Pete
Just to give you another option, I have had great success with these: http://pages.ebay.com/link/?nav=item.view&alt=web&id=121691238456&globalID=EBAY-GBI have one one of those Rolson(?) boxes that has about 100 different sizes of bits but found them to be pretty blunt and hard work. The bits (at the link) are much sharper and can be easily worked by hand. Because they have a common shank diameter, they can be easily interchanged in a pin vice.