Building moving head fixtures

[Guest lightscan]

Anyone ever had the idea of building a diy moving head light fixture? Do you think it would be impossible or easy?

[Renny]

Daft question. Maybe you are a prodigy but otherwise don't even think about it.

[lifeisacabaret]

Bizarre question.

 

Seriously- building your own Moving Head Fixture.?!

[Meduza]

Of course it is possible, but it would be a lot of work... and if you have to ask the question it will propably be to hard for you...

[Light Console]

Sort of. When I was at college, we made a motor system with closed feedback, so the circuit knew where the motor was, as there was a variable resistor on the end of the motor spindle. This gave me the idea to try to make the tilt part of a moving mirror. I found that the motor often over-shot due to the momentum of the mirror, and then wobbled until it corrected itself. This was done with normal motors; most, if not all, moving lights have stepper motors, which are something I didn't ever study. I think if you do want to try it, move to the mirrors rather than the whole lantern, as mirrors are easier and lighter to move. Good Luck!

[paulears]

I think I could make a moving light. My electronics background from the early 80's lets me figure out how to control a stepper motor, but I'd have no idea how to implement DMX to make things work. The programming would be far, far beyond me.

[bruce]

I would think that for the "home constructor", the electronics and programming would be the easy part - and that's not trivialising these issues.

 

The hardest part would probably be the mechanical side - not many people have the necessary tooling in their garage :)

 

As to whether it would be cost-effective, the answer is almost certainly "no". It would need a huge investment of time, labour and expertise, plus a massive array of mechanical and electronic tools.

 

Very few people build any non-trivial "diy" devices these days, when a commercial (tested, guaranteed!) equivalent is available.

 

Even looking at things like kit-cars and houses - it's not really "DIY" - it's assembling parts which have been custom-manufactured for you...

[Boggy]

I built a moving mirror as my final year university project about 15 years ago. Moving a mirror requires less force than a moving head and allows different light sources to be used. The basis of the design (and a lot of modern equipment) was to use stepper motors to drive the mirror. If you can get your hands on a stepper motor interface for a computer you can put together a unit that will operate on the bench and will teach you about this type of gear (providing you can build the mechanical parts - aluminium is your friend!). The result of my project was a good mark for my final year and a job with a local moving light equipment supplier.

 

The problem with this design in practice is that you usually cannot extend the cables to sufficient length to put the moving mirror in the rig. To overcome this I would use a PIC chip to read a DMX signal and provide output to a stepper motor driver (lots of things for you to Google here). The problem with this is that it would take me 12-24 months of my spare time to develop the software and hardware for such a system and I would much rather spend my time doing gigs!

[dbuckley]

I would think that for the "home constructor", the electronics and programming would be the easy part - and that's not trivialising these issues. The hardest part would probably be the mechanical side - not many people have the necessary tooling in their garage

 

Absolutely. You've got to be good at lots of things to build a mover, electronics, software, optics and mechanicals.

 

The electronics is reasonably achievable, even rather expensive moving lights have logic boards the designs of which are within the capability of the competent hobyist.

 

If your other hobby is building robots for Robot Wars and you make it to the last couple of rounds then you probably have the skills and workshop to build the mechanicals.

 

A moving mirror would be an easier start point than a moving yoke: a quick look at a CyberLight shows the mirror assembly isn't terribly complicated, it is little more than a mirror, some gearing, limit switches and a couple of stepper motors. But that still leaves you with the stuff in the optical path. I remain amazed that the Chinese companies can knock out a mover for about 50p, even a truly cr*p mover is still a thing of wonder.

 

If you fancy a do-able challenge, a steerable parcan would be a good start point, and if a reproducible and affordable design, something that many folks would seek to build.

[RichD]

Sort of. When I was at college, we made a motor system with closed feedback, so the circuit knew where the motor was, as there was a variable resistor on the end of the motor spindle.

The old Abstract Futurescans used the same idea. They used servos out of radio controlled models which have a resistor for feedback. They use a lot smaller motors than normal steppers so are geared down a lot to improve the power but this means they aren't particularly quick.

 

I have a few in need of repair and have been thinking about combining the innards out of them and those out of LED Pars to get a basic moving head LED. That's about as far as I'd go down the route of making my own and even then it would be a bit of work to not make it look an eyesore in the rig.

[DMXBandit]

Building a moving mirror fixture is very doable. It depends on how much you want to design and build yourself or buy as pre made modules, and what you want to use the end effect for. For example, Milford Instruments sell a DMX to servo controller board which you could hook a few servos up for pan, tilt, colour and gobo, then you would make an aluminium box, stick them in with a bulb and a couple of lenses and your sorted. I have a pair of very old NJD IQ250's in my mobile rig and this is essentially just what they are.

 

If you have a greater electronics knowledge then you could make the servo controller yourself. I have done this using PicAxe chips, which are basically PIC chips which are programed with a form of the BASIC language (which makes it as simple as just saying something like "Servo 1, 160", which moves the servo on connector 1 to point 160). I just haven't worked out decoding the DMX yet :)

 

That would be a good place to start, and you could add extra features such as rotating gobos (you can mod a servo to continually rotate and its position value becomes its speed and direction), shutter etc, later on.

 

The problem with servos is that they are noisy, they over shoot, they are juddery, and they have quite a short life span. If you have a better electronics background then me then you could use stepper motors as already mentioned in this thread.

 

 

I do intend to make a moving yoke effect at some point, but its not something I'd do instead of buying them for my rig or anything.

 

Hope thats some help.

[ben.suffolk]

The hardest part would probably be the mechanical side - not many people have the necessary tooling in their garage

 

That exactly what would stop me doing it, and to be honest even if I thought I could get the optics right and all the other mechanical bits sorted, I'm pretty sure it would not look half as good in a rig.....

 

I have quite a few big stepper motors from fruit machine reels kicking around somewhere in the garage. Last time I looked at them I though to myself, I wonder how powerful those are, but then the moment passed in a flash as I thought about all the other issues. I suspect the electronics / firmware would be pretty straight forward but given the price seems to be dropping all the time on movers is it really worth it?

 

Ben

[Tomo]

A moving mirror would be an easier start point than a moving yoke: a quick look at a CyberLight shows the mirror assembly isn't terribly complicated, it is little more than a mirror, some gearing, limit switches and a couple of stepper motors.

It's even simpler than that - the majority of moving-mirror lanterns have NO mirror position feedback whatsoever.

 

For example, the Cyberlight actually only has two stepper motors and nothing else to drive the mirror - one is glued to the back of the mirror, and the other is bolted to the body and tips the other motor.

When reset, it drives both stepper motors roughly twice the full-swing distance, which rams the mirror against the mechanical endstops.

This means that if an endstop moves the mirror position will always be offset, which can be rather annoying!

 

The Cyberlight drives the steppers in 'half-steps' to get a higher resolution at the mirror, at the expense of torque - it's very easy for a Cyberlight to lose position calibration during use, so they need to be reset fairly often.

 

If you don't understand the terms I've used so far - don't start building yet.

Do some research into stepper motors and the difference between closed and open-loop control.

 

In summary:

It's perfectly possible to build your own pan & scan moving mirror, and you will probably have a lot of fun doing it.

As to making any money from it - forget it.

 

Have fun, and learn from the mistakes you make.