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-   -   Where is the center of gravity on an XL2? (https://www.dvinfo.net/forum/jibs-cranes-booms/52980-where-center-gravity-xl2.html)

Jason Varner October 18th, 2005 09:27 PM

Where is the center of gravity on an XL2?
 
I recently built a small crane for my xl2. It's a fairly simple model using pulleys and an underhung sled. I want to modify it so that I have tilt control. If I can figure out the center of gravity I can have a sled fabricated that will put the camera's centerline on that of the pulley's and keep the apparatus balanced which seems to be the key in any jib/crane contraption. If anyone out there knows where the magic spot is I'd appreciate the help. Thanks, Jason.

Greg Boston October 18th, 2005 09:34 PM

As you probably know, the stock XL2 is a bit nose heavy. Your best bet is to put some weight on the rear accessory bracket that will put the CG right at the tripod connector screw. This will simplify the design of the support sled.

-gb-

James Emory October 19th, 2005 01:06 AM

Another way to find CG is to simply place a pen under the base on a flat, level table and adjust the pen back and forth until it balances on the pen. That point will be the CG.

Vence Vida November 4th, 2005 03:37 PM

Jason,

I know it's been a couple of weeks since you posted, but I'm just stumbing across your question.

I built a crane a few months ago for use with my XL2. Like Greg said, I used extra weight on the rear - an ankle weight, like you use to exercise attached to the accessory bracket. I even use is when the camera is on my shoulder, because it helps to balance it in that situation as well.

The only problem with this, as you may have already discovered, is that one of the keys to a small home-made crane is the effect of even a few extra ounces out on the business end of the thing. It requires a great deal of extra counterweight at the rear to then balance the crane, and depending on how light you built it, the total weight can overwhelm the design very quickly. You are much better off finding the "sweet-spot" and rigging a way to place the center of gravity on your pivot point, rather than just adding weight to the rear of the camera. I learned from experience.

James Emory November 7th, 2005 01:38 AM

Jason, you really need to make a cut out and centered X (fore & aft, left & right) on the mounting plate where the bolt that attaches the camera plate will slide in for adjustment. This way you can slide the camera fore and aft to achieve the correct balance. That's how my jib's mounting plate is made and most others are as well.


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