# How do rigs relate to weights?

I'm practicing rigging a finger. Why is the tip getting smaller when I rotate it? And hopefully someone has tips on rigging a hand/fingers.

• A small tip. Blend your weights more. It goes from red (100%) to blue (0%). As you can see, your geometry is overlapping. Feb 4, 2016 at 19:03

If vertices of the tip of your finger were weighted 1.0 to the last bone and 0.0 to every other bone in the rig, you would have your tip moving exactly with the tip bone. As I can see in your screenshot, the tip vertices of your finger do not follow the bone completely: surely they are weighted to some other bones, and this is the reason why they get distorted. Also if a vertex is weighted 0.1 to one bone and 0.0 to every other bone, it will exactly follow the movement of that bone(Blender always introduces a "normalization" of values: even 0.001 is infinitely higher than 0.0). So, select all the tip vertices, assign them a weight of 0.0 relative to all others bones, and you will have no deformations at all of the tip and exact following of the tip bone movement.

• Ah thanks a lot. What a dumb mistake, and the answer was also in Paul's picture. See I got confused. I thought that to move the finger at its root, everything from the root to the tip needed to be red, since you are moving the whole finger. Then, to move it at its first joint, everything from that joint up had to be red, etc. So how it really works is that everything from the root of the bone up will move, just that the blue area will move untouched and the red will stretch or bend. Or something like that lol.
– SRCP
Feb 4, 2016 at 22:37

Some tips:

• a good topology is very important for smooth joints transformations (try to model your finger as pictured below and you'll see how smooth it bends)

• a proper mesh weights assigment is crucial for realistic bend movement (I suggest you using the With Automatic Weights parenting option. Select your mesh, then the bones and press Ctrl+P-->With Automatic Weights. This'll automatically aassign the proper, blended weights for all bones)

• Thank you. Nice geometry. I do know to blend my weights and how to use automatic weights, and that the finger I show is pretty primitive but it's just an example. How would I need to modify my vertices or weight paint to achieve a result like in the link? It's alright if the vertices overlap and the joint is not the smoothest, I just want the tip to rotate rigidly without getting smaller. i.stack.imgur.com/t4M2a.png. In the picture you show, most of the tip is red too, I don't know why mine gets smaller.
– SRCP
Feb 4, 2016 at 20:03
• I just copied your geometry and it worked really, really well. Thanks again.
– SRCP
Feb 5, 2016 at 7:09