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Sled balance issue

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#1 maxfischer


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Posted 25 September 2014 - 06:55 PM

I'm prepping for a 4-month long job today and tomorrow, and have run into a balance issue that I'm hoping someone can solve ASAP.  FYI these issues just popped out of nowhere, they're weren't on the last job I did (which was of course with a completely different camera configuration)



PRO Cinelive

Stripped Alexa with Ultra Prime

Cinematic Precision plate

3-3.5 second drop time


I get the sled balanced on the docking pin.  Then I tilt the camera 90 degrees up for a drop time test. The camera settles tilted WAY up (at around 35-40 degrees).  If I tilt the camera 90 degrees down and do the drop test, it settles tilted WAY down.  


Things I've tried:

Tightened everything on the camera and sled, screws, collars, D box

Taped the batteries tightly in position on camera and sled

Removed all cables to eliminate their possible weight shift

Tried balancing with the battery rack both extended and collapsed

Talked to PRO (Chad was nice enough to take my call 4 times and talk me through some possible solutions)


The only thing I've noticed that's a bit unusual is that if I put my hand on the gimbal handle when doing a drop test, there is a noticeable "thunk" at a certain spot, bot on the upswing and downswing.  But the thunk happens nowhere near proper neutral balance, so I'm not sure if it could throw it off that much.  And Chad said that the clunk could be anywhere on the sled and just transferring to the handle when my hand is on it, so those bearings could be totally fine.


I can also tell you that this camera setup is LIGHT.  Maybe too light, it's going to be really sensitive.


Tomorrow I'm going to try a different camera body, different lens, etc, and just try to eliminate those items.  I didn't get far enough into the prep to actually see if it affects my operating, but either way it's not a confidence-inspiring way to start a show.


Thoughts anyone?  Thanks in advance!

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#2 David M. Aronson

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Posted 25 September 2014 - 07:19 PM

Can you shift the sled back and forth on the yoke of the gimbal? It could be as simple as some screws on the gimbal backing out or as horrifying are having a bent gimbal yoke. I don't know if PRO Gimbals can be centered in the field, but you might try that.

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#3 Jens Piotrowski SOC

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Posted 25 September 2014 - 07:32 PM

Make sure the pan bearing inside the Gimbal is not loose
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#4 Michael Wilson

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Posted 28 September 2014 - 03:34 PM

I recently had my DB2 repaired.  It wasn't holding the plate securely and would slip forward during drop tests leaving it tilted forward when it came back up.


Try putting a strip of gaff on the plate where the clamp pushes against the plate.  That solved the issue for me until I got a repair.

Try putting only the plate on the top stage, clamping it down and seeing if you can push it forward.  Not sure if that is your issue but its worth a try.  

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#5 Sam Law

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Posted 28 September 2014 - 08:41 PM

I had a similar issue using a friends pro dovetail on my db2, with his practice cage set up.  My pro dovetail fits fine, for some reason his is about a millimeter different, and the plate seemed clamped in, but it was slipping slightly through my top stage when I tried to drop test it.  A strip of gaff on the edge of the dovetail plate fixed it just fine.  hopefully your issue is as simple as mine and Michaels was

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#6 Shawn Wang

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Posted 29 September 2014 - 12:44 AM

I believe its the play in the DB2/3. 
it happens quite often to my situations (I need to service it once per 3-4 month I believe). but after last time I put some arri oil and some white lithium grease, it never got loose again, so far. 
its quite simple job, just tight the square screw of your Fore/aft shaft (don't know what its called, its a golden one, easy to spot)
pro has a tutorial on this




hope it helps. 

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#7 maxfischer


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Posted 30 September 2014 - 09:18 AM

Thanks everyone, it sounds like the DB may be the culprit, I'll check it out today

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#8 Tim Fabrizio

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Posted 02 October 2014 - 11:12 PM

Update to what the problem was?

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