# Track to Constraint Problem

**URL:** <https://blenderartists.org/t/track-to-constraint-problem/386229>\
**Category:** Animation and Rigging\
**Created:** [March 29, 2007, 1:45am UTC](https://blenderartists.org/t/track-to-constraint-problem/386229 "2007-03-29T01:45:02Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![3Deusz](https://blenderartists.org/user_avatar/blenderartists.org/3deusz/32/4683_2.png) [@3Deusz](https://blenderartists.org/u/3Deusz)\
**Post date:** [March 29, 2007, 1:45am UTC](https://blenderartists.org/t/track-to-constraint-problem/386229/1 "2007-03-29T01:45:02Z")

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Hi All,

I was riggin a simple blender character, when I noticed my track to constraint stopped  
working after I just checked if it worked. I apply the track to constraint by selecting the  
bone I want to point to the **knee.r bone**. After I applied it I can see it works when I select  
which axis to use. But If I choose an other axis than the default (y axis) then the **knee.r**  
 wont work no more as if its not constrained !?

This is really frustrating as I have ablsolutly no idea why It would do this ?

Any suggestions ?

Thanks in advance !

Tadeusz

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**Author:** ![ROUBAL](https://blenderartists.org/user_avatar/blenderartists.org/roubal/32/1006_2.png) [@ROUBAL](https://blenderartists.org/u/ROUBAL)\
**Post date:** [March 29, 2007, 4:59am UTC](https://blenderartists.org/t/track-to-constraint-problem/386229/2 "2007-03-29T04:59:27Z")

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Hi!  
I’m not sur that I’ve understood well, and I’ve not time right now to make a trial, but I think that you could solve your problem using an empty for the Track To constraint , and copy its rotation by applying a Copy rotation constraint to the bone.  
The only thing that I don’t see well is the parent that you would use for the empty…  
You could probably parent the empty to the previous bone in the chain, and put it at the center of rotation of the bone you need to constraint…  
Is it understandable ? Am I completely wrong ? :rolleyes:  
Philippe.

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**Author:** ![3Deusz](https://blenderartists.org/user_avatar/blenderartists.org/3deusz/32/4683_2.png) [@3Deusz](https://blenderartists.org/u/3Deusz)\
**Post date:** [March 31, 2007, 8:31am UTC](https://blenderartists.org/t/track-to-constraint-problem/386229/3 "2007-03-31T08:31:40Z")

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Hey Roubal

Thanks for your suggestion, but I must admit I used a IK in stead, and worked right away.  
I read somewhere in the wiki documents that the track to constraint could be alittle tricky.  
Something to do with the fact you wanna use the **Z axis** of the **upper\_leg** which is against  
the way orientation of the **upper\_leg** bone is set by default, if i got it right !?

But anyways if an IK sovler can do it then I wont have any problems with that. but thank again for helping.

Tadeusz