In article ,
Gunner wrote:
On Fri, 20 Feb 2004 15:09:32 +0800, "Dean"
wrote:

Just curious. How many of you work in inches still ? I was forced to go
metric at my technical college when I was being made all clever as an
apprentice. But back at my employers workshop he made me work in inches as "

[ ... ]

Virtually every machine shop I service machines in, still uses inches,
not metric. Even when cutting to metric dimensions. They simply
convert to decimal inches.

Hmm ... I work in both -- whatever fits the need. (And I keep a
calculator handy. :-)

But when I want to do relatively precise work on my little
Compact-5/CNC, I will convert everything to metric, because the smallest
step size in inches is 0.001", while metric has the smallest step size
at 0.01mm (which is 0.000394").

In particular, diameters are specified in those units, but
because it is really the radial motion which is controlled, not the
direct diameter, you have to specify diameters in steps of 0.002", or
0.02mm -- so working in metric lets me specify to slightly smaller than
0.001", while I am stuck with 0.002" in inch mode. (I can't switch back
and forth within a single program.) There is a switch on the front
panel, which defines all units and programs to be inch or metric, with
no switching in the middle. (And higher resolution is not available, as
the leadscrews are driven by stepper motors and full-step controllers.)
(Well ... I could replace with higher resolution steppers, or with
servo motors and encoders -- but then I would also have to replace the
controller, as there are not enough digits to handle finer units.

On the Clausing, however, I normally work to inch dimensions, as
the dials are all calibrated in inch units. (Though I can (and do, from
time to time) turn to a metric diameter on the inch machine. Threads
are another kettle of fish, however. I do have the metric gear set,
including the alternate spider that it requires, but I normally take
anything which requires metric threads to the Compact-5/CNC, where the y
are trivial.

Enjoy,
DoN.
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