I have an armature with two (Blender Armature Bones) parts as shown in the first pictures. Each part connects with a small piece of bone (real leg bone) by parenting. In each end of the complex is an independent plane. In the middle part where the two pieces of bone connect, there are 2 planes overlapping each other. I need to be careful of the use of the words Blender Armature Bone and Human Bone.

One of the two planes was connected with the armature by "With automatic Weights", the other was created by Shift + D. Each of the middle plane has the Boolean as shown in the right of the first picture. Figure 1

The armature is not in it original position. When I use the command Alt + R to return it to the original position, the attached bone and the two middle planes will follow (Figure 2). Figure 2 However, if I join the some of these items together Ctrl + J, the parenting connection was lost. (In detail, I would like to join the left independent plane, the left bone piece and the right middle plane into one complex, and the rest into another complex). And when I use Alt + R again, only the armature returns to the original position. The others don't follow (Figure 3). Figure 3 So, how can I make them to follow the armature after joining?

Regarding about what I am trying to do, I need to design the cutting guide to remove a tumor in the lower jaw bone, then I would like to replace it with 2 segments of a leg bone as shown in the pictures below: Figure 4 Figure 5 Figure 6

  • $\begingroup$ I suggest you archive your file. Then weight paint the planes so they behave as you want. Note that for hard objects that need only a single bone as a parent this goal can be achieved directly in the user interface, as parent to single bone. You can specify a single bone by name later as well. I am also suggesting you show the weight paint view of your defective items. I have not taken the time to merge meshes as you have done. I do not see the advantage of that. Perhaps you can explain the advantage. $\endgroup$ Dec 1, 2020 at 9:26
  • $\begingroup$ Although I half understand your problem I would say your current approach is not to your advantage. See a few videos on simple armatures on the web site with the name that rhymes with noonoob. Parenting to single bone or putting the meshes together first and then parenting will be simpler. Try merging later when you understand the simple cases first. $\endgroup$ Dec 1, 2020 at 9:30
  • $\begingroup$ Thank you for your kind response. I am trying to design the cutting guide for a surgical procedure. First I need to remove the tumor on the lower jaw bone (horseshoe shape), then I need to cut a straight bone (the leg bone) to replace the removed part. The 2 independent planes on Figure 1 are the planes that I make the cut in real life. Because the leg bone is straight, so it needed to be cut so that 2 segments can be taken to mimics the horseshoe-shaped bone (I have added some pictures to illustrate it). So I use 2 parts of a armature to simulate the poistion of the 2 leg bone segments. $\endgroup$
    – Quang Dong
    Dec 1, 2020 at 22:58
  • $\begingroup$ After I join the planes and the bone segment as describe above, I want to return the armature to the original position. The purpose of this is to transfer the position and angulation of the cutting plane to the original straight bone. Thank you for the advice, I will look for the video you mentioned. $\endgroup$
    – Quang Dong
    Dec 1, 2020 at 23:02
  • $\begingroup$ I may not understand fully. But at this time this is my advice. Join mesh pieces before you use the armature. Order of Blender operations to make life easier. The planes do not need to bend thus you can control them with a SINGLE bone. 2 bones control 2 complexes. Your items are hard bones ... not flexible skin. This is a 88 second operation for a quick approximation. You do not need automatic weights. $\endgroup$ Dec 2, 2020 at 0:06


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