I have attached my attempt at this. You can try to make it work for your application if you'd like.
I started off with a sketch to define the size of square bar and a circle started on the origin and tangent to the center of the square bar profile.
After that I created a parallel plane to define the height of the spiral. (In this case I'm using half of the heigh (height/2)
I then created a sketch on this plane to define the centerline diameter of the spiral. (If the outside diameter is your critical dimension you will need to experiment with this)
Now that everything is defined, I created a loft between the two guide circles to get the shape of the centerline.
Next I created the full profile of the square bar and the 2D path for it to follow.
I projected this 2D centerline path onto the 3D shape to create half of the "true" centerline.
From there I mirrored that centerline twice to get the inverse. (this creates a visable edge on the model that I don't know how to avoid[it looks great without edges though])
Now that the centerline and profiles are created, a simple sweep (parallel not path) will complete your bar.
Circular pattern your bar around the origin axis and its "complete"
I have named what I believe to be the critical dimensions as
half_height which defines your height.
CL_dia which defines the larger centerline diameter
sq_size which defines your square bar size
Being that i made size assumptions based on your image you will need to tweak these. I suggest doing this by going to Manage>Parameters.
These critical dimensions should be safe to change within reason. I would not touch the others unless in sketch environment.
If this solves your questions please select "accept as solution and give kudos if it was of help.
