On Thu, 13 May 2004 08:54:11 -0700, Grant Erwin
wrote:

I have to mill a profile out of 1/8" sheet brass, exact composition
unknown. It isn't very hard, though. This will be entirely edge
milling i.e. milling with the side of the end mill. I very rarely
mill brass and I'm unfamiliar with its machining properties. For
side milling of brass sheet stock should I just use any 4-flute
end mill, or is some special topology highly desirable?

Thanks!

Grant Erwin
Greetings Grant,
I machine a lot of brass. Sheet, round, hex, and square bar etc.. Your
sheet may be half hard brass or it may be soft. Half hard machines
best. The soft brass will be gummy. And making a conventional cut will
show this rapidly as the chips tend to stick to the cutter and get
pressed back onto the work. Use either a two or four flute cutter. If
your set up allows climb cutting is best. Use a non sulfurised cutting
oil. The sulfur stains the brass. Water soluble oils without chlorine
work great. Use 300 to 350 sfpm with HSS tools. The brass can be
routed easily. So, if the contour tolerance allows you might want to
consider making a template and routing it. Drilling half hard brass
with a regular drill risks having the material pull the drill into it.
Especially if you are enlarging a hole or drilling after center
drilling. Stoning a drill like one made for drilling plastic helps to
avoid this. Brass cuts so easily you will love it. If you have a
choice when buying the brass get the half hard. If you will be milling
pockets, even one that's quite shallow (.010) the half hard sheet will
warp. Just milling a contour on the oustide will not cause this major
warping though. If you use a 1/2" dia. cutter you can stack the sheets
up 8 at a time and cut them all at once. Clamping well of course. If
you can, make your setup so it is possible to add clamps and remove
others so the part can be milled all around in one clamping. The half
hard brass will make sharp chips that are like needles so watch out.
Cheers,
Eric R Snow,
E T Precision Machine