AUTO-POWERED ARC WELDER
By Norman E. Schuttz
'MALL ENOUGH to be hidden beneath
the hood of a passenger car, yet
power-ful enough to handle electrodes up
to3/16-in. dia., this 200-amp. welder is powered
by the engine of the car in which it is
installed, and can be taken anywhere that
an automobile can be driven.
The main component of the welder is a
war-surplus Delco Remy P-l aircraft
gen-erator that is rated at 24 v. and 200 amp.
at 2500 to 4000 r.p.m. Since this generator
has a counterclockwise rotation, it must be
turned end for end and driven from the
commutator end when rotated by a car
en-gine. This requires that the floating shaft,
which drives the free-turning armature, be
removed from the generator and modified.
First, cut this shaft about 1 1/2 in. from
the driving spline. Next, center-drill the
end of a 7-in. length of 3/4-in. steel
shafting to provide a press fit for the cutoff
shaft. Force the 1 1/2-in. length into the
hole in the new shaft and braze or weld it
in place. Mill a 3/16 x 3/16-in. keyway 4
in. long in the end of the shaft to hold the
pulleys and bore a clearance hole for the
shaft in the end housing of the generator
opposite the original location. The shaft
now will project from the end of the
Above, welder connected and ready to run. Below,
support frames bolted to head, ready for welder
\
WELDING MACHINES
generator, One flange of the 1/8 x1 1/2 x1 1/2
in, channel is cut back to 1/2 in. as indicated.
When assembling the frame, first mount
the two self-aligning, pillow-block
bear-ings on the shaft; then adjust the various
frame members to keep the shaft aligned
properly while they arc welded together.
Front and rear supports for the generator
frame are shown in Fig. 5. These supports
were designed to hold the Frame above the
spark plugs when they arc bolted to the head
of a 1953 or 1954 "flathead'
1V8 engine, Fig-
2. Supports for bolting the generator
frame to in-line-type engines
and
overhead-valve V8 engines will have
to be
modified or redesigned to suit a particular
engine. Steel angles, spaced by lengths of
3/4-in. pipe, were used on the original
supports. Holes in the bottom angles are
1/2-in, dia. to fit over the head bolts while
holes in the upper angles are 3/8-in. dia.,
and are matched by holes in the
generator-support frame. When considered necessary
for more rigid mounting, a center support
also can be used.
Drive Pulleys
A 3-in.-dia. double V-pulley is fitted on
the welding-generator shaft. A 6-in.-dia.
double V-pulley is welded to the
crank-shaft pulley of the car engine. Care must
be taken in the latter operation to make
sure the double pulley is centered on the
crankshaft pulley to prevent misalignment.
The center of the double pulley
is cut out
to permit
tightening the pulley
nut on the
crankshaft
Because the engine
-fan will
strike the
modified pulleys,
it is necessary
to reposition it. Remove
the
blades from
the fan hub, insert spacers and rerivet the
blades to the hub as shown in Fig. 8. On a
different type of engine, more or less
modi-fication of the fan may be required. When
the fan is. moved forward it requires that
the radiator be moved forward a similar
distance to keep the fan blades clear of it.
On the original car, four 5/8-in. hardwood
blocks were used as spacers to relocate the
radiator. Sheet-metal pans at the top and
bottom of the radiator may require cutting
or bending to allow the forward movement
of the radiator.
Arc Stabilizer and Rheostat
To assure that the welder produces a
steady arc, an arc stabilizer must be wired
into the welding circuit. The stabilizer,
Figs. 3 and 7, consists of a core of 2-in.-dia.
cold-rolled steel approximately 5 1/2 in.
long. First, a layer of insulating cloth is
wrapped on the core, then five layers of
4-ga. enamel-coated copper wire are wrapped
on the core, each layer being separated by
insulating cloth. Finally, the completed
core is wrapped with tape and tied to make
sure the wire stays wrapped tightly. The
beginning and end leads are left about 9
in. long to permit attaching them to the
terminals. Make sure the ends of the
stabi-lizer core make good contact with the metal
frame which is made of double 8-ga. sheet
steel. Short flanges are bent along the
edges, then mitered at the corners and
welded to provide additional strength as
shown in Fig. 7.
The frame for the stabilizer also is used
to support the rheostat, terminal
connec-tions and throttle for controlling engine
speed, Figs. 3 and 7. The rheostat is a
heavy-duty type, rated at 6 ohms, 11.1 amp.
Fig. 6 is a wiring diagram, showing the
connections between the stabilizer, welder
and rheostat. Note that all wires in this
circuit are 4 ga., except the lines to the
Arc-stabilizer-rheostat assembly. Note how flanges are bent on stabilizer frame for added rigidity
WELDING MACHINES
Original engine fan was modified by removing blade from hub, adding spacers, then reriveting blades
One method of controllong engine speed requires choke cable to which linkage is welded as shown
rheostat which are 14 ga. As shown in Figs,
1 and 2, the stabilizer-rheostat assembly is
bolted to the inside of a fender. Large
washers on the underside prevent the bolts
from pulling through the sheet, metal of
the lender.
Throttle Hookup
To control the speed of the car engine
and thus the r.p.m. of the welding
gener-ater, it is necessary to add an auxiliary
throttle control to the carburetor. As
shown in Fig. 9. some cars are equipped
with throttle linkage that has
spring-loaded connectors that easily snap off
with-out tools. An extra piece of the linkage is
welded or brazed to the end of a choke
cable that leads to the stabilizer frame
where it is easy lo reach when operating the
welder. To change from control by foot
throttle inside the car to hand control at
the welder' rcquires only unhooking one
control and hooking on the other,
On engines with other types of linkage
connectors it may he possible to locate the
2436
choke cable so that it can he hooked onto
the throttle lever without the necessity of
removing the regular foot-control linkage,
hi some cases, the latter-type linkage is
bolted together and requires the use of
wrenches for disassembly, The less time
required to connect the welder to the
en-gine, the more time used profitably for
welding, so it is important that any
short-cut in making the hookup be considered,
Operating the Welder
Two heavy-duty V-belts are used to
drive the welder from the crankshaft. Belts
for the original installation were 54 in.
long. Belts for other type installations are
selected by measuring the distance around
and between both sets of pulleys. To
in-stall the belts on the generator pulleys, the
front pillow-block bearing is removed, both
belts clipped over the pulleys, then the
bearing is reinstalled. To fit the belts on
the crankshaft pulleys, tip the forward end
of the welder frame down, loop the belts
over the crankshaft pulleys, then level the
welder. Belt tension is adjusted by fitting
thin washers or sheet-metal shims between
the forward ends of the welder frame and
the support frame.
When the welder is to be run. continu
ously for some time on a big job, connect
the air scoop of the welding generator. Fig,
5. to the air horn of the carburetor with
flexible tubing. Carburetor vacuum will
draw air through the generator housing,
thus cooling the generator. An ammeter
and voltmeter are not wired into the
welder, and since each welder will differ
in characteristics due to being custom-
built, no precise calibration of the rheostat
is suggested, After a few jobs with the
welder, the operator will become familiar
with the machine and can make his own
calibrations, which can be marked on the
frame under the rheostat dial,
* * *
-HIS
bandsaw,
made
largely
of
%-in.
fir
Tplywood,
has
a
12-in.
swing,
a
tilting
.
table
and cuts
2-in.
stock
with
ease
and
accuracy.
If
it is carefully
constructed,
sothat both wheels are in perfect alinement,
you
will
have
no
trouble
with
the saw
blade
r q m b g
off.
The cost of
building
the orig-
inal saw from wgch
these
plans were
tak-
en was four dollars.
e-.
-For
the
base
and core
of
the
vertical
frank
pfeee,
Fig.
l,l%-in.
yellow
pine
is
used.
The pattern for this
part
is
laid
out
on a piece of
heavy wrapping paper, as in
Fig. 3.
Cut
the piece
about
I/s
in. oversize,
to
Leaveemugh
stock
for
finishing.
The
plywood
,sides
are
then
cut
to
size
and
glued to the core,
using
casein
glue,
after
which
additional strength
at the edges is
obtained
by
driving in
wood screws.
After
the
glue has
dried, the edges of
the £rame
should
be
sanded
on
a
drum
or
spindle
instead
of
being
flat
and
covered
with
a
sander.
rubber
band,
should
have
a
V-groove.
W e
wheels
are bhilt
up
of
four
12-in.
The
hubs
for
the
wheels
and
pulley
are
plywood -5, which are glued together
4-in.
ceiling-outlet
covers,
used
in
elec-
with the
grain
running
crosswise
to pre-
trical
conduit
work.
Drill
a
%-in.hole
vent
warping.
If
desired,
the
outer,
ex-
through
the
exact
center
of
each,
and
posed
disk may have its center cut out to
screw
them to the
wheels as
shown
in
Fys.
£ o m
a ring.
Th6
6-in.
pulley
issimilarly
4 and
7,
t a k i i care
to
get
them
on cori-
built up from.pl$wood
disks,
but the edge,
centrically.
If
a %-in.
bolt, with the
head
11
BATTERY CHARGERS
DONT BE CAUGHT WITH A DEAD BATTERY
BUILD YOUR OWN QUICK-CHARGER
By Patrick K. Snook
FEW MOTORISTS are able to put back
what they take out of a battery during
winter driving- The extra drain of
cold-morning starts, increased use of lights and
added heater consumption takes its toil and
unless you do lots of highway driving, you
can't hope to keep the battery up to par
by mere driving alone. The in-town driver,
particularly, will do well to have his own
quick-charger which he can use on
occa-sion to keep up with the increased battery
drain that comes with winter driving.
A simple quick-charger can be put
to-gether at little cost from odd parts that
can be found in almost any junk yard. If
possible, select a generator and voltage
regulator from the same car—the generator
being of the same voltage as that in your
own car. You'd also better see if you can't
buy beg or borrow the proper wiring dia
you've cleaned the generator thoroughly,
make sure that the pulleys on both the
generator and the motor are equal in size.
The carriage, or dolly, which makes the
charger portable, consists of a 3/4-in. board
measuring approximately 12 x 27 in, which
is mounted on an axle and two 8-in. wheels
and provided with a handle. Mount the
motor on blocks of 2 x 4 cut to conform and
bolt this assembly to the dolly. To find the
proper position for the generator, bolt it to
its single mounting block, slip the 3/8 x
36-in. V-belt over the pulleys and move the
generator assembly back until the belt is
snug when the generator inclines about 15
deg. toward the motor, This will enable
you to mark the assembly's exact position.
The generator then may be removed from
its mounting block and the block bolted
permanently to the dolly At this point the
BATTERY CHARGERS
the wiring, at) that remains to be done now
is
to fit the foot block and handle. The
heavy-duty, two-wire power cable {No. 12
ga.) runs through the conduit and out of a
hole drilled near the base, then under the
dolly and up through a hole near the motor
to which it is connected. Since most 1/4-hp,
motors can be reversed make sure to
con-nect the wiring so that the motor runs
coun-terclockwise, viewing it from the shaft end.
There are probably half a dozen different
generator-regulator wiring set ups
depend-ing on the make and vintage of the car.
One possible set up is shown in the dia
gram below. The generator terminals as
well as those on the regulator are letter
coded so that there should be no problems
involved. One word of caution: On some
models the field terminal is grounded by
way of a resistor to the generator shell. In
this case, mount the negative lead of the
battery power cable to the screw that an
chors the resistor, not to the field terminal.
The direct lead from the field terminal
should be attached to the F-post of the
voltage regulator.
* * *
OLD MAGNETO PROVIDES PARTS FOR BUILDING
Small
Workshop
Compressor
The compressor partly disassembled to show piston, connecting rod, and crank disk made from contact breaker
ADE entirely out of scrap mate-rials, the small compressor illus-trated will raise a pressure of 25 lb. per sq. in. in a 6-cu. ft. tank in 25 min-utes, which is ample for the average small gas torch. The consumption of line-shaft power is very small, an important consid-eration in many small shops.
Construction of the compressor is clearly shown in the photograph and large draw-ing below. Simplicity is the keynote of its construction throughout. The magneto which supplied most of the larger parts was purchased for fifty cents.
The method of procedure will be gov-erned to some extent by the type of mag-neto available. Assuming the gear housing to be of cast iron and the end bearings to be of brass, it is a simple matter to saw and file out the gear housing to fit on the end bearing housing as shown. The two are fastened by a machine screw after be-ing sweated together with soft solder. To do this successfully, the cast iron must be thoroughly cleaned and well tinned. The axis of the shaft hole in the gear housing must be kept parallel with the finished face of the brass base, Do not fasten these
parts together permanently at this stage. Chuck the base in the lathe and bore for the cylinder. The size depends upon the bushing used for a cylinder, but the draw-ing indicates the proportionate allowances to be made for shoulders and the like.
The next step is to turn, bore, and lap the cylinder to an inside diameter of 7/8 in., with other dimensions to suit the actual bushing available.
The cylinder bottom is soldered into place after fitting the simple ball valve. Make the valve seat very narrow, use a new ball, and tap the ball lightly on its seat before assembling to insure a tight valve.
Mount the cylinder in the base and sol-der as shown. Care must be taken to see that the bore is at right angles to the fin-ished face of the base. Note the aluminum cooling fins, which can be turned in the form of washers and threaded on the cyl-inder before mounting, with aluminum separators between them.
The piston is built up from 1/8 in. sheet aluminum cut into disks 7/8 in. in diameter and riveted together. The rivets must be so placed that they will not interfere with the ring grooves or the piston-pin hole. The inlet valve in the base of the piston is re-tained with two turns of very light steel spring sprung into a groove just above the valve seat. The ring grooves are turned 1/16 in. wide and 1/16 in. plus .002 in. deep. The rings are 7/8 in. in diameter and 1/16 in. thick, split at an angle of 45 deg. and sprung over the body into place, care being taken not to deform them.
The connecting rod is also built up out of the 1/8-in. aluminum sheet, two pieces being riveted together through the center section. The ends are left square in sec-tion as shown in the photograph and are fitted with bronze bushings for suitable pins, as indicated in the drawing.
Care is necessary to insure that all joints are air-tight, because with such a small dis-placement a very small leak will seriously cut down the efficiency of the compressor. The best running speed is about 500 r.p.m. The lightness of the oscillating parts and the comparatively heavy driving pulley, acting as a flywheel, reduce vibration to a minimum, but the braces shown are nec-essary to give general lateral stiffness. They are bent out of 5/8-in. flat steel 1/8 in. thick, and fitted into place.
251 WORKSHOP HINTS
D R I V E N
by
means
of
a
I - h p .
electric
motor,
this
homemade
drillpress, built
mostly from old auto parts and a few items
obtainable from your local dollar
store, is
sturdy,
accurate and
smooth in operation.
Acut-off portion from
an
axle housing
is
bolted
to
a
brake drum, which, in turn,
is
bolted
to
the
bench
top.
The
spindle
bearing
is
a
small
grinder
head
and
isw
-
direct to the motor.
In either case it is
ad-
visable to
use
a
three-step
pulley
on
the
motor
to
provide
speed
adjustment.
Ac-
cessories such as the V-pulleys,
belts and
chuck
can
be
obtained
from
almost
any
*For Lathe Operators
If
you
occasionally
have a lathe job
that
requires
resetting
chucks
frequently
for
small work, this simple speed wrench will
save
considerable
time.
It
is
nothing more
than an ordinary hand
drillwith
the chuckremoved and the end of
the shaft squared
to
fit the chuck screws.
(rpunches
and
chisels for
model
makers
can be had
by grinding ice picks to shape,
Receptacle Built in Workbench 'it
Extinguishes
Lighted Matches
--
To
avoid fires
being
started by
matches
thrown
about his
shop,
after
lighting
gas
+burners
and
torches,
one
tinsmith
installed
*this
receptacle.
It
c o n s i s t s
of
a
length of
pipe run
throughthebench
top to end
in
a pail
or can underneath
t h e
b e n c h .
Aflange
at
the
upper
e n d
of
t h e p i p e
holds
it
in
place.
The
lower
end
of
the
pipe
must
rest
on
thebottom of
th
into
the
pipe
are
and
when filled, th
the matches in the
Just
mount
it on
the
cross
slide
and
do keyway cutting,
end
milling
and
surfacing
I
LLI
NG
d&.
a
HIS handy
milling
unit
for
small
metal-turning
lathes consists simply
f
a
drill-press
vise
mounted
on
the
of
the
carriage.
The
vise
is
a disk similar
to
the index disk
ound
rest,
Figs.
1
and
2.
Thus
0th
the
lateral
and
traverse
e depth of
the vise jaws
gives
a
considerable
range
of
vertical
adjust-
ment.
Also
the unit can
be
swiveled
to any
degree
desired
to
handle
angular
work.
Figs.
1
and
3 show
typical
operations on
parts
of
small
models.
Milling
cutters
should be held in a collet chuck but if
the
-
lathe is not fitted
with chuck
and
suitable
collets,
you can grip the cutters
in
a three-
jaw
scroll
or
center
chuck and, by
work-
ing
carefully,
get
very
good
results
on
light work.
Figs.
4and
5 show the
base
or pad
on
which the
drill-press
vise
is
mounted.
It is
.turned
from
a
single
piece
of
cold-rolled
steel and all the dimensions
given
adapt it
to
use
on
a
well-known
make
of
home
workshop
metal-turning
lathe.
Notice
in
Fig. 4 that the base is held in place with a
hardened pointed setscrew bearing against
the beveled projection on the underside of
the
disk.
The
setscrew
lock
is
regular
equipment on
this
particular lathe and
the
beveled
projection
on
the
vise
mounting
simply duplicates that on
the
regular
com-
pound
supplied
with the
lathe
as you
see
in Fig. 2,
where
the two parts
are shown
Soldering With
a Lead
Pencil
For
small
soldering
jobs,
you
can ef-
point of
the lead to the spot you wish to
fectively use a n automatic lead pencil. solder and then drawing it awayslowly,
Wire the metallic
part
of
the pencil to
will create a tiny arc.
Use hard lead in
the
negative pole of
a 6-volt storage bat-
the pencil, which should be a handle of
tery, and connect the
positive pole to the
bakelite
or
other
heat-proof
material.
work to be soldered.
Then, touching the
-Charles
A.Younger, Somerville,
N.
J.
i s ,
n o t
d r i l l e d
c
through and
are thre
with
a
bottom
tap.
take full
advantage of
chining the
base so
much
louder than a sigh.
The barrel
is
en-
cased
in concrete 4 in.
thick, the concrete
assuring a good mufffer long after the thin
sides of the barrel have rusted
away.
am-
---you want
a
smooth,
polished
finish
on w
turnings such as tool
handles, first
sand them carefully and then hold
anoiled
strip
of
cloth
or
leather against
the
work
,, +as it rotates in.
the
lathe.
leg
on
which the coil is to be wound,
mul-
tiplied by the thickness.
In the case of
the
core
shown,
the
center leg is .25 sq. in.
The
number of turns required is, therefore 493divided by -25, or 1972.
The
y i r esize
iscalculated
from
the
length
of
the magnetic
path,
as shown
in
the upper detail of
Fig. 7.
The
wire
size in
circular mils is found
bymultiplying
the
length by
50,000,
and then
dividing by the
number
of
turns.
For
a magnetic pathof
3% in., the wire size required is 3.25 times
50,000,
divided by1972,
or82.5
circukrmils.
The
required
gauge
number is
then
found from any magnet
wire
table, which
will show that No. 31
has an area of
80 cir-
cular mils, and
No.
30
has
an area of
101
circular
mils. In
such
a
case,
the
larger
\ '
The
armature
is
fastened
to
its
b r d
-
size
@WWBage
number)
should
be
with
two
flat-head
rivets,
counbrsunkL ia h b - k b s g ,Tha
c d l
will,
therefoh, be wound
the a~matupe.
Clearances and
- 'with iPt2 t-
of
No:
30enameled wire.
specified
should
be followed
cItre&By.
&
&
mast
transformersap
Eggraving
tooh
can be made of
%-b,
&.-
,
g i v qNos
3Q
wire
larger drill
rod.
The
tipscan
be
ground
t~
ere
aheavy-duty
various shapes, as shown
in
Pig, 2.
After
-,.
@**built'kom
large %stamp-
~ough-grinding
to shape, tb.
end. s h u ] $
'
larlargm
WW
will Be
necessary.
be
hardened
by heating to
a
straw yellowThe d tg wauhd on a woodan form a9 color and pl-g the aut'thg end om&
shorn
in5 w d
6.
The form should
, intocold
water.
After hardening&er
are
b
a h *
Iarger
than
the16g Qn
which
the
An&&
ground.
The
shankof the W1 can
-cd*,
rrnrl ,sh&tafso
have
a
slight
tag&
be
h d e d
ctnd l~crewed
h t o the_end
af
.
,#pmd
e&,
so th@
the
fbidhd,-coil
the amnature;
a h k
nut
and
bc&w d i q
"gle engraving bit
is
to
be
used, it can
be
held permanently in
place
by
peening.
The completed tool can be
mounted
on a
semi-circular
wooden
block,
and
placed
inside a fiber tube.
See Figs.
1
and 4.
Another way to make a
simple engrav-
ing
tool
is
to
take
an
inexpensive vibrator-
type
(labeled'
a.c.
only)
electric razor,
of
the kind which
contains an electromagnet
instead of
a motor.
See the
left detail of
Fig.
7.
Remove
the cutter
head
from the
shaver and, if
necessary, saw off
the end of
-the Bakelite case.
An
engraving
tool can
be
attached
to
the vibrating
shaft
of
the
'shaver.
One way to do this is
to
swage
the
shank
of
the tool flat, and
drill
it to
fit
the shaft.
It can be held
in
place by
peening, or the
,
shaft can be
threaded
and the tool tapped
and held with a lock nut.
Jackshaft
on
Motor Makes
VariableflSpeed
Unit
on
an electric motor,
The unit
can
be
fastened
in
a
fixed
position
for
driving
power
tools,
such as metal-turning
lathes,
drill
presses, etc., where
various speeds are
required,
or
it
can
be
carried
about
for
operating a
flexible
shaft
as
shown.
By
using two 5-in.
cone
pulleys
and a
motor
of
1,750 r.p.m.
on the original unit a
speed
range
of
700
to 4,375
r.p.m.
was
obtained.
Pillow
blocks
serve
as
bearings
for
the
shaft,
and
they
are
bolted
to
angle-iron
supports,
which are attached to the motor'
by
placing them under
the nuts of
the
tie
rods that
hold
the
motor housing
together.
In some
cases,
it may
be
necessary to sub-
stitute longer tie rods for the original
ones.
-Kent
H. Alverson, Niagara Falls, N.
Y.
Small Paper Cups Have
Many
Uses
in the Home Workshop
An
inexpensive
convenience
in
your
home workshop is
a
supply
of
small
paper
cups.
They
are
particularly
handy
when
doing small jobs of finishing, er in mixingpaints
and
stains.
When tin
cansare used
for
this
purpose
they
always
must
be
cleaned for
the
next
job,
and frequently
bits
of
skins
or
traces of
the old
color
re-
main.
But
paper
cups are merely
thrown
away
when
a
job
is
finished.
Labels and
measures can
be
marked
on
them
easily
with a pencil,
and liquid levels show clear-
ly through the translucent sides.
(TTo
remove
rust
from
the
flutes
of
an
auger bit use a
small
rope which is coated
.with
glue
or
shellac
and
sprinkled
with
fine emery.
C -
- * +
Rubber
Heels
Cushion
Motor
To
reduce vibration of
electric motors
the heel
and
plate
to
line up
with
rail
to a minimum,eksek-absorbing
motor
clips.Countersink
theflat-herd
bolt6mounts
for
floating-type
rails
canbe
in the plate and bolt the three
together.
made from
a pair
of
rubber
heels.
Cut
Fasten
the
heels to the bench with three
a metal plate to fitthe
recess in the top
screws
or
bolts,
using
washers
under
of
the heel and drill two
holes
through
the heads.
supports the intermediate and
top
pulleys
turns
in sets of
%-in:
babbitted split bear-
ings.
Note
that
setscrew collars are used
on each shaft.
One face of
thetop or driv-
ing
pulley
is
fitted
with
a
counterbalancing
steel plate as in Figs.
2 and 3..
The coun-
terbalance
is
bolted
to
the
pulley.
Con-
and screwed into a tapped
hole
in
one
end
of
the
counterbalance
and
through
the
pulley.
This
crankpin
is
secured
with
a
serves as a
driver
for
the
connecting
rod
which
is
made
from
a
length
of
+!!-in.
standard
pipe.
The
forward
end
of
the
connecting rod is drilled for a %a-in. steel
wrist
pin
threaded
at
both
ends for
lock
nuts.
The
assembly is
made as
in
Fig.
3.
To
guide the
hack
saw in a
straight path,
an S-shaped bend in the arm
as
in
Figs.
2can be
bent
cold.
The
surface of
the pipe
which supports the
hack-saw
guide
should
be
polished
smooth.
The slide is a length
of
brass tubing which will
telescope
over
the
polished
section
of
the
supporting
arm.
The
hack-saw
frame
is
fastened
to
the
guide
with
the
aid
of
clamps
as
in
Fig.
2.These
can
be
riveted
to
the
saw
frame or held with small bolts.
The
pressure
applied
to the blade when
cutting
is
regulated
by
weights
on
the
outer end of
the supporting arm as shown
in
Fig.
1.
These
weights
can
be
made by
drilling a
hole
in
cold-rolled steel plate of
such
a
size that
the piece
will
slip easily
over
the
pipe.
Setscrews
'or pins
can be
screws.
Fig. 4 shows
the
assembly
of
the
speed-
reducing drive. All
pul-
leys
are
of
the
V-type
for
%-in.
belt.
Shaped f r o m
a
p i e c e
o f
t h i n
ent
materials require
slight
variations
inblade pressure
for
the best-cutting
action.
The
support-arm
guide,
Fig.
3,can
be
you
to startmade
.from
%-in.
flat iron, the
slot
being
Screws inplaces
of
the3
same width as the
diameter of
the
where it is impos-
aipe.If
necessary,
the
guide
should
be
sible
to reach with
blocked up
on
.the
bench,
so
that
the
arm
the hands- A slotwill
reach
the
bottom
of
the
slot just
as
with a hole at one
the
saw
breaks
through the work.
e n d
p e r m i t s
a
A
standard toolmakers' vise
can
be used
screw head
to
be
inserted
and held
true
Power unit is simple box built from scrap to house small transformer and silicon rectifier. Cord at right plugs into wall outlet. Center cord (from rectifier) is positive, clips to work; one at left, to stencil pad.
Make an Electric
You use a common mimeo stencil,
but the printing agent isn't ink
—it's an electrochemical flow
By ROLAND LOEWENou can easily—and safely—put
electro-chemistry to work "branding" your name
on tools, or decorating aluminum sheets.
The stencil pad consists of a metal plate
(copper, aluminum—even a scrap of tin
can) covered with felt that's saturated
with a solution of table salt (or with
liquid Sani-Flush).
Over this pad you smooth a section of
an ordinary mimeograph stencil
(availa-ble at any office-supply store) which you
have typed on a typewriter set for stencil
cutting, or with a hand stylus—just as if
you were preparing it for inking.
Clip the leads from a DC power source
to the stencil pad and the workpiece and
press the two together for 10 to 90
sec-onds. This power source can be your auto
battery, a battery charger, or an
electro-plating unit. Or, to use house current, you
154 POPULAR SCIENCEcan easily assemble a unit costing under
six dollars from a small transformer, a
sili-con rectifier, a few feet of insulated wire,
a male plug, and two alligator clips. The
power needed is at only six to 12 volts low
amperage. I use a filament transformer
from Allied Radio (their stock number
54C1420) that's rated 110-120 volts
pri-mary, and 12.6 volts at two amps
secon-dary. I get about 12 volts, which speeds
up etching jobs.
I made two types of stencil pads—a
one-liner to hand-hold against tools and a
block against which metal plates can be
pressed. Both are sketched at right. For
the one-liner, glue the metal plate to the
slightly rounded edge of the wood strip
with epoxy cement, letting it extend at
one end and bending it up as shown for
attaching an alligator clip. Fasten a strip
of felt over the metal, gluing it lightly.
To use, soak the felt in the salt solution,
then dab with a cloth to remove excess.
Center stencil over felt so the lettering is
backwards as you look at it. Tuck ends
under a big paper clamp. The larger rig
has two spring-loaded bars for this
pur-pose; they seat in rabbets. Be sure your
stencil is large enough to cover the felt or
you'll leak current at the ends.
One-line stencil pad (left) is secured by spring clamp, as shown in sketch below. It's fine for applying name to hammer (above, with clip applied) or to steel punch and chromed tape case (far left, facing page).
Block-type stencil pad offers etching area about 2½" by 4"—ideal for address plates shown above. You induce electrochemical flow by holding positive clip in contact with back of plate centered on stencil.
Stencil to Etch Metal
NOVEMBER 1968 155 How electrochemical etching works Metal plate of stencil pad becomes cathode, charged with negative electricity (electrons). Above this (in cross sections below) is felt pad soaked in salt solution (sodium chloride: NaCl) plus a waxy stencil. Where latter is pierced, chlorine ions flow through to carry electrons to anode. Iron workpiece reacts with chlorine to form iron chloride (FeCl3), which dissolves, leav-ing mark. Other metals react similarly.
Engineer's Level
D
ESIGNED tobe easier to operate and capable of taking more abuse than a transit, this en-gineer's level can be used for such outdoor j o b s as landscaping, septic t a n k installation, drainage ditching, setting c o n c r e t e forms or any task requiring level or grade s i g h t i n g (Fig. 1). It can be made in o n e evening with hand tools.
The instrument consists of two major parts: The sighting level tube or telescope to which a level vial is attached, and the level bar. It. is supported by a camera tripod with or without a tilting head. The tilting head will enable the user to set up the instrument more easily but, on the other hand, detracts somewhat from the stability.
Make the level bar (Fig. 2) first. Use angle iron taken from an old bed rail because structural angle iron is too heavy and thick at the corner. With a hacksaw make a cut 2 in. long as close as possible to the
vertical side. Then bend up the 2 in. cut end. Since the bed rail steel may be brittle, heat the area to be bent to a dull red. Check the bent end with a square to make sure it is exactly 90° and saw off the extending vertical side 1/8 in. beyond the bent section. File the top edge of the bent end down to 1 3/4 in. above the bottom edge of the bar and parallel to it. Then file both sides to a
Using engineer's level on a camera tripod to set concrete forms.
By THOMAS E. RILEY
blunt knife edge. Finally draw the file lightly across the length of the knife edge to be sure the edge is a straight line parallel with the bottom. This knife edge is the one crucial point in the construction of the instrument because it serves as the "Y" support of the level, the pivot bearing and horizontal crosshair. Drill the two 9/32 in. holes and tap the middle hole 1/4-20 to fit any camera tripod head.
To make the level tube, cut pipe threads on one end of a 14 in. length of 3/4 in. standard pipe and saw the other end at an angle as in Fig. 3. Scribe a line lengthwise on the bottom of the pipe parallel with the sides. Measure and mark 11 15/16 in. from the threaded end for the loca-tion of the center of the pivot slot. Cut this slot 1/8 in. wide and file to the wedge shape (Fig. 3A). Round the bottom of the cut with a small rat tail file or abrasive cloth around a nail. The slot should extend exactly halfway through the pipe. Now lay out, drill and tap the two mount-ing holes on the scribed line and mark the opti-cal center point.
An ordinary 3-3 1/2 in. re-placement level vial for a car-penter's level is to be used. Purchase the vial first then se-cure a piece of copper or brass tubing just large enough so the vial will slide into it. Cut the tubing off 1/2 in. beyond each end of the vial and file an oval hole in the middle of the tub-ing to expose the vial bubble as in Fig. 4. Drill parallel 1/8 in. holes in each end of the tube for supporting bolts and cement the vial in the tube with household cement.
To locate the exact position the vial is to be fastened to the sighting level tube, hold the center of the vial bubble marking at the optical center mark scribed on the sighting tube and spot mark the loca-tions of the two 1/8 in. holes in the copper or brass tube on the sighting tube. Drill and tap the sighting tube for 5-40 threads.
Make the sighting disc Fig. 4 next. Cut a 15/16 in. dia. disc from 1/16 in. thick brass or steel. File and fit this disc to fit snugly inside a 3/4 in. con-duit pipe bushing. Drill a small hole (about #55 to #60 drill)
through the exact center of the disc and assem-ble to the threaded end of the sighting tube. It is important that the disc be secure. If the small hole is slightly off center, the final adjustment of the instrument will correct the error; but, if the disc moves after adjustment, the instrument will give false readings.
Before assembling the parts give them a coat of paint. A crackle finish type of paint used by radio repairmen will give the instrument a pro-fessional appearance. Do not paint the knife edge or pivot slot. After the paint dries, cut the heads off two 5-40 x l 1/4 in. long machine screws and screw into the tapped holes in the sighting tube. Lock the screws to the tube with a nut on each one (Fig. 4). Place another nut on each screw, then the level vial tube and fasten with a third nut on each screw. Adjust the nuts on either side of the vial tube until the vial appears par-allel with the sighting tube.
Next, cut the head off a 1/4-20 x 2 in. bolt and screw into the tapped hole nearest the sighting disc or eyepiece of the sighting tube. Lock in place with a nut on the outside of the tube. Slip a lV4-in. compression spring and washer over the bolt and assemble the tube in its position on the level bar with another washer and wingnut. At-tach another 1/4-20 x 2-in. bolt into the tapped hole nearest the pivot slot with a nut on the outside as before. Place a 5/8-in. compression
spring, washer and nut underneath the level bar (Fig. 4). Screw the bolt into the tube until the spring exerts tension on the knife edge bearing. Then lock the bolt to the sighting tube with the nut on the outside of the level tube and the instrument is assembled.
The level is adjusted by the collimation or peg adjustment. The object is to place the axis of the level vial exactly parallel to the line of sight through the level tube. You will need a sur-veyor's level rod for this adjustment and also for your surveys. One can be made inexpensively by purchasing a level rod ribbon and gluing it to a 1x3-in. board. These ribbons are l 1/2 in. wide cloth tapes with easily read graduations in hun-dredths of feet instead of inches. They may be purchased in any engineer's supply store.
Set up the level in a convenient area outdoors. To set it up properly, place the legs of the tripod or adjust the tilt head by eye so that the bar seems level. Next, sight the instrument on the level rod and then center the bubble in the vial by means of the wing nut. Have an assistant bal-ance the level rod on top of a stake driven in the ground fifty feet in front of the instrument. Sight through your level at the rod, and, after carefully centering the bubble, record the read-ing made by the knife-edge on the rod. The assistant rodman, then picks up his rod without disturbing the stake and moves to a point fifty
feet behind your instrument. Here he drives a second stake in the ground and balances his rod on it. You now swing your level around and sight on the rod again. Record this second read-ing after readjustread-ing the bubble. Next, pick up the instrument and set it up directly alongside the second stake. Measure up from the top of the stake to the small hole of the eyepiece after the level bubble is centered.
Even though your instrument was not yet in adjustment, your first two readings gave you the actual difference in elevation between the two stakes Why? Because equidistant level shots eliminate the collimation error and your two shots were equidistant. Now, if you add or sub-tract the difference in elevation (whichever it is) to the height of your instrument above the second stake, you will know what the instrument should read on the rod when the rod is on the first stake. With the rod balanced on the first stake, adjust the level tube with the wing nut to the correct reading, disregarding the bubble in the vial. Then without disturbing the level tube, carefully adjust the level vial with the four nuts until the bubble is centered. Your instru-ment is now in adjustinstru-ment and ready to use, but the procedure may be repeated for a check.
When observing through the level, always sight so that the rod is in the center of the horizontal knife edge. At that point any possible divergence of the knife edge from a horizontal line will be zero. A few hours study of a manual on surveying will acquaint you with the many uses of an engineer's level and with the proced-ures used by surveyors on complicated layouts of grade.
Fig. 15-21. An electric pencil is a useful tool for writing names or identification marks on tools and metal objects.
ELECTRIC PENCIL
Project IX
This is a real practical project. You
will find many uses for it around the home
and shop. By means of the electric pencil,
you can write your name on any metal
ob-ject. Tools with your name permanently
etched on them are easily identified. See
Fig. 15-21.
Two additional electrical principles are
demonstrated in the construction of this
project. First, a current flowing through
a coil or inductor resists a change in
the value of current. This property of a
coil is called inductance. In the electric
pencil when the circuit is broken as a
re-sult of magnetic action, the current
attempts to continue flowing as a result
of the inductance of the coil. This results
in a small spark which jumps across the
gap between the pencil point and the tool on
which you are writing. Second, an electric
spark has an intense heat and actually
eats into the metal, thus causing a
per-manent mark on the metal.
To write well with the electric pencil
will require a few minutes of practice. At
first you will notice that the point tries to
stick to the metal tool. You will learn to
write with just the correct pressure so
that an arc is continually jumping the gap.
An electric welder must learn to strike
and hold an arc as one of the first lessons
in welding.
Construction Hints:
1. Your first consideration in making
this pencil is to keep the size small
enough so that it may be easily handled
as a pencil.
2. Fig. 15-22 gives you a detailed
drawing of one way that this can be
accom-plished.
3. The core is a 16-d. nail, threaded
on one end, on which is cemented two
3/8 in. fiber or plastic washers, to act
as coil ends. The coil is wound with two
layers of #18 enamel covered wire. One
coil end runs to the connecting terminal
at the end of the pencil. The other coil
end is attached to the moving armature.
4. The armature is made of 20 ga.
spring brass 1/4 in. wide, cut to suitable
length.
5. The end of the brass armature is
drilled for a 1/4-6-32 bolt. The bolt serves
two purposes. It provides a piece of iron
which the magnet can attract and also
provides a means of attaching a short
16 D NAIL
BRASS ARMATURE WASHER FLAT ON ONE SIDE TO ALLOW ARMATURE MOVEMENT
FIBER WASHER
Fig. 15-22. Construction plan for an electric pencil.
94
Electricity - PROJECT SECTION
piece of copper wire to be used as a
writ-ing point.
6. After the pencil assembly has been
made, it can be fitted into a 6 in. length
of 3/4 in. dowel. See Fig. 15-22. Mount
the dowel in a lathe and bore a 3/8 in.
hole in one end of sufficient depth to take
the coil. Then drill a 1/8 in. hole all the
way through the dowel for the connecting
wire.
7. To use the pencil, connect one t e r
-minal of a 6 v battery to the tool on which
you wish to write. Connect the pencil to
the other battery terminal. When the pencil
touches the tool, the circuit is closed and
a current will flow, creating magnetism
which draws the point from the tool, which
opens the circuit. The point then touches
the tool again. The resulting ar c will mark
the tool.
SPRING HOLD-DOW
I
can is splashed by
the crankshaft to keep
-
the mechanism weII
lubricated.
The
complete
drive
unit
is
shown
in
Fig.
1,
partly
cutaway so that you can get
a
better
idea of
its
assembly.
Bronze spin-
dle
bushings (Ford
model-T type) are
used
as sleeves
for the vertical shaft and
also
as
SCARCITY
of
metal
leed
not
keep you
a
bearing
for
the crankshaft.
Fig, 3 shows
from having a scroll
'saw,
as
this one is
how
the
channel
isclamped
to
flattened
mqde mostly
of
wood.
Abide from
the
bolts
places
on
the
shaft,
and
how
the
lower
and
bushings
required,
t p
few
other pieces
bushing is mounted in a flat-iron bracket.
of
metal needed
can be,
salvaged, in most
Note from
Fig. 4 that the bolts in
the latter
cases,
from
odds
and
efnds
found
inthe
fasten both
it and the
can to
the wooden
junk
box.
If
plywood
i;s
not
available
in
base.
YOU
can work the channel to shape
your particular
locality,l
you
can
resort
to
by
hand
using
a
hacksaw,
chisel andefile,
solid
stock
by
gluing
up panels of sufficient
or
YOUcan
have the
channel and
crank-
width.
The
crankshaft mechanism
of
the
shaft
made.
Thick
felt
washers
prevent
drive head
operates
in labath
of
oil and
leakage
of
oil
at
points
where
the
two
,is sealed inside an ordingry
1-qt.
paint
can
shafts pass through the can.
The oil level,
of
the
type
having
a
p
ess-fit
lid.
Fig.
4of
course,
should be
kept
below
thehole
will give you an idea o
how
i t
works.
A
in
the
side
of
the can,
as
shown in Fig.
4.
crankshaft, entering
the
side
of
the
can,
Itis
important that the block holding
therth
crankshaft bearing be rigid.
Fig.
2
show
a
way
of
bolting
thii,
which
allows it
be
retightened
easily
if
it
should
w
loose.
When insfaJling
the
crankshaft
must
be
no end
play, as
the
face of
the
TO LEG REACH
the top of
the plywood
sides.
With
this
fill-
er
block
in
place,
you can go ahead and add
the
blade
chuck to the
slotted end
of
the
shaft.
This
consists
of
a
hexagon
nut
screwed and
soldered
to the end
and
then
a
%-in.
elbow to be
pinned
to
the project-
drilled and
tapped crosswise for a setscrew
ing end and soldered to'the
flange.
If
you
to clamp the blade as shown in
Fig.
7.
The
are unable to
have
the bushings turned of
blade
can
be
made
self-centering
in
the
metal
to fit the pipe shaft, satisfactory
ones
width as
the blade.
pipe
shaft
by
two
floar flanges which are
i f
short
pipe arms make a neat job.
centered and screwed opposlte each other.
to
the
size
of
the
plywood
drive
One
end
of
the
shaft
is
threaded
to
pass
you'll
have to
true
it
on
the outer
throu+hGp
flanges far
enough
to
permit
the lathe as shown in Fig. 10.
.c.z:*- ,;:b4 :
ins
Hold
Bandsaw
Blade in Vise While
BI
Instead
of
making up a special
jig
to hold
the
ends of
broken
bandsaw
blades in perfed alignment
while
brazing,
just
slip
a
couple of
large cotter
pins
over the blade and
clamp
them
in
a
vise as shown.
To protect vise jaws against excessive
heat
from
SLOT PERMITS ' TILTING TO ANGLE OF TABLl