Hand Tools Archive

The other part of the point..
Response To:
Re: Not unprecedented ()

david weaver
..as information trickles into my brain a little at a time. Maybe it's age, I don't know.

Anyway, the whole thing started as a question about why Nicholson uses the word "concentric" when he talks about the cap iron. That's an interesting question to me. I don't believe it has a practical purpose on my planes, but as warren points out quite often, I've been wrong before, and I suppose I might be too dumb to be worried about being wrong again!

So, I'm still listening to this to see if I can find out over time why Nicholson would've made such a recommendation.

That brings us back to potential reason number one. Cap iron hangs over the edge of a cambered iron in a given cut. This has occurred for me with curly cherry a couple of times (two that I can remember - jack work, thicknessing), but the part of the iron that had been overlapped was also recessed inside the plane.

So to understand why Nicholson would recommend concentric, if it's reasonable for the cap iron to extend below the plane, that helps us with our conclusion (we can never know if we're necessarily right without his reason in writing). If it's unreasonable for the plane to be used with the cap iron extending into the cut (which to me is just a matter of reality. Not an issue of impossibility, but an issue of zero practicality), we're back to guessing again why the edges where a shaving would be thinner would benefit from the cap iron being profiled to the iron.

It's sort of a pain to measure all of this stuff (at least for me), because I have things I want to make right now, and it's kind of going backwards (Steve and I talked about this a long time ago, and we experimented a bit - me with trying to plane with the cap iron below the plane and steve possibly so, but also, I'm pretty sure he radiused a cap).

I'm leaning on two potential things, let's go with three (with nicholson). I have clue if they have stayed constant, my memory is shot:
* the radius helps feeding. I'm almost sure that could be the case sometimes based on my experience as a builder. I could be cast as not a very qualified builder because I've probably only built 20 wooden planes of this type, but the variety of irons that I've used has forced me to think a whole lot more about feeding than I've wanted to. Or rather, the variety of cap iron profiles.
* the radius conquers the most likely part of the tearout in the middle of the shaving but relieves a bit of effort at the edges. That's possible, too. It may relate to less labor, but I'm not sure about that.
* gutter type or less than flat jack planes may have been more common years ago (warren would have to comment, I haven't read nicholson). There's a potential labor savings here, too. In boat building, it would be a necessity, as it is in making actual gutters, and possibly hand rail planes (I haven't looked at a lot of hand rail planes, because who needs to make enough of them to justify one, but I wouldn't be surprised to find one with a cap iron on it).

When you start to sweat dimensioning wood, and I don't mean doing ten board feet of it, but when you're doing a project where you're sweating at ten and you have another 190, then you start to think about these things. Even then, they're not vital. I usually do my woodworking two hours at a time because that's about the point where I start making mental mistakes and getting in a hurry. But for someone running a shop 200 years ago, economy in this part of the work would've been a HUGE deal. There's not that much time to be saved in smoothing.

Some of this to me is like legalized gambling. I could read more. Charlie can always troll me when he wants to because I haven't read most of this stuff, and i'm not motivated to because my brain isn't stimulated that well by just reading. So, I'm going along learning all of this and supposing things based on understanding "the machine" and how "the machine operates in context". The gambling part is that I'm often wrong.

The "machine in context" has to do with what's probable or what's likely.

I think it's likely that the lower effort of the double iron was above all what eliminated the single iron, despite the higher cost. I don't know if that's written anywhere. My time (perhaps my wood isn't as good as it should be) dimensioning decreased significantly when I learned to use the double iron, and planing with the butcher long plane is what sent me in that direction (that plane is made in a spec very similar to the CW longer planes - tight mouth, 50 degrees, single iron).

Very long explanation going back to what Warren says quite often, though - subtle experience doesn't tell me for certain that I'm right and Nicholson's wrong. if I was betting at LLoyds, I wouldn't know what odds to take. But subtle experience does tell me that in planing stuff from pine to cocobolo, I haven't encountered any useful set with the cap iron below the plane, and I've set it too closely more than one time.

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