Building a mast base.
An introduction to DIY building of a concrete base for a 45' mast.
At the beginning of May 2000 I aquired a second hand 40 - 45' 2 section telescopic tiltover mast to replace the ageing set of scaffold poles that had supported my many variations of aerials for the past 10+ years.It required that a concrete base be constructed to take the mast. This is how I constructed the base which I feel might be of use to others.
The main block was constructed by using concrete breeze blocks. The sides were 2 and 1/4 blocks per side - giving 40 " per side. The depth was 4 blocks - giving a depth of 36 - 40 " with a small base to lay them on. This is a bit larger than the recpmmended base as in the manufacturers literature. I also gained a bit of easy height by extending up 1 block above ground level, which also made itfar eassier to get the base level -the most important thing. Most of the technique I used is self evident in the following photos I took.
This clearly shows the base at about 80% complete. This took about a week to construct - I did a couple of hours per night - also the materials were at the front of the house - 400' away and each item required to be carried by wheel barrow a bit at a time!! The concrete blocks are clearly visible as is the apron I built (the ground is about 1' of soil and then clay - I felt that it would perhaps help for stability - probably overkill). The wooden box around the blocks is there so that the top 2" of the base are made into a solid cap. It was also how I made the top of the base perfectly level. The box was rawl bolted to the breeze block. As can be seen the base of the mast is sat on 3 strong wooden formers that make the base the same height as the wooden collar. The block base was pre filled to the middle of the second course of blocks from the top - this gives a solid cap to be filled - the top of the inner filling is of course totally rough for keying the top layer of cement.
This is another view at the same stage - pre making of the top cap.
I was so careful with my construction of the block cage that I only needed
to put a 1/16" washer under one of the wooden formers to perfectly level
the base!!!
Here is the completed base - I made and laid the top cap all in one
sssion - 4 hours and hard graft!!!. The mast base was laid on the wooden
formers (with the fixing bolts held with the nuts to give postion) which
were left in the cement cap for a day whilst the cement started to cure.
I then removed the base, removed the wooden formers (with as little disturbance
as possible) and then filled in and levelled to the origonal cap with a
cement mix. The cap was left to cure for a week before the base was fixed
- there was no problem and within a few days the mast was erected - it
still stands today!!! I believe that the same technique could be used for
a post mount - build completely to the top of the cap - with a hole 6"
bigger that is reauired for the post - set it up for level etc - and fill
in around.
I hope this may be of use to some of you - if it is please let me know.
Here is the finisherd mast - the 20' small tower in the left foreground is the remains of my old system - there is about 30' between them
This is the view from one of my back bedroom windows - the mast is some 150' up the garden - the end is 250' away!!!
As another point of interest I affixed by means of some old guy wire 3 concrete blocks to the base of the tilt over portion of the mast - I set it up so that as the mast gets to about 15 degrees from the vertical 2 blocks start to lift from the ground and counteract the weigth of the aerial etc.and at about 30degrees from the vertical the 3rd block picks up - this has a noticeable effect on the ease which the winch operates.
