I mill all kinds even steel, tougher materials just take a bit slower. Only real draw back I have found is the spindle is a bit on the slow side.
I have also added the larger table from Arc-euro, only problem I now have is that using the rotary table plus chuck does not leave much room under the chuck. Back to the design board on that one. I originally went with the 180Ncm steppers from Arc-euro but lost steps on the Z-axis so went with a 3Ncm on there for drivers I purchased a cnc2 unit from http://www.eaziform.co.uk/index.php?products mainly because I dont like the printer port units which rely on the PC to supply all timing signals. The cnc2 unit it is a bit pricey but considering all the infomation I got bombarded with when I started in 2005 I felt it should work out of the box so to speak.
I only wish I had found this forum then I may have made less mistakes.
The biggest mistake I made was to think to hard about most things instead of getting er done as even with the mill running there are still many things to iron out. Simply producing the code is not proving that easy.

Peter