Re: [CAD_CAM_EDM_DRO] Re: Advice on low cost system

> How difficult is it using standard milling to do arcs, bowls,
> threads, chamfers, etc? Chamfers I assume is probably just a matter
> of the right bit but the others seem incredibly difficult using a
> manual machine is that not the case?
> thx,

I would agree that many of these operations are best suited to manual
lathes. Threads which are large enought to be milled can be done on
any cnc mill which supports full 3 axis coordinated motion, however
good results on these or any other circular features will only be
obtained with near zero backlash on the X and Y axis, something
usually found only on machines equipped with ballscrews. Smaller
threads are probably best done tapping by hand or with a mechanical
tapping head.

I've not heard of knurling on mill, but it can actually be done by
hand. There is a little tool out there for manually ID knurling an
accidentally oversize bore to effectively shrink it.

I don't think a sherline or maxcnc size machine will be really happy
milling 1" deep in many cases as that is a lot of overhang for the
narrow (1/4", 3/8" in a pinch) cutters that these mills are designed
to use - most such endmills don't have flutes that long. Even with
cutters long enough, many passes would be required to reach 1" depth
in most materials.

I would agree that cnc, especially on lightweight machines, requires
experience cutting by hand in order to have a feel for what it is
reasonable to ask the machine to do. The CNC control will quite
happily stall, break cutters, throw workpieces in you face, or bend
machines if you tell it to do something unreasonable.

Chris

-------------------------------------------------
Christopher C. Stratton
Engineer, Instrument Maker, and Horn Player
ccs@... 617 628 1062
http://web.mit.edu/~stratton/www/brassbuild.html