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Tooling for Feel: On the Ergonomics of Tool use



Derek, you use the LV router, and have designed and made granny tooth routers.

Are there substantial differences that make one preferred over the other?



I was asked this question in a thread on the LV router plane on the WoodNet forum after I posted this picture of using the LV router plane for hinge mortices ..

Here is another picture (from my review - but sporting a shopmade depth stop, which has since been replaced) ...

What stimulated the question was a recent post I made of a smaller wooden router plane I designed (borrowing a little from the ECE) and built ...

Keep in mind that the thread is about "feel" and not these router planes. What is "feel"? I think of this as the feedback you receive when the blade hits the wood. You know exactly what is going on at the coal face. It is akin to driving a big Cadillac with so much suspension that you float over the road never knowing whether there are bumps or potholes .... versus .... a Morgan, with its wooden chassis and hard suspension and direct steering. Made to go fast, and not great on the road, but completely involving.

One of the advantages of planing wood with a hand plane rather than a machine is that you get to know the surface of the wood (although sometimes too much of a good thing is a bad thing - such as this mongrel Curly Marri I am planing up for a blanket chest!  ). When planing interlocked grain you feel when the plane is starting to struggle and resist cutting. You stop in mid shaving, adjust the stroke/depth of blade/direction of cut.

In my experience the difference in feedback varies in part with the centre of gravity. The further from the work surface, the lower the feedback. Conversely, the lower the centre of gravity, the greater the feedback. In part, feedback also depends on the "centre of effort". C of E is a yachting term to refer to the action of the wind on the sail - where it places it force ... low or high on the sail. Pressure at the top of the sail is different to pressure at the bottom of the sail. In a similar manner, force directed at the low end of the blade creates more stability and controlled power. For this reason, a plane with a low centre of gravity requires less effort to push than a plane with a high centre of gravity, for example, a traditional jointer versus a razee jointer ...

This is the reason I build razee woodies ... and yet I often return to the LV BU Jointer ...

Add to the equation a plane with a low centre of effort - a bevel up plane is an example of this - and you will understand their attractiveness to many. They are easy to push and easy to control.

I could make a similar case among backsaws - those with tall plates versus those with low plates. Some will argue that tenon saws benefit from a tall plate to aid in orientating in the vertical. I agree. I am only pointing out which feels easier to use. However we then get to dovetail saws, and a low plate saw, such as the Gramercy, has a very different feel to high plate saws (with a similar teeth configuration).

So, what about the router plane?

I recall a comparison of router planes by Chris Schwarz where he preferred the high knobs of the LN/Stanley over the lower, canted knobs of the LV. Interestingly, he commented that "the rakish handles (of the LV) feel better when you grip them with your pinky fingers at the base of the tool (palms on the sides of the knobs)". In other words, when you are pushing the router plane from directly behind the blade. (Link: http://www.popularwoodworking.com/article/lie-nielsen-large-router-plane).

This is the way I often use the LV router plane - pushing with my thumbs directly behind the blade (not in the picture above, where the router plane was being held one-handed for the photo of the hinge mortice). I prefer the lower slung LV knobs to the upright LN/Stanley knobs because they direct the C of E downward. (I must admit that none of this occurred to me when I was comparing the Stanley and the LV in my review written in 2006: http://www.inthewoodshop.com/ToolReviews/The%20Veritas%20Router%20Plane.html)

When I built the wooden router plane, it was expressively designed to be used this way - thumbs behind the blade. This creates not only a low centre of gravity, but a low C of E. To describe it, it feels closer to paring with a short chisel (see ... short butt chisels for feel verses long paring chisels for directionality).

There is plenty of power in this small router plane, in spite of the low weight, since the centre of effort minimises wasted energy. The high centre of effort importantly maximises the feedback one receives, and it is this that makes it my current go-to router plane.

A rather long winded answer to a short question.

Regards from Perth

Derek

May 2013