I have two bones in an armature that derive their Y location from a separate Master bone. One uses a simple Copy Location constraint, the other uses a driver.

If I grab the Master bone and move it around, the two other bones' Y locations update as appropriate, though the one using the driver lags a bit.

If I reset (aborting the move of the Master bone) the bone with the driver remains stuck at its location. The bone with the constraint pops back to the original location as expected. If I then initiate another move of the Master, the driven bone snaps to where it should be and then follows again, though the lag remains.

How can I eliminate the lag of the driven bone as well as have it always update its Y location correctly? I can't use a constraint on that bone because eventually it will evaluate an expression to set its value rather than simply copying the Master's Y location.

The Blend is : here


Screen Grab


1 Answer 1


I believe that is a limitation of the current dependency graph and one of the reasons behind the work on creating a new improved one.

For now a workaround would be to have the bone with the driver to be part of a different armature than the bone being followed.

  • $\begingroup$ Excellent! The workaround does indeed fix the problem. And thanks for the explanation regarding the dependency graph. I've heard talk about work that's being done on that but never really understood what it was. Cheers! $\endgroup$
    – D. Waschow
    Commented Jan 13, 2015 at 13:34

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