Not sure if rescue
line fulfills the concept of a
safety cable. Fairly certain it would not due to the fire factor. Big spark of light hitting
boom, rope catching it even if flame resistant and melting type thing in no longer being a
safety cable. That's in
broad concept even why many venues are requiring GACFlex for the spansets as opposed to normal spansets also in many cases.
Wire rope core spansets... good stuff, as with steel in the air. For me at least a “
Sunday” is a loop of
wire rope that’s crimped into a circle. Doesn’t quite grab a vertical pipe as well when not under tension - given the double loop on the pipe even, but once under tension it will either grab or stop when it hits something else. Not gonna melt, and not gonna fall to the floor. Only problem being the loop at the
point of stress - where the
safety cable hooks to it - minimum bending radius of
wire rope on
safety cables if not especially a
sunday in use will
play a large
role in it's safe use very much dependant upon weight and how far the fall is. (See below on supplemental clamps or stop bolts and safetying off to the ceiling. By the way if
boom on
stage that doesn't have top clamp - it should be safetyed to the
grid in some way so it cannot fall over - perhaps a
spot line and ladder might be necessary as concept if necessary. This getting into other topics of
safety.) Could also
wire rope off to a rig
point on the ceiling above the
boom as a concept. This especially if using a standard side arm I might recommend to do. Over the
sunday, much less chance for slippage short of something to stop that slippage which becomes extra materials. Perhaps something as simple as
wire rope off to eye
bolt mounted I-Beam clamp mounted to the same steel the
boom is attached to as a simple method that could in some instances be work able given short side arms. (and now a whole new debate...) gafftaper, brilliant and perfect in solutions all materials and brands presented.
Could also in all concepts of
safety cable and the friction clamp thru-bolt stops to the vertical pipe or use secondary clamps of almost any type for use as a stop also. Normally I would in the past just put an un-used
C-Clamp below what ever I was doing. This given later other options. I’m sure sources like
Altman, J.R.
Clancy, Sapsis Rigging, and
City Theatrical have specialized products for doing a
boom side arm also, if not Tomcat.
Not familiar with a allen key clamp if the allen key is what’s providing the friction as opposed to a
socket head
flat head screw that mounts the cheseborough to what it’s mounting. Such half cheseboroughs when mounted to the
yoke of a
fixture are correct in being termed friction clamp, but ya gotta remember that it’s on a vertical pole not roostering out on a horizontal
batten. You not just have that friction, but also have the torque keeping the clamp in place - this given the friction clamp is at a proper tension in the first place. Also see the above options for
safety by way of bolts, secondary clamps
etc. to prevent sliding.
Another
point that might be discussed given problems with cheseboroughs is a
scaffold clamp type cheseborough that’s forged steel and hex
bolt base plus designed for a 1.1/2" pipe in similar situations, verses say an aluminum cheseborough that’s
wing bolt based and engineered for quick install
truss install but often not as wise to use for water pipe in a vertical situation such as on a
boom. I would trust the specs on what makes a
scaffold clamp to sufficiently do the job and believe that’s what I have always been taught is the proper way to do this even back before the days of
Seachanger. I’m also changing my opinion of the
Seachanger fixture attached directly to a
batten by way of normal
C-Clamp - don’t think even that’s sufficient even with a heavy duty
Altman clamp or heavy duty
ETC clamp. Need a half cheseborough in my opinion and see above about slippage
safety. Otherwise another similar type of clamp only possibly. It’s a heavy
fixture on a vertical pipe. We are not just talking slippage from a mounted elevation above dead hang, we are also talking side loading torque on that clamp. Normal C-Clamps with a
bolt to hold the
fixture won’t have that concept of what is it 10:1
safety factor - the
bolt is gonna give if the clamp is not over-torqued in failing or bending at least. This is a concept beyond just the normal of hanging a 6x12 on a
stock side arm on a
boom that I also don’t recommend. Such a concept is normal to the industry and changing,... heck I can remember using such
C-Clamp mounted fixtures and side arms as ladder rungs as I climbed the pipe, but don't include that above
safety factor - something hitting it or falling against it in a side loading situation is I believe the general
point to the latter posts on this topic. C-Clamps in general and especially side arm C-Clamps are just not designed for mounting on a vertical pipe. Sure, you can say mount a 6"
Fresnel with out a problem, after that it's a
bit more getting into stuff that should not be done with the correct
safety factor or
design factor for what you are doing.
Also
point of definition - a side arm for me in a typical way is an
Altman normal
C-Clamp with a (typically) ½" Sch. 40 water pipe and Tee mounted on it. Both ends of the pipe are bolted or in some way such as
cotter pin prevented from coming loose by way of the clamp or tee. Problem is as with a normal
C-Clamp, half the force in holding it in place is that
bolt and holding that
bolt plus the rest of the clamp is all dependant upon the cast metal. Anyone ever get the non-domestic C-Clamps mixed up into their
stock years back before? Got a sort of
varnish covered black paint on them Total crap metal in the casting and fail easily in all ways. A more heavy
ETC style clamp won’t accept a Sch. 40 pipe and to my knowledge short of reaming the hole is not in general service as a side arm. Such clamps might stand up a
bit better in the casting but reaming them out for a pipe would destroy the engineering concept behind them. The heavy
Altman clamps also are not really designed for such side loading in any better way.
Other options I have seen is aluminum ½ cheseborougs welded to a section of aluminum structural tubing. Not sure if I have ever seen a steel version of this. This concept of cheseborough that’s
portable and pipe attached to clamp would work but as pointed out is a friction clamp and one not really sized for the smaller that 2" OD tubing 1.1/2" ID steel water pipe used on a
boom. Works often but not really sized for a vertical
boom situation to work best.
My recommendation and what I remember others in the past recommend stands - the scaff cheseborough with a pipe in it is the best side arm for a vertical
boom. This especially given the vertical pipe.
Ship--those were some great ideas about safetying off to a
boom. Never found a good solution, but I like the double wrapped
sunday idea. I think using some 6mm static rescue
line for that on my booms would be perfect.
Soundlight--the only thing that bothers me about the Allan key clamps is while they essentially are a friction clamp and the set screw is only supposed to provide tension on the
jig, they inherently seem less stable to me than a cheesborough, especially in a torqued, constant stress situation. I agree though, my preferred method has always been 1 1/2" schedule 40 as opposed to side arms.
Another great use of side arms-- A good way to keep cables off the same pipe as instruments to facilitate hanging is to clamp 12" sidearms every place you have a pick
point vertically with the arm facing up towards the
grid. Then attach a piece of standard drapery "
bottom pipe" to the tops of the sidearms, sundaying off this new pipe to the ropes to keep it from falling over. Tie off your
soco to this new pipe and
drop your
tails down.