How do I / or what's the best way to.......?

[macten]

Hex cut-out with angle grinder and pipe collar.
Rotozip if it needs to be super accurate and on show.

 

[Mr T]

Hi Guys,

Thank you very much for your guidance, the job is now done. What I ended up doing is using a grinder to mark out the hole, similar to the video posted above, then cutting a square hole in the middle of the circle about 75mm square extending the cuts to the edge of the circle and used my nibblers to break out the remaining sections..... took about 5 minutes..... great!
Smoothed off cut edge with a rotary file........

Always a first time for everything eh?

Once again, thanks for your help.....

Mr T