plane and tear out question

[Noah Magnuson]

Don't forget (maybe I missed it), that on the LV LAJ you can close up the mouth as well. I have been able to tackle most anything with a combination of bevel and mouth. Is it as fully capable as a BD with a chipbreaker? No, but it is perfectly adequate for most common jack situations.

[Matt Lau]

Hey guys,

I think the LAJ is actually a great plane, but I'm biased since it was the first good plane that I ever bought.

For building guitars, it works as a good jointer and a decent smoother...and is much better made than the LN version. However, I can't for the life of me figure out how to camber a BU plane.

However, for general smoothing I'm a total neophtye and can't say too much there. Maybe I should learn how to use a regular #4 plane?

[Patrick Chase]

Patrick said most of what I was thinking and said it better than I would. But one more thing that seems clear is that setting a chip-breaker optimally is a skill. Set it too close and the plane won't push well, set it too far and you've (effectively) got a single iron blade. How close? It depends on the depth of cut and the wood. Also, the face of the chip-breaker as well as its mating surface may need to be tuned for best results. It short, it's not hard to see how someone could get it wrong and conclude a BU plane works as well or better. (Add in the Internet "everyone's an expert", in their own mind, mentality, and the path to well intentioned, but wrong or incomplete, information is no stretch.)

David brings up a good point that I touched on but probably didn't expand on enough: BU planes aren't optimal for smoothing, but they make it very easy to get OK results.

Take the iron out of your plane, hone the tip at ~40 deg, and give it a go. Doing so will take you a minute, and will mostly fix your problem assuming the iron is sharp to begin with and that you aren't taking overly thick shavings. If there's still too much tearout, increase it to 50 deg. It will be harder to push and you'll have to take thinner shavings than you would be able to with a properly tuned BD plane, but it will get the job done. The resulting surface also won't be as shiny as could be achieved with a lower-angle BD plane, but how shiny does a workbench need to be?

In contrast proper cap iron use takes some finesse. I've practiced smoothing with my double-iron planes literally ever day for years, and I'm still figuring things out. Others have had similar experiences. Search for "David Weaver cap iron" to get an introductory overview (I can't link it because it's on a rival forum). Admittedly you could figure out how to use a double iron for relatively simple work like your benchtop without understanding all of the ins and outs, as you won't care about some of the refinements that really drive people nuts, but even so there's a significant learning curve.

You can also take advantage of the LAJ's adjustable mouth as somebody else suggested. I didn't bring that up because it's a bit trickier than just increasing the cutting angle angle (though still closer to "fire and forget" than sorting out a double iron). For starters the mouth insert itself needs to be flush to the surrounding plane sole for it to be effective, which may require lapping. In addition the mouth has to be set very close (<1/100") to truly prevent tearout as opposed to just limiting the severity a bit, and to get there you may need to do some fettling on the mouth insert, for example to make it perfectly parallel to the edge.

[Patrick Chase]

However, I can't for the life of me figure out how to camber a BU plane.

It's straightforward: The effective "depth" of the camber is proportional to the sin of the bed angle. That means that a 12 deg BU plane needs sin(45)/sin(12) = 3.4 times as much camber as a 45 deg BD one does.

So in other words, use a really small camber radius. A bench grinder is your friend here. If applying camber to a higher-angle iron, use Derek's trick of starting with a 25 deg iron and only applying camber to the secondary bevel. That will hugely reduce the amount of material you have to remove.

[John Kaye]

I have the same plane plus the smoother from Veritas. I also purchased additional blades (they use the same width blade). Things I learned and practice now. First sharpen/hone those blades - factory is pretty good but it's good to go farther. Look at Rob Cosman sharpening on youtube.com. Second lightly wax bottom of plane. Third set to take light shavings (I can do shavings of less than a thousandth of an inch if I want). Other is that you may want to slightly round corners of the blade(s), grind a blade to a higher angle (I have one to provide 67 degree planing with scary thin shavings on hardwoods).
With tearout, look where it's happening. If it's around swirling knot free grain, take lighter shavings. If around knots then sanding could be best. The 5 is a good smoothing plane if you keep blades sharpened and shavings ultra thin.