shirt modifier stack:
Given the two cloths with collisions I admit there’s a lot that could go wrong.
My self collision has lowest distance value and so does collision. Quality steps don’t appear to be making much difference. This behavior happens even without the pants sim. So I think the pants probably don’t play a factor here. How to stop the bunching from happening?
Cloth physics + armature = bad. You should bake your cloth physics to shape keys if you want good results
Well, at a guess I’m just going to go with my standard reply and shameless video plug.
That would be the issues of Scale, willing to bet its at real world sizes and Cloth Sim doesn’t work that well until you scale everything up.
And the plug for more info and tips can be found here:
I don’t know, I followed a tut and did scale it up, however don’t know if its big enough or if there’s a rule of thumb for scaling it.
However I am going to watch your tut as well. Hopefully I can find a fix.
If the object is real world size, then I tend to scale by a factor of 10 and it usually works out OK.
I guess the other thing to watch out for are some of the Cloth Physics settings. The numbers under Stiffness and Damping, especially the Bending amount can make things go wrong with only a little difference either way in the amount entered.
Apart from that make sure there’s no overlap or intersection between the cloth and collision object, there needs to be a gap all the way around.
If the scale is good then based on the video, my best guess will be that Bending amount at this stage.
As mentioned before by Joseph that armature and cloth physics running at the same time is not a good idea. They both are deformers, so even though you can use them both, but it’s a bad idea.
You can just use cloth simulation without the armature, since you’ve set the body as a collision object, so the cloth will change its shape as the body move around.
However, I guess it’s not about the scaling though because 1 mm distance is more than enough as collision distance. I personally have never experience any problem with 1:1 scale.
Have you adjusted the collision distance?
I find if it starts doing this, it is usually because of some intersection between the cloth and the model. Did you also check the face orientation? If the normals are back facing it can also cause issues.
I have used cloth sims with armatures now and again, didn’t realise this was the “bad” way to do it. I guess I’ll need to look into shapekeys further…
Yep. It had the lowest collision distance around 0.001 units.
Normals were alright as well.
This is the tutorial that I was following :
If it works for you, it’s not the bad way 
using cloth sim with armatures is extremely buggy and hard to control, but if it works in your workflow, keep doing it for sure. I just don’t recommend it to anyone who doesn’t have extensive experience with physics in Blender
If that’s the case, then the first thing I’d so is scale everything up by 10x and apply scale and then play around with the Cloth settings.
As before, the Bending number under Stiffness and Damping is usually the main cause of cloth ‘crunching’ up. Don’t use large numbers for it, sometimes all it takes is going from 0.5 to 1 to make a big difference.
This should work - it’s how I learned how to do clothing too, and is very similar to how Marvelous designer operates (i.e. start with tailor patterns and stitch together).
Only other thing that comes to mind - is the collision mesh friction set to max?
One other small point - I typically turn off other modifiers when simulating (e.g. that second subD modifier). I would probably also just apply the first subD modifier in your stack too. It will break your simulation geometry if you toggle it after baking anyway. I put the original mesh in an archive collection in case I need to go back to it, but usually I find adding modifiers before the cloth sim (other than armature) can break stuff.
