Limiting rotation to plane or normal

Hi folks.

I’m sure I’ve learnt this before but I’ve been away from Blender for far too long. I need to write my own idiot sheet.

Example
I have 3 objects, a, b, and c.

A was created and rotated.
B was created and rotated to match a face on A
C was created and rotated to match a face on B

I’m ok with how to parent these objects, c to b, b to a. But I’m getting lost locking down rotation. C needs to revolve around its ‘Normal’ x. B needs to revolve around its 'Normal y. A needs to revolve its ‘Normal’ Z.

I realise I should really have sorted this out first, or should I?

I thought I was doing the right things to set the new normal xyz to the current rotation, but when rotating the objects around the locked down axis it’s still trying to revolve around the Global.

What am I missing?

Thanks.

I thought I was doing the right things to set the new normal xyz to the current rotation

Do you mean you have applied the rotation to those objects ?
How are you rotating ? key board short cut ? 3D widget ?
Can you post a screen shot ?