 4X magnifier with bright lightning, but realized that that was unneccessarily time-consuming. You can judge it well enough with the naked eye if you get a good specular reflection from the blade back.

Wow. 5 mils is really close. Is that with a number 4? I recall you talking previously about a cambered blade also. Do you set it that close with a cambered blade? Me, I would need a 30X microscope to see 4 mils - no chance with naked eye - thank god you are young! I wonder if Warren ever gets that close? For me its probably more like 10 to 16 mils and thats just a guess

[Patrick Chase]

Wow. 5 mils is really close. Is that with a number 4? I recall you talking previously about a cambered blade also. Do you set it that close with a cambered blade? Me, I would need a 30X microscope to see 4 mils - no chance with naked eye - thank god you are young! I wonder if Warren ever gets that close? For me its probably more like 10 to 16 mils and thats just a guess

To be clear, nobody can directly and accurately evaluate distances that small unassisted. An unassisted human with 20/20 vision can resolve modulations as high as 250 cyc/inch or so, but there's a big difference between "resolve" and "accurately evaluate". That's where the bright light comes in. If you create a bright specular reflection off of the exposed leading edge of the blade (the part between the leading edge of the cap iron and the cutting edge), then the intensity of that reflection serves as a very good proxy for size. Even someone with less than perfect vision can manage that unassisted.

It's basically the same principle that we use when checking flatness with a straightedge. Your eye can't possibly detect a 0.1 mil gap, but if you use a strong enough backlight you can easily perceive the "leakage" from a gap that small. The only difference is that in one case we rely on a specular reflection while in the other we rely on transmission/leakage.

My "personal record" was on either a 3 or a 4. I can't remember which. My smoothing irons are ground straight across through the middle, with a few mils of rounding at either edge. When I go for a minimum cap-iron set I aim for a the aforementioned reflection to be symmetric and to extend all the way across, though tapering noticeably (i.e. fainter) at the corners.

I would be willing to bet that Warren rarely if ever measure his setbacks. Like highly skilled practitioners in many domains, he seems to have a set of extremely well-practiced techniques that he's evolved over the years, to the point where he can intuitively deploy them without overthinking it. I can do that on skis or in code, but not on wood :-).

[Pat Barry]

To be clear, nobody can directly and accurately evaluate distances that small unassisted. An unassisted human with 20/20 vision can resolve modulations as high as 250 cyc/inch or so, but there's a big difference between "resolve" and "accurately evaluate". That's where the bright light comes in. If you create a bright specular reflection off of the exposed leading edge of the blade (the part between the leading edge of the cap iron and the cutting edge), then the intensity of that reflection serves as a very good proxy for size. Even someone with less than perfect vision can manage that unassisted.

It's basically the same principle that we use when checking flatness with a straightedge. Your eye can't possibly detect a 0.1 mil gap, but if you use a strong enough backlight you can easily perceive the "leakage" from a gap that small. The only difference is that in one case we rely on a specular reflection while in the other we rely on transmission/leakage.

My "personal record" was on either a 3 or a 4. I can't remember which. My smoothing irons are ground straight across through the middle, with a few mils of rounding at either edge. When I go for a minimum cap-iron set I aim for a the aforementioned reflection to be symmetric and to extend all the way across, though tapering noticeable (i.e. fainter) at the corners.

I would be willing to bet that Warren rarely if ever measure his setbacks. Like extremely skilled practitioners in many domains, he seems to have a set of extremely well-practiced techniques that he's evolved over the years, to the point where he can intuitively deploy them without overthinking it. I can do that on skis, but not on wood :-).

Back in the day I could see that but those days are gone. Now I wonder why videos look so good but I can't see that good in real life. Makes me think I should work by camera LOL. I'm starting to think a wee bit of tearout is a bit of character since I don't French polish either and dont seem to need that great a finish. I sure would like to see some of your projects though.

[Gary Cunningham]

You are on a perilous slope.

With apologies to The Fixx: One planes leads to another...........

[Jim Koepke]

How many people actually use the cap iron here, apart from Warren,George,Kees and Derek ?

Guilty as charged, the chip breaker has performed well for me, even more so after having it explained here and other forums.

It works wonders with a sharp blade on an old type 6 Stanley/Bailey #4 with a sharp type 11 blade:

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The plane looks like a piece of junk, but it can make a smooth surface.

When smoothing if an area has a rough feel after a couple of passes the plane direction can often be changed and plane against the grain over the rest of the piece to good effect. A thin shaving will not tear out much more than its own thickness.

jtk