Also crossposted to rec.crafts.metalworking
Installing Hardie Plank siding. (Fiber cement combination) Manufacture
states that I should use a special blade. Went to Home Depot, and yes, they
make a special blade. It is simply a carbide tooth blade with with a total
of 6 teeth. 7-1/4 inch diameter.
Can somebody explaing why a six tooth carbide blade would cut any better
than, say, a 24 or 40 tooth blade that I use for lumber? I don't understand
The "special" blade is usually a diamond blade. The crew that did my
house had a set of them. When I did the shed, I just used an old
carbide, it worked OK but wore down *very* fast (we threw it out at
the end of the job). Same with jigsaw blades. They work, but they
last about ten minutes each.
Are you sure the blade you got was carbide, and not diamond? Diamond
is common in masonary blades.
As for the teeth, remember you're not cutting wood. You aren't going
to get a smooth surface, so "more teeth" is useless. As long as you
have *enough* teeth, it works, and you certainly don't want to be
making a fine dust of that stuff - coarse dust is better. If you have
too many teeth, it acts more like a grinder and less like a cutter -
and if it's a grinder, it'll be the hardie plank grinding the saw
blade, not the other way around.
I do not know that a 6 tooth would work better than a 24 tooth blade except
for the fact that there will be better chip clearance with fewer teeth.
Sorta like a single flute router bit cutting better than a double flute bit.
That said, I have had moderate experience with cutting fiber cement siding
and for my first project of residing the side of my home I used a 24 tooth
circle saw blade. The results tend to be rough and jagged.
For about $15-20 dollars I bought a diamond coated blade for cutting ceramic
tile and masonry products and had very food results. These have no teeth
other than the abrasive edge.
Physics of the blades aside, I suggest looking at shears instead... The dust
is brutal from the saws and the shears make none. The silica has to
potential to kill you in the long run if you breath it in... I wore a mask
and used a diamond blade in an angle grinder to cut the fiber cement trim on
my house but the siding was done with the shears.
Porter Cable 6605 Hardiplank Fiber Cement Siding Shear
DEWALT D28605 Heavy-Duty 1/2-Inch Variable Speed Cement Shear
I've got the PC shears and they work fine.
potential to kill you in the long >run if you breath it in... I wore a mask and
used a >diamond blade in an angle grinder to cut the fiber >cement trim on
No kidding. After buying a garden full of landscaping (my drifting
cementitious dust was floating one way all day onto a neighbor of my
client) and then later replacing the grass and dirt near the area we
were using on the driveway to cut, and still later to have to buy 3
I ONLY use shears for cementitious fiberboard siding. By the time you
cut a long gable piece on a low slope with that saw they will think
you are signalling them on the space station. The amount of dust is
unbelievable, and in a residential neighborhood, completely
unacceptable. Never again.
They make a perfectly acceptable cut if you use them correctly... which
means keeping the anvil side of the jaws flat on the siding. Failing to use
them properly will result in a ragged edge. The learning curve is real
short... if you pay attention to what you're doing!
They are much improved from the ones we had many years ago. I have
had the PC shears now for a few years and have cut Hardie plank,
Duraplank and Maxiplank as needed. It works great on all of them and
if you use them correctly the shear will roll up a coil of material in
front of the shears and throw out a few chips. That's it. Cutting on
a driveway it is easy to clean up with just a broom. And it cuts
When you cut a long piece for under a gable (say in a 5/12 or 4/12
roof) it will easily handle the 3'+ cut on the long cuts up at the
soffit or rake. With a little practice you can use them as a nibbler
around pipes, and can even cut (large) crescents.
Make sure the two sides that ride on the siding or sitting dead flat
on the siding when you are cutting though, or you can chip up the
edges. It isn't as smooth as a saw cut, but who sees the end cuts
under window or corner trims anyway? Applied properly, all of these
products are applied so that any exposed ends are factory made, so all
your cuts are covered.
On the next cement plank job, buy it, you'll love it! Any of my
contractor buddies I have lent it to have gone out and immediately
bought their own. That says a lot there as most would rather
I have to agree with the guys recommending the shears. You can rent
some or buy a set and sell them on Ebay when your finished with your
project. If you have your supplier give you the safety sheet you'll
find all kinds of ugly stuff on there about breathing the dust.
When these products first became available here, all the siding guys
tried to use saws for cutting it but nowadays all the pros use shears.
I've found the dust to be somewhat more manageable using my 18v Makita
with an old carbide blade. Fewer rpms, somewhat less dust but a dust mask
still a necessity.
That said, if I were doing a whole house now I'd spring for the shears.
I used Hardie Plank siding on my house and cut it with an old B&D
circular saw with a diamond tipped masonary blade from HD. The saw was
toast after this job- bearings were shot because of all the dust. If I
was going to do it again (hopefully never) I would buy the shears. I
bought a PC coil framing nailer just for the job and it worked like a
champ. I was going to sell it again the job but because I liked it so
much I decided to keep it to do fencing projects. I can't believe my
neighbors didn't complain what with the dust clouds I was sending up
cutting the fiber cement siding with a circular saw. Ripping a 12 foot
length was a joy. To cut out small notches I used my 4" angle grinder
with a diamond blade and for holes I used a Rotozip with a tile
cutting carbide bit. I learned that on the ends it was necessary to
pre-drill and hand nail. I'm very happy with the Hardie siding.
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