Metal Casting Made Easy P1 potx

A worldwide hobby metal casting renaissance is occurring, hobbiest’s around the globe are re-discovering the metal casting skills and techniques of the “Old Masters, who achieved spectac

Metal casting made easy

A complete guide for the hobby

metal caster

Learn the techniques for green sand casting

How to select scrap aluminium & bronze, How to melt metal in your hobby foundry

Section two of this hobby foundry ebook will show you all the details

and complete specifications to build a “Gas Fired Crucible Furnace”

The last section will show how to build the best

labour saving device any, hobby foundry

worker could wish for…

“The Motorised Gyratory Riddle” will deliver

silky smooth freshly conditioned sand every

time

Eliminate “manual sieving” of your sand

forever!

This hobby foundry ebook has been written and compiled by

Col Croucher Australia

Copyright: Aug 2002

You are licensed to print one edition of this ebook

Please respect my intellectual rights

You are licensed to print one edition of this ebook 1

Introduction to the backyard foundry 4

The subjects covered in this ebook: 4

Castings from metal 5

About the author 6

DISCLAIMER 7

Operating and reading this ebook 8

Moulding and foundry work 9

Sand Mould Schematic Diagram 9

Foundry equipment & tools 10

Foundry tools 1a 11

Foundry tools 1b 12

Foundry tools 1c 13

Foundry tools 1d 14

Making foundry patterns 15

Pattern making materials 16

Pattern draft 17

Core prints 18

Pattern basics 19

Silicon R.T.V & Reproduction patterns 20

Casting shake out time 21

Gates & Runners 22

Reconditioning foundry sand 23

WARNING ABOUT WET SAND 23

Eleven steps for sand moulding 24

Step two: Setting the pattern on the mould board 25

Green sand & baked sand cores 29

Using sand & steel cores 30

Building your gas-fired furnace 32

Furnace lid lift arrangement 33

Scrap metal: what to melt 34

Melting scrap bronze metal 35

Furnace ignition: Lighting up for the first time 36

Follow These Steps: 36

Common Sand Casting Faults 37

Glossary: Common foundry terms. 38

Judging temperatures by eye 39

The Home Metal Foundry 40

Home foundry projects 41

Project 01:Door hinges 41

Project 02: Clutch slave cylinder 43

Project 03: Timing chest back-plate 44

Project 04: M.G T Type Aero Screen Base 45

Green sand recipes 46

Temperature Control Methods 47

The Pine Stick Temperature Method 47

Simplicity! 48

Part 02 49

Building a propane gas fired furnace 50

Introduction 50

The furnace building materials 51

Notes Cont’d 52

Sheet metal former 52

Authors disclaimer 53

Constructing the furnace 54

Construction notes 55

The outer rolled steel reinforcing bands 55

Determining the furnace dimensions 56

Furnace illustrations 57

Furnace illustrations contd 58

Furnace Floor Levelling Adjuster 59

Construction details of furnace frame 59

The Upper Support Column 61

Furnace Lid Clamp Band 62

Furnace lid lifting & swivel mechanism 63

Furnace building specification sheet 65

Building spec sheet cont’d 66

Designing and building the furnace burner 67

The furnace burner illustration 68

The burner pipe venturi section 69

Burner nozzle 70

Machining the gas Jet 70

Assembled gas jet 72

The outer burner pipe 72

Air blast control 72

Controlling the air blast 73

How to cure flame blowouts 73

Controlling the total gas flow 74

The refractory material 75

Filling the furnace walls 76

Old time refractory mix for crucible or cupola furnace 77

The following steps are by volume & not weight! 77

Running in your new furnace 78

Follow These Steps: 78

Different views of furnace 79

Furnace Views Cont’d 79

Crucible specifications 80

Part 03 82

The Motorised Gyratory Riddle. 83

Introduction 83

Disclaimer 84

Safety Hints 84

Riddle construction outline 85

Flexible Drive coupling 87

Rotating Disc Shaker Assembly. 88

Images for construction reference 89

Self-Aligning Bearing Layout 90

Sieve Cradle Clamp Assembly Details 91

Building methods: Gyratory Sand Riddle 93

Building sequence 93

Building the riddle: 94

Fabrication tips 95

Machining parts 96

Welding 96

Operating the gyratory riddle safely 97

Introduction to the backyard foundry

A worldwide hobby metal casting renaissance is occurring, hobbiest’s around the globe are re-discovering the metal casting skills and techniques of the “Old Masters,

who achieved spectacular results using basic tools, equipment &“Know How”, learnt

through many years of trial and error, as well as well proven methods & techniques Don’t ever be afraid of making a mistake, for, without mistakes, you will never truly learn! The author has been metal casting for about thirteen years All of the

equipment needed for backyard foundry work was built in the home workshop I call it

my boutique foundry because it is so small

This 3-part volume hobby casting guide ebook will give you information on how to

build all of your own foundry gear You will need some basic metal workshop tools, e.g Welder, angle grinder, power drill and other small hand tools that most people entering into foundry work seem to have already Hopefully this will be the case with

you If you don’t, then why not do a joint project with a friend Share the COST, and share the FUN

The subjects covered in this ebook:

1 How to melt & cast metals

2 Building a Gas Fired Furnace

3 Building a Motorized Gyratory Riddle

Section One: Metal casting Made Easy

The topics covered in this ebook will range from making simple wood patterns & cores, preparing foundry sand & ramming up your mould boxes

How to select bronze and aluminium scrap metal to break up & melt into ingots to use later for your casting work

The various tools & equipment you will need for moulding work will be explained

We’ll discuss the different furnaces that can be built to melt your metal, (covered in the next section) plus a host of other material you will need to know about, to get started in this age old craft of “METAL CASTING”

In this ebook you’ll find high quality photographs that accompany the text all the way through The step-by-step sand moulding photographs and description will help you

to fully understand the methods & techniques involved with moulding and casting metal

Hobby metal casting is highly contagious, and after a couple of sessions of melting and pouring, you will be hooked on the process Your imagination and the skills that you develop will be the only limiting factor in your progress & success

When I started out fourteen years ago, there was very little info around for the home

metal caster that made any sense, I searched high and low for the right books,

(especially for info on die cast Al pistons) but found that most of them were for the foundry industry specialists While these books were excellent for the purpose, they were not much help to the home foundry worker!

Whether you intend to just make things for your own enjoyment, or you aim to get

serious & gain enough skills to start making things for payment, is entirely up to you Whatever you do, “DON’T RUSH" into trying to make money out of your venture,

take it slowly, learn your craft, and practice all you can, which will help you to make

the best product possible

Castings from metal

Bronze & Aluminium items are the result of

Sand casting techniques

Have been used for thousands of years to Cast Iron, Bronze, Gold & Silver artworks

as well as simple tools and implements used by various civilizations, such as the Egyptians, the ancient craftsmen produced amazing bronze castings with their simple equipment Teams of people blowing air down long tubes provided the heat to the primative furnaces

Society has now become more reliant on new technology, the old techniques of hands on small-scale metal casting have started to rapidly disappear into the annals

of history Except for the small band of interested people like you, who’ll help to keep the craft alive

Today there is a great resurgence in backyard metal casting; people wanting to melt

& pour metal, can do so right in their own backyards, with basic tools & equipment There is no rocket science involved!

Whether you want to cast Vintage Car or Motorcycle parts, or you want to cast your very own Artworks in Bronze or Aluminium Or, you just want to have a go at metal casting; this book has been written for you, the novice & semi advanced metal caster

There is nothing more satisfying than creating something, and showing you’re new found skills to your friends and family This ebook will show & describe how to

achieve metal casting results that maybe you never thought possible

As you learn basic foundry skills, you will be amazed at what you can achieve by learning and applying the simple skills of this intriguingcraft

There are plenty of foundry sites around on the net that will simply show you some photos of home built items, but they do not cover the full details required to enable you to build the same item Feel free to print one copy of this manual, but please respect my intellectual property & copyright It is illegal to provide pirate copies of copyright work If you want to use text from this ebook for some reason, then please email us for permission I want you to treasure this ebook

You may print your own hard copy instruction manual to have by your side, to refer to when required You can quickly look up and read about certain subjects or articles, or look at well illustrated pictures and plans, which help you to learn how to do all the different processes required during the moulding & casting processes Or to build the equipment you want for your home foundry workshop

About the author

My interest in metal work stems from my boyhood days, I was fascinated as I watched my father work the farm “Blacksmith Charcoal Forge” to heat metal to do repair's to farm

Building a go-kart project started me on the road to ”HOME FOUNDRY WORK” The go-kart

needed wheels, so the quest for ”casting know how” started (In this e book you will see the turned patterns for the wheel project) By following simple pattern making methods I made useable wheel rim patterns and then cast the wheels (Success at last)

The First Furnace Built

This was the crudest contraption one could find, but it worked, I was able to melt enough aluminium to cast the Kart wheels after a couple of initial failures?

(Remember… you learn from your mistakes)

The furnace was built from a few old house bricks stacked up on the ground, to form a round container to hold a pile of fuel charcoal A short length of 2” pipe fed into the bottom of the charcoal bed provided the air blast (From a borrowed household vacuum cleaner)?

Don’t underestimate the melting capability of charcoal It is an amazing fuel With the correct air blast, it will melt most metals (especially when used in a cupola furnace), it is quite

effective when used to melt aluminium, and many hobby casters start out with a charcoal furnace The only problem is the charcoal supply; if you cant make your own, then you may find it difficult to find a reliable supply (We have a free charcoal-making guide available from our web site)

Every furnace needs “Air blast”; you won't have to look for anything too fancy to supply a good quantity of air for your furnace A good second-hand domestic vacuum cleaner will

deliver plenty of air to melt Aluminium or Bronze in a Gas Fired Furnace

The domestic vacuum cleaner is an excellent choice to provide the blast for a charcoal furnace Just check before you buy a vacuum cleaner to make sure the hose can be attached

on an outlet socket to make it blow instead of suck, most important!

There is nothing more satisfying, than creating something unique in your own workshop

Especially when you conceive an idea, make a pattern, ram the sand mould, pour the casting, and then finish it on your own lathe, etc

There are home metal casters all over the world creating their own unique products; you will

be joining these ranks of backyard founders, creating your own special items

You don’t need sophisticated equipment to achieve good results with your home foundry operation It certainly makes life a lot easier to use good equipment But if you can’t afford to have the best right from the outset, understand that you don’t need it

Several years passed before I was able to build really good equipment, but, it was only after operating simple equipment, which enabled me to custom design and build an excellent Gas

Fired Furnace, and the associated gear that went with it I am still making equipment as

required The equipment is really just a miniature version of the big commercial gear Always keep your eye out for good ideas that you can adopt to your foundry operation

DISCLAIMER

Foundry work is lots of fun

You will get much enjoyment from your metal casting creations, but please take

CARE when handling molten metal Temperatures from 740DegC to 1300Deg C can

inflict a very serious injury due to unsafe practices Don't ever put wet scrap metal

or ingots into molten metal, it will explode, showering you with molten metal You are dealing with old technology here; the associated risk of injury should

be fully understood by all who attempt this craft!

Please go and buy protective clothing, eye & face shields, Leather apron & good quality leatherwork boots Nothing will spoil your fun more than a serious burn on your body I have experienced the pain of small splashes of hot metal I can tell you it

is “NO FUN”

Please read this e book, not as an entire lesson on the art of metal casting, but more

as an introduction to setting up your own backyard foundry One section read by itself will “NOT FULLFILL” your needs, Although there is enough ground covered for most people to grasp the methods required to build your own equipment, and to do some good sand castings

This hobby foundry ebook has had worldwide acclaim for the info, and teaching it contains, but your learning should not stop with this ebook alone Hobby foundry work is a journey of discovery & fulfilment as you learn the techniques of this

intriguing craft Seek out others with an interest in metal casting & learn from them also

Building your own foundry equipment

The tools and methods explained in this e book have worked extremely well for the author However there are lots of tools & equipment that you will be able to construct your self Arc welding will be involved in the construction If you feel that you are a competent welder, then by all means go ahead and make your own tools

Please be careful if you are constructing a pair of CRUCIBLE TONGS Think what would happen if the lifting tongs “Failed” while removing a full crucible of “molten metal” out of the furnace, it would not be nice, would it?

If you are not a competent welder, go find someone who is! Perhaps you have a

friend who is interested in what you are doing Combine your talents to create the things you need for your foundry With a combined effort, you will soon build the basics to get started Then you can move onto the more advanced facets of sand casting

You are accepting responsibility for your own actions

The Author “WILL NOT” be held responsible for carelessness on your behalf I have

no control over the way you conduct the practices in your home workshop All I can

do is warn you to be very careful in the way that you carry out your craft Abide by the rules and everything will be fine Be CARELESS and you will PAY for it through INJURY

Your foundry equipment can be fabricated with normal tools, machines & equipment found in well-equipped home workshops At times you will need to have access to a lathe The machined parts will not be complicated or difficult to make Basic lathe turning methods will suffice, & I’m sure that most people who are attracted to metal casting would already have reasonable machines in the backyard workshop

If not I would suggest that you talk with friends who may know of someone who can help you out

Another way to get access to good workshop machines, is to enrol in a night class at the local Tech College… and work on your own projects…simple The course will be worth every penny you pay for it

Operating and reading this ebook

•This ebook has been written and compiled as a PDF ebook; it is readable on any computer platform providing you have the FREE Acrobat Reader installed on your computer

•All images displayed within are copyright of “Coljan Photography” Australia, May

2003

•International Copyright protects all Images & text appearing in this eBook Images are Low - Res, watermark embedded

• If you are new to metal casting, please read the book as a whole, and not just in

sections, the more experienced metal caster may choose to read individual chapters

if they are familiar with certain operations

•Navigation from start to finish is quite simple, choose any page from the bookmarks

or contents shown, and use the black forward & backward arrows to go from page

to page You can also enlarge or reduce the font size to fit your computer screen for easier reading

•Click on the bookmark tab and the entire major subject heading titles will show as

an index for easy reference & selection

•If you place your mouse arrow on the side scroll bar and click the mouse & hold it down you will notice a small side bar with all the page numbers shown This method can be used to find a certain page very rapidly if you know the page location or page

number

•This ebook requires an encrypted operating password If you obtained the

password other than from our website then you may have an illegal copy, please

email us for details of how to correct that situation

Or email us at: mailto:colin@myhomefoundry.com

For more information visit our web site:

Quote

Use what talents you posses

The forests would be very quiet indeed

If the birds that sang there

Were only those that sang best

Author unknown

****

"A man only learns in two ways, one by reading,

and the other by association with smarter

people"

==Will Rogers==

*****

Tuition is high in the school of experience and

there are no free scholarships

Benefit by the experience of others

Moulding and foundry work

Moulding is the process where a pattern is pressed or imbedded into special sand to the desired shape or form Or the pattern can be placed on a moulding board, and the sand is rammed or compressed around the pattern

After the pattern has been carefully moulded, rapped & extracted from the sand mould, the mould is lightly blown out (to rid the cavity of loose sand particles) closed,

& molten metal is then poured into the cavity When the metal has cooled, the casting

is extracted from the sand complete with gates, runners & risers attached to the raw casting

The Home Foundry worker will principally be involved with Green Sand Moulding and casting Other forms of sand casting can be used, but for now, we’ll concentrate on the green sand method

Your green sand must posses the following properties:

Porosity: To allow air and steam to escape from the mould during casting

Cohesion: Ability of sand particles to cling or adhere together while the mould is

being rammed up (Bentonite is the binder used for this purpose)

Refractoriness: Ability of the sand to withstand the severe heat of the molten

metal

For Aluminium castings, the green sand needs to be a fine grade (ASF 80 to 130) If you have sourced your sand from a commercial foundry, it would most likely be about right for you to start using in your home foundry set up

Sand Mould Schematic Diagram

Section view of Green Sand Mould box

Study the above diagram carefully; this is the type of mould box that would be used

in a commercial foundry operation Spend some time studying this sketch; there is a lot to be learnt from it Use this sketch as a reference at any stage of your casting

work, you may learn more from it as you improve your skill levels NOTE: The set up

above would normally include an internal core!

Foundry equipment & tools

Quick Tip: For a Cheap Starter Crucible

Weld a plate on the bottom of some heavy pipe (4”w x 6” tall) lined with

a mixture made of fireclay & graphite, will make a good cheap crucible Dry it carefully before fireing to cure the lining

A plain steel pot can be used for small melts, but pieces of oxidized metal will flake off and end up mixed with the melt

Crucible

The crucible is the vessel used to hold the molten metal, they are available in many different sizes, and a good size start out with is a number 6 or 8 You need a crucible

that holds about 6 to 8KG of Aluminium Capacity is quoted by weight in Bronze Ask

your supplier to help you with your choice You will find suppliers under foundry supplies in the yellow pages, or on the net, silicon carbide crucibles are the best quality crucibles Cheaper clay graphite crucibles are also available at a lower price and may suit your purpose

Mould Boxes

You will need one or two to start with A handy size to have is 10 X 12“ X 3”

constructed from steel or wood They are made in two halves, the bottom is called

The Drag; the top one is called The Cope I chose steel for mine, which is a lot

stronger, and will last a lot longer than wooden boxes Steel boxes won't burn when

hot metal is spilt on them, which does happen The boxes need to have a pin

register at each end to provide an accurate register for the mould boxes during the

moulding operations Identify matching corners with coloured paint or marks of some

sort There is nothing more frustrating than putting your mould boxes back together the wrong way around, and only realizing this after you have poured & retrieved your ugly casting from the sand mould

Plastic Rubbish Bins

You need at least two bins, use them to store your green sand; the sand is not really green in colour The colour is really quite black You use water to temper or condition the sand, so that you can ram it around your patterns and mould with it Your sand will keep nice and moist in the bins for several weeks You will find that there are periods where you might not do any casting for a month or so If you could not keep it moist during that time, the sand would need complete reconditioning all over again

Hand Ramming Tool

A simple device, turn this item on your lathe out of hardwood, one end is round and

flat like a large hammer and the other end is wedge shaped for getting into corners

etc Just make the part that you hold in you hand a comfortable fit Make your ramming tool to the size you require Two or three ramming tools could be made up

hand-in different sizes to suit the different size mould boxes & patterns you might have

Foundry tools 1a

Crucible Tongs

These are tools that you can construct your self, as long as you have confidence in your own welding, The flat steel material to use is 1"X 1/4" or 5/16" thick (Depending

on the weight of the crucible) Take a look at the image above, which should give you

an idea on how to construct them This design is used to lift the crucible straight up and out of the furnace The crucible is then placed in to the pouring shank The tongs need to be a neat fit around the crucible, without putting any undue pressure on any one part of the crucible

Vent Wire Rod

This is used to put vent holes in the sand moulds A normal bicycle wheel spoke is

just ideal for this purpose Sometimes you may have to use a rod that is 1/8” thick

Make it long enough to go down through the sand to just touch the pattern You put several holes all over the mould The holes allow the steam to escape, which is

generated by the molten metal as it flows into the sand mould This helps prevent

porosity and steam blows in the casting To make the tool easier to use, put a small wooden knob on the top, which will rest in palm of the hand while venting the mould

Gate Cutting Tool

A gate cutting tool is used to hand cut a flow channel for the metal to flow from the

down sprue across to where the metal enters the mould cavity, it is simply made from

a piece of thin sheet metal Cut from an old jam tin, make it about 2 1/2"long Bend it

into a “U” shape, and you have your gate cutter There is an easier way to do this

and I will show you later on in the book in the moulding section

Sprue Tool & Riser’s

Another small tool to make on the lathe, you might like to make a few of these, as

they come in handy For now, turn up a couple in the following size 7” long X 1.1/2”

at the top, tapering down to 1/2” at the bottom This tool creates the vertical-pouring hole, which directs the hot metal to the in-gate, or flow channel that you created and into the mould cavity The sprue will also act as a choke to control the flow of metal

into the mould cavity

Quick Tip

The length of the handles needs to be about three to four feet in length This length will keep your hands a good distance from the hot crucible (wear your arm length glovThe clamping leverage to hold the pot full of metal will also

be less with long ha

es.) ndles

Quick Tip

Any type of timber will suffice for sprue sticks, turn up as many as you may need, sand them smooth and finish with some shellac so that they are easy to pull from the sand

Drill a small hole and place a small locating pin in one end, the pin locates in another hole drilled in the pattern or ingate, which prevents the sprue from shifting during ramming

Foundry tools 1b

Quick Tip

Build and use one of these motorized riddles and you will wonder how you ever lived without one! Reconditioning foundry sand would have to

be the most labour intensive chore in the home foundry

“The Motorized Gyratory Riddle” The complete plans are included in this three part ebook

Hand Sieve or Riddle

A hand sieve is used to place finely sieved sand over the patterns as you start to

mould You will also use the sieve to recondition your sand after you have done some moulding/casting operations Using your hand sieve to recondition your sand can become quite labour intensive Complete construction details are available in the

next section “How To Build The Motorized Gyratory Riddle.” This will make the job

much easier, quicker and a lot more efficient After using the motorized riddle you would not use a hand sieve again

Quick Tip

Your moulding bench can be of any size; unless you are limitedwith the size of your work area Make sure you mount the bench on casters; shopping trolley caster wheels are ideal

The top of the bench needs to be of timber or a zinc coated sheet metal, a good base for the sheet metal is ¾” thick craft- wood

Moulding Bench

Build your self a sturdy moulding bench, you will be doing a lot of moulding on it, so

make it good & solid I built mine out of second-hand RHS (Rectangular Hollow

Section) Steel tube; it measures about 6-foot long, and about 3 1/2 foot wide, it seems to be about right for the work that I do Don’t spend money on new materials; try to obtain recycled timber or steel You will find it an advantage to put some caster wheels on the bench so that you are able to move it about your shed (Look for caster wheels at the junkyard) Add some lower shelves for extra storage space Build the bench at a height to suit you and no one else; you will be the one doing all the

work on it You don’t want it to be too high or to low

Foundry tools 1c

Mould blower tube

A simple tool used to blow small grains of sand out of the mould This is a short length of plastic tube (1/4”Dia), place one end in your mouth, the other in your hand and guide it around the cavity while blowing gently to get rid of loose sand particles etc out of the cavity A small air compressor can also be used to do the job, but you have to be careful you don’t blow bits of your sand mould away in the process Best

to stick with the mouth blower first

Furnace air blower

No need to spend big dollars here Look around the house; have you got an old

Vacuum Cleaner lying around that is not being used anymore? If not, buy an old Electrolux model, which has a sliding electronic speed control on it You will find it just right for adjusting the airspeed/volume to the furnace Most second hand shops would have one This type of vacuum cleaner will deliver as much air as you need for

a home size gas fired furnace (Remember to reverse to BLOW & NOT SUCK) If it

delivers too much air, you may have to put an adjustable waste or blast gate on the

delivery line to adjust the pressure

Corer makers trowel

Take a trip to your hardware store; just buy a cheap long narrow trowel, something like a plasterer would use, a straight narrow rectangular blade You don’t have to buy the proper tool; you can use other things as well You may possibly be able to even make your own trowel

Foundry tools 1d

Pattern draw spikes

Make these from old wood screws, braze a piece of 1/4” rod and add a ”T” piece on

top so that you can turn it into your wood pattern to remove it from the sand Simple tools like this that will make your work much easier Make some draw spikes in different sizes as your patterns will be large & small

Rapping bar & rapper

These two items are used to “Loosen” the pattern before removal from the sand,

when you rap a pattern; it has the effect of slightly enlarging the size of the

impression made by the pattern in the sand The rapping bar is held down firmly on

the pattern and then you take the Rapper, which is a “U” shaped device, with a handle, and rap side to side on the bar very quickly to loosen the pattern Rap north -

south then east - west on your pattern A large open - end spanner can be used in an emergency as a rapper

Bottom & top mould boards

Cut two boards from 3/4” thick form ply, a little larger than the size of your mould boxes that you made On one of them put some 1 1/4” X 1 3/4” runners on the

bottom as supports, so that it sits evenly on your bench or the floor, the runners also stiffen the board

Quick Tip:

Use a length of 1x1x 3/16” angle iron

to make your screed bar, weld somhandles on each end for comfort e

Mould strike of screed bar

Use this tool to scrape or screed of excess sand that is left on the mould after the ramming process is complete (Especially the bottom of the Drag), this will leave a nice flat surface, to continue moulding operations after you have inverted (rolled) the mould box onto the mould board Made cheaply from a piece of timber or some metal, put some handles on it and it’s ready to use

Making foundry patterns

Before you can create any “casting” a pattern of the object to be cast must be made

in order to form the necessary “impression” in the “sand mould” One would normally

use timber to produce patterns, i.e White pine, cedar, maple , mahogany etc Other

materials such as casting plaster can be used to make simple shape one off

patterns, or to create impressions of something that you may have already made, and wish to replicate the item to create more patterns To enable a multiple pattern set up on the mould board

The timber used for pattern making should be easy to work with, should not splinter and kiln dried, otherwise shrinkage and warpage will ruin your good work!

The home craft person will use standard carpenters tools, with the addition of a few special ones such as a wood or metal turning lathe, routers and special cutters used

in a pedestal drill You may own a band saw and other luxury power equipment in your workshop These tools will enable you to produce some good patterns to work with in your foundry But excellent patterns can be made with simple wood work hand tools, so there is no need to buy expensive new tools

Pattern shrinkage

Owing to the shrinkage of molten metal on solidification, your pattern must be made

slightly over size to allow for this All metals have a different “shrinkage ratio” this

“Ratio” is determined from a “pattern makers” rule (Available at foundry suppliers) This is like a standard rule except it has four shrinkage ratios on it When you draw

up your pattern, you scale it from the correct shrinkage ratio, to allow for shrinkage, machining & boring etc, (E.g Aluminium has a ratio of 3/16” per foot shrinkage) Pattern draft

Remember to allow plenty of draft or taper on vertical walls, and to create a generous radius where the vertical walls meet horizontal planes on your patterns The quickest way to make radius fillets is with a ball bearing of the right size, brazed onto a thin steel rod Heat the ball bearing tool gently in a soft flame; lay the small bits of bees wax in the area you wish to fill

Run the warm ball tool back and forth along the fillet line, the melted wax will form a nice clean fillet radius Clean excess wax of with a small scraper, and then rub

smooth with steel wool (You can even shellac over the wax when finishing) Sand the patterns smooth all over; finally finish the pattern of with two or three coats of shellac, sanding smooth between each coat

Pattern identification

Some pattern makers use colour codes on the patterns, to denote various operations

to be carried out on the casting If you feel like doing this, then by all means do it, although not required in the home foundry This will also help to remind you as to which way you should mould and cast the object

BLACK: Indicates the surface to be left rough

RED: indicates the surface to be machined

YELLOW: Indicates where the core prints are to be located You can also devise your own colour scheme to denote certain other things

Generally speaking, a casting face to be machined should be cast “FACE DOWN” giving you a good clean flat surface to work with