All well and good, but there's a potential problem always lurking -- just because information is printed on the pages of a book doesn't make it true. It may be damnable nonsense. How does one sort out the wheat from the chaff?
I wish I had a good answer to that. I don't, except to advise that one bring a healthy scepticism to bear on one's reading.
The more that I've learned about machinery and woodworking and metalworking through actual experience and empirical study, the more I'm able to spot nonsense in print. And the amount of it that I find amazes me. It's everywhere. It's to the point where my scepticism is bordering on disdain. Following is but one small example.
This example is from a book titled "Small Gas Engines -- How to Repair and Maintain Them" by Paul Weissler, published by Sterling Publishing Co. Inc. of New York. The cover bears the imprint of Popular Science, a respectable American mainstream magazine. It's a 282 page soft-cover published in 1987. It's copiously illustrated. It has the look of authoritativeness about it.
On page 208, there's a photograph purporting to show how one begins to dismantle a recoil starter. The photograph is preposterous. [I lack the equipment to reproduce the subject photograph here. Please bear with me while I try to paint a word picture.][1]
A typical recoil starter has a stamped sheet metal shell that houses a spring-loaded pulley/clutch with the pull-cord wrapped around it. Extending from the circular shell are the mounting ears for bolting the unit to an engine's cowl. Bolted in place on an engine, the stamped steel shell is a very strong item. Off the engine, the shell has its weaknesses and mustn't be subjected to thoughtlessly applied, inappropriate forces.
A starter that's off the engine reveals a central screw that holds the pulley/clutch affair in place. The screw must be removed in order to service the unit's innards. The screw is very tightly in place; one that I encountered in the course of repairing a broken pull-cord showed evidence of having been installed with a thread locking compound applied to it.
Now, a helpful tool for loosening stubborn screws is an impact driver -- a hammer powered specialty screwdriver. The driver contains a mechanism that converts the axial force of a hammer blow at the end of its handle, to a rotary force at its tip. In order for it to work effectively, the item containing the screw to be loosened must be rigidly backed up, and secured against rotation; else the driver simply cannot work -- a hammer blow's force will dissipate to no useful effect.
In the photograph mentioned earlier, the recoil starter is suspended by its mounting ears across the wide-open jaws of a big mechanic's vise. We see the impact driver held to the screw head and a hammer poised above. The photograph is patent nonsense. Such a setup could not possibly work. All that could result from it would be bent mounting ears on the starter.
And there's more. On the occasion that I had to dismantle a similar starter, I ended up breaking the screw; it was that tight because of the thread locking compound. Had I known, I might have held a big soldering iron to the screw's head for a while to heat it up and soften the thread locker first (although that might have been problematical; I seem to recall that the screw's shoulder was the spindle for the plastic pulley). That may have worked, and saved me the trouble of having to fabricate a replacement for the broken screw. Nowhere in the book's photos or text is there any mention of the possibility of thread locker being present, or the application of heat to soften it.
The photographs go on to show a fully disassembled recoil starter. How the author got from the ridiculous to the sublime is a mystery to me.
Such hogwash is not uncommon. One wonders what's behind it. How can writers present patently false information as authoritative gospel?
Some of it may be due to deadline pressures, although I'd expect those to be more operative in periodical publications than in books. The curious thing about the example cited above is that it would have been no more time-consuming or difficult to illustrate a correct setup for impact driver use than it was to compose that ludicrous tableau at the vise.
Another thing that may be at work is what I call 'plausible extrapolation'; a tendency to write on further about a subject than one actually has any right to, given how much one truly knows and has experienced of the subject. I know I'm not immune to that. I occasionally find myself lapsing into it, and I have to figuratively grab myself by the shirt collar and shake myself loose from it. I suspect that a lot of technical writing is riddled with flimsy 'information' of that provenance.
And it could well be that some authors are simply out of their depth, and/or contemptuous of their subject matter and their readership. But they have a job to do filling up blank space with text and illustrations, so they fill it up with text and illustrations. Job done.
In any case, be wary. Publication is no guarantee of veracity in technical books and magazines. There's a lot of insubstantial, misleading 'information' that gets printed and bound between covers. It's an unfortunate irony that the target market for such tripe is precisely those who genuinely want to learn.
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Note -- SATURDAY, MARCH 21, 2015:
[1] I've acquired a camera since. Here's a photograph of the subject photograph:
You're absolutely right! What a ridiculous set-up for using an impact driver! Hard to imagine how any semi-competent shade-tree mechanic would propose such a set-up, let alone someone purporting to be an expert. A good lesson for all of us on the importance of avoiding gullibility.
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