Milling heat sinks

Ok so I have a 3d printer. I’ve never been satisfied by it’s cooling capability so I designed a heatsink. It needs to be held in three positions. I trying cutting the fins ?

Worked perfectly but trying to re Orient the part I wrecked my bit. It has Casually buried it self into the material like it didn’t know where it was at.

I thought I had everything right. Has anyone else experienced this?

 

Yes. A number of things could have caused this. Pretty easy mistake to make when flipping your part, or yes it could have just been a random error.