Neil Hampson Posted February 18, 2008 Share Posted February 18, 2008 For years the 'Followspots' in the Studio at the school I often work for have been hung from the main lighting grid, just over the gallery level where the control room is. The gallery is only about 4 foot wide so a stand is realistically out of the question. so up until now the lights (Which are actually standard CCT Sil 15's with an iris) have been hung on these, with a standard spigot:http://i45.photobucket.com/albums/f86/neilhampson/TVClamp.jpgAll was happy... until last week when I found that a person unknown had decided to move the followspot further along the gallery, and failed to re-tighten the clamp, or put a bond on it (But thats another rant!) On closer inspection the clamp, which is about 15-20 years old is now quite worn, the clamp will not tighten properly on the bar, and when the spigot is set so the lantern can swivel, there is a tendency for the bolt to come loose, meaning that the lantern is hung only on the (very loose) cotter-pin on the spigot. I have taken the lanterns out of service and removed the clamps, but I am at a loss of what to replace them with? Is there a clamp available where I can 'hang' a followspot. I am thinking something along the lines of a doughty clamp, but with some kind of swivel plate instead of leaving the bolt-set loose (even if I used a locking type nut I imagine there is a risk of loosening the nut through the movement of the spot. On another point I have asked for a 35Kg bond for each unit, as the school seem to be happy with the old unrated safety chain, but I am unsure on the best way to bond them, just a short bond around the bar and the yoke, or a (much) longer one running to the attachment point at the back of the lantern. The problem with the latter is due to the angle of the light and the position of the eye, the lantern would drop well over 300mm before the bond was tightened. (As an aside, the ONLY failure of a lantern I have experianced is where the lantern body parted company with the Yoke, leaving the yoke nicely safetied to the bar, and two sheared bolts falling to the floor. Luckily I was focusing the unit at the time and caught it) Link to comment Share on other sites More sharing options...
paulears Posted February 18, 2008 Share Posted February 18, 2008 The modern TV spigots can have a pin shoved through the spigot when fitted into the clamp, as well as the side screw - so even if is undone too much, the spigot won't fall out. TV style safety bonds should be fine - a big 5K is a heavy beast - but TV clamps are built to manage them. The pin, on a short captive lanyard has been quite common for years - I assume yours must be actually really old, not to have one? Link to comment Share on other sites More sharing options...
Neil Hampson Posted February 18, 2008 Author Share Posted February 18, 2008 Our TV clamps do have the pin, I refered to it as a 'cotter pin', although this may be more a engineering term, it's a large split pin passing through the spigot. The problem is, this pin can jam up due to the constant use as a followspot, and over the years the pins have been lost and the replacements have always been too soft. (the captive lanyard didn't last long) as a precaution I passed a long stainless bolt through the spigot and used a nylon lock washer, this has lasted the longest so far, but I'm worried that this is the last defence before the fall (except the bond of course). The biggest problem that I have is that the clamps don't actually sit on the bar properly, the innner face of the clamp seems to have a curved profile that means that the clamp is free to rock backwards and forwards, even if the screw is tight. I am assuming that the 'TV' clamps aren't really designed for the use that we put them to, I have never used them other than in our studio in the 'followspot position. Iwas wondering if there was some kind of intermediate bearing that would allow me to tighten the clamps up properly onto the spigot (or even to get rid of the TV clamp altogether and use a doughty clamp and 'a device' that would allow the lantern to pan. Link to comment Share on other sites More sharing options...
paulears Posted February 18, 2008 Share Posted February 18, 2008 Sorry - me misunderstanding. Somewhere, I seem to remember a TV spigot with a ballrace on the end. In fact, I'm pretty sure there is one about somewhere, but I can't find it. I'll have a search and if I can find it, maybe there is a brand. Might take me a day or two - and there's no guarantee I still have it - BUT, they do exist. Link to comment Share on other sites More sharing options...
neild Posted February 18, 2008 Share Posted February 18, 2008 Doughty offer a roller race spigot specifically for followspot applications. (T74200) This allows the spigot to be locked tightly into the receiving clamp, and the lantern to be tightly fixed to the spigot. Pan can then be loosened by an additional wing bolt. I'd suggest just touching base with your Doughty rep or dealer to ascertain that these can hang the 'wrong' way up! Hope that may be of some help. (I think it may be what Paulears is referring to?) Neil Link to comment Share on other sites More sharing options...
paulears Posted February 18, 2008 Share Posted February 18, 2008 That's the one! Saved me a lot of hunting about - thanks for that.P Link to comment Share on other sites More sharing options...
Neil Hampson Posted February 18, 2008 Author Share Posted February 18, 2008 Thanks for that, Northern Stage are coming in later this week anyway so I'll enquire then. Regards, Neil Link to comment Share on other sites More sharing options...
Neil Hampson Posted February 19, 2008 Author Share Posted February 19, 2008 I have been in contact direct with Doughty about theT74200 ball race spigot, unfortunatly it cannot be used upside down, only on a stand with the lantern on the top. Doughty have however suggested the following part:http://i45.photobucket.com/albums/f86/neilhampson/t74800.jpgT74800 (T74801 is Black) TV Quick reciever. which although it dosen't have a ball race it is designed to allow the lantern to be panned around without risk of becoming loose. I can then fit this to a standard Doughty clamp above and continue to use the spigot that I already have. Link to comment Share on other sites More sharing options...
peternewman Posted February 19, 2008 Share Posted February 19, 2008 Presumably that pin locates in the groove near the top/bottom of the spigot? Link to comment Share on other sites More sharing options...
tokm Posted February 20, 2008 Share Posted February 20, 2008 Presumably that pin locates in the groove near the top/bottom of the spigot?Yes, it indeed does. I believe the reason why is for very similar reasons to the OP's.. you suitably tighten up the bolt that goes through the lantern yoke into the spigot so it doesn't move, then any adjustment of the pan of the lantern is done by loosening the wing-bolt. Obviously it goes without saying that this safety system only works when your using proper TV spigots.. not just some 32mm cylinder with an m10/m12 thread attached to the top like Ive seen on some f/spots around :) Glad you've found something suitable. Tom Link to comment Share on other sites More sharing options...
Pete Posted March 26, 2008 Share Posted March 26, 2008 How's this working out for you Neil as I may have a very similar need in the not to distant future Link to comment Share on other sites More sharing options...
Neil Hampson Posted March 27, 2008 Author Share Posted March 27, 2008 How's this working out for you Neil as I may have a very similar need in the not to distant future Unfortunately being a school, money isn't always available to fix stuff as soon as it's broken or found to be defective. I have to wait until April before I can order the bits I need( I was hoping there would be a bit of cash left over at the end of the year), the two spots are currently in the Lx store waiting for them to be ordered. In the end I needed to order new spigots as well because the ones I have had the groove in the wrong place. Link to comment Share on other sites More sharing options...
JDLX Posted March 28, 2008 Share Posted March 28, 2008 Another option is a conventional Hook clamp with double nuts and washers on the yolk. (The lower nut will pivot and the top one should stay put) Link to comment Share on other sites More sharing options...
Seano Posted March 28, 2008 Share Posted March 28, 2008 Another option is a conventional Hook clamp with double nuts and washers on the yolk. Not a great idea imo. You could end up with egg on your face. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.