How to Remove This

[Woodworker]

View attachment 226212 View attachment 226212 OK, just joined so here is my first hopefully not to dumb question, what tool o do I use to remove this shell mill cutter for this R8 arbor?

 

[Billh50]

Without the proper wrench, I would just take some flat stock as thick as the notches are wide and mill the center to fit in the notches. Then use an adjustable to turn it.

 

[Woodworker]

Thanks.

 

[kd4gij]

The proper tool would b a spanner wrench. Like this