First, falling on the audience shouldn’t be a factor if you properly
safety cable the
fixture - that’s what they are for and you always use them. Even at work bought a bunch of the improved Euro versions of them in three classes of load rated weight for use on gear, though I still buy in bulk factory manufactured
safety cables of the normal 3/16" and 1/4" size both and or make by way of go/no-go
gauge checked other than normal length
safety cable for other gear. That’s the key. If hanging say a 10K
Fresnel, it’s not a
safety cable it’s at least 3/16" steel with a
shackle or load rated chain.
Next, the clamps have been discussed over the years in depth on stagecraft forum and the way of the industry will some day go with the above Euro style load rated
safety cables that are much safer in
shock load but at yet won’t work with most gear given the thimbles that are very important. This much less you cannot buy the same screw
gate snap hooks in the states yet. And yet I mean in shopping for them.
Also on the above past debate from stagecraft, or perhaps more recent one... was mostly about clamps. Different domestic ones and Euro ones plus the cheseborough types. Lots of options amongst them amongst the
Mega Clamp that would tear up a
truss beyond what a
truss condom would work with in dealing with a normal, heavy or extra heavy duty type
C-Clamp.
On the clamps, this once the concept of
safety cable is mentioned.... once got into a long off-line discussion with Frank from stagecraft about the subject a few years ago. One might given his unique personality guess how the debate went. Still it was of interest and I certainly also use other types of clamp at work as with those more normal
Altman type or Heavy duty
ETC or
Altman type or Extra heavy duty
Altman or even
Colortran type. This in addition to the various G, J and cheseborough clamps of various types. And mega and other clamps.
Whole bin full of half cheseboroughs of both Doughty style with hex
nut bolt and normal
flat head screw style plus a few others in the bin for repair constantly. Spend hundreds of dollars per year in just replacing the
swing arm
bolt assembly for each and any brand. This after the three minute rule in repairing the threads do a dinged up
bolt. If it will take more than three minutes to repair the
bolt by way of triangle or thread file, damage is substantial or more than a minor ding to the threads in the lower half of the
swing arm thus structural, the
swing arm assembly gets replaced. Major liability issue in figuring out what can be fixed, repaced or as Doughty sees it in not providing replacement
swing arms... not safe once bad.
J or G clamps... seen just as many bent, threads dinged and lots of other in such clamps for me being a secondary choice. Lots of them on the market, in my opinion none are better though bent as opposed to cast is a valid
point in strength or reliability due to fatigue. On the other
hand, not as easy to use. You know that as it were in other terms, screw you set screw is useful if in good condition. Even of these clamps at one
point bent up a few dozen of my own out of 1/4"x2" steel plate. Not easy but can be done and they still function properly. For the set screws, it was carriage bolts
ground down to set screws and than as typical with grade 2 bolts used as a retaining mechanism for the clamp.. Plus the un-supported distance of between the
bolt touching the pipe and clamp in distorting it =- some even factory knobs or screws of this type are not sufficient in size or grade. All about tension and torque on them also. Grade 5 is available as with proper aircraft grade set screws.
On the other
hand as with any screw or clamp, take the 10"
C-Wrench away from the tech people in thinking that the torque of 1/4 turn past finger tight for them is the same as that of 1/4 turn past finger tight for that of a 8"
C-Wrench. “That’s nice.. You go sweep the floor.”
No matter what the clamp or tool, and I do have some
wing nut T-handle tighteners I custom make even, over tension is a problem that any clamp will fail with.
On the clamp age... Got some C-Clamps that are in perfectly good condition that are at least 50 years old now, at least at home. I still use them. No signs of metal fatigue or bending and that’s what you are looking for. During the late 90's there was one run of C-Clamps that were made off shore without a name brand on them to watch out for on the other
hand. Sort of have a
varnish coating to them in look. Not real finish, sort of a brownish like gloss coat above the clamp casting. Destroy these clamps - they are unsafe in being lesser casting materials used and not a real
C-Clamp one can most often see deformed or cracked.
Beyond this, never use other than a hardened
bolt/set screw for the clamp. Such bolts get mushroomed and or deformed in bending and not holding. If you need a longer
bolt, only use proper set screws if not at least grade five cup ones. Far too often I see C-Clamps coming back from shows with grade two hex screws in them with a mushroomed tip. Once that tip’s mushroomed, cut the
bolt before attempting to remove it. This otherwise the flared tip will ding and screw up the threading in the clamp. If stuck
bolt or bent
bolt, cut it where its possible in removing it from the top or bottom, don’t attempt to remove it anyway or you will get a bad clamp.
Mostly, C-Clamps... different grades of them, and age is not persay a factor in safely using them. Yes metal fatigue is a good concept to study and valid in
point but for the most part if properly used and mostly you can see this, a
C-Clamp don’t have an age just as it don’t have a load
rating. More a question of inspection and proper use. Ages old or brand new... just cut the
bolt off of an
ETC clamp tonight.
Bolt was bent and it was having problems getting removed. Took a lot of re-tapping of the clamp to make it proper again and the clamp itself was inspected to verify its
safety.
Overall. If in doubt,
throw it out and or damage it so someone else won’t take it home without understanding why it went into the trash. Cut it in half or ding the heck out of it so it can no longer be used. At times without proper supervision, that even if more expensive is the only solution. I properly train and or supervise anyone working on clamps at work. Didn’t ask for that responsibility but it’s my job and supervision I am tasked with. Very important yet on the other
hand age of the clamp is less a factor over proper use and inspection of it.