Breaking cutters machining aluminium

[John S]

or the broken shanks of HSS end mills and slot drills

[ukpete]

Thanks for the advice. I'm going to try a 2 flute cutter instead of the single flute, perhaps better balanced? I've ordered a batch of the cheap EBay cutters. At a tenth the price of those I'm currently using it'll be interesting to see what the tool life is. I'll look at the stub drill option. V cutter won't work as I'm cutting 2mm into the stock with multiple passes and need a vertical edge. Thanks Peter.