Whirlwind Safety Device Patentend

[chopnhack]

Good guard design is paramount to safety.... all the t.s. I have ever seen, worked on or owned have no guard. To clarify, the only t.s. I have ever had brand new is the BT3k. And sadly the guard has been on the saw only a few times... I too dislike what the pawls do to the workpiece and the inability to do through cuts.

[david10]

Answerto Your Question and Some Background

Hi Erik,

When the Whirlwind guard is in place it offers full anti-kickback protection without splitters, riving knives, or so-called anti-kickback pawls. This method for preventing kickback works because the workpiece is held down against the table and cannot be lifted by the trailing edge teeth. When the saw blade trailing edge teeth, which are tangentially rising, lift the workpiece – even slightly – it sets up a positive feedback loop instantly causing the force and speed to increase and the workpiece may then be hurled back. During a rip cut there is also a CCW twisting motion which may drag the operators hand into the blade. All of this WILL happen in a fraction of a second LONG before the operator can react of even recognize the event. I believe there are some website videos which show me standing behind the (Makita?) saw and trying to force a kickback event to the point where I nearly stall the blade, but without kickback. I also show a climb cut starting at the back of the saw and feeding the stock toward the front to rip without any kickback. PLEASE don’t try this on a conventional saw setup.

I should probably offer to explain my unusual personal woodworking background to justify what may seem an “unusual approach” to table saw safety and before offering further opinion here. At the high-school level, in the early 1950s I attended a four-year course in industrial woodworking and cabinetmaking --where I saw accidents – but never saw a blade guard. Subsequently, the US Navy accepted me and trained me in basic electronics and I went on to much further electronics education and eventually make my professional career in the computer field. Woodworking became an avocation and over the years I’ve built furniture as time and shop equipment allowed. I especially favor both the elaborate American Federal and the contrasting simple American Shaker furniture styles, but seldom have time these days to build. After my professional retirement I actually did build a few classic furniture pieces under one-off commissions.

WHAT I HAVE LEARNED ABOUT TABLE SAW SAFETY

I have been kicked around by table saws over the years and can recount the experiences of many sudden and unexpected injuries – usually related to kickback. I still have all my digits. I like to think that is because I’m so smart; but far more likely it is just plain luck of the draw. I have two friends with advanced degrees in engineering who have both lost fingers to table saws. The surprising national statistics are showing an almost even spread of accidents between novices and advanced table saw users. Given this long perspective, I believe this is because our newbies have insufficient training and experience and our veterans have “too much saw time,” and eventually become complacent in order to save time on this next simple cut. I believe that saving time is the basis for our most common table saw safety errors and I have met a few of these very experienced folks who will share “…if you’re at it long enough it will hit you.”

David

[Stytooner]

That hold down is a good feature and was part of the shark design from the start. It was initially designed to fit the Ryobi saw, which has a riving knife. Adjust the blade guard to the stock being cut and you automatically have that hold down in the mechanism that holds the guard.
Unfortunately it does not work the same way on saws with splitters. This is why I use two different height splitters on those saws so that the guard can be as low as possible and get at least a little benefit from that hold down.
I don't recommend pawls on saws with a riving knife, but do recommend them on saws with splitters.
How would your mechanism handle being mounted on a splitter type saw when different thicknesses of stock are being cut?

[david10]

Hi Lee and others,

Lee, I’m not sure what you mean by “…that hold down is a good feature and was part of the shark design from the start.” I visited your website but somehow had considerable trouble navigating and did not get a complete understanding of your product, so I don’t fully understand your fixed hold down feature. If you are like me you probably don’t check in on your website very often unless someone mentions a problem.

We began with splitter and riving knife mounts on our early “legacy” designs where the guard can be easily adjusted and locked in place above the work piece. The Makita 2703 bench top saw video we show uses the riving mount and therefore moves in height together with the saw blade just as you mention.

However; currently our design work employs only the overhead mount because in the long run it is superior to either splitter or riving mount. Soon the splitter will be considered obsolete and will quite likely disappear altogether.

We solved the anti-kickback pawl problem very early and it is incorporated into our first issued patent. We used a pair of non-serrated and fairly heavy aluminum fingers with a rubberized coating where they contact the stock. These are arranged at a far more obtuse pawl angle of 75 degrees to the workpiece than conventional anti-kickback pawls and they work beautifully ALL the time without marring $56/ft recycled Cuban mahogany or anything else. A piece of glass could not move backwards with these in place.

Today, we no longer use any anti-kickback pawls at all because they have proven unnecessary with our current blade guard/enclosure design. Though they are probably not well known and rarely used, we can even do cove cuts far more safely than was done in "the good old days."

David