I ran into an unusual problem in the August rocking chair class. When the same thing happened again in the 2 Kids chair class last week I decided to write about it. The situation occurred while legging up. I’ll review that demo, which means that everyone who has taken a class with us is about to experience a flood of recollection of their Tuesday afternoon at The Windsor Institute.
When legging up we arrange the four leg angles on a descending scale of importance, focusing our attention on the most important aspect of that angle. Job #1 is front splay, the highest priority. We are seeking symmetry, 14 degrees in sack back. Job #2 is front rake. We make the pair of front legs coplanar in a flexible, narrow range of about 10 degrees. When accomplishing job #3 remember we have to make the second paradigm shift, also on the Tip Sheet. “When it comes to rear legs, there are no angles.” We establish identical rear rake angles with applied geometry. We measure between the legs at the location of the scribes and adjust to a tolerance of 1/8 inch within the maximum and minimum. That brings us to job #4, the least important. We eyeball rear splay to eliminate gross error.
Our operating principle is that we do not put a higher priority at risk for a lower. That’s why we keep repeating the mantra “Better is the enemy of good,” advice so important it is included on the sack back Tip Sheet. I explain there is no such thing as a perfect Windsor chair and that our standard is determined by what our worst critic (our brother-in-law) can detect. I use the analogy of a fighter plane flying below the radar. We only need get below our brother-in-law’s radar and he will see the chair as perfect when he comes by to criticize our work.
Usually when reaming the rear leg angles the process of the hierarchy of the four jobs determines where to make adjustments. For example, the distance between pairs of legs is more than 1/8 inch; or one exceeds the minimum or maximum; or one rear splay angle is obviously askew; or one tenon projects more than its mate. In those situations the solution is obvious. We use the Arrow System to record the required adjustments and return the seat to the vise for reaming.
I would have been happy to run into such problems. They are simple to explain and the class can follow the reasoning that leads to the solution. However, with my rocker and my youth (high) chair, both pairs of legs (front and corresponding rear) were perfectly acceptable and within tolerances. All tenons projected the same height. The pairs just weren’t the same. I could live happily with the result on either side, just not with them both. Herein is the problem. Which one to adjust? When the results are equally valid and acceptable, yet different, how do you decide on which one to change?
The image I drew for the class was a scale in perfect balance. Changing the balance requires nothing more than a feather. I recalled for the class the Egyptian goddess Maat who places her feather on one side of a scale with the deceased’s heart on the other side. I had to find a feather to place on one side of my scale and I had no choice but to delve the class into minutia. I hate doing this because in explaining such a fine point I risk guys becoming obsessed with an obscure detail. They focus on a seedling and miss the forest.
This was my feather. In the Aristotelian sack back – the perfect chair that exists only in metaphysics – the side stretchers are connected to the medial at three degrees. This angle aligns the side stretches with the vanishing point located six and one half feet behind the seat’s rear edge. I measured my rear splay angles. One would have resulted in a medial/side stretcher joint of five degrees (perfectly acceptable) and the other at three. I made a minor tweak (about one very slow turn of the reamer) to the rear socket on that side, reducing the splay angle and slightly altering the distance between the scribes. The result was dead on.
Arriving at a decision rarely requires ascending to this level of detail, but you now what to do should it ever happen to you. I also know that in future classes I will have guys who have missed my point and are obsessed with three degrees. I will frequently remind them, better is the enemy of good.
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The Hampton Summit, and The Lost Crew, the first two novels in my series for young teens (and for adults that are young at heart) is now available in both softcover and eBook at these links: http://www.amazon.com/Hampton-Summit-Castleton-Series-Volume/dp/1482731622/ref=sr_1_sc_1?ie=UTF8&qid=1367421699&sr=8-1-spell&keywords=the+hamton+summit
The third book, The End of Time will be published October 15. Meanwhile, it is being serialized at my other blog http://www.tumblr.com/blog/mikedunbar
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