Never use a zero-clearance insert while cutting tapers on a table saw.
Reason? The tapered offcut can wedge between the blade and the ZCI, pushing the blade
into the workpiece. Makes a helluva noise, too.
Think anybody will notice that one of the four legs on an end table is about 1/16" narrower than
the other three?
S**t, s**t, s**t.
On Thursday, August 21, 2014 1:02:50 AM UTC-5, Bill wrote:
about 1/16" narrower than the other three?
I didn't notice it, until you mentioned it.
it even upended as a result).
I guess one would have to anticipate that the sharp edged piece would fall
into the narrow space. In that anticipated case, glue a scrap piece to tha
t cutoff edge, which would prevent the problem. Somewhat similarly, scrap
pieces are glued to mitered corners, to facilitate clamping, then cut off,
sanded off, after the job is done
No, of course not. I know better than that. The fence was a good six, eight inches away.
Seemed to me, too, that it should just fall down and away from the blade. And, in fact, that is
exactly what happened on the first 13 tapers I cut (of 16 total).
A "zero clearance" insert is actually zero clearance *only* at the tips of the teeth. Because a
saw kerf is necessarily wider than the plate of the blade, there is a gap of some 15 or 20
thousandths of an inch between the plate and the insert everywhere except at the ends. If
the tapered offcut should chance to drop straight down, the tip of it goes right into that gap --
where friction with the spinning blade pulls it in farther.
Which I clearly failed to do -- a mistake I won't make again.
Easier to replace the zero-clearance insert with the factory insert, so that the offcuts drop all
the way through. In fact, since I cut all my tapers using a sled that rides in one of the miter
slots (see my post a couple years ago titled The Ultimate Taper Sled) there's no need for
any insert in the saw throat at all. Might even improve dust collection.
Ouch. Underscores the need to always think one or two steps ahead
of our actions.
In this case, there was no danger to any of my body parts, only
the workpiece. As you might remember from a post I made a couple
years ago, I cut tapers using a sled that rides in the left miter
slot, so I'm standing at the left end of the saw, well out of the
path of the blade. The stop blocks on the sled double as handles,
so my hands don't come within half a foot of the blade. The risk
of personal injury in this setup is as close to zero as any table
saw operation can be.
Ok, I'm picturing that fine and understand what you're describing.
I guess what I'm having trouble picturing is how that wedge can fall
into the blade when it's still connected to the longer stock.
I know that tension in many woods can make for some really strange
movement in freshly cut wood. I can see where the cut off sliver might
start to bow down into the ZCI slot. But wouldn't that sliver then
catch the front of the slot and stop the stock from moving any further
forward? Or is that exactly what happened, only after the damamge was done?
"Playing is not something I do at night, it's my function in life"
I cut tapers with the blade entering the stock at the end and exiting on the side. I've found that
cutting the other way, entering on the side and exiting at the end, can produce some deflection
of the blade at entry.
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