Article "TOWER OF BABBLE"
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This article was first published in the February 2007 issue of More Woodturning

Below are three statements which have recently appeared in the woodturning press:

1.  “I talked with four knowledgeable people [about sharpening]. Seems sharpening is a Tower of Babble thing, everyone having their own preferences”.

2.  “Every expert has a different way to sharpen their tools and in many cases special tools that no one else uses. Why? Because the tools and sharpening method they use works for them. There is no right or wrong method only what works or doesn’t work for you.”

3.  “[Woodturning] chisels ground flat simply work better than those which are hollow-ground”.

The first statement is alas largely true; the second is a restatement of the “it works for me” syndrome, and is wrong; the third statement is also wrong. In this article I will explain why and what you should do about it.

Woodturners are and should be free to turn how they like in the privacy of their own workshops. If however you decide to advise others, you surely bear some responsibility for the quality of the advice you give. What qualities should an advice possess if it is offered to others unqualified? I hope we all agree that the advice should not lead to those who take it being at increased risk of injury or worse. But should we expect woodturning advice to have other qualities?

Statement 2 implies that for each turner there are methods which will suit him or her better than other competing methods. For example, for a particular turning operation turner A might be best suited to, say, method a, and should use it in preference to the alternative methods b, c, or d. Turner B, however might be better suited to and should therefore use, say, method c. If you accept the premise that different methods suit different turners, then turner A should not advise all other turners to use method a because method a is only best suited to a proportion of other turners. To be responsible, a turning teacher should instead teach all four methods and advise each student to select the one which suits he or she best. Only if a turning teacher knows the factors which determine whether another turner is best suited to a particular method can he or she responsibly teach particular methods to particular students.

If anyone has discovered the factors which determine which methods are best suited to which turners, I haven’t heard about it. And very few teach all the likely alternatives for any particular situation, and advise each student to experiment to determine that which suits he or she best. The norm is that teachers promote one method for each situation. Even those who teach a technique with the qualification “it works for me”, really intend you to believe not only that “it will also work for you”, but that “it will work for you at least as well or better than any other technique”. Why? Because most teachers would hardly teach

 

technique which they believed to be inferior without clarifying that fact. Yet I have proved above that if you accept the “it works for me” premise, it is irresponsible to teach or promote only one method unless you can be certain that it best suited to all the students present at the time.I fully support the intention to teach only the best methods. But statements 1 and 2 suggest that for any particular woodturning situation, several, or indeed many, alternatives are being implicitly promoted as the best by woodturning teachers. All the alternatives could be equally good, but it's more likely some are better than others or one is better than all the others. The choice of which is or are best may also differ according to certain variables, which would then need to be specified.

If the teachers who subscribe to the “it works for me” premise are both numerous and irresponsible when teaching ill-suited methods to particular students, why do they seem to be held in high regard? There seems to be an acceptance that such teachers can promote their preferred methods without hindrance. It can hardly be otherwise because while the premise is a Hydra, and, to mix metaphors, a house of cards, it is also a commercial imperative. The turnovers of woodturning hardware manufacturers and suppliers would be decimated if it was accepted that there was only one best tool or piece of equipment for each turning situation. Equally, our woodturning magazines can only get enough content if they include competing methods.

Next to statement 3, a statement which is clear, unequivocal, and, as I said earlier, wrong.

When tool access for cutting (as opposed to scraping) is unimpeded, only a very narrow (say 1/32” wide) band of bevel immediately adjacent to the cutting edge is in contact with the just-cut wood surface (see the back cover of my book The Fundamentals of Woodturning). This band provides all the bevel support, or as I more-accurately call it cutting-edge support, needed to keep the tool tip stable. Because this band is so narrow, the wood being cut cannot “know” whether the bevel is hollow- or flat-ground; also even if the hollow grind is extreme there will rarely be any forced increase in the clearance angle.

Statement three is wrong. So is its converse. Yet I promote a hollow-ground bevel despite just having proved that it works no better than a flat bevel. To not appear hypocritical I need to explain, and do below.

Edge sharpness is essentially determined by the sharpening angle between the two faces which meet to form the edge, and the quality of their meeting. You can improve that quality by using a finer-grained abrasive to “cut” and thereby refine the two meeting surfaces. Honing typically uses a finer-grained abrasive than grinding, with the abrasive usually being aggregated to form slipstones. The finer the grain size of that abrasive, the sharper and more durable should be the resulting edge.

Most turners grind on the cylindrical periphery of a grinding wheel because it’s cheap and convenient, but until I invented the Darlow templates detailed in my DVD Sharpening Woodturning Tools, setting a grinding jig was slow and inaccurate because of grinding-wheel wear. Grinding on a belt sander largely eliminates the problem of jig setting because the position and curvature of the grinding surface doesn’t change. However, in most grinding on a belt sander, the bevels are ground on the abrasive belt where it’s running over a flat platen. I in my DVD grind over an 8” diameter jockey wheel to achieve a hollow-ground bevel. However, I don’t advocate hollow-grinding because it makes the cutting edge sharper, but because it makes refining the edge and the next several resharpenings by honing much quicker and self-jigging.

I have proved statement 3 wrong. Yet it has already been read by several thousand turners and not to my knowledge publicly challenged. Like most false woodturning statements it may not have been consciously accepted as Gospel by those turners who read it. Nor if accepted and acted on, would it be either unsafe or the ruination of their turning futures. But its widespread acceptance would be another increase to the ever-growing pile of conflicting and confusing advice which is so off-putting, particularly to beginners.

Nelson turned a blind eye in 1801 to win the battle of Copenhagen. I could have done the same to the three statements. But as a woodturning teacher should I turn a blind eye merely not to rock a boat which should have never sailed. And the name of the boat? It works for me.

In the professions, the governing bodies are supposed to ensure that their members adhere to the best practices. In woodturning there are no standard-setting bodies (nor do I advocate any), so woodturning students are unprotected. Students should therefore protect themselves. How? By being prepared to demand that every woodturning teacher, including me, substantiates the advice they give. That substantiation should where appropriate include comparisons with the conflicting advice of other teachers.

 

To read another article click on "Sanitized Sameness" or "To Cut or Scrape?"

 

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