It's just a Jet 1.5 horse contractor's saw. I was cutting the ends
off of a 2 in thick slab of cherry and maple (cutting board season).
Normally not a big deal. I was using my homemade crosscutting box
with my 1/4" lexan guard (similar design to Kelly Mehler's). Anyway,
I didn't notice but the cutoff (roughly 1/4" x 2"W x 11"L) had not
fallen by the wayside but instead ended up riding on top of the blade.
Before I could power down, the blade caught and threw this seemingly
miniscule piece. Well, that little piece of wood shattered my lexan
guard (the front piece that sits at 90 to the blade...see Kelly's
design) and there were splinters of wood and lexan flying all over the
place. Fortunately for me, I always wear a face shield so I survived
just fine. Checked out the saw blade, no missing teeth. I almost
shudder to think what a 3hp saw could do!!
So my question, is 1/4" lexan enough? After today, I don't think so.
I was looking at purchasing an Exaktor or Excalibur but from what I
saw today, I think I'll build my own that acts similarly to the Brett
guard (ie. guard does not ride up and over the workpiece...it actually
will hold the workpiece down). Not sure if I should go with 1/4" or
thicker on the lexan.
Glad to hear your weren't hurt. You say that was 1/4" lexan and it
shattered? Sure doesn't sound like lexan to me, more like Plexiglas. I
have 1/8" thick lexan in the windows I built for my shed and I've clobbered
them with ends of wood while stacking and with garden tool handles and never
I won't say lexan can't break under the right conditions but a 1/4" piece is
some very tough material to break and as I recall, it isn't supposed to
Yup. It was lexan for sure. Peeled the clear protective coating off
of it myself. I've been looking at the guard a little more.
Appears that the lexan came apart right where the glue joint was. I
didn't see it, but I suspect the wood put pressure on the piece and it
came loose and flew into the saw blade at which time it was shattered.
So I suppose it really wasn't the lexan that failed, but the glue
I've had Lexan shatter myself. I was using it as a zero clearance insert,
making a new one in fact, probably 15 years ago. Brought the saw blade up into
it too fast and had Lexan all over the shop. Knocked my glasses off, generally
startled the daylights out of me.
Also made me glad I was no longer riding motorcycles, where I had for years
used Lexan helmets.
All it takes is a slight glitch anywhere in the process, and weaknesses are
cast in, I guess.
"I have as much authority as the Pope, I just don't have as many people who
believe it." George Carlin
LEXAN is polycarbonate, and can be formed cold like sheet metal. Local fab
shop routinely bends 1/4" material to make machinery guards. It is
succeptable to scratching. Mills nicely with a router, especially when you
use end mills designed to cut polycarbonate.
Plexiglas is methyl acrylic, and is brittle. It WILL shatter if you
overstress it, but it is much harder to scratch than LEXAN. Haven't milled
any Plexiglas in quite a while.
You may well have had Plexiglas Charlie ... at least from the symptoms. Sure
don't want to experience ballistic plastic in any form.
"Charlie Self" wrote >
| Also made me glad I was no longer riding motorcycles, where I
| had for years used Lexan helmets.
The Apollo-era "fishbowl" space helmets and visors are 1/4" Lexan too. It's
normally *very* impact resistant, which makes me wonder if the machine guard
in question had a manufacturing defect, as you suggest. Or perhaps the glue
chemically compromised it in some way.
Lexan is prone to chemical damage that then makes it brittle.
I once saw a spectacular accident when an 8' x 4' Lexan window around
a CNC machining centre let go after a fairly small impact. It turned
out to be the detergents in a water soluble cutting oil.
Die Gotterspammerung - Junkmail of the Gods
Like Bob S., I wonder if you've got genuine Lexan. I work as a
cameraman in film/TV. Whenever we need to set up a safety for
explosions and gunfire in front of the camera, we always use 1/4" Lex.
I've had some pretty scary pieces of shrapnel propelled my way over
the years, but nothing more than a small scratch on the Lex ever
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