Re: [CAD_CAM_EDM_DRO] Re: Mill Opinions & CNC simulators

> A $1500 1/5 horsepower sherline is not going to do what I need. And I
> find it hard to believe that a $999 1.5 HP enco is not a better mill -
> sure it is not a $10,000 bridgeport but it has got to be better than
> a tiny sherline that costs more. But I keep hearing, "dont buy one of
> those."

The Enco is a bigger machine shure, but many of the models have some
usability issues which become serious when you contemplate CNC
control.

- Many of the models have round columns. These loose rotational
alignment when you move the head up and down to account for different
length tools (like a drill in a chuck vs a shorter endmill in a collet).
There are some workarounds, and some models with non-rotating ways instead.

- The quill is usually driven by a rack and pinion which has
substantially more slop than the backlash on the sherline Z axis.
There are ways to tighten them up some... Even on a bridgeport sized
machine, fitting a ballscrew to the quill axis is quite a challenge,
which is why some of these conversions CNC the knee rather than the
quill.

- The X and Y screws may have more backlash than the little ones on
the sherline, and getting in under the table to fit ballscrews and
their larger nuts can be a challenge.

My personal suggestion would be to either look at one of the roughly
$2k smaller knee mills, a dovetail column mill drill, or if you have
the space for it, shop for a used bridgeport, which you should be able
to find for $3k-4k, maybe less.

Lastly, I should point out that the base price of the sherline mill is
around $600 - it only becomes $1500 when you add some of the CNC
stuff. So it's not fair to compare it to a $1k ENCO, that will need
larger and hence more expensive CNC components.

Chris

--
Christopher C. Stratton, stratton@...
Instrument Maker, Horn Player & Engineer
22 Adrian Street, Somerville, MA 02143
http://www.mdc.net/~stratton
NEW PHONE NUMBER: (617) 628-1062 home, 253-2606 MIT