DMX Drop Box

[OllieDuff]

All this electricity seems vastly too complicated - just got back off a tour of King Lear that required a noose to drop from the grid on cue, which was done mechanically using a pin hinge and a bit of string.

 

To summarise: pin hinge, tripped by a bit of 3-4mm black nylon cord (22 quid for a 100m drum from Flints Hire and Supply, and it's worth buying some to have around as it solves an awful lot of problems in theatre), run through some cable ties looped around the grid to your desired location (control point, wings, even to the green room!). Give it a sharp tug and problem solved. As for finding someone to pull it, either press-gang someone into ASMing, or get an offstage cast member to do it on cue.

 

We only had one early drop and that was when we ran the line into the wings and down into the path of a half-dozen cast members running onstage. Solutions include taping the line to the wall at around chest height and pulling it above the tape; prevents it getting snagged on anyone and even if it snags below the tape, it doesn't matter unless you properly yank on it.

[paulears]

Super systems are fine - Tom on here has a superb one with kabuki style solenoids all wired up to a purpose built control. Really great. Drop boxes tend to be the thing the carpenter knocks up in ten minutes when the director has the idea, sticks a lighting clamp on the top to fly it and a bit of chord. If you are doing a multi-event show with a demand for beat accurate operation from the desk, then go ahead - but we're drifting into delusions here for the stated purpose.

[CharlieH]

Super systems are fine - Tom on here has a superb one with kabuki style solenoids all wired up to a purpose built control. Really great. Drop boxes tend to be the thing the carpenter knocks up in ten minutes when the director has the idea, sticks a lighting clamp on the top to fly it and a bit of chord. If you are doing a multi-event show with a demand for beat accurate operation from the desk, then go ahead - but we're drifting into delusions here for the stated purpose.

Although the show in question is only small, I am building the box to last (hopefully), so when I am in a production meeting and the director wants something to fall I haven't got to think about it, but just know I have one sitting at home waiting. Granted, it doesn't need DMX and all of that, but I would like something a bit neater than string (although I am sure it works fine, and that was my plan way back at the beginning!).

 

I also want to build it to test myself - to see if I can, and to give me confidence to build more devices like this in the future if necessary. Yes, I could get the maintenance team at school to build the box, but what do I learn form that? At least this way I can be sure I am capable, should something need doing again in the future.

 

Thank you for all your help, and I Smallsy I may PM you for advice in a week or so http://www.blue-room.org.uk/public/style_emoticons/default/smile.gif

Charlie

[brainwave-generator]

I think you've forgotten there is a way you could do this that:

a) Still allows you to control it from a cue on the desk; but

b) Doesn't require it to be connected by DMX.

 

Using the correct size transformer, you could connect it to a dimmer out.

 

I would probably use an electric motor to pull a drawbolt away from the door, rather than using electromagnets. Shut the door, move the bolt over by hand. Bolt has a rack on it and motor attached to the pinion. When motor is sent power, it draws back the bolt and the door drops open. Simple.

 

By connecting it to a dimmer out you escape all the DMX problems but it can still be saved as a cue.

[mac.calder]

I have done DMX drop boxes before - the trick for getting around the safety aspect is similar to how DMX flame jets etc work - Multiple channels required to fire. The one I made was 7 ways using a DMX mains switch pack and an 8 way relay card. Ch 1 would turn on the switch pack, the next 7 channels were for setting which drop boxes would fire then the 8th was for FIRE.

[Ynot]

Another vote from me for KISS.

 

The last two drop boxes I've done have both been VERY simple mechanisms, made from timber and a pin hinge, with LX hook clamps holding it up and 3 or 4 eye bolts to run the line through to stop it sagging.

 

You say there is no-one off stage who caan be trusted to carry out a task as simple as yanking on a piece of sash line on cue? I would say you're perhaps not giving those on stage the credit that they may be due. FIND someone who can be trusted to act on cue. Simple.

 

 

 

[TomHoward]

We used solenoids with a marine snap shackle, mounted on a folded piece of perspex, and a 8-channel DMX relay box to fire them. They run at 24V, and we used two-channel safety in a way - we connected the power supply up to a lighting channel, so that the channel has to be turned on and the DMX relay closed in order to fire them. They would drop most things with a bit of fishing line tied to them.

 

http://img829.imageshack.us/img829/1739/drop1d.jpg

 

The way that we had them mounted up meant they were easy to reset - you just close the shackle. To be honest, although the door release solenoid you linked to is a bit pricier than a chassis solenoid, the fact that you don't have to worry about the spring return etc means that if you're only making one, it's what I'd probably use. Just be careful extending it with mic cables - the solenoid pulls 1.3A - you want to be careful that isn't too much for the cables - might be better to just use a proper bit of two-core flex mains cable (shouldn't be expensive) - or speaker cable would be more suitable than mic cable at least.

[CharlieH]

I would say you're perhaps not giving those on stage the credit that they may be due.

 

 

I didn't say nobody could be trusted, I said there was nobody there at all! There is a cast of 6 in the performance, and all 6 are onstage at that moment. There is no other stage crew, and Senior Management don't want to get other people involved as it would involve taking them out of lessons for rehearsals/performances.....so it's not that I'm not giving them credit, but that there is no-one to give credit too http://www.blue-room.org.uk/public/style_emoticons/default/wink.gif

[paulears]

Charlie - you need to ask the question that if the project is not considered important enough by the management (and I'm amazed your teacher isn't able to do it - if it's for the exam) then why are you even considering it? If you cannot find the extra person, and surely a bit of string hidden for somebody to tug isn't too much to ask, then the school have their priorities very wrong. You mentioned it's moderated, so that means a member of staff has to be there. Tell them to make it happen at the right moment!

[the kid]

Unless I missed it what is being dropped ? and where ? and what context?

 

I am SURE someone could be called upon.

 

OR can you move the desks to side of stage ? it would me you can do everything needed.

[indyld]

I know you can hire a device to do this, but I would like to build one as a) I believe it would be good for me, and b) I think it would be useful to have in future.

 

 

This smacks of an age old BR style of thread where enthusiastic learner comes to the table for advice on a project they have in mind, followed by the more experienced members saying "Hey why make it so complicated. At the National, we just use blu tack... etc"

 

The issue is that in the first instance, the project is dreamed up by the learner to test themselves, while the latter group are simply concerned with getting shows on in a cheap and reliable manner. There has been plenty of sensible suggestions to the technical query, so I'll leave that.

 

To the OP, the "I would like to build one" is a perfectly valid reason for doing it. My question would be "Why does it have to be built for this show?"

 

If it's a question of funding, is the show budget really going to fund such a whim? Presumably, there are plenty of other things that the money/time could be directed at. In the production world, we all do big and small calculations all the time, namely: How much better will this make the show? Is is worth a piece of string or 60 man hours and half the Farnell inventory? Every show comes up with a different answer and I've worked on plenty of large tours where you can't help feeling that a certain £20,000 or all that additional crew could have been better deployed. But we do the mental calc, on using that extra bit of gaffa tape, right through to needing another 45 footer. How much better will this make the show?

 

The idea that such a drop box system would be a capital item (I.e would be worth the money/time because it may be used again) is pretty obscure in most show environments unless you were a hire company or a producing theatre with a space in the sub-stage LX storage cage. How many shows a year get put on using a fresnel? How many need an electricity controlled drop box?

 

But in an educational environment, we can add the cost/benefit of learning. Great. Ok, hang on, that dismisses the capital theory completely, as how will the next lot of learners learn if they don't need to make their own drop boxes?

 

So we are not sure about the cost/benefit to the show and we have written off the item as a capital project. We are left with the learning opportunity for the OP. What if there was a better learning opportunity? What if time would be better spent on, I dunno, the lighting design or the soundscape or painting the set or taking a few more hours over the focus? Perhaps that's all someone else's job and the OP is simply Head Of Drop, in which case they can be tempted to make it as complex as possible in order to make the role worthy of such a title.

 

If not, then perhaps the time/money would be better spent on something that makes the show better as a whole. Better posters or interval drinks if no one can come up with a production improvement.

 

None of this precludes learning, it's actually learning to pick your winners in amongst the many facets of making a great show. And if the OP still fancies having a bash at a DMX controlled drop box, no harm in that. I would just not hide that curiousity behind the the supposed needs of the show or the notion that it will provide a legacy of production kit.

[CharlieH]

(and I'm amazed your teacher isn't able to do it

I imagine he would be able to, but the whole point is I want to do it myself! If he had done it then this discussion wouldn't have started, and I wouldn't have learned what I have done from googling subsequent to it. And I hope to learn much more whilst building the box; none of which I would get from him doing it.

 

I imagine a person could be found if necessary, I have been asked to avoid it if possible, but it is a fallback if required.

 

@TheKid: Somebody will shoot into the ceiling, and we want sugar glass to fall from the grid when this happens, along with sound and lighting cues to portray realism (our chosen practitioner is Stanislavski).

 

@indyld: The project is going to be funded by me, which is why I am not so fussed about it being the cheapest option. Because of this, it will be mine and so should someone want to make one in the future then they will have the opportunity to; however should it be needed again then I can use it at school. Your logic re cost vs effect makes sense, but at the end of the day its usefulness in the real world is an added advantage. In the same way people sped money on model train tracks.....they are effectively useless for actual jobs, but people buy them for the fun. If this can be useful, as well as giving me the experience of building it, then bonus!

[J Pearce]

Charlie - make it with a solenoid, run it back to the control position on cheap twincore speaker cable, wire it into a lab supply pack on hire from the science techs (schools have an internal currency of biscuits) via a small push to make switch.

 

Then discuss in your portfolio work how you could have made it DMX controlled, but decided it wasn't worth the financial outlay and hours.

 

The cues would probably have to go at different times anyway, LX flash + sound for gun, shortly followed by solenoid + sound for falling glass. This is another thing to talk about in your portfolio work...

 

Have fun!

[indyld]

Then discuss in your portfolio work how you could have made it DMX controlled, but decided it wasn't worth the financial outlay and hours.

 

Yes! Do this, bearing mind my previous post about cost/benefit to the show. Then you are really motoring in the world of professional production.

[Smallsy]

Mate just make the DMX Drop Box.

 

I have no idea why people are telling you to use a pin and string after you've said you want to make it and learn from the experience. Plus looking forward into the season ahead for myself, I have countless needs of DMX drop boxes, hell I'll buy yours off you to add to mine if its well made!

 

From some of the good posts on this topic you might have figured a solenoid is probably going to be your best bet. The only real tricky bit would be turning your DMX signal into a power source to power the solenoid.

 

I directed you to milinst where they have a DMX relay box. I would suggest looking into something like that or some kind of relay. Do you have DMX non Dims in your venue?

 

Let me know if you need any more information. While I'm happy to walk you through making one you might want to do some research on a few topics first e.g AC/DC Power, Relays, DMX, Solenoids, Transformers.