Has anyone tips for lathe turning silver. I am having trouble
getting the cutting speed and tool shape right.
David
If you are turning, or to some degree milling, silver, you need to
look for clues about tooling in the aluminum business. Silver
machines almost identically to aluminum - a good sharp milling
cutter gives a mirror finish, but turning it leaves chatter marks
ALL over the place. The reason for this is because you are most
likely using general purpose (i.e. “for steel” tooling). Those
tools usually have a rake angle of 0deg to 7deg or so. For aluminum
an silver, you need a rake angle of more like 15 degrees - it’s
more like a knife than a scraper. If you go to www.travers.com (a
great tool supply, by the way), and search for these pages: 172 and
202 are milling sutters, but you can see the extreme angle of the
cutting edges - that’s what most high-helix cutters are for, is soft
materials. Page 396, at the bottom (items 22-286-700 thru
22-286-780) are inserts for aluminum, and that’s what you need to
cut your tools to look like (silver is a candidate for chipbreakers,
if you want to cut them, too). If you cut a HSS tool to look like
those, with strong angles, I promise your turnings will be smooth as
glass…