I would like some help on what tools I should use for engraving. I have a small CNC mill which can run at 3600RPM. I use the RhinoCam software to create the toolpaths/G-code. For engraving text, what would you recommend for engraving bits? I have tried using dremel bits with a ball nose but I either break them or the text is sloppy. My engraving is always done on a flat surface so nothing fancy.

I generally use 6160 aluminum but will be doing some mild carbon steel too? If you have help, please let me know.

Use a one flute Carbide Engraving tool. Most machine shop suppliers stock them.

another good resource is www.2Linc.com. nice selection at reasonable prices.

What do you recommend for shape of cutter for general text?

I'm assuming you are engraving in steel since you are using a mill. Use a 60 degree included angle split point (single lip) carbide cutter with about 25 degrees relief clearance , 5 degrees side clearance,and 10 degrees back clearance. 3,600 rpm is a little slow, but doable; just reduce tool feed to compensate. Antaresinc.net has a wide selection of cutters and lots of information on choosing the right one for your situation.