I am putting wood planking in my living room. Some of the planks will butt
against the fireplace hearth, which consists of petrified wood set in
mortar. The area where the stones meet the concrete pad is very irregular
due to the irregular shaped stones. The floor is a concrete pad.
For a neat installation and in order to provide for some expansion, I will
need to undercut the fireplace hearth by 1/2" so that I can slip the ends of
the planks under the stones.
I have a 4" electric grinder. Will that be suitable for cutting a 1/2"
undercut into the rocks? What kind of blade(s) should I use? I bet this is
going to be a very dusty affair!?
Any advice appreciated
You cannot imagine the amount of dust. Considering the location, the entire
amount of material removed is probably going to be made into dust rather
than cut out. You need an abrasive blade. Just get one because by the time
you cut a few inches, you'll probably see it is a bad, messy, idea. Butt he
wood and come up with a trim strip of some sort.
Would a 4" diamond blade reduce the dust and cut a thin slice? Can I reduce
the dust and enhance the cutting action by having my wife cover the area
with a water mist/spray?
Unless you have a steady trickle of water running on the blade it is
going to make dusst like you have never seen. If you do have water
running on it, you will have one muddy mess that will dry to a grey
powder everywhere it runs. BTDT but fortunately outside. Take the
advice given above and use a trim strip to cover the gap.
contract that much, put a kerf in the trim strip so it rides over the
flooring, with a bullnose on top to avoid splinters. Scribe the fireplace
side to match the stonework. Having a trim strip 1/4" taller than floor will
barely be noticable. Trying to put a kerf in the existing stone is just
asking for trouble.
Rent a jamb saw from the local shop. Many places won't rent to you if they
know you're doing a fireplace, so keep looking. Use two shopvacs, one on
each side of the blade. This will keep the mess to a minimum.
You have gone to all this trouble to get petrified wood and you're
going to grind parts of it away. What if something happens like a
chunk of it from the top half inch breaks off. It seems to me that
could happen with anything, during the grinding or later, (and
especially with petrified wood which might not have been a perfect log
before it petrified. My firewood has cracks in it, some cracks with
air in them, and others that don't appear to be cracks, but I know one
piece of wood is not attached to the wood next to it.)
Why not get a profile gauge, or whatever it's called, the thing with
the big set of parallel pins in a clamp, and trim the fresh wood to
match the petrifed wood. If it doesn't come out right, you can get
another plank. If " butt against" mean it is the ends that abut, you
can just cut a couple inches off the plank and start again.
FTR, I've not worked with petrified wood (I'd be too scared) and I've
never used my pin thing, even though I have one, and I've never done a
floor. Just consider my post a suggestion. (I'm watching "24" and it
makes me more assertive. Well, actually more violent, but all I have
is my keyboard.)
I don't know whether a segmented or continuous rim blade will work better.
I think a segmented blade cuts faster but rougher.
In order to get a good straight cutt you need to make some sort of holder
for the grinder that slides along the floor that can hold the blade the
requierd 1/2" above the floor.
Its going to make a ton of dust, you may want to make a tent out of sheet
plastic and hold a shopvac hose close to the grinder.
Thank you for your advice, Cliff
All the pros I talked to recommended the undercutting method. The way you
describe it, it should work. My 4" angle grinder sits 1/2" off the ground
and should give me the perfect height and depth of cut.
What concerned me also was the need to allow for the expansion of the
hardwood floor. The best way of doing this is to let the wood move in the
undercut under the stones.
My only concern is that your 4" grinder will cut deep enough. That's some
pretty rough stone.
If you have never cut stone like this with a diamond blade you will be
surprised just how smooth it cuts. You may think that you aren't cutting at
all. Just don't bind the blade or its going to kick and chip.
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