Action Constraint question?

I’ve searched all through the Blender Bible, the Elysiun forum and looking for an example and an explanation of the action constraint and still can’t find a clear explanation.

I have Nozzy’s hand grabbing rig that uses this Action Constraint. But I can not figure out what the AC is and how it’s used.

Are there any tutotials that explain the action constraint and how it’s used.

Nozzy, if your out there, great rigging!

This is Nozzy’s gif, his thread is at

AC is the name of the Action datablock that you’re using.

I also have an example file on action constraints. You can probably find it lying around here quite easily, if not, I could fetch you a link.


I tried to find it but couldn’t. A link would be nice.

Theeth, I swear your brain is hard wired right into the internet. :smiley: It’s greatly appreciated!

Eureka, I found it! The answer that is.

The reason I was so confused was that I could not figure out were the action (In the AC window) was listed… So I did a little exploring and hit the browse button in the Action window, and there was a list of all the actions. (Light bulb goes on here.) Duh!

So, let me see if I have this correct.

  1. create an action for a bone, (give it a name that makes sense.)
  2. Now you can link that action VIA the Action Constraint and point it to the triggering bone. (Any bone can now call this action.)

In Nozzy’s hand rig, the finger bone movement is triggered by rotating the Handle.

It seems that there is a lot more to it but at least it’s starrting to make sense.

That’s correct.
There is indeed lots of applications. I usually use action constraints to create control objects. In a character armature, these could be used to control breathing for example. Mostly, I use them to quickly control complex but repititive motion.

And my file is there:





Theeth / Nozzy I tried it last night but could not get it to work.

After you create an action for the bone (index finger, bone 1, 2 & 3), is there another step before you enter the name of that action in the AC window? Do you have to do something to the handle?

I can’t seem to get a lnk between the finger bones and the triggering handle?

scroll down or use "search to find the action constraint


I saw that,

Perhaps I’m missing something in creating the action, do I need to to use the NLA editor with the action editor?

(1): The action-editor creates the actions that are then strung together in time using the NLA editor. Actions are a building-block which is then used in the NLA editor.

Calling it an action “constraint” might be a slight misnomer. What really happens is that, the rotation or other movement of a particular object on a particular axis, is mapped to the degree to which a certain action is to be applied. The example-de-jour is a muscle-bulge. As the elbow joint rotates in, the bulge-amount increases and vice versa. The action-contraint establishes and defines this correlation.

Ok, but what are the steps to make this happen.

1.)I created bone.001 then added an action and called it “move.something”

2.)then I added an action constraint to the same bone, in the Target OB textbox I entered armature name.

3.) in the Target BO I put the controlling bone “index” which is parented to another bone that is used as a controller.

4.) In AC textbox I entered the “move.something” action name.

i used the same parameters shown on the picture above.

When I select the handle in pose mode and rotate it, bone.001 does not move. :frowning:

In Nozzy’s hand rig when you move the handle, it moves all of the fingers.

Did I miss a step or is there a bug ???

For anyone following this thread, I finally figured out that I was not refering to the correct rotation of the target bone. Duh! I hate when that happens.

If anyone cares about learning how this all works, let me know if you want me to do a tutorial on it. If there’s enough interest I’d be happy to do it.

Theeth and Nozzy have some nice rigs too. Nozzy has a full body rig coming soon. Can’t wait to see it.

yes, please. i have been following along with this thread, and i think i am getting the general concepts, but i am still a little unclear on some of the finer points. a tutorial would certainly help.

jim ww

Thanks :slight_smile:

Check it out at