New to rigging. FK/IK rig. FK rig does not move with mesh

Hi there!

I’m new to rigging. I’m trying to put a rig together for a piece that I’m trying to finish up. I found these videos by DanPro on youtube:

I feel like I was able to follow along well, but when I got to part 3 I’m noticing that it looks like my FK rig is not affecting my tentacle’s mesh when I move/rotate any of the bones on the FK control rig. It works fine with my IK control rig though. I was hoping someone could maybe help me figure out what I’m missing or did incorrectly. (attaching a copy of my .blend file here:

I took a little video of how the mesh behaves with IK vs FK as well:

Any help would be greatly appreciated. Thanks!

there can be a lot missing,
but in your video you can see the FK-IK-switch right at the beginning in the Npanel,
so you should be able to switch.

in your video you only make the layer with the Ctrl-bones visible

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The behavior is the same whether my FK/IK switch’s value is at 0 or at 1. If it was working as intended that would indeed due the trick.

I’m not sure if that means that I set up the driver for that switch wrong or if something else is the offender. I’m still trying to figure it out.

I had overlooked the file.

Actually, you just used the wrong deform-bones for the tentakel-geo!

with these bones it should work:

then it works


the setup was correct so far,
I would only recommend to model and rig the arm straight,

if you wanted to learn okay, if you only need a still i would rig it only with one fk-chain

there was still a difference between restpose and poseposition,
this must not be and must be avoided.


maybe using wrong spaces

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@walt1 Thanks so much for taking a look at my file. I’m glad to hear that it was just some user error on my part. I’m not sure I completely follow though on how to fix what is incorrect in my file. As far as I can tell in the file I provided the MCH.INT.ARM.001 - 011 bones have the deform box in bone properties check boxed to on already like in your screenshot. What am I missing here?

I’m definitely still learning. I’d definitely model a straight tentacle next time around. This originally started as just a sculpt for fun in zbrush, but then I decided I wanted to push it to a complete and textured piece. I figured it was an opportunity to learn something about rigging and also a smart move as opposed to having to retopo/bake/texture 8 bespoke tentacles. I figured easier and more effective to do all that for one tentacle and then pose the other seven to match the pose of the concept.

the fastest way is to rename the vertexgroups from the tentacel
eg DEF.ARM.009 to MCH.INT.ARM.009 and so on at the end these are the groups
MCH.INT.ARM.001 till MCH.INT.ARM.011

see gif


you find them in the green triangle of the GeometryProperty.

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Awesome. Thanks so much that got it working for me. I really appreciate the help!