View Full Version : hinged arm rig

04 April 2008, 06:19 PM
I'm rigging a hinged arm (see image below), and I've been trying to use expressions without success. For example, rotating joints based on translation of the end controller to get collapsing effect.

I suppose set-driven key will work, but I don't really like it. Whatever solution I use I will want to be flexible enough to have squash and stretch option.

I found a 'lift door rig' on highend 3d maya rig downloads, but need it in .ma. Tried the .mb to .ma converter app (PC only), but couldn't get the app to run.

Anyone have a minute to save it out as a .ma?


04 April 2008, 06:53 PM
It was too big to upload, so here's a link. Hope it's the right one. (

04 April 2008, 07:14 PM
What version of maya are you using? If you're using 8 or higher you can use the "ignore version" in the open scene options. Or you can use the file that Yung got set for you:)

04 April 2008, 07:22 PM
Yungimoto, thanks a ton. Now to reverse engineer...looks like he used expressions.

X, good tip.

04 April 2008, 08:04 PM
Ok, so it looks like as the arm stretches out the translation of the joints (or locators the joints are constrained to) should increase exponentially, or ramp based on a translate value of a control.

Ideas about how to create an expression to do this?

SDK would create animation curve (ramp) based on start and end keys I guess, although I would prefer not to use SDK.


04 April 2008, 01:11 PM

04 April 2008, 09:22 PM
Perfect Nate, thanks.

04 April 2008, 09:26 PM
was good timing on your part - they just posted that vid last week I believe...

04 April 2008, 10:47 PM
another way, probably the easiest, would be to just use the spring-ik-solver which basically is built to do excatly that ;-)

just make a joint chain and an ik-handle, type "ikSpringSolver"
and switch the ik solver to the new created springsolver

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04 April 2008, 10:47 PM
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