Bit depth and spindle collisions in 3D work

[foamman]

Hello,
I was wondering if anyone knew a way to calculate or check to see if there would be a collision with the spindle chuck and the piece when machine particularly deep parts. Is there any software with a collision detector? I would like to be able to maximize the depth I can achieve without splitting the 3D part and to do so means using the shortest bit possible.

Any ideas?

Thanks
Ben