I have a tripod mounted on a concrete block and an old 6 in. X 6 in. by
three ft; conctrete slab the previous owner left here. The tripod holds
up an aluminum pipe with an anemometer and a universal antenna. Since the
area is shielded by trees about 100 ft. away, the anemometer does not give
a very accurate estimate of wind speed or direction.
My fireplace chimney has a 4 in. thick slab, not reinforced, cap on the
top. I am coonsidering moving the tripod to the top of the chimney cap
but wonder how close to the edge would be safe to drill for the tapcon
screws to hold the tripod down against the wind. We had a tornado, small
one but big enough to tear the neighbors roof off and uproot some trees
about 14 in. in diameter, go between my house an my neighbor's house (not
the one that lost the roof). This would lift the anemometer up into
\"clean\" air and make it much more accurate. The anemometer radios the
speed and direction to my recording station and is powered by solar so I
wouldn't have to change batteries very often. I figure 4 in. from the
edge for the 1/4 X 2-3/4 in. tapcon screws. If three and a half would be
OK, I could spread the tripod legs a little further apart which might be
better for stability. What do you think?
I have routinely installed the 3/16 (1/4' hex head) within an inch of edges
with no problems. This is sheltered or semi sheltered locations not subject
to high winds.
I see the pound in, 1/4" anchors installed within 1.5" of the edges of many
porches. IMO, in 3.5" on a sound structure should present no problems.
It depends on the condition of the cap. That is a hard weather area.
Generally an inch of penetration is all that is required. Do you really need
2.75" of length?
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The 4 inches in setback should be OK. A rule of thumb is to assume a 45
degree angle up from the edge so 4 inches in on a 4 inch slab should work
but use the outside edge of the hole not the center - it is a good idea to
have a safety factor on the 45 degree theory. You should not go closer than
4 inches to the edge.
On Feb 28, 9:55 pm, bobcox_at_mchsi_dot firstname.lastname@example.org (bobcox) wrote:
Tapcons are great in their place, but given the location you chose it
would make more sense to simply drill holes where they are needed and
use a two part epoxy from Abatron or similar to anchor stainless steel
threaded rods in place. That way if removal is ever required it can be
accomplished without butchering any part of the chimney cap.
It is likely that the holding power of the SS + epoxy system will
exceed the Tapcon. IIRC, the concrete panels in the Boston subway were
installed in that fashion. The contractor who used the wrong epoxy
(fast cure) on the Boston panels had some failures which were
corrected with the proper epoxy adhesive.
On Feb 28, 10:55 pm, bobcox_at_mchsi_dot email@example.com (bobcox) wrote:
So how tall is this pipe that the tripod mount is holding up ?
Mounting it to the cap on the chimney might not be the best
idea, have you considered mounting it with straps around the
chimney itself, just the pipe, as you would an antenna mast ?
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