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Another clamp question...

Discussion in 'Lighting and Electrics' started by JohnA, Oct 6, 2007.

  1. JohnA

    JohnA Active Member

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    Greetings to all,
    A couple of posts ago, recommendations were made concerning clamps for moving lights. My question is: what clamp do you recommend when mounting conventional ellipsoidals (Source 4) on an aluminum truss (2 in diameter x 12 in wide x 10 ft length)?
    Thanks for your suggestions.
     
  2. soundlight

    soundlight Well-Known Member

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    If they're just going to be mounted on truss, you could always go with a "half-burger" style clamp, like the Light Source's "Mega Coupler". Or, if you can shell out the dough, just get Mega-Claws for all of 'em. Honestly, I'd be perfectly happy with mega-claws on just about any instrument!
     
  3. BillESC

    BillESC Well-Known Member Premium Member

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    The use of an O clamp is recommended when mounting to round aluminum tubing as it will not bite into or mar the surface.

    [​IMG]
    The CLP 15 above is rated for 660 lbs. and costs under $ 10.00

    [​IMG]
    The CLP 6 is rated for 220 lbs. and has an adjustable grip range from 1 to 2 inches and costs only $ 12.00
     
  4. JD

    JD Well-Known Member

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    Same here. You want to pick a clamp that is not going to dig into the truss as the damage is cumulative. One must always remember that the tubing on the bottom section of the truss is under very high tensile stress. (Unless your lights ride on a pipe within the truss.) Never heard of a failure, but why tempt fait. Also, nice to keep the trussing looking good by avoiding the cosmetic marring. The "trigger clamps" (shown in the last post) have a lot of surface area.

    PS: CLP6 above looks like a trigger clamp, but I just picked one of mine up and they are stamped for 250Kg as a weight load, which works out to well over double the 220 pound rating.
     
    Last edited: Oct 7, 2007
  5. JD

    JD Well-Known Member

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    Actually, on second look, the trigger clamps look a lot fatter, and have a large cast wing nut. (See picture) They are around $20
     
    Last edited: Aug 30, 2008
  6. BillESC

    BillESC Well-Known Member Premium Member

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    I'm curious to know how many of you are hanging fixtures that weigh more than 220 lbs.?
     
  7. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    I'm not sure the width or length of your truss matters.;)

    I cannot accurately answer your questions without asking you some:
    Are the fixtures in question going to ever be mounted on anything other than 50mm (2") aluminum truss? If yes, what? Maybe 1.5" Schedule40 black iron pipe? Do you foresee hanging the fixtures in a position other than straight down, i.e. do you typically "side-hang" "yoke out" "overhang" or "rooster" your fixtures so they don't interfere with the moving lights? Do you enjoy changing clamps on all your conventionals everytime you hang them from a different material/location or would you rather be lighting the show?

    I, myself, have no problem using the standard theatrical lighting C-Clamp, (Altman-clamp, ETC-clamp) and this device:
    http://www.citytheatrical.com/ "C-clip" Truss Protector (or TMB's brand).
    <or>
    the shop-fabricated variety made of 2" PVC or ABS pipe run through a band saw,
    when hanging conventionals on lighting truss.
    Yes it's a loose extra part, but maybe a piece of #4 black trickline appropriately tied at each end to the "truss condom" <te he he he> and the C-Clamp could prevent loss. Speaking of loose parts, you have taken the fixture's side bolt out and slipped the safety "permanently" on the yoke haven't you?

    For conventional lighting fixtures, I actually prefer the LightSource Mega-Clamp™ as it has fewer moving parts, but would never replace all the standard C-clamps that came with my fixtures with them. That's just wasteful and silly.

    For moving lights I prefer the LightSource Mega-Claw™ in black, above all others. Really annoying is when one Mega-Claw is black and the other is anodized aluminum. I've been know to hunt down another fixture and trade. Just feels like wearing "odd socks" to steal a Briitsh phrase.

    I believe the "other thread" mentioned this: (I wasn't going to involve myself in that thread.) http://thelightsource.com/products/24/view
    Never seen it, never used it, don't like it, advise against it.

    While I despise half-couplers on moving lights, just like everyone else, I do respect their cost-benefits. And here's a useful tip: ever need to attach an out rigger pipe to a truss corner clock? Take two half couplers and bolt to them thru the corner block's unused trussbolt holes (grade8 hardware only, of course). Clamp the 2" pipe to the half-burgers, safety everything and viola!

    For some reason, "trigger clamps" always seem to bind up on me, and seem not as secure. I don't see them that often, so maybe it's me. But since I don't see them that often, it can be inferred they're not used that often.

    YMMV.
     
    Last edited: Oct 7, 2007
  8. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    +1

    Yesterday. 23 Synchrolites ranging from 3K - 10K. Used 3-4 aluminum swivel-cheeseboroughs for each fixture. Some 3K fixtures on tail-down inverted-Tee pipes used 2 Mega-Couplers™ each.
     
  9. jmcclint

    jmcclint Member

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    I have to side with derek, at least for hanging conventionals (which was the question.) Simple PVC 'Truss Protectors' (sometimes questionably called truss condoms) work fine (make sure the 'teeth' of the c-clamp are in contact with the truss, especially when using sidearms. Mega-Clamps, etc. work, but they're expensive and large, especially for one-offs or lower budget situations. Don't run if you're not being chased.
     
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  10. len

    len Well-Known Member

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    If you're hanging off truss, then any kind of wide grip clamp (half coupler, gravity clamp, etc.), will work without marring the truss. But if it's a schedule 40 pipe, I just use the old fashioned ETC clamps. Unfortunately, this is the only pix I could find http://cgi.ebay.com/Pipe-Clamps-for...ryZ29943QQssPageNameZWDVWQQrdZ1QQcmdZViewItem A 10' pipe runs $20 at Home Depot so it's not the end of the world to replace one every so often. And if you're tightening the clamp into the pipe that deep that it's causing the pipe to deteriorate, then you're either the world's strongest stagehand or you're using an impact wrench. Either way, you're making it way too tight. A quarter turn past snug is all you really need.

    Bill, is that Chauvet gravity clamp comparable to the global truss product in quality?
     
  11. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    I just remembered another benefit of the traditional C-clamp: They'll work on round pipe 1/2" to 2," and square tubing 3/4" to 2."
    I've had to remove Mega-Claws and use old, rusty C-clamps to hang Studio Colors from my catwalks' handrails: 1.25"x1.25" (sorry Gafftaper) square steel tube.
    Sidearms are my favorite underused fixture mounting device.
     
  12. JD

    JD Well-Known Member

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    Not Many! ;)

    However, when you are mounting movers, all equipment should have a very high safety factor as it is a moving load. (Not a problem with Source 4's) The rule of thumb is a factor 10, so a fixture weighing 60 pounds should be rigged as if it was 600.
     
  13. JohnA

    JohnA Active Member

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    Thanks for the replies

    Hey guys,
    Thanks for all your suggestions. To clarify & answer some of the questions raised:

    I am using the truss for this production only. For the others, I will be using 10ft sections of Sch 40 black pipe, so a few dings are not significant.

    I will need to hang these S4 instruments off the front of the truss to avoid interfering with 2 intels mounted on the "bottom" of the truss {intels are ~40lbs each}. That required alot of torque on the mega clamp bolt to insure the instrument did not 'slide' down.

    I only do a few shows each year, with a crew of 2 (including myself).

    I do the shows as a 'volunteer service' to the local schools. Therefore cost is an extremely important consideration.

    I always rent the truss, so I don't want to have to pay for any damage I may cause.

    Thanks again... John
     
  14. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Your fixtures already have clamps on them, then? Had you told us that, we would have "cut to the chase." If you need step by step instructions as to how to fabricate your own "truss protectors," just ask.

    "That required alot of torque on the mega clamp bolt to insure the instrument did not 'slide' down." Now I'm confused again. Are the four 2" tubes of the truss horizontal or vertical? If the movers are hung from the bottom, where do they want to 'slide down' to?

    Here's what I'm picturing. Please correct as necessary.

    A 10' long x 12"x12" truss is hanging as a traditonal first electric, horizontally. Movers are hanging on the bottom, upstage chord. You want to hang S4 ERSs on the bottom DS chord, but can't hang them with yoke straight down as they would interfere with the moving heads? How many lights are you hanging on this stick of truss that you can't hang all you need to? Are your Leko's yoke parallel to the floor? The Mega-Claw isn't very good at that. To me "front" of a truss indicates the side the audience sees, thus DS.

    I'm not trying to be cantankerous-- I want to offer advice but don't understand the situation.
     
  15. JohnA

    JohnA Active Member

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    Hi derekleffew,
    No offense taken. I appreciate any/all suggetions. I shoud have provided alot more info in the first post.

    Most importantly the truss is hung horizontally in the house from steel beams. It is a 10 ft long 12x12 inch aluminum truss with 2in diameter chords.

    The movers are hung along the bottom of the truss. They have (2) mounting holes 12 inches apart, so there is a mount on both the "front and rear" chords for each. The movers aren't the lights that "want to slide down--the Source 4s are the problem.

    There are seven Source 4 ellipsoidals, each weighing ~15 lbs. If I could hang the lekos from the top chord that "faces" the stage, they would not interfere with the output of the movers. The yoke for each would be at about a 45 degree angle to the floor--definitely not parallel, as that would create the most force on the yoke and the chord.

    As for the C clamps I have, that does not mean they are necessarily the best means of attachment. I wanted suggestions as to all options.
     
  16. ship

    ship Senior Team Emeritus Premium Member

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    Can use normal C-Clamps with the jaws and bolt that dig into and ruin truss only if using a truss condom - this a commercial thing or a 2" PVC pipe cut up into 3/4"x like 3" sections for use as pressure clamp converters without the digging into the aluminum tubing damage. Trick is to insert the PVC tubing over the aluminum truss in a way that the C-Clamp will still clamp the fixture to the truss but without damaging the truss.

    After that, don't clamp directly to truss with a C-Clamp.
     
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  17. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    A neat trick, THAT I CANNOT RECOMMEND, is to put a penny (1¢ US) between the truss and the end of the C-Clamp bolt. Copper being soft will conform to the curvature of the 2" Aluminum alloy truss tube. OP--Why not over-hang your Lekos, with the yoke straight up? Only problem is getting a steep downward angle, but I doubt you'd want that on an FOH truss. I've found it awkward to focus a fixture that doesn't have it's yoke vertical, either up or down. Otherwise, You try to pan toward SR, but the beam goes US also. Then you lock the pan, and move the tilt, but again, rather than moving US-DS, the beam goes slightly sideways. So you lock off tilt, and go back to pan... vicious cycle.

    Now that we understand your application, I wouldn't suggest any clamp other than the standard theatrical c-clamp. You just need to buy or fabricate some Truss Protectors.
     
    JohnA likes this.

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