Notes added after I read my own post:
If you slant the top of your concrete for water drainage (a good idea to
keep water from puddling around your metal stubs and encouraging rust--
crowning from the center outward is more difficult, but accomplishes the
same job), be sure to know that so slanted, the frame/form will mis-align
your base stubs UNLESS you shim up the lower side of your crossing 2X4s to
equal the slant of the top of the concrete and the flat tops of your
frame/form. That is, if using slanted concrete grade, compensate with
shims so that your base stubs remain straight upright.
When the concrete is poured, the stubs will move around somewhat despite
your best intentions. So, stand by the pouring to re-center and realign
the stubs as many times as necessary during the pouring process.
PS: If your concrete delivery brings too little concrete to fully fill
the hole (as did for me)-- a short load-- be sure to rough up the top of
what concrete you do have and drop in vertically extra re-bar half down
into the concrete and half sticking out awaiting the next load that comes
some hours later. This helps to stick the bottom rapidly hardening
concrete to the newer and later delivered concrete that comes into the
Do not use a flat plate of plywood horiz. over the top of the concrete
with the bolts or base stubs attached unless you can afford and do use 3/4
inch thick or even thicker plywood. Some instructions say use a temporary
flat plate of plywood to hold the stubs in place, but even one inch thick
plywood will not give enough stability when the concrete goes in and
pushes the stubs or base rods around. Use the system of 2X4s noted below
If u are pouring near your house or other tender thing (bushes?), be ready
with a big sheet of 1/4 inch plywood to act as a backsplash to keep
concrete splatter off your house, etc. Maybe a tarp will work as well?
If u are using base rods (not stubs), u will have to beef up the crossing
2X4s with additional wooden blocks so that the vert. rods will have enuf
surface to bite into and be solidly bolted to.
Do not be pushed around by the concrete deliverer person, who will want to
hurry you. Same goes if u are using a professional concrete top finisher.
The latter guy will want the wood forms taken off too soon so that he can
make a really smooth job. Stop that early removal before concrete is
solid! U can only set the base straight while concrete is soft, don't
forget. And, a little mistake down here means a big lean (Pisa?) up
Use a LONG carpenter's level and use it on each of all three tower legs if
u use the tower in any way to help set the base (not advised, due to
sinking feeling described below).
On Tue, 7 Apr 1998, Charles H. Harpole wrote:
> I installed my HDBX-48 twice with the tilt over base-- long one inch bolts
> that go down into the concrete, but the base stubs are the same principal.
> build a two by four frame (also called a form for the concrete)
> around the top outer edge of the hole,
> level it
> or allow for a drainage to one side, but either way make the top flat
> surfaces of your 2X4 frame the top grade of your concrete pad. Then screw
> --using wood screws-- more two by fours across the frame, lined up with
> the proper placement for the base stubs. Use one 2X4 for each stub and
> your whole assemblege will look, from the top view, like a picture frame
> (the form around the outside edges) with three stripes through it (like a
> football field with one sideline, and the two inner lines that run from
> goal line to goal line --not the "hash marks"). Then BOLT the stubs to
> the crossing 2X4s , using two bolts per stub. Pour concrete and be sure
> the stubs are not moved during the pour. For extra safety, attach two
> 2X4s across the three-- just like the hash marks (yardage markers) that
> run across the football field-- for more bracing.
> Alternately, make the frame/form as stated above, and make up, but do not
> install, the crossing 2X4s and attached stubs.
> Pour hole full. Then push the stubs down into the wet crete, lining them
> up with pre-marked marks on your frame/form. Screw the crossing pieces to
> the frame/form.
> In either case, re-measure the whole thing after the pour has settled and
> has been smoothed on top. Then walk away and wait.
> The use of screws and bolts above will make removal of the wood from the
> concrete and metal stubs much easier than using nails.
> If you mistakenly install one or more of the tower sections onto the base
> stubs, the weight of the sections will submerge the lower part of the
> tower --along with the stubs-- down into the wet concrete. You could
> counteract that factor by bracing with a maze of wooden struts and
> crossing members, but lacking proper advance planning, the whole will sink
> and so will your heart (and pocketbook).
> de K4VUD
> FAQ on WWW: http://www.contesting.com/towertalkfaq.html
> Submissions: email@example.com
> Administrative requests: towertalk-REQUEST@contesting.com
> Problems: firstname.lastname@example.org
> Search: http://www.contesting.com/km9p/search
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Administrative requests: towertalk-REQUEST@contesting.com