First: i have searched and read all the threads, tried the solutions! I just can't get the rigging to work. I have a model and a rig, when i try to apply the parenting-part (With automatic weights) i get the dreaded "Bone heat weighting"-error. I have applied/cleared all scales/rotation, removed doubles, set a subsurf before the armature-modifier.... i just can't figure it out. The .blend-file is attached, hope you with more knowledge can figure out why it's not working and help me with a solution.
Rigging doesn't work: Bone heat weighting: failed to find solution for one or more bones
You need to remove doubles: Select your mesh, go in Edit mode, select all, press W > Remove Doubles, and on the bottom of the Tools panel (on the left), choose a Merge Distance of 0.2mm
$\begingroup$ Thanks! Never knew about the Merge Distance! Is 0.2mm the best option? $\endgroup$– JacoJan 11, 2019 at 7:42
1$\begingroup$ It's just the distance below which you want the vertices to merge, so it may be more or less, depending on the object, you need to test ;) in your case it seems like it's the best option $\endgroup$ Jan 11, 2019 at 7:53
1$\begingroup$ by the way, when you apply a tool, always take a look at the bottom of the T panel, most of the time you can play with parameters (it will be more visible in 2.8) $\endgroup$ Jan 11, 2019 at 7:59