The Omaha morning bee., 1924-11-29
Method of Laying Out Radio Instrument Panels Shown This
Important Sub bject Is Giuen Too Little Attention by Aat

| much space being given to the mat
ter. But it is a fact that the general
instructions for building apparatus
have not covered this phase com
pletely enough for those who are com
paratively unfamiliar with instru-
ment work.
Very frequently eyperimenters take
panels to radio stores to have them
laid out and drilled, quite unaware
that they could save rs per cent of
| the cost of such work by marking
the positions of the holes themselves.
When told this set builders often
take their panels back and soon re-
turn with the location of holes indi-
Gated by soft pencil marks, one-eighth
inch in diameter. Quite obviously,
holes may be drilled in these places
and still be a long way from the
positions they should OCCUPY.
Cases are also common where anna
teurs bring in instruments for repair
which show the lack of proper in
structions in the laying out of the
panels. The distance between switch
points vary, binding posts are not in
line, and the location of the various
adjusting knobs seems to bear no
relation to each other. Visits to sew
eral amateur stations are quite in
teresting from this point of view, for
1t is found that the man with the
most money seldom has the best ap-
pearing equipment.
Ma of
pie and comparatively inexpensive ap.
paratus, but constructed and ar
ranged so neatly that they eclipse in
appearance and working qualities the
equipment OF stations whose owners
are not limited in a financial way.
And the majority of the owners of
the neat and efficient outfits agree
that the chief reason for this superi-
ority of their equipment Is the care
ful laying out of the instrument
panels.
Some Causes OF Errors.
The poor appearance of some in
struments is often the result of in
sufficient time spent in laying out
the panel. This, OF course, is bad
economy. The use of a pencil or
blunt marking tool accounts for
large number of misplaced holes, and
the dependence upon a mark rather
than center punch hole for starting
the drill ranks next as a cause for
these errors. With many. the fault
lies In the fact that they are not
careful, or accurate, in transferring
dimensions from scale drawing to
their work. while others can trace
their trouble to the use OF panels
the adjacent edges of which are not
exactly at right angle. The latter
occurrence is quite common where
panels are purchased from dealers
who cut their material from large
pieces into any size desired by the
customer. Edges are seldom straight
or at right angles, and the instru-
ment builder finds It necessary to
spend considerable time to square
the edges so that he can make meas
urements from them to locate his
holes.
The experimenter. building ap-
finds less difficulty than the man who
follows vague directions, for he usu-
ally employs accurately cut panels
which have perfectly straight edges
and right angle corners With this
stock to work upon, the Job resolves
itself into a matter of the use of
tools.
Tools Required
The builder should provide himself
with a pair of diYidess, scriber
square. center-punch. hammer and
hand drill. The dividers should be
capable Of covering a radius of about
two inches. the points should be
sharp, and the joint firm. Errors are
frequently made by an accidental
change in setting of loose dividers.
The only requirement of the xcriber
Is that It should have a sharp, hard
point.
A combination square of the type
shown in Figs. /. and Is rec
commended, and the blade should be
at least six inches long, with divisions
to 1-32 inch or finer. A hard. conical
point Is necessary for center punch.
Instruments are often resharpened to
point which Is not truly conical
and to use them. one runs the risk
Of centering the hole a little distance
from the place where II should be
located When struck with the ham.
mer, the center punch will move
slightly in the direction OF that part
OF the tapering point which is most
nearly vertical. A four-ounce. ball
pin hammer Is heavy enough for this
class of work, although almost any
kind will serve the purpose. The
hand drill is Of the familiar type
shown In figure g. The chuck should
have drill capacity up to one
quarter inch. An ordinary brace js
used by most experimenters for larger
drills.
Dividers are used for transferring
measurements made upon the draw
Ing TO the scale, and for measure
ments wholly upon the surface ..of
the panel. They should not be EN-.
ployed for locating point from the
edge of the panel. for the reason that
1t is inconvenlent, IL not impossible.
to set the very point of the nstru.
ment on the upper edge of the panel.
as would be necessary for accurate
work. The combination square should
always be used for making measure
ments from the edge of tho panel.
All straight lines and points are
made with the scrlber used In the
manner illustrated In Fig. 2. Note