Complete guide to hobby metal casting. Resin Coated Silicate Sands. U sing cold set resins, mixed with the silica sand can also be used to make cores. These resins allow you to work the sand for a short time until it starts to go of. Generally only available in 20 litre drums or larger, so it is not really feasible for the home founder to do this until some sizeable production runs are planned. There are several foundry companies that supply these products. Foseco, a worldwide foundry supply house, has many different kinds of products to cover every foundry situation. It is well worth your while to investigate using these products, as they are easy to use and give very repeatable results with all types of metal casting applications. Ask for the information sheets to be sent to you. There is no, one, correct way to do things with foundry work. If three different foundries were visited you would find that they all have different ways & methods of doing things. You will discover certain methods that will work well for you. The idea is to get “REPEATABLE RESULTS”, It helps to make notes as you work on your projects, don’t rely on your memory for details. If you don’t go near your foundry work for a month or two, you might be lost if you can’t remember a certain process or method that you used to get a particular result. An easy way to create special shaped holes in castings is to make up steel cores in the lathe; they are then set in the pattern before you start ramming up. When the mould is complete, and the pattern extracted, the steel core is held captive by the sand. After the pour is complete and the casting has been retrieved from the sand, you can cut the gates and runners off. The steel core is then pressed out of the casting. I use this method to make the spring caps, which are shown in a previous discussion. The method is quick and easy, and works every time. The steel core is smeared with oil and dipped into a container of graphite powder. (The graphite coating prevents condensation on the steel core, which will blow when the hot metal hits it) Captive Nuts. Can remain, as part of the casting, a simple way to achieve this is to turn up the nuts or threaded collars on your lathe to the required size. For secure retention in the casting, machine some grooves on the outside edge, then locate the nuts in the mould where required. The molten metal will run into the grooves during casting. When the metal cools, it will shrink even tighter onto the captive nut, they are not likely to pull out of the casting. (The buttons or nuts also act as heat sinks or chills on the metal) After this operation, holes can be drilled and threaded into the captive nuts to the size to be used as anchors in the object that you have made. Several captive nuts or plugs could be installed into the one casting if you wish. Don’t be to generous with the graphite powder when installing captive nuts into castings, remember you need them to be held securely, too much graphite may help to release the nuts if under a heavy load. Note: The author does not have a financial interest in the company of Foseco. Written by Col Croucher Australia. You are entitled to one Printed edition of this ebook, please respect my copyright and intellectual Property. 31 Complete guide to hobby metal casting. Building your gas-fired furnace. Construction Notes . Many ideas can be gleaned from this photograph. The rolled former can be seen which is set up ready to start placing the refractory into the wall cavity. The steel supports are welded to the 2’x1/8”straps formed around the drum. Wood plugs have been turned up on the lathe to create holes in the refractory for the burner & also the exhaust port on the other side of the furnace. The tall column is for the levers & sliding brackets to be attached for removing the lid safely from the furnace. A sub frame was constructed to mount the whole unit on so that the furnace can be moved around or stored away out of the road. (The next section deals with building this furnace.) Please note: This overview of building the gas-fired furnace was left in this ebook to quickly show you some details, the full project is dealt with in depth in the next section. Go there now . Please click the link above to that section if you wish, or click on the bookmark tab to view all headings. Rear Side View The furnace shell is made from an old drum, note the rolled sheet metal former used to make the furnace walls. The wood plugs create the holes for the burner pipe and exhaust pipe. Put lots of grease on the plugs to help removal. Roll some 2” X 1/8” steel straps to go around the drum shell to weld supports and other fixtures to. Make up some plates to hold the burner inside & outside the furnace, held together with bolts. Lots of details are clearly visible here. Your furnace can be scaled up or down to suit your operation. Roll the sheet metal Former . The size you elect to roll the former will be dictated by your crucible, allow about 2” of area between the furnace wall and the crucible sides. Sheet metal rollers are ideal for performing this operation, enabling a perfect circle to be formed. You will need to secure the former with some self-taping screws, to hold it at the diameter that you require for your furnace. It may be two or three days after ramming or pouring the furnace walls before you remove the former, so you need to be able to collapse the former before you can remove it from the furnace. The furnace featured here was built from scrap materials scrounged from around the workshop; you can use secondhand steel and discarded materials to make yours also. The dearest part of the whole furnace construction will be the refractory for the walls, floor and furnace lid, don’t skimp on this, high quality refractory will outlast any cheap or inferior materials, The furnace you see here has been in service for many years, it has virtually been maintenance free all this time. A burner needs to be constructed, A piece of black pipe 1 ¾” to 2” in Dia and about 16” long will make a nice burner, again the details are all revealed in the ebook mentioned above, There is no Rocket science involved with this, but you need to take care with certain things to make the burner easy to light and adjust to the optimum heat out-put for your furnace, Written by Col Croucher Australia. You are entitled to one Printed edition of this ebook, please respect my copyright and intellectual Property. 32 Complete guide to hobby metal casting. Furnace lid lift arrangement. Furnace layout. Furnace Notes . Building a gas-fired furnace is really just a lot of common sense and straightforward planning of the order in which you do the construction. The biggest problem facing most people is designing and building an efficient burner. The burner (LHS of furnace) designed for the furnace shown in this picture, is simple but highly efficient. It does not have an external flare or a fine jet, which is unnecessary. The gas line pressure runs at almost zero. LP gas is fed from a 100lb tank through an adjustable regulator. A 6 Kilo melt can be done in less than 35 minutes from a cold start. T his image shows the general arrangement of the furnace body, wheels and the lid- lifting lever. The lugs on the main upright are quite visible. The lid and the support rods are bolted to these, the ends of the rods are threaded with nuts either side of the lugs. Which allow the lid to be adjusted for proper fit on top of the furnace walls. There are no hard and fast rules for the size of your furnace; it will all hinge around the size of the crucible that you choose. Always allow at least 2” of free area between the furnace wall and the crucible. So size up or down depending on what you want. I built this furnace from ideas of my own after studying other furnaces. Pour the floor of the furnace first. Make the furnace floor 3” (75mm) thick. The steel former is rolled to the correct diameter, it is held in place with some wood wedges as the refractory is poured in. (Refractory can be rammed also) don’t forget to drill holes in the bottom and the walls of the drum shell to let water drain from the refractory. When the walls have air dried, remove the former carefully. You will marvel at the simplicity of the burner design, which is a highly efficient design and not difficult to build. Please move forward to that project to read more about it. Every dimension and component of the furnace is outlined for you in imperial & metric, no need for guesswork or trying to workout the sizes of things to make, it is all explained in plain English for you. Hours of work have been spent laying out an easy path for you to follow to help you construct a furnace that will last you for years in your home foundry operation. Written by Col Croucher Australia. You are entitled to one Printed edition of this ebook, please respect my copyright and intellectual Property. 33 Complete guide to hobby metal casting. Scrap metal: what to melt. Aluminium. M ost hobby caster’s are never quite sure what kind of scrap they should melt for their castings. The best source of Aluminium metal is scrap cylinder heads, inlet manifold castings, & gearbox casings if you can be bothered stripping, & cleaning the muck of them. Try to source your metal privately, or from engine repair workshops. Scrap metal yards will rip you off when they find out what you are up to. Beware also of mixing Magnesium in with your scrap, it may catch alight during melting, it is impossible to put it out. To Identify magnesium scrap metal, the metal looks grey in colour. Polish a small area with emery paper. Then apply a small drop of 1 % silver nitrate to the polished surface. A black stain will appear on the metal. Aluminium will not stain. Other sources of scrap metal could be from old machinery castings such as wheel hubs, casings & cover plates etc, If the item is painted and your not sure if it is Aluminium or not, just place a magnet on the metal, if it sticks, leave it there, as it’s probably cast iron. Now, I can hear you asking how on earth does one melt a cylinder head in the little old crucible I’ve scrounged from another metal caster. Method 1. The idea is to take your cylinder head to a machine shop or someone who has a good sized power hacksaw, or better still a metal band saw, ask them to cut the cylinder head into small chunks to fit into your crucible! Quick Tip. Getting good scrap will be the biggest problem for hobby metal casters. Most will not be prepared to buy metal from a commercial supplier. Melting your own is the next best thing. If you stick with what I have said to melt you wont go far wrong. Don’t concern your self with metal compositions yet; leave that for the experts to sort out. All you want to do is have some metal casting fun! Aluminium Ingot Stock. Method 2 (My Favourite) If you happen to have a charcoal forge stored in the corner of your workshop, drag it out and get it ready to do some serious melting. Firstly you need a good supply of charcoal. (Read…. A good large bag full) You can make it your self. Complete instructions are available free at our web site http://.www.myhomefoundry.com Now, you have to make up a square or rectangular shaped iron pot with a handle attached to one side. Light up the forge and attach your blower, and set the blast to a low setting, once the bed of charcoal is burning nice and hot, place the steel pot in the hot coals, place the first chunk of cylinder head in and just leave it, it will take awhile to start to show signs of melting. With a good supply of charcoal, and the right blast, it won’t be long before you will have to pour the melt into your ingot bar. The illustration above shows the shape of the ingot bar that I have used, it was made from a piece of folded heavy gauge metal, the notches were formed from pieces of angle iron cut to fit and welded inside the ingot bar. The ingot bars in the photograph weight about 6 Kilos each. When the bar has solidified, knock it out and get ready to pour the next melt. The stacks of ingots in the photo were made in an afternoon’s work…. The cost = $00.00. Plus fun time. Written by Col Croucher Australia. You are entitled to one Printed edition of this ebook, please respect my copyright and intellectual Property. 34 Complete guide to hobby metal casting. Melting scrap bronze metal. S ourcing & melting Bronze is going to present another problem for you to solve. The heat involved in the actual melting is considerably higher than Aluminium, and the metal losses involved as you melt will also be much higher. Finding suitable sized scrap bronze is going to make you search harder than you would for Aluminium. Hunting around junkyards and private places for your metal may well turn up what you require. Probably the best source of good bronze metal is going to be by purchasing your supply from an ingot supply house. Buying it here will give you the exact metal composition that you need, eg. Silicon bronze is one of the best types of bronze to melt in your crucible. It is easy to cast, and does not present any problems while melting, and needs very little if any fluxing before the pour. It won’t be cheap to buy, but you will know the exact make up of the metal. If you were to continue collecting scrap bronze, you will have difficulty determining whether it is silicon bronze, manganese bronze * or perhaps Aluminium bronze *, gun metal bronze etc. All these metals have different fluxing & degassing requirements for melting and pouring. Some are just too difficult* for the hobby caster to even attempt to melt & cast. There is nothing wrong with you experimenting and melting your own scrap, just don’t get too upset if some of your castings are not turning out as good as you may want them to. Try to keep your different metals apart if you can, but with scrap bronze it can be very hard to tell the difference between the mixes used commercially, even for the professionals! (Without chemical tests & analysis etc) An excellent source of bronze is buying the sprues and runners from a foundry involved in casting bronze art castings for sculptors, they will most likely charge you only half the normal ingot cost. Art casting foundries use silicon bronze…, which is very easy to melt & pour. At least with buying ingots you will be able to cut them up into small pieces with a power hacksaw, so they will fit easily into the crucible used for melting. Cutting up chunks of scrap may give you more headaches than it is worth in the long run. Bronze is a lot more difficult to break down into smaller sizes, and bronze castings do not smash easily like Aluminium does. One of the easiest ways to handle larger pieces of scrap bronze is to do all your melting in another type of furnace called the “Cupola Furnace”, these furnaces are the most ancient in operating principle, but are still used today in many places. Cupola furnaces are fuelled by charcoal and require a considerable amount of air blast to create the high heat needed for melting cast iron or bronze. We cannot go into the technical aspects of the Cupola Furnace here, as it would take a large book to cover the subject. It may be worth your while to investigate this type of furnace as you advance along the metal casting journey. Written by Col Croucher Australia. You are entitled to one Printed edition of this ebook, please respect my copyright and intellectual Property. 35 Complete guide to hobby metal casting. Many hobby caster’s usually end up building one of these after a lot of experience has been acquired with crucible melting, it just seems to be the next step in the long journey. Furnace ignition: Lighting up for the first time. W hen lighting the furnace for the very first time. It is important to “run” the furnace in before doing any serious melting with it. The refractory material has to be dried ”very slowly” so that it cures to a hard tough material to enable it to withstand the high temperatures involved with metal casting. The NEW furnace refractory should be allowed to air dry for several days. Then and only then can you light the furnace and run it for a maximum of only FIVE minutes and shut it down and let it cool. Repeat this procedure until no more steam can be detected issuing from the holes in the side of the furnace. Once it is fully cured then you can run it for an hour or so, even do your first melt in it to help vitrify the refractory and cure it fully. Follow These Steps: 1. Lighting up your furnace for the first time can be a daunting affair. If a simple practice is adopted, there is nothing to fear from the lighting up of the gas-fired furnace. 2. The easiest way to light up is to scrunch up a small piece of newspaper and push this between the furnace wall & the crucible pedestal. (The block that the crucible sits on in the furnace) 3. Light the paper with a match and let it burn for a few seconds. 4. Turn the cylinder regulator gas valve on very slowly, only let a small amount of gas flow down the line, a second or two after this you will see & hear a small flame erupt in the furnace with a pop. 5. If you are using a vacuum cleaner for the blast, switch it on now, but on it’s lowest setting (some have an adjustable speed control). Bring the air speed up gently until the flame starts to swirl around the inside walls. It will be running very rich at this stage. 6. Increase the air blast again, but not too much as the flame may blow out. As the furnace warms up, and it will very quickly, adjust the Air/Gas ratio until it is running evenly with a gentle roar. Let the furnace run at this low setting for about five minutes to warm up. The ideal air/gas mixture is when there is a blue primary flame, leading out to an orange colour flame coming out of the exhaust port. 7. If the flame blows out SHUT EVERYTHING DOWN INSTANTLY. The starting process will have to be carried out again. (Put The blower back on to blow unburnt gas out of the furnace interior, if you don’t do this, any residual gas will explode and burn you when you go to relight, LPG gas is heavier than air) 8. The furnace will most likely be too hot at this stage, to put your hand in to light the paper with a match, so use a long instrument to light the paper on the second time around. 9. Once the lighting sequence has been carried out a few times and you have come to grips with the behavior of your furnace, lighting up should be a success every time that you attempt to light up. • WARNING: DO NOT leave the furnace unattended while it is running, If there is a power failure the blower stops, but the gas keeps going, this is a potentially very dangerous situation, It only requires a small amount of LP Gas MIXED WITH AIR to create a life threatening situation…Read…. “EXPLOSION” Written by Col Croucher Australia. You are entitled to one Printed edition of this ebook, please respect my copyright and intellectual Property. 36 Complete guide to hobby metal casting. Common Sand Casting Faults. Casting Mismatch. This is what happens when you are not thinking what you are doing while reassembling the Cope & Drag moulds. The mould was poured only to find the boxes had been turned around. This is the very reason we said to colour match one corner of your mould boxes to avoid this mistake. You think I got mad when I saw this… You bet… Only one solution, scrap the casting (& remelt it), and re-mould & pour it again! Cold Pour or Cold Shut . The metal was poured way to cold; it cooled even more while traveling through the cool sand and stopped right at the casting cavity. Sometimes a low sprue height will also cause this to happen. A combination of factors can at times confuse you to what actually caused the problem. Some form of temperature control should be used to monitor the exact temperature that you will pour at. Usually smaller items have to be poured at higher temps than larger items, simply because larger amounts of hot metal will keep hotter for longer. Quick Tip. Using uncoated steel chills or cores can also cause steam blows. A good method I have found to prevent this is to smear some oil on the steel core or chill and then dunk the core in a box full of fine graphite flakes or powder. Place the core or chill carefully in the mould. When the metal is poured, the graphite acts as a barrier to moisture. It does not affect the chilling action on the metal. Steam induced Core Blow. This steam blow originated from the sand core. The likely cause was the core not baked long enough. The core may have absorbed moisture from lying around for too long. The casting is a clutch slave cylinder. The steam blow has just destroyed the casting. Looking from the outside you wouldn't know what was wrong with it, as it looked quite normal, looks can be deceiving. As a pressure vessel this had to be a very good quality casting, steel chills were inserted while moulding along the barrel & at the end of the cylinder to promote a dense grain structure. (Chill effect) Needless to say, some new cores were made and some fresh moulds were made up and they turned out just fine. Written by Col Croucher Australia. You are entitled to one Printed edition of this ebook, please respect my copyright and intellectual Property. 37 Complete guide to hobby metal casting. Glossary: Common foundry terms . Absorption: Ability of any material to absorb certain gases from the atmosphere. Use a good flux & degasser to purge gasses from molten metal, especially Aluminium Aerating: Reworking & reconditioning your moulding sand with hand sieve/Shovel/or Motorized riddle. (A great machine for any Foundry!) Binder: A material such as Bentonite used to bind sand particles together. Foundry sand and bentonite is mixed in a Muller. Blowholes: Gassy metal due to lack of de-gassing before pouring. Can also be caused by wet foundry sand, sand should not stick to your hand when squeeze tested. Cast: To pour molten metal into the sand mould. (Cavity) Chill: Cast Iron or steel objects used to promote rapid solidification of metal, reduces porosity. Creates very tight metal. Core Shift: The result of a core moving with the pressure of the metal entering the mould. Make sure that core prints on the pattern are the correct size for the core being used. Crucible: You’re melting utensil, quality crucibles are made from silicon carbide materials, buy the best you can afford. (Cheap Clay Graphite items are available also). A make shift crucible can be lined with fire clay. Dross: The rubbish & oxides that form on top of the melt. Always degas the metal. Fluidity: The ability of a metal to flow freely when in its molten state. (Correct temperature) Flux: Special powders available from foundry supply houses, helps to remove oxides etc from the melt. (Sprinkle on top of melt to prevent gas pick up from atmosphere) Gate-In: The last part of the flow channel for the metal before it enters the mould cavity. Gated pattern: Patterns & ingates mounted to mould board, saves hand cutting of runners. (Rapid moulding system, great technique) Inclusions: Particles and rubbish in finished casting. (Degas metal and blow mould cavity out) Ladle: A crucible or refractory lined steel pot used to pour or (ladle metal) from larger melting device. (Pre heat required before pouring) Melting Point: Critical temperature that metal turns to liquid form. (This is not the pouring temperature.) Mould: Sand/ Metal/ Clay etc, used to make the casting. (Green sand, Permanent or die cast, Investment casting type of mould) Moulding Medium: sand used for the mould making process, e.g. green sand/silica sand/ casting plaster, etc. Oxidation: The reaction where an element combines with oxygen to form oxides or dross etc. Pouring Basin: The top funnel section of the mould. I.e. sprue. Pyrometer: Special instrument used to determine temperature of molten metal before pouring. Refractory: Heat resisting material, used in furnace walls, ladles, moulds & crucibles. Cupola furnace pouring spouts etc Riser: A large head of molten metal used to feed casting as it cools. Always feed to heaviest sections. Shakeout: The operation of removing your castings from the sand moulds. Southern Bentonite: Special foundry quality clay used in the refractory, and as a binder for green mould sands. (Green sand moulds would mould without this compound) Written by Col Croucher Australia. You are entitled to one Printed edition of this ebook, please respect my copyright and intellectual Property. 38 Complete guide to hobby metal casting. Judging temperatures by eye. W ith a reasonable amount of metal melting and pouring experience, you will soon get a feel for the correct time to lift the crucible out of the furnace and pour the casting. Don’t worry too much if you have some failures; this is just a natural part of the learning curve that all hobby caster’s go through. There are times when you think the metal is spot on and ready to pour, only to find out that it’s not. Experience is a great teacher. Approximate temperature readings only. Faint Red: 877 Deg F. Dull Red 991 Deg F. Full Blood Red 1051 Deg F Dull cherry Red. 1196 Deg F Full Cherry Red 1376 Deg F Light Cherry 1551 Deg F Deep Orange 1641 Deg F Light Orange 1731 Deg F Yellow 1961 Deg F Light Yellow 1975 Deg F White 2210 Deg F Bright White 2551 Deg F Dazzling White 2731 Deg F Looking at hot metal and trying to guess its temperature is really just a guessing game. You have to view the hot metal under dark conditions. A little difficult if you’re melting metal in bright daylight. Aluminium is even more difficult to determine what temperature it is at, because it does not change in colour like molten cast iron or bronze. Aluminium looks silver at solid & looks a silvery pink colour when it’s at full melt. The colour can vary with the amount of light in the foundry. I still like the pine stick method that I discuss in the book. However the most accurate method is with an industrial optical pyrometer. You can also make up a thermal couple device and use a cheap multi meter calibrated to determine the temperature of the melt. The meter is made using two pieces of dissimilar Alumal metal; they have been proven to be quite accurate for measuring molten metal, although it can take awhile to dial in the accuracy. Written by Col Croucher Australia. You are entitled to one Printed edition of this ebook, please respect my copyright and intellectual Property. 39 Complete guide to hobby metal casting. The Home Metal Foundry. Y our home metal foundry will be a constant source of satisfaction & amazement to you and your friends. As you acquire more confidence with the projects that are attempted, you will find that after a while, people will ask you to cast small items for them. If you feel confident with your skills, by all means, do some outside jobs, whether for fun, or a paid service is up to you. Don’t take on a job if it is outside your foundry skills, it is better to carry out trial and error casting jobs of your own, rather than practice on other peoples work, which may end defeating you and suffer the embarrassment of not being able to do the job. Some people will pick up the required foundry skills quicker than others, that’s OK, it is better to learn at your own pace, rather than rush things through and not grasp the skills and techniques needed to successfully mould and pour your own castings. When you become totally familiar with metal casting, everything will become second nature, it is a bit like driving a car, you don’t think twice about what to do next do you? All it takes is practice and lots of learning. Don’t be afraid to seek out others that might be doing the same as you. Visit mainstream commercial foundries for guided tours; you’re bound to pick up some really good ideas & new technology. I still remember the tour we had of the General Motors Holden Foundry at Fisherman's Bend, Melbourne, Australia, during a foundry course that I was undertaking. On the last day of the course we were able to take a look at this large fully computerized manufacturing foundry plant. The principles of this large foundry were basically the same as what we were doing during the course, only the scale of the operation was simply huge. The memory still lives with me today. Build as much of your own equipment as you can, you will not only save lots of $$$, but the custom-made gear will suit your operation perfectly. If you have a reasonable workshop, it should not be too much trouble building your own equipment. In the next section of this ebook we will be taking you through all the steps to build your own gas fired furnace as well as a motorised riddle. It’s time to start getting up to scratch with your metal welding and fabrication skills. Your’e going to have a lot of fun Don’t forget the safety aspect of your craft, Molten metal can be very dangerous and can inflict some nasty injuries, buy the proper safety gear, it’s an investment in you and your own safety. Do not allow small children in the workshop during metal casting operations. There will be enough things to look after with out having to worry about small children at the same time. Enjoy the fascinating journey into home metal casting, only your imagination & creativity will limit the things you can make with this craft. Following this we have some outlines of casting projects completed in the home foundry which you can read about, and perhaps learn some techniques which will help you to further your foundry knowledge. These projects were all produced with basic foundry equipment explained in this ebook. Written by Col Croucher Australia. You are entitled to one Printed edition of this ebook, please respect my copyright and intellectual Property. 40 [...]...Complete guide to hobby metal casting Home foundry projects Project 01:Door hinges The cast aluminium door hinges, were made from homemade timber patterns Pattern dimensions and details were made to be the same as the original item, plus a small allowance for shrinkage The patterns were made as split patterns and mounted on both sides of the pattern board,... runners and any spots where a riser or feeder may be needed If your casting has a heavy section close to a lighter section, feed it generously with metal other wise the heavy section will pull metal away from the light metal section leaving you with a weak hot tear, and a porous casting The door hinges above may not look like heavy castings, but even they needed to have generous feeders on the top of... It is a far cry from those first few efforts at metal casting well over a decade ago This casting machined far better than we expected The machine marks are quite visible even in this digital image While not a totally complicated casting, it was complex enough to get the gating and feeding of the casting right Note also the numbers used to identify the casting, these are cheap stick on plastic letters... hobby metal casting eye as some also swear by and you can get pretty close to the correct pouring temperature in the home foundry set up It is not as hard as it look’s, try it and you will see Simplicity! You see, all through this ebook I have preached the simplicity of home metal casting, yet, I still see people doing casting at home who get them selves tied up in so many knots regarding the metallurgy,... they miss the whole point of the backyard metal casting craft, and that is to experiment and create things in metal, working at your own pace without getting bogged down with the technical aspects of the craft Some people even give up on metal casting, and take up lawn bowls! Now, it is unlikely that NASA will call you to do any wiz-bang hi tech Aerospace castings Start out small; you have to crawl... casting work ============)o0o(============= The end of volume one Metal casting made easy The next part of this ebook guides you through building your gas-fired furnace Written by Col Croucher Australia You are entitled to one Printed edition of this ebook, please respect my copyright and intellectual Property 48 Complete guide to hobby metal casting Please continue Part 02 A fully illustrated - How to... years of Practical Metal Casting experience Written & compiled By Col Croucher Copyright: June 2003 Written by Col Croucher Australia You are entitled to one Printed edition of this ebook, please respect my copyright and intellectual Property 49 Complete guide to hobby metal casting Building a propane gas fired furnace Introduction Efficient melting of any metal requires a well designed & easy to operate... to feed metal into the casting for the upper and lower boss! This is the timber master pattern; the master was used to make three-replica patterns from aluminium castings There was a small amount of shrinkage by doing this, so we made the master pattern slightly oversize to allow for this Pattern makers rules allow accurate sizing of patterns to take into account of any shrinkage with any metal being... for carrying out this operation 2 Porous: The ability of the sand to pass steam and or vapors through the sand when the hot metal is poured 3 Refractoriness: The ability of the sand to withstand the heat of the molten metal during the casting operation At the start of your metal casting and foundry journey I would suggest that you find a foundry somewhere that is still using the green sand method, ask... hobby metal casting A fter the patterns have been turned carefully to size, split the patterns by inserting a fine blade into the glue line The paper will start to part company, keep working the blade into the glue joint until the paper splits and the two pattern halves are separated Pattern making can take up many hours of your time; there is really no easy way to achieve good patterns for casting . hobby metal casting. Scrap metal: what to melt. Aluminium. M ost hobby caster’s are never quite sure what kind of scrap they should melt for their castings. The best source of Aluminium metal. hobby metal casting. Home foundry projects. Project 01:Door hinges. T he cast aluminium door hinges, were made from homemade timber patterns. Pattern dimensions and details were made. sand when the hot metal is poured. 3. Refractoriness: The ability of the sand to withstand the heat of the molten metal during the casting operation. At the start of your metal casting and foundry