PJohn

Surely you jest. This technique is an example of the classic Chinese attitude that "if it looks the same, it must be the same" - which among other things has yielded dazzling but poisonous toys. This method is a poorly conceived shortcut.

As with any other method of utilizing a powered tool, this one can remove human body parts when practiced by one inexperienced or untrained. There are specific safety violations (see below), but my foremost objection lies in encouraging readers to "do it the wrong way" in hopes that some may eventually come to realize that their joints aren't any good.

As to having ones' digits in close proximity to the blade - - how does one perform accurate and delicate work without such closeness? That's about learning and practicing good technique with fanatic diligence. Otherwise, we lose body parts. Good methods, good sense, and enough smarts to use both are the basic prerequisites for safe work.

Classic techniques for tenon-making include hand-planing to fit, so as to maximize joint efficiency. The technique demonstrated for this table saw routine can only leave a surface that's not flat - it's not good practice, and is likely to lead all but the most experienced worker to produce a surface that only fits the mortise at 0.002" clearance in a couple of places. It may, however, suffice as a rough-sizing operation provided the operator has sufficient experience to visualize and correct a surface that's not only rough, but not planar (that is, it's curved, not flat.)

There are references in some letters to cove-making jigs, but that technique, if exercised at proper speed, can yield a surface with virtually no imperfections because the blade is in near-parallel orientation and is guaranteed to contact the entirety of the surface similarly if the workpiece is not advanced too quickly - 100% of the workpiece is made to glide at a very shallow angle to the blade angle with the blade.

Conversely, the feed method for the table saw tenon relies upon unregulated manual advance for each successive cut, which guarantees flaky surface character. At 90 degrees, as in the proposed method, the results can never be made to yield a 100% contact cut unless the manual advancement method is controlled at something like exactly 0.020" per pass - good luck with that. As well, the non-flat-bottom characteristic of tablesaw blades (other than dado blades with straight-face chippers)also guarantees that the surface rendered cannot possibly be even close to flat enough for a glue joint.

The practice of simultaneously guiding against both fence and miter gauge face is an open invitation to trouble - the slightest problem can instantly escalate into a finger-buster. Stoopid, in my opinion.

The best bet is to make your own tenoning jig if you can't afford a good one, then cut 'em right and plane to fit. If you've the patience, they can be rough-cut with a tenoning jig and then recut to near-perfection with a dado blade, with only minor planing adjustments left to complete. The method is great for large numbers of identical tenons, but for one or two it's just a s fast to use a marking device, a vise, and a fine backsaw.

Finally, I suggest that FWW forget about trying to teach every yahoo everything he needs to know to make toothpicks and sawdust. Either you're about fine woodworking, or you're competing with the handy-homey rags - your choice. Stick with handy-homey, and watch my subscription evaporate.

Bah, humbug.

Anyone who believes that this has to do with genuinely useful and fully researched societal advancement is encouraged to disabuse themselves of the notion and perhaps seek counseling. Social engineering driven by the profit potential for insurers and a few patent holders is driving this, not altruistic (dream on!) interest in preserving our hides. Follow the money - always follow the money.

It's the overzealous work of the same gaggle of uninformed Foggy Bottom lawyers who banished the 150w flood and (in 2012) incandescent bulbs (over which issues I too am incandescent.) I've worked with power tools for nearly 60 years, yet they never interviewed me to discover why it is that all my digits remain attached - haven't heard much about their deposing you other experienced hands out there, either.

As typified by this threat, our elected solons seem unable to sort grain from chaff, and impose witless legislation willy-nilly in the school of "Do something even if it's stupid so they know we're in here pitching for them," especially if there's a buck or two under the table(saw.)

There is no simplistic inherent safety attached to the human condition, and there is no means by which to guarantee a level outcome for every person, regardless of subject arena. The overweening compulsion of these ignoramuses to do good on every front, regardless of their knowledge and understanding, and no matter the harm they do, will eventually render us all paralytic if we allow it.

Hang on to yer jointers, boys; we ain't seen nothin' yet. Remember the OSHA horse! Don't let 'em see yer hammer! With what gratuitous interference will we be blessed when they discover that we deploy large scary-sharp chisels and other nefarious implements of dismemberment that DON'T have motors attached?

Sorry to write twice - the contact page does not acknowledge receipt of message, which may be important to some readers. Message to Taunton:

On this web page, http://www.finewoodworking.com/item/17562/reader-says-mythbusters-missed-on-hammer-strikes , you feature a photo of some misbegotten soul striking the upper surface of a miter gauge bar.

That surface must NOT be abused, lest it project above the table surface or bow the bar out-of-flat. The subject concerns improving fit in the slide, which requires work on the SIDES of the miter bar.

You've shaken my faith with this error.

Striking one hardened surface against another is patently risky. The steel may not "shatter" ( an absurd notion unless it's frozen to cryogenic temperature) but it will shatter in small locales, and send sharp, dangerous shards flying. It will, it does, and there are a lot of one-eyed unfortunates who learned it the hard way. I am frankly dumbfounded that any engineer might have espoused such a test and claimed the prohibition to be myth, thus risking the vision of countless trusting listeners or readers.

The trick is always to use a hammer against a softer material. In this case, a hammer and center punch would have been appropriate. Needless to say, using any hammer or similarly violent tool without eye protection is foolhardy, no matter how light the blows. Stand beside the tiger long enough, and he'll eventually invite you to lunch...

It is not safe to claim that "I was only going to hit it a few times, and not with much force." Hardened steel against hardened steel is dangerous in any striking situation.

Striking purpose-built steel tools together is an investment in faith in the manufacturer, because all steels are not equal, and the differences are not detectable to the unaided eye. Tool manufacturers operate within strict tolerances for metal composition, strength, hardness, grain size and orientation, etc. so as to ensure that striking surfaces are compatible with one another among purpose-designed tools. For example, a center punch may have its tip tempered to extreme hardness, but feature softer steel at its striking surface. Similarly so for wood chisels, plane blades, etc.

If the user has so little sense as to "abuse the system", the tiger heads home for lunch.

Cheap hammers nearly always come from countries and manufacturers who profit from "looks like" tools aimed at amateurs who don't know the necessary details. For myself, I never purchase a steel-head hammer not manufactured in the U.S., England, or Germany by a reputable, time-proven manufacturer.

Incidentally, there are two rows of center punch marks down each side of my miter square's bar, which I struck and then filed to perfect fit over 25 years ago. The effort is lasting, and well worth the time to perform properly. My daily user is a newer Incra with screwed buttons for slide clearance adjustment.