This is a hard one to believe, but I think I've found the cause....
I was building a new sharpening station yesterday (pics on ABPW, btw) when
it happened. Just finished the last rip from some 1/4" ply for drawer
bottoms when WHAM... the off cut flew out of nowhere and hit me hard just
below the beltline. Then, the damn thing bounced off me, flew under the
blade guard, hit the blade again, and WHAM, this time it nailed my arm which
I'd just put down around the first wound.
I powered down and unzipped to check my gut, it's definately gonna leave a
mark. There actually a 1/2" hole in my blue jeans where the corner of that
1/4" ply hit me, and a large welt on my arm where it hit me again.....
OK.. time to stop and figure out WTF just happened. I have a new 3hp Jet
cabinet saw that was been an absolute joy. Recently, I fitted it with an
Excalibur overhead blade guard with DC which, by the way, was in use during
the cut. The piece of ply was 24" by 20" or so an I was ripping 4" off the
20" side. Only one hand was on the stock, so I didn't bind the blade. But
what the #$%^ happened???
Well, I was starting to ache badly, my side and arm, so I opened up a beer,
(and another, (etc...) and pondered this for a while. My technique was
fine, guard and splitter were in place. What caused this?????????
My best theory is that the off cut was actually pulled off the table and
into the blade by the suction from the dust collection on the blade guard,
which caused the kickback. It didn't take long (another beer) before I
unplugged the saw, fired up the DC and started "testing". Going through the
motions of the last cut, I discovered that the suction from the DC, when the
guard was lowered fully to the table, was enough to pull up my ZCI. It
didn't pull it completely out from the saw throat, but it could pull it up
enough for the blade to catch it. The DC also had enough suction to pull
pieces of the 1/4" ply up off the table, even though the guard was 1/2" or
more above the ply. I didn't get very scientific with this test, and by
that time I was under the influence, but the conclusion is the DC surely can
pull stuff off the table and into the blade. Oddly enough, this experience
happened to someone who is in no way accustomed to using a blade guard at
all, let alone one with built in DC. I've a nice welt on my arm, and a good
sized black and blue mark on my gut from this. I'm certainly gonna continue
using the guard, and the DC, but I think the DC certainly will not be used
for thinner or smaller materials. Anyone else have an experience like
this??? --dave
Hello Dave,
I'm glad to read you are not severely injured. I posted a while back
about my table insert being lifted by the basket type guard I had on my
saw. Some adhesive from a prior cut (some construction scrap I was
using for a makeshift shelf) adhered to the guard and this picked up
the insert as I pushed a new piece toward the blade. No damage
occurred.
A question to you, or anyone else that does have a vaccuum port on the
guard;
How noticeable a difference is there if you don't use the guard vacuum
hook-up? Does the setup really get rid of that much dust? My saw
produces very little dust up top so I don't see the need to have a
guard hook-up.
Marc
Dave Jackson wrote:
> My best theory is that the off cut was actually pulled off the table and
> into the blade by the suction from the dust collection on the blade guard,
> which caused the kickback.
> I'm certainly gonna continue
> using the guard, and the DC, but I think the DC certainly will not be used
> for thinner or smaller materials.
Maybe raise the guard a bit for lighter materials to reduce the suction?
Or use hold-downs?
Chris
Yes my Biesemeyer has a dust port. I use a very large
Craftsman shop vac and it is very effective.
The dust coming off the blade is generally VERY fine
and this is the exact stuff you want to try to capture.
marc rosen wrote:
> A question to you, or anyone else that does have a vaccuum port on the
> guard;
> How noticeable a difference is there if you don't use the guard vacuum
> hook-up? Does the setup really get rid of that much dust? My saw
> produces very little dust up top so I don't see the need to have a
> guard hook-up.
Jeez Dave, I am certainly glad to hear that you survived that accident. I
have seen that happen before and it's a shame that a guard sometimes is the
cause of a problem. The same can happen when small cut off pieces get
trapped between the guard and the blade. If you feel safer using the guard,
by all means keep using it. I think I would also look into finding a way to
anchor the ZCI in place. Perhaps a screw that turns a locking arm under the
table top.
"Dave Jackson" <[email protected]> wrote in message
news:[email protected]...
> This is a hard one to believe, but I think I've found the cause....
> I was building a new sharpening station yesterday (pics on ABPW, btw) when
> it happened. Just finished the last rip from some 1/4" ply for drawer
> bottoms when WHAM... the off cut flew out of nowhere and hit me hard just
> below the beltline. Then, the damn thing bounced off me, flew under the
> blade guard, hit the blade again, and WHAM, this time it nailed my arm
> which I'd just put down around the first wound.
> I powered down and unzipped to check my gut, it's definately gonna leave a
> mark. There actually a 1/2" hole in my blue jeans where the corner of
> that 1/4" ply hit me, and a large welt on my arm where it hit me
> again.....
> OK.. time to stop and figure out WTF just happened. I have a new 3hp Jet
> cabinet saw that was been an absolute joy. Recently, I fitted it with an
> Excalibur overhead blade guard with DC which, by the way, was in use
> during the cut. The piece of ply was 24" by 20" or so an I was ripping 4"
> off the 20" side. Only one hand was on the stock, so I didn't bind the
> blade. But what the #$%^ happened???
> Well, I was starting to ache badly, my side and arm, so I opened up a
> beer, (and another, (etc...) and pondered this for a while. My technique
> was fine, guard and splitter were in place. What caused this?????????
> My best theory is that the off cut was actually pulled off the table and
> into the blade by the suction from the dust collection on the blade guard,
> which caused the kickback. It didn't take long (another beer) before I
> unplugged the saw, fired up the DC and started "testing". Going through
> the motions of the last cut, I discovered that the suction from the DC,
> when the guard was lowered fully to the table, was enough to pull up my
> ZCI. It didn't pull it completely out from the saw throat, but it could
> pull it up enough for the blade to catch it. The DC also had enough
> suction to pull pieces of the 1/4" ply up off the table, even though the
> guard was 1/2" or more above the ply. I didn't get very scientific with
> this test, and by that time I was under the influence, but the conclusion
> is the DC surely can pull stuff off the table and into the blade. Oddly
> enough, this experience happened to someone who is in no way accustomed to
> using a blade guard at all, let alone one with built in DC. I've a nice
> welt on my arm, and a good sized black and blue mark on my gut from this.
> I'm certainly gonna continue using the guard, and the DC, but I think the
> DC certainly will not be used for thinner or smaller materials. Anyone
> else have an experience like this??? --dave
>
In article <[email protected]>,
Dave Jackson <[email protected]> wrote:
<...snipped...>
>My best theory is that the off cut was actually pulled off the table and
>into the blade by the suction from the dust collection on the blade guard,
>which caused the kickback. It didn't take long (another beer) before I
>unplugged the saw, fired up the DC and started "testing". Going through the
>motions of the last cut, I discovered that the suction from the DC, when the
>guard was lowered fully to the table, was enough to pull up my ZCI. It
>didn't pull it completely out from the saw throat, but it could pull it up
>enough for the blade to catch it. The DC also had enough suction to pull
>pieces of the 1/4" ply up off the table, even though the guard was 1/2" or
>more above the ply.
<...more snipped...>
Sorry about your injury. get ready, here it comes...
That sucks!
--
For every complicated, difficult problem, there is a simple, easy
solution that does not work.
Larry Wasserman - Baltimore Maryland - [email protected]