So I exclusively set out to make a simple character for animation. I decided instead of a hand, I’ll use a claw (like a lobster’s) because it’s simple and won’t requie a lot of technical stuff. Well, I can’t get it to animate right even after following an IKA tutorial. For example, say I rotate the whole claw (big pincher and small pincher) 45 degrees . From there, I want only the small pincer to open ( as if it were to grab something) but it goes everywhere but perpendicular to the large claw. I tried setting up a constraint and still can’t get it right. Any suggestions?
use a locked track constraint on each part to specify where they point
create new bones which they lock track to
Here’s a pic of what I have going:
Could anyone tell me where to put the bones, and if there should be any special null bones or parenting going on. Everything is one mesh.
Nice mesh 
If I were you I would carefully align the bone of the mobile part of the claw so that one of its axis (z?) is perpendicular to the plane you want your claw to move on, then when animating I would make constrained (local z axis) rotations
Stefano
Thanks S68! I still have some tweaking to do though. 
I’m in a rush to leave the house, sorry if this is confusing…
Here’s a simple example of what armatures I’ve tried using, sometimes with null bones or IKA’s according to tutorials. On the claw on the right, the bones are usually parented to the second bone segment.
Where would I put bones to line up the constraint to? This screen was taken from the Top View (num pad 7).
Thanks for the help, I still need to be walked through the basics! 
this is the way i’d do it: (see sketch)
the empty moves the bone chain, the claw itself can be moved using keyframe animation or action constrints
When I try to add an IK solver to the empty, it’s not on the list of constraints. I’ve been messing around for a while now with basic animation tutorials on the web and what not, heck I even read the documentation. I had no trouble animating Gus.
I’m getting off topic.
A few questions:
Does the empty take the place of the bone connecting the claw to the arm?
When I try adding an IK solver, sometimes the name of it turns red. What does this mean?
if anyone wants to contact me on AIM, it’s Noplasticrobots.
Thanks for all the help, this is a great community!
sorry i wasn’t clear enough:
- make sure you know the name of the empty (e.g. Empty.001)
- select the armature, press CTRL+TAB (pose mode)
- select the bone in the red circle (from my picture)
- add an IK constraint, in the Ob field enter the name of the empty and press enter
- the bone will move now to match the position of the empty
- leave pose mode (CTRL+TAB again)
- moving the empty will move the whole arm now.
I followed everything down to the tee, but its still not working. Believe it or not, I completely understand all the instructions.
Based on your set up, when the whole claw is at an angle and the small claw bone opens, it should open along the same plane as the empty instead of going in a tight circle like it does now?
Send the .blend with claw to me (e-mail in profile) if you wish…
I’ll try to rig it
Stefano
Sent! Thanks.
Re-sent!
Stefano