Hi, Andrew –
This is assuming that your questions are about manual machining. If
you had CNC I doubt you’d be asking the question. First off, while
you don’t have to have a lathe to go with your miller, they do
complement each other. And to get your other question out of the
way, too: A Jacobs chuck is not intended to do milling. For light
milling on a Sherline you’re not going to hurt yourself or anything,
and it should work, but it’s not right. Aside from the axial load
part, it’s also just not really concentric compared to collets or
toolholders. Just get the collets, they don’t cost much. Jacobs
chucks are meant for casual drilling only. What to do? Millers alone
do mostly plain milling, sawing, grooving and slotting - and
precision drilling. Use the marks on your handwheels. Example: to
make a checkerboard, clamp down your stock, and go over the face of
it with a cutter that spans the whole piece (if you have it - just
an example). Put in a small diameter cutter, and put it to a height
that works for you below the surface of the work - like 1mm or
something, and position it precisely at one corner. Turn on the
machine, and turn the “X” handle 5 turns exactly, so it lands on the
same exact number you started with (and learn about controlling
backlash—), and turn “Y” so it mills across the piece. Do that
again and again, 5 turns exactly, and then go back to start and do
the same the other way - turn the “Y” 5 turns, and mill with the “X”
handle - there’s your checkerboard. To drill at each intersection,
do the same with a drill bit in the machine - 5 “X”, 5 “Y”, drill,
repeat. Then put a 45 degree, or a chamfering bit or whatever in and
go around the edge, like a router, or prop it on it’s edge, put a
slitting saw in the arbor, and cut it down square all around. You
can also use the slitting saw to do the grooving part, indexing the
“Z”, but then you’ll have to reposition the work to get squares. You
can do all sorts of stuff related to this - make a pyramid by milling
around a small square in the center, go outwards 5 turns and lower
“Z”, mill again, out and down again, etc. With skill you can even do
things like signage and stuff, but it’s hard to control. Now, if you
get a rotary table, or I have a real dividing head, then you double
the capacity of your machine, because you can do indexing - drilling
eternity rings, make gears, groove a band equally around across the
axis, make a circular pendant with holes or stones equally spaced.
Indexing is dividing a circle into a certain number of segments.
Even if you’re not drilling or gear making, I use it at times just
to mark off the spacing of things - just touch it with a center
drill to mark it, and index all around or partly around. To put 5
stones across the top of the finger you need 25 stones to go all
around, for the stone size (say), so you pretend it’s 25 but only
mark 5 of the spots. Stuff like that. I got a call to do a 1 1/4"
cube of solid sterling for a paper weight. That’s a huge job by
hand, but I just put a block in the miller, set the Z, mill, turn
the work, mill, turn the work, and out pops a perfect
cube…Cool! It doesn’t take a genius to understand that a
milling machine is just that. It works on x,y and z, and without
computer control, and sometimes even with it, it’s just not good at
doing flowing curves and complex curves (curves that move in more
than one dimension). It is perfect with squares, rectangles and
circles, though, and if that’s what’s needed, it’s great. I have a
“real” miller of the benchtop variety: R8, 2 hp, geared head,
dovetail mounted head, 10 x 42" table, but you can do the same in
miniature on a mini - your tooling will be limited is all. I just
refaced a bench block with my 3 1/2" indexable, and you won’t be
using that on a Sherline!! I would also say (finances permitting) to
get a lathe. I use my lathe 5x as much as the miller, and often the
miller uses work that comes off the lathe to begin with. Have fun -
and be careful…
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