how to stop this ForeArm_second bone from
turning… (it should keep up its angle)
please help…
For this sort of thing, you probably want a 2-bone chain for the arm IK. One bone for the upper-arm, and another for the lower-arm.
Then you can have two ‘twist’ bones parented or constrained to the lower arm. These will be the actual deform bones.
It’s quite common to have multiple copies of the arm. One for deformation, one for FK controls, another for IK controls. Then you can have constraints and drivers to blend between the different control types.