I needed to machine some odd shaped holes, and some large slots, in 0.008" steel shim. To make sure that there was almost no burr on the cut edges, I set the shim up on the mill with a piece of 1mm steel sheet underneath the area to have the shapes, with a second piece of 1mm steel sheet on top top sandwich the shim. I was then able to mill the hole shapes carefully, with the 1mm carbide cutter. Luckily I had bought 5 cutters as I anticipated some breakages! I didn't realise that even with careful, very slow cuts (about half the speed of the slowest table feed), and just 2 thou deep, the cutters would quickly break!! Then another, single, 1mm 3 flute, 45 degree flute, slot drill, for aluminium came in the post. I'd forgotten I'd ordered it from a UK company, but at least I could do a bit more shaping, while waiting for the new batch of cutters to come from China.
As it turned out, I would only have needed that one aluminium cutter. It has performed superbly on the steel. The cuts are cleaner and I was able to take 5 thou deep cuts, in the steel sheet, on the slowest feed speed on the table. The cutter did cost twice the price of the others, but it has lasted 5 times as long and is still sharp, and able to do much more. In the long run, much cheaper than the Chinese cheapjack cutters!!! Next time I buy cutters, I will buy cutters for aluminium, even though they are more expensive. They seem to be much sharper and produce a much cleaner cut.
Likewise here Bob, I don’t get much life or indeed success out of little carbide cutters. Unlike Roger’s super setup, you need the patience of a saint to use them with manual feed, which is all I have. Carbide mini drills are fine, though they also break quite easily, but so cheap it doesn’t matter. A drawback of carbide cutters of any sort is that if the broken bit gets stuck in the work, you can’t get rid of it with the Alum trick (or any other method I’ve tried :-( )
1mm Pcb cutters are very fragile indeed, and beyond the bottom feed achievable with power feed on a manual mill. You also need a pretty high spindle speed, say 10-15KRPM to make them work. They are amazingly cheap though, which is why I use them. 1mm Carbide cutters for Steel or Aluminium are much shorter, and they're optimised for metal cutting, unlike PCB cutters which are optimised for Fibreglass. They are much more expensive, but also much more robust.