Kees - More Cap Iron Study Stuff - Surface Quality?

[David Weaver]

Well, I posted the topic with a question mark, but I really don't need to use one.

http://planetuning.infillplane.com/html/cap_iron_study_by_kees_van_der.html

I tracked down this article that's posted on Steve Elliot's site. Who is steve elliot? One of the two (the other being Bill Tindall) who went to the trouble to dig up the kato and kawai stuff, as bill has clarified - for the purpose of studying wear, but with the lovely side benefit of providing a close up visual of a double iron in use.

All of the numbers in the article make my head spin, but there are a lot of folks who need to see numbers and comparisons before they'll believe much. It does quantify some of the things we've talked about (how does common pitch with a cap iron compare to steep pitch). And a separate conclusion that I've been beating the drum about for a while, that the cap iron is extremely useful in a heavy cut to limit tearout to something that can easily be removed by a smoother - something that is not managed well with a single iron in a heavy cut in something like quartered wood.

Yesterday, I was flattening door panels, and I had one that I had to thickness (the lumber I have to work with is various thicknesses), which is a painful job when the lumber is overthick to start with. It's 6/4 quartered cherry, which tears out. I jacked the thickness off of the board and then used a try plane to level it and measured the shavings (somethign I almost never do) in a very heavy cut - .011 once all of the humps were out, with minimal tearout - some very light depth tearing but nothing that I couldn't remove with a quick follow up by a metal jointer set cutting .005".

I would never have thought of making cuts like those pre-double iron, and if I had tried, I would've gone past my depth mark or spent 20 minutes taking off the last 16th with some steep angle plane with a heavy smoother set.

Thanks for taking the considerable time, Kees, that it does to catalog and organize your thoughts with this stuff.

[Joe Tilson]

Very interesting. We'll have to study this for a while.

Very well done, Kees and company

Thank you for the post Dave.

Joe

[Kees Heiden]

Well spotted David,

To be sure, this is just about tear out performance. Not about all the other aspects of using capirons and high angle planes.

You are right about the ability of the capiron to limit tearout, even if it can't quite prevent it totally. That's a very obvious feature. A 60 degree angle plane has a similar effect, but rough work is not exactly the main occupation of high angle planes. Jack planes are build usually at 45 degrees, otherwise pushing them becomes too much effort. Setting the capiron close, but not too close, can help a lot in a jack plane. This is also observable in the Kato video. Planing against the grain with a 0.1 mm shaving causes deep and wild tearout whithout a capiron. Setting a capiron with 50 degree bevel at 0.3mm still creates tearout, but it isn't nearly as bad. And when you look at the force mesurements they did, you will see that such settings don't effect the pushing force much.

[David Weaver]

For some reason, all of those other thoughts were floating through my head, they didn't have to do with your article so much!

Mitigation of tearout (even without elimination) in thicker cuts does have another purpose in terms of planing force - that being that it is still tolerable. A plane that is tearing out considerably and seemingly randomly can deliver serious shots to the elbows and shoulders. The obvious want is to plan downgrain, but in quartered wood or some poor wood, it can't be avoided.

I cannot take a tearout free shaving a hundredth thick in quartered wood, but I can take one that is quite good - and that's important. You've continued to do good work tracking the details and rebuttals that I lost interest in as soon as I realized that I don't have anything that I plane that can't be finish planed with a common pitch 4. Sort of, I found what I was looking for and I'm out of the detail discussions sort of thing. But people like the details before they master the practical.

Steves whole site is a good archive of things, even if folks don't love all of the topics or have interest in some of the things, there's something on there for about everyone. His discussion of chipping and where it stops with the modern diemaking steels is very useful for the average person who just wants to set up a smoother to remove planer chatter and clean up dovetails and face frames.

[Chris Griggs]

Very nice Kees.

Am I reading those charts right...they appear to show that in some instances shaving where taken that were thicker than the amount the cap iron was set from the edge? That doesn't seem right...what am I missing here?

[Kees Heiden]

That means that the capiron was protruding below the sole which means very hard pushing! In other words, not a practical setting.

Also the shavings get compressed. So what you measure with the caliper is more then the actual depth of cut.

Like Warren always sais, you must adjust the capiron to the type of cut you are going to take. But this was a bit if research and thus looking for extremes.

[Chris Griggs]

That means that the capiron was protruding below the sole which means very hard pushing! In other words, not a practical setting.

Also the shavings get compressed. So what you measure with the caliper is more then the actual depth of cut.

Like Warren always sais, you must adjust the capiron to the type of cut you are going to take. But this was a bit if research and thus looking for extremes.

Okay, that's kinda what I thought; that is that it was just for the sake of testing. Just wanted to clarify.

Nice experiment/article. Good stuff.