Family Cooker : instruction how to make and use them

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Overhaart, J. C. (1979). Family Cooker : instruction how to make and use them. Eindhoven University of Technology.

Document status and date: Published: 01/01/1979

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M031365

Family Cooker

·-by J.C. Overhaart

Eindhoven University of Technology Faculty of lndustrial Engineering Department of Appropriate Technology The Netherlands

I"'

-dv,

I

datum

I

FAMILV COOKER

Instructien how to make and use them

design

by

J.C. Overhaart

Department of Appropriate Technology Eindhoven University of Technology

Eindhoven the Netherlands

P R E F A C E

Food production, eating habits, preparatien of meal& and methods of cooking are some of the primary considerations of mankind.

Fuel ~s scarce and, for the sake of preserving the environment, it to be used· as sparingly as possible.

I t is a lso necessary to prevent smoke accuroulating ~n dwellings ~n der to prevent a number of diseases.

has

or-·It was on the initiative of J.C.Overhaart that the Family Cooker was developed. It obtained an international award: the I C S I D - Philips Diploma 1978, given by the United Nations Industrial Design Organisation,

the International Council of Societies of Industrial Design and the Philips company. His initiative produced a world-wide interest.

A discussion will take place about the application of the Family Cooker and ether cooking devices between volunteers and field workers from dif-ferent parts of the world.

Recently, scientific researchwerk started and it ~s expected that in future better understanding will be gained about the processes of burning wood for heat transfer when cooking.

After studying traditional fuel uses, it will be possible to design opti-mal cooking devices that are in harmony with local conditions.

In

to campare it

December 1979

Dr. Ir. J.W.

investigate the use of the Family-Cooker and cooking stoves in order to try to imprave it.

Family Cooker Aim

Introduetion

What is the new FC and how does i t work? What fuels can be used?

From what materials can the FC be made? Advantages of using the FC

I n s t r u c t i o n

f o r t h e m a n u f a c t u r e o f a FC

C o m b u s t i o n - u n i t:

Housing Fire-box

Marking out the cylinders Connecting or air inlet-pipes Connecting of housing to fire-box

Bottom for the fire-box Grate and grate-supports

Grips

P

r i n c i p

1

e

Example for manufacturing a flue-chamber

End covers of the flue-chamber

'

Pipe-element for the draught-regulator

D r a u g h t - r e g u 1 a t o r

Connecting the pipe-element to the flue-chamber

Smoke-channel or chimney-pipes Chimney cowl

Using pots with flat and globular bottoms

1 1 2 2 3 3 3 4 4 5 6 8 8 10 10 11 13 13 16 17 18 20 20 21 22

C 0 N T E N T S (continuation)

Directions for use of the Family Cooker Rough-and-ready rules

Same tests results

D i r e c t i v e s f o r u s i

Housing and fire box Flue-chamber

Chimneypipes Grate

Air inlet-connecting pip es

Using rings on the cambustion-unit

Removable cover-plates Marking off campasses Rivets

Variety in design

n g a 1 t

Questionnaire regarding this instructien book

A C K N 0 W L E D G E M E N T S e r n Page 23 24 25 a t i 27 27 27 28 28 28 28 29 29 30 31 v e s

I am greatly indebted to the department of Appropriate Technology of

the Faculty of Industrial Engineering of the Eindhoven University of

Technology for offering me the opportunity to realize this project.

To Mr. P. Doorakkers,for his advice and c~operation with respect to

the diagrams.

To Mr. J. de Groot, for his technical advice with respect to the

The Family Cooker - abbreviated FC - bas been developed in order to meet the great fuel scarcity in many parts

ot

developing countries.

Roughly estimated, by using the FC, we can count upon a saving of 75% of the wood-fuel in cornparison with an "open fire".

A very favourable factor is the completely smokefree operatien of the FC in the dwelling-places of the population, so that eye-dis .... eases, nasal catarrh, infections of bronchial tubes - aften accuring in wamen preparing food in smoky rooms - will diminish.

Ecologically the FC is of great importance in those districts where disafforestation and desiccation occur.

A i m

Though this instructien portfolio was in principle intended for people with some manuel dexterity, it would be adequate and desi-rable - also in view of the many reactions recieved from various countries - if local education-centres, training-schools, technica l-schools, small-scale workshops, etc. in developing countries, were the first to undertake the manufacture of the FC. In fact, they know the local cooking-customs and the sizes of the pots and pans that are generally used, and to which the FC must be adapted.

When once the FC is in use here and there, the handyman will get a clear and better insight into the farm and the construction an~ have less trouble in manufacturing the cooker.

Moreover, when developing and describing the FC, the materials ob-tainable locally have constantly been taken into account.

For that reasou additional attention has been paid to the application of alternatives.

2

-I n t r o d u c t i o n

This portfolio contains a description of the manufacture of one of the types of FC.

It is very we'll possible to enlarge the combustionuni t and the flue··· chamber or to diminish them. The necessi ty depends on the si ze of the

pots and pans to be used on the FC.

The description of the work has purposefully been kept very simple, so that even the not 100% handyman can make the FC.

Using this description one can obtain satisfactory results even with

simple tools among which a pair of shears.

Holes can be made in sheet-iron; with a good steel drift, a hand-drilling machine is of course very convenient but is not always

in-dispensable.

W h a t i s t h e n e w FC a n d h o w d o e s i t w o r k?

The FC is a simple cookingappliance, with which it will be possible to bring water and food to boiling-temperature in the house without

causing smoke and with a minimum of fuel.

The upward draught in the cooker makes cambustion possible. The re-leased heat, as well as the favourable distribution of the

flue-gases, will give a great heat-transfer to the bottoms of the pots

and pans. These hot gases then pass one or more warrrting-up places before being carried off through the chimney. A draught-regulator in the chimney regulates the intensity of the combustion.

W h a t f u e l s c a n b e u s e d?

All conceivable SOLID fuels may be used, but they must be thoroughly dry. Soft and hard wood, branches, tree-bark, bamboo, coal, charcoal,

possibly also coconut-shells, pressed briquets of sawdust, pe anut-shells, hard grasses, etc.

For reasans of safety it is advisable not to use liquid fuels.

F r o m w h a t m a t e r i a l s c a n t h e FC b e m a d e?

The description in this portfolio has been based on the use of the right materials. Starting from the idea that the most suitable

mate-rials will not be locally available, much information is supplied

under "Directives for using alternatives". A d v a n t a g e s o f ru s i n g a FC No smoke or smell in the cooking rooms

Practically;: no ash-residues owing tototal combustion ·

A minimum of fuel consumption Light weight and portable

It can be placed on the ground and at any desirable height

It can be made fully dismantable Easily cleaned

It can be made of materials available in developing countries

Cheap as to the manufacture and the materials used Boiling temperature is quickly reached

Nat bad for the health in comparison with the traditional combustion-systems.

4

-I n s t r u c t i o n s f o r t h e m a n u f a c t u r e o f a FC

C o m b u s t i o n u n i t:

H o u s i n g

Cuta strip of at least l mm thick sheet-iron, 645 mm long and 175 mm wide.

This strip to be marked out by straight lines and square with a scri-ber. Now the strip is rolled into a cylinderorbent with the help of, for example, a round hardwood stem.

The ends of the strip should overlap 15 mm for the rivet-seam.

When rolling the housing it is recommended to wind an iron-wire around it to prevent it from unrolling.

In order to ensure the roundness of the cylinder, i t is desirable to mark a line at 15 mm from one edge over the whole width of the strip. Another line is marked over the whole width of the other edge at 7 mm distance from it. See fig. 1. This line denotes the place of the four or five riveting holes, which are drilled or drifted through both edges. Fig. l shows five holes.

Use four or five brass or iron rivets abt. 3 mm thick, or use bolts and nuts or sheet-metal screws. In this way we have obtained a cylin-der of 200 mm in diameter. See fig. 1. Make the cylincylin-der as round as possible; this facilitates the further proceedings.

fig. 1

all si zes are in mm ~

7

.F i r e - b o x

From an iron tube or pipe with a wall thickness of abt.

4

mro and a diameter of abt. 130 mro, a length of 140 mro, is sawn or cut off square.

If no such tube is available, use a strip of sheet-iron, at least 2 mm thick.

Cut or saw off a piece 425 mro long and 140 mro wide. This piece must also be marked off by straight lines at right angles as described for the housing, it should be bent with the help of, for example, a round hardwood stem.

The ends of this strip should overlap 15 mm for marking a rivet-seam. When rounding the strip, it is recomroended to wind an iron-wire round

the cylinder to prevent the cylinder from unrolling.

It is better

n21

to use an iron hamroer for rounding the strip; a wao-den hamroer is preferable.

To keep the correct width of the cylinder visible, it is desirable to mark a line at 15 mm from one edge of the strip over the whole width. Another line is scribed over the whole width of the other edge at 7mm distance from it. This line shows the places of the five holes to be drilled or drifted through the overlap.

Only iron or brass rivets, abt.

3

mm thick should be used. Use at least five rivets.

We now have a cylinder of 130 mm in diameter. See fig. 2. Make this cylinder as round as possible; this will facilitate the further ope-rations.

fig. 2

- 6

~

M a r k i n g o u t t h e c y l i n d e r s

For this purpose we first use a makeshift in the form of a sheet of paper of abt. 500x500 mm.

Draw on it two lines crossing each other at right angles (90°) in the centre of the paper.

Now measure the diametèr of the housing and transfer it to the two lines with the point of intersection as centre.

The marking should have a certain thickness. See fig.

3.

fig.3

.

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I

'

I

+

mark·ing housing

_,.",.--' .- ,.- -= ... / ...

/"/

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'~,

.(

--r· --

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I ~~ ... , \ I " ' , \

"

.

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/

/

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---.--·---,--

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---+---·-t·-·i-·---·

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\\'\

',....,_T ..,/

//markingfirc-box

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----+---/-i

c o I' l' e s p o 11 J i n g m a r ~

I

Place the housing on the paper and ~f it is duly round, the f~ur

markings inside or outside the housing are'visible.

One of the lines on the paper is marked with (x) outside the marked-out diameter of the housing.

There where the marked line (x) disappears under the housing, the

latter is marked by bringing in a dot with a centre punch.

This is done to be able to replace the housing always in the same position.

Now place paper and housing on a flat surface. Using a try-square

0

or a metal sheet with an angle of 90 , mark off four perpendicular lines on the housing, there where the intercepting lines project from under the housing. See fig. 4.

driven-in centre I I o I fig.4 '*-.correspondfng mark s q u a r e · · ... -:-:---':..__ _ _ ~;?____:_::_:_:_::...:.:.

"'--..

These four markings have a lengthof abt. 65mm. each.

Afterwards, a centre is made in those four markings, at 50mm. from the bottorn of the housing.

The same method is applied to the fire-box. See fig. 3 and 4. Th~ length of the four perpendicular markings on the fire-box is now 45mm., while the eentres are made at 27mm. from the bottorn of the fire-box.

- g

-A i r i n 1 e t-p i p e s.

These pipes have a double purpose. They form a firm conneetion

between the two cylinders and, allow air to enter for cambustion

in the fire-box.

Obtain a pipe of abt. 25 mm. outside diameter which is the most

suitable for the purpose, but slight deviations are permissible.

To avoid failures, use iron or brass pipes.

Saw off four pipes of 45 mm. long. File the end,s square and polish

the edges.

C o n n e c t i o n o f h o u s i n g t o f i r e - b o x.

Using a pair of scriber-compasses (see also at "Directives for

Alterna ti ves" ). Small circles are sera tched on the driven-in

eentres of the tw9 cylinders. Their diameter must be the same as

that of the pipes.

Practice has taught us that it is impossible to drill a hole of

25 mm. diameter in the two cylinders.

So cut as big a hole as possible with a small chisel inside the

scratched circle, and file up thè hole with a half-round file.

The connecting pipes must be press fits in the fire-box; later on they will be hammered into it.

In the housing the holes should be fited so accurately that the

pipes fit the holes without play.

Now place the fire-box in the housing. See to it that the mark (~)

correspond with the driven-in centres.

The holes in both cylinders should now be lying in ~ horizontal

plane; for that reason some padding should be placed under the

fire-box.

After that the pipes can be placed through the housing into the

fire-box. Applying light hammer blows they are driven slightly

Now place a heavy round spindle i~ the beneh-vice and put the fire-box over the spindle. This provides a bearing surface for further

driving in the pipes. See fig.

5.

When the pipes have been hammered

in straight and ar~sticking out a bit through the fire-box abt. l

mm, they have to be secured in their places. This is done as fellows. Remove the workpiece from the spindle and place it so on a flat

bearing surface that one of the pipes stands vertically on it.

See fig. 6.

Passing a long drift or chisel through the opposite pipe, the edge of the pipe is upset in such a manner that it is anchored in the fire-box. When the four pipes have been thus secured, the conneetion between the two cylinders is complete.

If the above-mentioned directives have been executed correctly, the top of the fire-box will be abt. 12 mm below that of the housing. This is an important condition.

pipe is hammered fnto the fire-box

12 hearing spindle - - · -_·- --.,...----{ fire-box housing

A_

·

_f=!-g--.6

u-

J

-drift or chisel

[)-

· - ·

·-:1 edge of the pipe to be upset

~

V

flat bearinR surface

10

-B

o t t o m f o r t h e f i r e - b o x

A circle is marked off on a piece of sheet-iron, l mm thick. Its

diameter is equal to that of the fire~box. A~ter cutting out this bottom, it is filed to measure in such a way that it fits tightly into the fire-box.

After that, using a drift or a centre-punch, the lower edge of the fire-box is upset in a number of places so that the bottorn cannot fall out. See fig. 7.

G r a t e a n d g r a t e - s u p p o r t s

of fire-hox

to he up set

r'IG.?

From thicker material, at least 3 mm thick, a round plate is made which should fit into the fire-box with some play so that it can be

readil~ removed. A sufficient number of holes -10 mm in diameter

each-must be drilled in the plate (also see under "Directives for

Alter-natives"). If necessary the drilled holes are connected with each

other, here and there, by cutting out or filing away the interjacent

material in order to facilitate the circulation of air. The grate is

to be provided with four supports, which may be made from abt. 4 mm

nails.

Therefore, four holes are to be drilled in the edge of the grate at

equal distauces from each other to recieve the nails.

The ends of the nails, 45 mm long, are filed somewhat conically, so

as to be press fits in the holes and aftér that they are riveted to

fig. 8

grate supports

fixed by means of riveting

It will be clear that the four grate-supports rest on the bottorn of the fire-box.

The supports should be so long that the grate is always above the air-inlets.

G r i p s

A grip may be a simple ear, riveted on to the housing and made of a piece of band iron or a strip of sheet-iron abt. 2 mm thick, 250 mm long and 15 mm wide.

The space required for the hand is 120 mm wide, and height 40 mm; the length of the connecting lugs is 25 mm. See fig. 9 and exploded view page 12.

It is recommended to fix one grip to the riveted seam of the housing, becàuse the thickness of the housing is double.

It is handy to fix a second grip on the opposite of the housing, for easier removal of the combustion-unit.

fig. 9

120

gri p

I

_I

- 12 -exploded view grate with riveted supports fire box bottorn of fire-box

housing with connecting or air-inlet pipes

It is impossible to keep a fire burning without air-circulation. The FC cannot work withou~ chimney-draught (this is the draught in a pipe

or smoke-channel, which mostly rises above the top of the roof).

Therefore this draught is obtained in the FC with the help of a hori-zontal conneetion between chimney and cambustion-unit - the flue-chamber -. In fact chimney-draught depends on the temperature of the

smoke-gases that are transported via the chimney and on the dimensions of the chimney (height and diameter).

The flue-chamber is a flat box - it does not matter what form - on which the cernbustion-unit is placed. If a pipe-connection is made with that box (smoke-channel), the draught will also exist in that box.

In the top of the box is made a round hole with a diameter of 170 to

180 mm, so that the housing of the cambustion-unit covers it. When the

cernbustion-unit is now closedat the top- by a pan or a kettle - there

will also be a draught in the combustion-unit.

The whole principle is based on that! _;

The area of the cross-section of the flue-chamber should be in some

proportion to the diameter of the pipe or the smoke-channel to be used. In other words, i t is desirable to make the passage in a flue-chamber not smaller than the diameter of the smoke-channel.

E x a m p l e f o r m a k i n g a f l u e - c h a m b e r

Cut two plates of sheet-iron of at least l mm thickness, 630 mm length

and 330 mm width. They are to be marked out straight and square with a

scriber.

T o p o f t h e f l u e - c h a m b e r

Before drawing the circles, we first mark the centrelines on the plate

according to the sizes indicated in fig. 10. Where the centrelines interseet we strike a dot.

630 scratched line 0 ....

- - - - -

- -

---

--- ---

- -

- -

- --,-,----.. 110 180 105 0 .... :fig.lO

14

-After that, mark the circles to the dimensions indicated using a pair

of scriber compasses. (see also under nnirectives for Alternatives~~").

Then mark two lines at 40 mm from the long edges. See fig. 10.

The material has to be drilled out or chiseled out along the inside of the circles.

Then file the edges in accordance with the circles, using a halfround

file. Removing the material with a pair of curved shears is not

re-commended in view of possible deformation of the material.

Further the two marked-out strips of 40 mm width, are to be bent over at right angles (90°) in a work-bench. When no work-bench or

sheet-clamp is available, we can take two hardwood beamq, between which the

sheet is clamped as far as the scribed lines; after that the strips are bent over, using a wooden hammer. See fig. 11.

fig.ll

B o t t o m o f t h e f l u e - c h a m b e r

On the second strip of sheet-iron are scratched only two lines at 40 mm from the long edges. This strip is also bent over at right angles (90°) as described above.

C o n n e c t i o n o f t h e t w o

f l u e - c h a m b e r h a l v e s

The flue-chàmber halves can be fitted together in two ways, both of

which are quite satisfactory. The methods have been indicated in fig.

12 on page 15. In each side two holes of 4 mm bored, at 20 mm from the

ends and halfway the height. Than fits the halves with sheet metal screws or bolts.

me thod I top half over the bottorn half

FIG. 12

metbod 2 top half in the bottorn half

16

-E n d c o v e r s o f t h e f l u e - c h a m b e r

The flue-chamber has now to be closed at the ends. It is not possible to give the dimensions of the required material already now.

Therefore, first measure the inside lengthand heigth.

Example: You measure 248 mm length, 42 mm heigth. Add to this length and heigth 20 mm, so that the actual dimensions will be 268 and 62 mm. Cut off two pieces of l mm sheet-iron, 268 mm long and 62 mm wide, to be marked off straight and at right angles.

The dimensions mentioned here have only been given as an example, Only after measuring the actual length and heigth inside the flue-chamber and adding the 20 mm, can the right dimensions be found! At ll mm from the long and short edges of the plates, lines are scratched. See fig. 13.

Then cut out the four corners at the crossings of those lines, in order to make it possible to bend over the four marked-off sides.

fig. 13 scratched lines

11

cut out corners

The sides can be bent over quite satisfactorily with the help of an appropriate strip of thick metal and using a beneh-vice or a couple of clams. But the condition is that the end covers should be press fits in the flue-chamber. See fig. 14

fig.l4

.The corners of the end covers are to be filed somewhat round; this

will facilitate the press fitting.

After insertion, the end covers need not be secure any further.

This has the advantage that, when the flue-chamber has to be cleaned,

they can be removed and replaced easily.

P i p e - e l e m e n t f o r t h e d r a u g h t _ r e g u l a t o r

If there is any sheet-iron pipe with a diameter of 110 mm and a

length of abt. 170 mm, it could be used very well for making a

pipe-element for the draught regulator.

If no such pipe is available, i t must be made.

Cut off a plate of sheet-iron abt. l mm thick, 360 mm long and 170

mm wide. To be marked off straight and at right angles.

Along one end a line is scratched at 15 mm distance from the edge over the width. This line marks off that part of the plate in which

rivet holes will be drilled. Along the other end a line is scratched

at 7 mm from the edge, the latter indicates the place of the four or

five holes which are to be drilled or drifted through the two plate

ends. This plate is now bent into a cylinder with the help of a

hardwood stem. It is recommended to wind an iron wire aróund the

cylinder when rounding it, to prevent unrolling. Now the four or five

holes mentioned abDve are drilled or drifted in the overlapping section to complete the cylinder. Note that the top and bottorn holes leave a distance of 15 mm free from the top and bottorn of the

cylinder. See fig. 15.

lo I I 10 I ...

-•

/ -t·· / I 10 0 ... fig.15 I 10 I I I I

I.

I I I I 10 <·)--:-'-r.::. :·:! ;-.... -...

>

I.

I I B sawcut fig.16

18

-Use iron 9r brass rivets abt. 3 mm thick. The pipe should be made as round as possible. This will facilitate further operations. The pipe thus formed has a diameter of 110 mm.

Now a line is scratched round the outside of the pipe, abt. 12 mm from one of the ädges. Then lengthwise cuts are made in the pipe all around, the spacings being 10 mm. The cuts end at the scratched line. The lugs thus formed are to be bent outwards at right angles(90°). In six or eight lugs, holes. are drilled or drifted at equal distance from each other.

The pipe may not yet be fixed to the flue-chamber, first a. draught-regulator must be fitted in the pipe which will now be called the " pipe-element".

D r a u g h ~ -r e g u l a t o r( See fig. 12 and 17)

This regulator is a simple disc inside the pipe-element, with a

handle outside. It may be made of a piece of 1 mm sheet-iron and its diameter must be made 2 mm less than the inner-diameter of the pipe-element.

H a n d 1 e

Obtain an iron spindle, for instanee concrete-iron, of abt. 8 mm round and 250 mm long. One end is bent into an eye with an inside diameter

of abt. 25 mm. This can be done on a beneh-vice and with the help of a round spindle. It may be done cold. It is also possible to forge the handle.

A lengthwise cut must be sawn in the shank of the handle. The length of the sawcut should be equal to the diameter of the pipe-element plus 15 mm, that is 125 mm. Note that the sawcut should be in the same plane as the eye of the handle. See fig.I6.

The handle should now be placed in the pipe-element that has already be formed. For this purpose we draw a scratch round about the pipe -element about 85 mm from the pipe-end. A strip of paper, for instance, 20 mm wide is laid tightly around the pipe beside the scratched line and we see to it that the ends of the strip touch each other.

it along the scratched line on the pipe. At bath ends of the folded strip a scratch is made on the pipe at right angles to.the strip. At the crossings with the scratched line a dot is made with the help of a centre punch.

Take care that the dots are made at some distance from the rivet seam. See fig. 17.

'

108 I ' 0 I '-. ..._ ' I

-

' 0 .L • • •• • ,.· ·' J . regulator disc scratched lines

marking line scratched round

_the pipe-element with two 8 m m holes --- /

., .... _

'.,',.""--·

At both eentres we now drill a hole equal to the thickness of the shank of the handle. It is desirable that the shank should turn in the holes with some friction.

Then the handle is put through the two holes and the disc is pushed into the slit of the shank.

When by turning the handle it appears that the disc closes off the interior of the pipe-element reasonably well, we mark off both sides of the shank with the scriber. At 20 mm distance from the wall of the pipe-element, we scratch two cross-lines on the shank to indicate the places of the holes to be bored in the shank and the disc. See fig. 17.

By taking away the disc and the handle out of the pipe-element and fitting them into each other, the dots can be driven in on the cross-lines on the shank, in order to drill two holes through it for abt.

3 mm bolts or rivets.

See to it that handle and disc are replaced in the pipe-element in the same position before taking away.

If the above~mentioned operations have been executed correctly, a reliable regulator should be the result.

C o n n e c t i n g t h e p i p e - e l e m e n t t o t h e f l u e - c h a m b e r

Place the pipe-element on the flue-chamber, in such way that the handle is at right angles to the long sides of the flue-chamber. See fig. 12.

Through the holes in the lugs of the pipe-element, we mark the places on the flue-chamber where the holes in the flue-chamber are to be drilled. After that, fix pipe-element on the flue-chamber by means of bolts or rivets.

S m o k e - c h a n n e l o r c h i m n e y - p i p e s

For best results the smoke-channel or chimney-pipes can best be placed right above the flue-chamber, and if possible it should reach up to above the top of the roof.

It is also possible to fit the Family Cooker on to an existing smoke-channel, using elbows if necessary.

Many varieties are possible but always bear in mind that a good chim-ney-draught is essential.

If no suitable sheet-iron pipes for a smoke-channel are available, a 200 litre oil-barrel might supply the required material.

After removing the two flat surfaces of the barrel, the cylinder thus obtained is cut or sawn vertically.

Using a wooden hammer, the sheet is now hammered flat on a flat surface.

Long strips are then marked out, then cut and formed into pipes. It shou1d be recommended to make the pipes not 1onger than abt. 1 metre. They shou1d be made so that they fit tight1y into each other.

For other possibi1ities see under w Directives and A1ternatives".

C h i m n e y c o w 1

It is advisable to fix a cow1 on the top of the smoke-channe1. This wi11 prevent gusts from b1owing into the pipe and it may at the same

time serve as a rain cap.

Sufficient space shou1d be 1eft between the top of the pipe and cap. Smoke shou1d be capab1e of escaping easi1y. See fig. 18.

-

_{__}

·

_{_} ···_-· -· --

--

---_-~·:::­

-

-·--

-___ _.

__ _

.:.-·.:.:_:~ ---

---::~---=-

.·

.

~ --~ -:::-fig. 18 flat cowl connecting braces smoke channel

- 22

-U s i n g p o t s w i t h f 1 a t a n d g 1 o b u 1 a r b o t t o m s

When the bottorn of a globular pot threatens to shut off the fire-box

by sinking too deeply, we make a flat ring of some sheet-iron, abt. Zmm thick which rests on the combustion-unit.

The inside diameter of this ring should be made such, that, when the

globular pot rests on it, the required distance of 10 to 15 mm between

the top of the fire-box and the pot is maintained. See fig. 19. Of course the ring should be taken away when using a pan which can

rest on the housing of the combustion-unit.

Gross-section of cambustion unit with globular pot

fig. 19

to be maintained

at 10 to 15

housing

D i r e c t i o n s f o r u s e

o f t h e F a m i 1 y C o o k e r •

Before starting to use the FC and also when using it again later on, it must be preheated.

For this purpose some paper or other easily inflammable material is burnt in the round opening of the flue-chamber, there where the cambustion-unit will be placed.

The draught-regulator must be fully open and the warming-up place covered. As soon as we find that the chimney•pipe draws

and that it is getting warm, the preheating is finished~ The rising hot air-current increases the draught. Now place the

cambustion-unit on the flue-chamber and make in the fire-box a starting fire of some dry paper and small pieces of wrod. As soon as they burn, put a pan or kettle of, for instance,

water on the combustion-unit.

The whole combustion-system is now closed and the draught will keep cambustion going.

The smoke and the hot combustion-gases escape over the upper edge of the fire-box, pass between it and the housing to the flue-chamber and disappear via the smoke-channel.

When the beginning fire burns well, add a handfull of wood (cut or sawn pieces abt. 60 mm long).

The cooking of food or the boiling of water should offer no difficulties now. The radiating heat in the fire-box and the hot gases passing between it and the housing, heat the bottorn

of kettle or pan over the whole surface of the housing. During combustion, the draught-regulator should be used to

regulate the fire, otherwise too much heat will get lost via

the smoke-channel, through the fully open regulator.

Experience of the user with the FC will soon develop in him the

feeling how to cook efficiently and economically by placing the regulator in the correct position.

The light-weight construction of the FC will make it easily

possible to place it on the ground or at any desired height. Because the flue-chamber may get rather hot, it is advisable to

place the FC on a surface of flat stones or of sand.

If you have stove-polish or graphite-powder, use it on the

out-side of the FC. It protects it against oxidation and gives it

24

-This ends the description of how to make a FC.

Experience has taught us that when once you have made an FC and you have become familiar with its use, you may feel inclined to make another, possibly a bigger one.

Thanks to the goed results like quick heating, smoke-free werking and last but not least the extremely low fuel-consumption, enthusiasm will certainly increase.

R o u g h

a n

d r e a d y r u l e s •

See to it that no pan or pot should be used that sinks to deeply into the housing of the combustion-unit, because it would close off the top of the fire-box and so make it impossible for smoke and gases to pass through. See "using pots with flat and globular bottoms".

Do not use aluminium or zinc for making the FC.

Do not use liquid fuels in the FC; this is dangerous!

All fuels to be used should be thoroughly dry.

When using the FC you should see to it that the cambustion-unit as well as the warming-up place(s) are always covered, either by a pan or a pot or by cover-plates. If nat, there will be no draught and smoke might develop.

If a pan or pot is too small to be placed on the top of the combustion-unit, use an appropriate cover-ring that reduces the cambustion-unit diameter and allows a small pan to just cover the opening of the ring.

When using the FC outdoors, use a smoke-channel of sufficient height.

S o m e t e s t - r e s u 1 t s

Experiment F. Eringing water to boiling-point

Flue-chamter model C

Combustion-unit-

-Aluminium pan

-two holes

200 mm diameter

capacity 3 litres

Volume of water - - - 1 litre

Fuel - - - branch-wood (elms)

0 p e r a t i o n s Time in minutes

Making fire (paper and small pieces of wood) 0

Addition of branch-wood 130 grammes 1

Heating of the water up to boiling-point

7

Water keeps boiling up to 16

Wood totally burnt, almost no residue 19

Total duration from beginning to end 19 minutes.

Experiment E.

Flue-chamber model

Cambustion-unit Aluminium pan -Volume of water -Fuel - -

-c -

-

two holes 200 rnm diameter capacity 7 litres

5

litres

hardwood and charcoal

0 p e r a t i o n s Time in minutes

Making fire (paper and smal l pieces of wood) 0

Addition of hardwood 100 grammes l

Addition of charcoal 150 grammes 9

Heating of the water up to boiling-point 18

Water keeps boiling up to 24

Totally burnt, almost no residue 30

26

-G. Cooking rice

E

x p e r i m e n t

Flue-chamber model C---two holes

Combustion-unit---200 mm diameter

Aluminium pan---~---capacity 3 litres

Rice, not processed---broken rice (200 g.) Volume of water---6 decilitres (0.6 1.)

Fuel---hardwood and

0 p e r a t i o n s

Making fire (paper and small

pieces of wood)

Addition of hardwood 150 grammes

Heating of the water up to boiling-point

Addition of charcoal 50 grammes

Rice cooked in

23

minutes

T'btal dura ti on from beginning to end 23 minutes charcoal T i m e i n m i n u t e s 0 1 4~ 12~

When carrying out these experiments, cambustion-unit and flue-chamber

were on using-temperature.

During cambustion i t appeared useful to regulate the draught in such a way, that cambustion did not take place too fast.

D i r e c t i v e s f o r u s i n g a 1 t e r n a t i v e s

H o u s i n g a n d f i r e - b o x

If the right material is not available the housing and the fire-box can also be made of thinner sheet·-iron, for instanee, oil drums, motorcar body sheet, canisters, oil-tins and such like.

Sheet-iron of a motor-truck is generally thicker, so more favourable.

E x a m p 1 e

When using sufficiently tbick material, the housing and fire-box can consist of only one winding.

When,however, thinner sheet-iron is used, more windings should be

applied in order to get strenger elements.

It is also possible to saw a fire-box out of the rear-axle of a motor·-car (differential gear casing). The diameter of the rear-axle casing should, however, be more or less in correspondence with the sizes of the fire-box.

F 1 u e - c h a m b e r

Especiall~ the top of the flue-chamber should be of material that is

sufficiently thick, at least 1 mm.

Too thin sheet will deform sooner and not remain flat, with the result

that the bottoros of the cambustion-unit and öf the pots and pans do not cover the holes of the flue-chamber sufficiently well.

If only thin sheet is available, the top should be made of two or three layers, of course provided with the round incisions as indicated.

Rivet these sheets together with small rivets to the flue-chamber. It may happen that in a certain district there is not sufficient or no sheet-iron available. In such a case it is often possible to make the flue-chamber of clay.

In India this solution is frequently used.

C h i m

n

e y - p i p e s

An alternative for chimney-pipes has already been given earlier in theàe'instructions.

A smoke-channel already existing in the house can be used.

A construction of brick and clay or cement is also a possibility~

A construction of chimney-pipes formed of clay is already applied in

- 28

-G r a t e

On a wreek motor-truck a piece of metal is sure to be found of which a grate can be made.

If no sufficiently thick material is to be obtained, three or four 1 mm sheets may be riveted together.

Any thicker malleable material is suitable as well.

If after hammering out , it is not possible to drill holes in the

material because it has been hardened, the holes can also be made by heating the sheet in the fire and driving the holes in the glowing material with a big: drift.

After that a number of these holes can, if necessary, be connected

with each other.

By sawing or cutüing out the interjacent material, slits will be

produced that will admit more oxygen.

A i r i n 1 e t - c o n n e c t i n g p i p e s

Always try to use solid pipes, as have already been described.

The thick part of an old front fork and a rather heavy handle bar of an old bicycle are no doubt good substitutes.

The frame of an old children-bicycle can help to supply

pipe-material.

Do. not use too thin pipes; when driving them into the fire-box they

could easily be deformed·.

U s i n g r i n g s o n t h e c o m b u s t i o n - u n i t

If you wish to use small pots and pans, with a smaller diameter than the housing, appropriate rings have to be used. These can be made of l to 2 mm thick sheet-iron, if possible with a rivetew grasp.

But see to it that the inside diameter of such rings leaves free as

large a part as possible of the pan or pot botiJ·om.

R e m o v a b 1 e c o v e r - p 1 a t e s

It is desirable to use two cover-plates for the type of FC described

in these instructions, one for temporary covering of the

cambustion-unit when no pan or pot is standing on it, the other for the warming-up place. If possible with a riveted handle.

These cover-plates are not required when the user makes i t a custom

R

i V e t s

When no suitable rivets are to be had, we can make them ourselves. Iron-wire or nails can be annealed to red heat in a fire and then left to cool in warm ashes or warm sand.

The metal is now softer and the pieces can be cut to length.

A sheet of heavier metal with a hole in it equal to the diameter of the nail, can be used for making the rivet-heads.

Rivet-heads can also be very well made in a bench-vice.

M a r k i n g - o f f c o m p a s s e s

For marking-off the circles on housing and fire-box, as well as the larger circles on the flue-chamber, very simple substitutes of a pair of marking-off campasses can be made.

For the small circles on the housing and fire-box we take, for in-stance, a long nail and file the ends into sharp and round points like the point of a lead-pencil.

The nail is then bent into the farm of a cramp. See fig. 20.

Bending the legs inwards or outwards to suit the desired diameter.

Alternative for a pair of scribing campasses

~-~~---~---1-::>-long nail bent round

30

-For the lär6er ci::cles on the flue-chamber we fellow another method. We need a piece of hardwood abt. l5 .G1ill square and 120 mm long. Two

nails abt.

4

mm thick and

45

mm long, are made into scribers with sharp points as described above.

Now we drill four holes in the piece of hardwood through, which the nails must be press fits.

One hole is drilled at 15 mm from one of the ends. The other holes are drilled at distauces of

55, 65

and 90 mm from the centre of the first hole respectively.

One scriber is now inserted in the hole drilled first and is placed in the respective eentres of the circles to be scribed. The other scriber is put in one of the other holes to suit the radius of the required circle. See fig. 21.

centre-nail

hardwood scriber holder

scriber

fig.21 V a r i e t y i n d e s i g n.

Much variety of design of the FC as described is possible.

For instance, a larger flue-chamber can accommodate more combustion-units. A langer flue-chamber can contain more then one warming-up place.

When using larger kettles and pots, the cambustion-unit should be adapted.

The diameters of housing and fire~box should be proportionately larger and the flue-chamber will also have to be adapted.

Q u e s t i o n n a i r e r e g a r d i n g t h i s

i n s

t

r u c t i o n b o o k

Because what is called your "experiences in the field", aften produce inforrnation that is not available in the Netherlands, it is of

inestimable importance that you inforrn us about your experience, so that we may pass it on to others.

That's why we urgently request you to answer the under-mentioned questions.

Please write your answers on a separate sheet, mentioning the number of the question concerned and send the sheet to us.

Wri te the word "Family-Cooker" at the top of the sheet.

C l e a r n e s s

l. Was the text clear?

2.a If not, where not? b Why not?

3.a Were the diagrams clear? b If not, which not?

c Why not?

d Were there enough diagrams?

4.

lfuve you any suggestions for a possible ether presentation of the inforrnation given in this book?

T e c h n i c a l c o n t e n t s

5.a Was it possible for you to construct a FC without many problems

on the basis of this construction book?

b If not, where did problems arise? c Please indicate why?

d Did you find a solution?

e Were the materials mentioned available in your surroundings?

f Did you use materials which are not mentioned in this instructien book?

6. Have you any remarke to make?

Additional copies of this handhook at the cost of Dfl. including postage, can be obtained by writing to:

Bureau Development Cooperation (B 0 S)

Eindhoven University of Technology