Here's a stress test of the head and shaft with 800N applied. This is almost double what its going to see in use. And only moves one tenth(average). This was worst case scenario of all the force being applied at its edge. Which the head will also not ever see. So this should hold up quite well for its use.
Thought I should mention I'll be working with aluminum. Which is why my cutting forces on average will be quite low. But if anyone wanted to say...cut steel or stainless. There might be a problem if this is based solely around aluminum cutting.