suitable cutpath for machining complex undercut.

[j.stewartSMPHK]

Hello there

I am trying to machine an uneven undercut and am struggling to get any clever tool paths to work within Inventor  2021 CAM 

I can get 3D pocket and or contour to work for a finishing pass but I cant get a roughing strategy to recognise the undercut. 

I have tediously generated trace paths using sketches to take small radial cuts similar to the 3d contour but it still ends up with one of the cuts plungeing into the narrow section and therefore cutting on  50% of the diamter of the cutter which generates a huge ammount of vibration. This leaves and awful finish and an even worse noise whilst doing it.

Id like a trachoidal path that the adaptive strategy uses in order to nibble into this tight section, leaving room for swarf to escape. 

The cutter we're using is a 40mm od 20mm shank with 5mm rad button inserts. And we will rough the outer shape with a 20mm end mill before hand.

Can anyone recomend an alternative Cutter to achieve the same depth of undercut?

This is the result of a 3d contour path -note the outer cut takes a huge cut into the tight area.

Thanks

Jack