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(1)

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

\

(2)

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'

1

V8 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

(3)

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,

* * *

(4)
(5)

-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,

so

that 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

Leave

emugh

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

is

similarly

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

(6)
(7)

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

(8)

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.

* * *

(9)

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

(10)
(11)

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.

A

cut-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

is

w

-

(12)

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

drill

with

the chuck

removed 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 .

A

flange

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

(13)

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.

4

and

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 away

slowly,

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.

(14)

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

an

oiled

strip

of

cloth

or

leather against

the

work

,, +

as it rotates in.

the

lathe.

(15)

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 493

divided by -25, or 1972.

The

y i r e

size

is

calculated

from

the

length

of

the magnetic

path,

as shown

in

the upper detail of

Fig. 7.

The

wire

size in

circular mils is found

by

multiplying

the

length by

50,000,

and then

dividing by the

number

of

turns.

For

a magnetic path

of

3% in., the wire size required is 3.25 times

50,000,

divided by

1972,

or

82.5

circukr

mils.

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

(16)

\ '

The

armature

is

fastened

to

its

b r d

-

size

@WW

Bage

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:

30

enameled wire.

specified

should

be followed

cItre&By.

&

&

mast

transformersap

Eggraving

tooh

can be made of

%-b,

&.-

,

g i v q

Nos

3Q

wire

larger drill

rod.

The

tips

can

be

ground

t~

ere

a

heavy-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 yellow

The d tg wauhd on a woodan form a9 color and pl-g the aut'thg end om&

shorn

in

5 w d

6.

The form should

, into

cold

water.

After hardening&er

are

b

a h *

Iarger

than

the

16g Qn

which

the

An&&

ground.

The

shank

of 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

"

(17)

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 mixing

paints

and

stains.

When tin

cans

are 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.

(18)

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

the

flat-herd

bolt6

mounts

for

floating-type

rails

can

be

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 fit

the

recess in the top

screws

or

bolts,

using

washers

under

of

the heel and drill two

holes

through

the heads.

(19)

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

the

top 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.

2

(20)

can 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

in

blade pressure

for

the best-cutting

action.

The

support-arm

guide,

Fig.

3,

can

be

you

to start

made

.from

%-in.

flat iron, the

slot

being

Screws in

places

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 slot

will

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

(21)

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 LOEWEN

ou 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 SCIENCE

can 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.

(22)

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.

(23)

Engineer's Level

D

ESIGNED to

be 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.

(24)

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

(25)

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.

(26)

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

(27)

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.

(28)

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

is

clamped

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

in

the

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

YOU

can

have the

channel and

crank-

width.

The

crankshaft mechanism

of

the

shaft

made.

Thick

felt

washers

prevent

drive head

operates

in la

bath

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.

4

of

course,

should be

kept

below

the

hole

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,

It

is

important that the block holding

the

rth

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

(29)
(30)

TO LEG REACH

(31)

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

(32)
(33)

SLOT PERMITS ' TILTING TO ANGLE OF TABLl

tracking

without

twist

by

engaging

a

cross

pin in

the shaft

in

slots

in the

tube.

Needless

to

say,

the

slots

in

the

tube

must be cut down each side

exactly

in

the center,

otherwise

the pin

is

apt

to

bind

or

prevent

assembly.

The

shaft,

with

the

cross

pin

either

threaded

or

pressed

into

it, must

be

slipped inside

the tube

and both

inserted in the hole

at

the same time, after

which'the spring

is added

and

the

lower bushing and its

As

..

-, portan ant that the holes be in

lime

sleeve are pressed in the end

to

hold

the

centrally

through

the

block,

a

drill press,

tube in place.

The width

of

the

slots

in

the

is

preferred

to

boring

them

by

hand, al-

tube

should

equal

the

diameter of

the

cross

though

the

Iatter

can be done fairly accu-

pin.

Note

that

a

thick

felt washer

is

pro-

rately

if

you

are

careful

to

keep

the

bit

vided

between

the bushing

and the

metal

running

as

straight

as

possible.

Bore the

plate

which

holds

the former in

place,

to

top hole

3

in.

deep,

then

turn the block end

prevent oil from

being thrown

out through

for end,

and

with a 1-in. bit,

bore through

the

shaft

clearance

in the plate.

The upper

to

meet

the

first

hole.

Next,

groove

the

blade chuck is made

the

same way

as the

rear

edge

of

the

block

to

take the

hold-

lower one,

which

was described

previous-

down,

after

which

the

uppet.

corner

is

ly, the end of

the shaft being

threaded for

notched according to the dimensions

given

the

nut

before the shaft is installed in the

in

Fig.

15.

housing.

The

cutaway

sectional

view

in

Fig.

15

A

turn of

a

handwheel

clamps

the unit

ahows what

the tension

mechanism

looks

securely-in

the

arm.

This can be made of

like

when

installed

in

the

counterbored

wood

and fitted

with a carriage

bolt

to

en-

housing.

Bronze bushings

of

the type that

gage

an

embedded

nut

in

the

opposite

side

were

used in

the

drive head are used here

as shown in the top view

of

Fig.

15.

The

to carry the

shaft;

the upper bushing being

completed

unit

must

be

mounted

in

the

pinned

to

the

block

through

the flange and

arm

so

that

the

upper

chuck

will

be

di-

the

lower one bushed centrally in the hole

rectly

in line with the

lower

one.

You can

with

a

turned wooden

sleeve.

Fitting the

do

this

best

by

clamping

the

unit

ten

Figure

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References

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