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Author Topic: Moving Heads keep ending up off-target??  (Read 662 times)

Paul G. OBrien

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Re: Moving Heads keep ending up off-target??
« Reply #10 on: October 18, 2017, 08:15:57 pm »

Okay, so I have four moving heads which sit on the floor in a row.

Another possibility here, these heads don't weigh much and sounds like they aren't attached to anything so check that they aren't just twisting on the floor, it wouldn't take much movement of the base to change the spot position 20ft out a couple inches.
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Shane Crabtree

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Re: Moving Heads keep ending up off-target??
« Reply #11 on: October 18, 2017, 09:19:53 pm »

Did you also make sure the belt's gear/pulley is tight on the motor shaft?  I've had one or two instances where the set screw came a bit loose and caused the affected parameter to drift.  Aside from that and what you already tried, this is unfortunately one of the common issues with low-dollar moving lights.  Drifting a few inches isn't horrible though - I've seen much worse from generic fixtures, to the point that it can't hit the same location twice!  There's a reason why some lights cost $100, some $1000, and some $10,000...  Best of luck though!

Thanks! Yes, I've opened the first one and made sure the pan/tilt belts were tight. Had to pull just a bit to take a little slack out. Didn't do a lot to fix the issue, so I've gone through turning it on & off and doing tests with that, with both my DMX software open & closed.

Seems the issue arises when I turn on the unit, it goes through it's first initial panning check, and goes to Zero like normal, before I start any scenes. It's almost like it resets its' own XY parameters so that it goes way too far off target when I start up the first scene (pointing at a mirror ball.)

It's got one of those little spindle catch things around the panning gear that hits a sensor switch to start over when it's reached its' maximum pan rotation. I then tried creating a "calibration" scene, if you will, with some wonky rotation effects. After running that, I reverted back to my first initial scene, and it had at least moved the beam over the mirror ball.

Sooo, anyone have any good ideas for calibration-type scenes?
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Shane Crabtree

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Re: Moving Heads keep ending up off-target??
« Reply #12 on: October 18, 2017, 09:22:28 pm »

Another possibility here, these heads don't weigh much and sounds like they aren't attached to anything so check that they aren't just twisting on the floor, it wouldn't take much movement of the base to change the spot position 20ft out a couple inches.

Thanks Paul. To remedy that possibility, I've put masking tape on the floor at the corners to check whether or not they're moving. There doesn't seem to be any noticeable difference. Any tips on weighing them down just in case?
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Mark Cadwallader

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Re: Moving Heads keep ending up off-target??
« Reply #13 on: October 18, 2017, 11:45:05 pm »

Thanks Paul. To remedy that possibility, I've put masking tape on the floor at the corners to check whether or not they're moving. There doesn't seem to be any noticeable difference. Any tips on weighing them down just in case?

A old skool approach is to make a simple plywood and 2x4 base plate for the fixture to be bolted down upon. (Use the threads that are there for attaching an O-clamp.)  The added mass and friction will decrease any tendency for the fixture to "walk".

Slowing down the speed of movement will, as you found, increase the accuracy of positioning.  You are more likely to be able to stop your car exactly 12" from a wall if you are driving at 10 mph than if you are approaching at 30 mph.
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