Delta rod end adapter

I've found my present delta rod end solution to be a bit skewed and unstable due to counting on the strength of glue from a heat glue gun.

So I wanted to make a more rigid solution that is a very tight fit to my delta arms. I use a aluminium rod with a diameter of 8mm. Balls are 10mm with a threaded hole. I use a M4 thread to connect the ball to this adapter.

Balls:
http://www.ebay.com/sch/sis.html?_nkw=16Pcs+Threaded+Steel+Ball+%CE%A610+M4+Rod+Ends+For+Kossel+3D+Printer+Magnetic+Joints&_id=141802986701&&_trksid=p2057872.m2749.l2658