OakwoodSteve Posted May 27, 2014 Share Posted May 27, 2014 Hi. Apologies if this has been discussed before - I did search and didn't find anything related. I sometimes hang mirror balls in venues that will run unattended. I hang the ball on a chain from the motor (which is generally strapped to a nice strong beam). I put a steel safety from the ball to the motor's safety point (which obviously turns with the motor), and also one on the motor going around the beam. What I'm wondering is what would happen if for any reason the ball or chain got caught on something? For example someone decides to hang some fabric drapes and puts them too close to the mirror ball. As far as I know the motor would continue turning, winding the fabric up until it starts ripping it apart and generally wreaking havoc. The motors I use are pretty strong! So would it be a good idea to use a swivel coupling between the motor and the chain? That way if anything got caught the ball would stop turning even though the motor's still going. However the swivel coupling becomes a single point of failure as I would have to attach the safety to the swivel coupling rather than the motor's safety attachment point. I hope that makes sense. Anyone have any experience or suggestions? Many thanks,Steve Link to comment Share on other sites More sharing options...
timmeh2 Posted May 27, 2014 Share Posted May 27, 2014 Hi Attaching two safeties to the same point will essentially make it worthless. The rotators I use have a closed eye at the bottom of the spindle for attaching the ball chain and then another eye sticking out the side of it for doing the safety. I presume yours are similar? Putting all your eggs in one basket would be a no-no. In any case, the mirror ball really isn't the issue as it offers a fairly smooth surface to something brushing against it. Your problem is going to be the chain. What I do is cable-tie the safety and chain together so they don't flap around and then put either black spira-wrap or split PVC tube around the chain to reduce the risk of it snagging something. All you can do is eliminate the risk as much as you can; if some numpty sticks a bit of cloth and it gets caught then it's their issue really. If this is a dry or long-term hire type of thing then it's the venue's responsibility to make sure this doesn't happen, not yours really. All the bestTimmeh Link to comment Share on other sites More sharing options...
OakwoodSteve Posted May 27, 2014 Author Share Posted May 27, 2014 Hi Attaching two safeties to the same point will essentially make it worthless. The rotators I use have a closed eye at the bottom of the spindle for attaching the ball chain and then another eye sticking out the side of it for doing the safety. I presume yours are similar? Putting all your eggs in one basket would be a no-no. In any case, the mirror ball really isn't the issue as it offers a fairly smooth surface to something brushing against it. Your problem is going to be the chain. What I do is cable-tie the safety and chain together so they don't flap around and then put either black spira-wrap or split PVC tube around the chain to reduce the risk of it snagging something. All you can do is eliminate the risk as much as you can; if some numpty sticks a bit of cloth and it gets caught then it's their issue really. If this is a dry or long-term hire type of thing then it's the venue's responsibility to make sure this doesn't happen, not yours really. All the bestTimmeh Hi Timmeh, Thanks for that. Yes, my motors are the same. That's always been my thinking as far as attaching the safety and chain to the same point being worthless. I suppose I'm evaluating the trade-off between having a properly attached safety vs. the risk of something snagging, but you've confirmed my original thought that a single point of failure is a bad thing. Good idea re the spiral wrap on the chain, might look into that. Another thought that's just occurred is that I could set up an emergency stop button if I'm really worried. Maybe a bit OTT but that and a proper safety would certainly seem an easier setup to defend if necessary. Many thanks,Steve Link to comment Share on other sites More sharing options...
empyfree Posted May 27, 2014 Share Posted May 27, 2014 Usually doesn't take too much to stall a mirror ball motor. We've some "heavy duty" motors for our 1m dia balls, a stray XLR snagged onto one and wound itself into a knot, the gearbox gave way fairly swiftly. Link to comment Share on other sites More sharing options...
AHYoung Posted May 27, 2014 Share Posted May 27, 2014 On the few occasions where utter numpties have taken it upon themselves to attach a safety chain to a secondary point on one of our large mirror balls, the motor doesnt stall but keeps going untill it snaps the links of welded chain after wrapping it round and round this has happened more than once. Its an occasion where the actions of inexperienced being safety minded results in exactly the opposite. To The OP, why introduce a very real point of failure to a tried and tested design the modification to mitigate an extremely unlikely set of circumsrances which in reality adds a much greater risk of failure - in all reality, how many actual mirror ball failures have there been, and there are a lot up there... Link to comment Share on other sites More sharing options...
bigclive Posted May 27, 2014 Share Posted May 27, 2014 Most small to medium weight rotators are not excessively powerful, and the use of a non-direction al synchronous motor usually means that when they are stalled they will just reverse direction. I suppose it's all down to how strong a chain you use. Cue the mirrorball cartoon.... Link to comment Share on other sites More sharing options...
Seano Posted May 28, 2014 Share Posted May 28, 2014 Most small to medium weight rotators are not excessively powerful, and the use of a non-direction al synchronous motor usually means that when they are stalled they will just reverse direction. I suppose it's all down to how strong a chain you use. If the motor isn't excessively powerful, it does seem that the chain is excessively weedy. Doesn't sound right to me. Cue the mirrorball cartoon....Fab. Not seen that for ages. :) Cue Boy George reference.All together now: "Do you really want to huuuuurt meeee...." Link to comment Share on other sites More sharing options...
OakwoodSteve Posted May 28, 2014 Author Share Posted May 28, 2014 To The OP, why introduce a very real point of failure to a tried and tested design the modification to mitigate an extremely unlikely set of circumsrances which in reality adds a much greater risk of failure - in all reality, how many actual mirror ball failures have there been, and there are a lot up there... Yep, sorted. Forget the swivel and carry on as before. Link to comment Share on other sites More sharing options...
AHYoung Posted May 28, 2014 Share Posted May 28, 2014 ive got a few syncronious motors ie only go one way that are still fairly small, but definitely will wind a chain to snapping point, its happened several times. Im talking standard safety chain ie welded links and reasonably strong but it still breaks. But I think the point is that the only time ive seen a mirror ball disaster is when someones shoved an access tower into a mirror ball that turned out to be hung on the thinest cable tie youve ever seen, no doubt because the thing like you keep your keys on got lost . Ie clumsy stupidity combined with bodging a fix after loosing a cruicial part. anyone know of a actual mirror ball failure? even when we rented our 2 man lift 1m one out and the customer didnt use the supplied 1/2 rpm hd motor but swapped it for the fast 5prm one off an 6" ball thats rated at about 1kg and attached it with some green garden wire no-one died, Link to comment Share on other sites More sharing options...
AlRamsay Posted June 2, 2014 Share Posted June 2, 2014 even when we rented our 2 man lift 1m one out and the customer didnt use the supplied 1/2 rpm hd motor but swapped it for the fast 5prm one off an 6" ball thats rated at about 1kg and attached it with some green garden wire no-one died, I personally hate mirror balls, but that doesn't stop me owning a 2'6 millstone of a mirrorball that despite my best efforts keeps being returned to me http://www.blue-room.org.uk/public/style_emoticons/default/mad.gif Link to comment Share on other sites More sharing options...
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