Wooden Planes #2: A Jack

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Blog entry by Mark Kornell posted 04-13-2014 06:02 AM 2463 reads 1 time favorited 2 comments Add to Favorites Watch
« Part 1: The first one Part 2 of Wooden Planes series Part 3: The Mouse »

Conceptually, a plane is a fairly simple device. It holds some kind of cutter that can be passed over a piece of wood to effect a cut. To work well, it needs to hold the cutter securely, and may have fences, guides or stops to help control the path of the cut. And even those fences, guides and stops aren’t there to help with making the cut, just to ensure consistency.

So that’s it. Hold the cutter securely. In a Krenov-style plane, there are a small number of pieces that factor into this. The bed, the iron, the wedge, the pin sleeve, and the pin. And the more traditional plane style with internal ears to hold the wedge in place has a smaller number of discrete pieces. The key is that those pieces need to fit together nearly perfectly for the plane to work well.

To be useful, most planes needs to be capable of taking shavings in some small multiple of 1/1000th of an inch. A thicker shaving can be useful when dimensioning or doing rough work, but we like our smoothers to be capable of taking us to surfaces that are ready for finishing. And blocks to be able to do final fitting or trimming of joints, among other things.

To create this plane that is capable of thin shavings, we need to be able to work wood in small tolerances. Wood is relatively imprecise at the 1/1000th of an inch scale – that is getting close to size of a wood cell. A board of wood can move more than this amount in a single day. This is why well set up woodworking machinery only aims for a tolerance of 1 or 2 thous – anything finer than that is often irrelevant.

So, when you need to stack the bed, the iron, the wedge and the pin assembly together – as simple as those individual pieces are – it is hard to get them to fit together so that the end result is within a spec that allows for a 1 or 2 thou shaving consistent across the width of the plane.

It boils down to getting the bed flat and fitting the wedge properly. And having a sharp iron, but how to achieve the pointy end is debated endlessly, so no need to cover the same ground here.

It obviously can be done. Witness the many examples of fine wooden planes that have survived 100 years and are still capable of producing good work. And the newly made ones where the wood hasn’t suffered the effects of many seasons of movement.

For my second plane, the first good decision I made was to get myself a good iron. Not wanting to deal with a double iron, I picked one of the thick Lee Valley irons designed for wooden planes.

And I paid a lot more attention to the little details that make a plane work. The bed flatness. The drilling setup for the pin assembly. The wedge shape and fit.

And the aesthetics, of course. First, making it comfortable to use, and second, making it comfortable to look at.

The result was this:

A jack plane with a hickory and beech body, beech sole and walnut wedge. Finish is tung oil.

To my eye, it has flowing, organic lines to it, aided by the natural color in the hickory. To my hands, it fits as if it were molded. It is fairly heavy, but can be used all day. The significant mass is a good thing.

I was cautious in opening up the mouth, and left it set at less than 1/32” of an opening. A bit more than 1/64”. So, it really doesn’t function like a traditional jack would, but more like a large smoother. Recently, I opened up the mouth to about 1/16” as I have other planes that are more appropriate to smoothing tasks and this one needs to be able to take off thick shavings.

At one point, it was the only plane I used. Clumsy in doing smaller work, though, so I realized I needed to revisit the block plane format. With how well this jack worked, I thought I had the plane-making thing all figured out, so plane number 3 would be a different kind of block plane. Stay tuned…

-- Mark Kornell, Kornell Wood Design

2 comments so far

View Don W's profile

Don W

18791 posts in 2622 days

#1 posted 04-13-2014 11:25 AM

Nice blog Mark. The plane looks great.

-- - Collecting is an investment in the past, and the future.

View Mauricio's profile


7144 posts in 3206 days

#2 posted 04-14-2014 02:48 PM

Its a beauty!

-- Mauricio - Woodstock, GA - "Confusion is the Womb of Learning, with utter conviction being it's Tomb" Prof. T.O. Nitsch

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