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faulty gimbal or bad DB?


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#1 Wing Gee

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Posted 05 July 2006 - 11:16 AM

Trying to figure out if my gimbal is out of whack or i'm just not balancing correctly. When I static balance. Then spin the rig 180 degrees from it's original position, (camera facing opposite direction) the top of the rig is now tipped a bit forward. Trying to figure out if this is a gimbal issue or me not spending enough time trying to get it in to dynamic balance.

Thanks!
Wing
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#2 Afton Grant

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Posted 05 July 2006 - 11:40 AM

Hi Wing,

It's almost definitely a balance problem. Unless you hear or feel any strange noises, grindings, or other odd phenomena coming from the gimbal, you can be assured it's most likely operating properly.

Dynamic balance is a tricky thing at first - and can be tricky for long after that, too. If you haven't already, study Jerry Holway's Dynamic Balance Primer. Also, read through other posts here regarding the issue. There are a lot of different tips and techniques you can try out.

Best of luck,
Afton Grant
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#3 Wing Gee

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Posted 05 July 2006 - 12:01 PM

I guess i should have mentioned this first. The gimbal I have is a home built gimbal, I got it on a groupbuy on hbs. the bearings are really smooth. One thing i'm not certain about is whether or not the yoke is centered with the rest of the gimbal.

This gimbal is on my 3a sled.

Here are some pictures of the gimbal.

http://www.turborocc...ingcam2/gimbal/

I guess i should have mentioned this first. The gimbal I have is a home built gimbal, I got it on a groupbuy on hbs. the bearings are really smooth. One thing i'm not certain about is whether or not the yoke is centered with the rest of the gimbal.

This gimbal is on my 3a sled.

Here are some pictures of the gimbal.

http://www.turborocc...ingcam2/gimbal/
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#4 Peter Milanov

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Posted 05 July 2006 - 12:20 PM

I would say it sounds like a problem with the gimbal. It´s definitely not a dynamic balance issue as the rig is still static and just facing the opposite direction.
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#5 Yookidoo71

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Posted 05 July 2006 - 01:33 PM

I have to concur with Peter. What you have here is a faulty gimbal. The tilting you have described after panning 180 indicates that the pan axis is not aligned with the tilt axis (the axis in the yoke handle). Depending on the design of your gimbal, this could be corrected to some degree by placing small shims between the pan housing and the yoke. This will effectively move the pan axis into position so that it agrees with the tilt axis.

On a side note, the misalignment you describe is the reason why a really good gimbal (PRO, XCS, Tiffen) costs upwards of $5-7k. The precise alignment of the axes is all in the design and the machining.

Good luck,

Jeff L. Clark, SOC
Los Angeles
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#6 Brant S. Fagan SOC

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Posted 05 July 2006 - 02:06 PM

Wing--

This sitation is common for gimbals whether they are home made or a factory produced unit.

Most often, the pan bearings have worn to the point of failure to align with each other and the bearing carrier thus allowing your rig to balance in one position and not in another.

What has to happen is a precise measuring of the components and new bearings installed along with shims to correct the dimensions inside the bearing carrier housing. Once things are realigned and reassembled correctly, your repositioning or panning of the sled should not affect the trim of the sled.

Best,

Brant S. Fagan, SOC
Steadicam/Camera Operator
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#7 Wing Gee

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Posted 05 July 2006 - 02:18 PM

Thanks everyone for the advice and comments.

The bearings are all new (new gimbal). I think i just need to shim it correctly. which i had to do with a older crappy progear 3a gimbal.

At least i have a better understanding now and not freaking out cause i can't get the sled into DB.

Thanks!
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#8 Wing Gee

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Posted 05 July 2006 - 09:56 PM

The gimbal works fine now. I placed some shims in it and now it holds balance. Sweet!
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