magnet works nice to determine carbide vs hssBought some cheapies on ebay. Supposed to be carbide
http://www.ebay.com/itm/311450091789?_trksid=p2060353.m2749.l2649&var=610498904487&ssPageName=STRK:MEBIDX:IT
what is the best way to determine what they are?
magnet works nice to determine carbide vs hss
Those tool bits look to have a pretty long cutting relief on them, makes them a little weaker. That type of bit is commonly called a "D" bit.
RepRap has a wiki with a lot of different PCB software on it, even some that work with some of the PCB schematic programs. And it has a lot of general PCB milling info.
http://reprap.org/wiki/PCB_Milling#Engraving_Tips
I was going by the picture in the link. That type of bit is commonly called a 'wax milling bit', due to its way of being made it is usually to fragile to with stand much side force when in use. You'll see that they brake pretty easy,especially the very tip, the part you need.Does not say too much about bit length unless I am missing something.
by Aaron Carman
by Jake Hertz