"Bert Morris" <bertmorris@[EMAIL PROTECTED]
> wrote in message
news:479F9EA5.2060107@[EMAIL PROTECTED]
>
> Dear Rob,
>
> It is a common practice but only where 2 1/2" to 3" long lag screws can
be
> driven into the deck through the four flange holes. The point of doing a
> boom lag/flange arrangement is that the base isn't any bigger than
> necessary to hold the boom down. The weight is ALL held up at the top in
> the grid by safely and properly tied off lines that have been very
> carefully spotted, either through sheaves and head blocks to the
pinrail,
> or tied off at their spot points in the grid. NOTE: Only well maintained
> lines and professional flymen should be allowed to rig this.
>
> Traditionally, whole booms - sidearms, instruments, twofers, cables and
> breakouts - are built horizontally on the deck across sawhorses, with a
> flange at the bottom and boom pickup line at the top, properly
> half-hitched at the top and secured to the boom below the topmost
> instrument's sidearm C-clamp with a clove hitch finished with one
> half-hitch. Circuit cable is dressed up the pipe if being fed from
> overhead drops or cable picks in the air. When ready to be flown, the
crew
> on the deck gives the boom a helping shove up as the grid crew [or
pinrail
> flymen] take the strain and pull the boom vertical until it floats about
a
> foot off the deck. The boom is allowed to stretch the pickup line for a
> while so it gets as taut as possible under the full weight of the
> assembled boom.
>
> When it is time to actually 'spot' the boom to its floor mark, the most
> secure procedure is to have the boom line let in very easy on its pin
> until the flange is about two inches off the deck. The line is secured
> with a 'good double tie' on the pin and then the deck crew waits until
the
> flyman gives the OK to lag. At that point, one stagehand with an impact
> wrench drives each lag [with a washer on top of the flange hole] into
the
> deck while two other stagehands hold the boom steady at the correct
angle
> for the sidearms. They step on the flange, adding their weight to the
boom
> to stretch it the last two inches so it is truly tight. The lags do the
> rest and hold it until load out. Once tied off, the boomline is marked
or
> tagged by the flyman as a line in use [under a load] which the double
tie
> should tell you anyway.
>
> This method is as safe as a full 24"+ boom base, loaded with sandbags
and
> an overhead safety line. The advantage is that the small footprint of a
5"
> flange allows spotting the boom very close to legs, set pieces, and it
> never sticks out any further than any instrument on the boom itself. For
> fine 'tuning' the boom, the 5" flange should have at least one 180
degree
> thread spin of freeplay so any re-angling of the sidearms can be done by
> simply twisting the whole boom one way or the other. If the flange is on
> so tight that you cannot turn it after lagging, you've boxed yourself
in.
> When the LD/TD is happy with the whole position, a right angle
'crowsfoot'
> should be attached to the base of the boompipe above the flange by its
> C-clamp and its mini 3" flange drilled to the deck with regular drywall
or
> any short 1" screws.
>
> Bad ASCII art:
>
> Boom crowsfoot [standard sidearm parts]
> | |
> C-clamp======== <== 1/2" pipe 90 elbow
> | | || <== 1/2" pipe
> | | ||
> | | ||
> ------------ ----<== 3" flange
>
>
> When all is done, then tighten the C-clamp to lock in everything. The
> advantage of a crowsfoot is that it can be angled in any direction off
the
> boom pipe and secured out of the way of performer's feet passing by. The
> most used angle is directly under the instruments or on-off stage, but
the
> most im****tant position is the one that's out of the way.
>
> Without having to fight the rigidity of a wide boom base on the floor,
> breast lines can be used to straighten or correct a leaning boom from up
> to down or offstage by tying the breastline off the boomline and pulling
> it to the desired angle to offset and make a perfectly vertical boom.
This
> makes doing really tight shutter cuts manageable in close spaces.
>
> As long as this method is correctly applied, the boom must be considered
a
> flown piece and treated as such. This means qualified personnel on the
> flyfloor or grid. If the boom lines must be dead tied to the grid, then
> you must have experienced hands who know how to properly tie off a line
> under full load. Slipping is NOT an option.
>
> In practice over the years, I have built many 20' - 24' booms with 10 to
> 12 instruments, double sidearms, loaded with color scrollers, strobes,
> cables, foldback speakers from sound, and the whole thing flown, dead
> tied, and just marrying the deck on a well lagged 5" flange - on one
> single hemp line [when I began]; now, synthetic braided lines and wire
> rope safeties everywhere.
>
> Regards,
> Bert
>
Bert
I love all of your your post.
They are like reading a book that was written by someone that knows what
he
is doing.
David
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