Milling Slots
Milling slots is the signature operation for a vertical milling machine. For
example, to make a belt-adjustment slot, you plunge mill through the
workpiece at one end of the slot, mill the length of the slot and raise the end
mill at the other end.
But of course, life is not as simple as this. You may or may not be able to
remove all the material in one pass. If the workpiece is thick you might need to
make multiple passes along the length of the slot, lowering the end mill
between passes.
And, if you use an end mill where the diameter of the end mill is the same as
the width of the slot, you are conventional milling on one side of the slot, and
climb milling on the other. You will see markedly different surface finishes on
the two sides of the slot. But since slots usually need to provide some
clearance for the bolt that will go through them, the solution is easy. Use an
end mill the same size as the bolt, then take a few cleanup passes to widen the
slot slightly wider than the end mill diameter. Your final passes should be
climb-milling passes on each side of the slot.
Surfacing
Surfacing is used to square a workpiece and to provide a good-looking surface
as well as to change the size of a workpiece.
If you are trying to make a good-looking surface, use as large a diameter cutter
as is practical. While a fly cutter can surface a large area in one pass, we do
not recommend their use on the mini mill. If the single point tool in the fly
cutter catches on the work, it almost guarantees that the mini mill will break a
gear. It is prudent to use a smaller diameter cutter, such as an indexable end
mill for surfacing.
Common Accessories
You will soon find that the purchase of a mill is just an initial step. There are
many tools and accessories that you will need to get full use from your mill.
Following are some common accessories used with the mini mill.
End Mills
Conventional wisdom is that 2-flute end mills are used on aluminum, while 4-
flute end mills are used on steel and brass. Take a look at why before you make
a choice.
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