The International Hobby Metal Casting ezine.
Brought To You By:
Col Croucher, administrator of: www.myhomefoundry.com
Australia.
September Edition: 2008. Volume: .Number: 59
After producing the past two months monster ezine editions, this months edition is going to be a bit less spectacular, I apologize for that, but I thank all of the people who forwarded their hobby casting submissions for the small comp we ran, it was, I believe a great success if the emails we received were any indication.
I think what it really provided was a window to view the current hobby casting world and the many imaginative things being cast by so many different people, the great beauty of this wonderful metal craft we are involved in is that you don't need a degree in metallurgy, you don't need a degree in mechanical engineering, you don't need to have a masters in something or other to actually do metal casting.
But having said that you would be surprised at the number of highly qualified people who are actually involved in hobby metal casting, we see it with each and every download through our web site, it would be fair to say that most people are just everyday people who have a passion to simply cast something, sometimes that need or passion is a basic straightforward item, other times the need is approaching that of the very advanced commercial foundry skill requirement phase.
We have on our data base people from all walks of life, people from mining regions who want a meaningfull & rewarding hobby, people from isolated rural outback stations, people living in cities both large and small, metal craft artists who want to combine different skills to create their unique projects, we have many artistic people, community arts people, corporate people, Doctors and other professional people, all of them want to try their hand at this craft, and why not, the days of creating beautiful things with your hands are slowly disappearing, but wait, maybe I am wrong when I say that, perhaps there is a deep awakening within the population who are tired of the things available today that really only provide instant, short lived gratification and not long lasting rewards that practical hobbies provide, well that's my theory anyway.
There are no hard and fast rules, yet there are plenty of people around to tell you that you cant do this & you can't do that, and yes, I am one of those people who ask assertively "Why not". Many a dream and passion has been squashed long before an idea even managed to get of the ground because a self proclaimed expert told someone "you cant do that".... If you are like me you'll just hate it when they tell you that.
If you are an old ezine subscriber from way back you may remember in one of the early text only ezines, I wrote about the die cast pistons I made for an aircooled garden tractor engine, I have an ebook half finished about this project and I just never seem to find the time to get on with it and complete it.... I guarantee you would love to read it, producing die cast pistons is a lot of fun and one hell of a casting challenge, and the results are extremely rewarding... especially when you show the finished project to a young bright eyed automotive mechanic who will look at you in disbelief when you tell them that you "made it your self".
Yes, there are just so many things to learn about this ancient old metal craft, the more you learn, the more you can do, and the more you can do the better you get at it, each small success automatically builds from the previous success, before long you are mastering things that you never thought possible, but at the same time you do need to keep things in perspective, I sometimes receive emails from people with much more enthusiasm than deep practical experience and they are asking how to cast a cylinder head for a motor bike engine, I'm not saying that it is impossible to do in the hobby foundry, but it is not something you would try to make on your first attempt at pattern making and foundry work, you could eventually master the small cylinder head project, but only after a long list of successes with less daunting projects.
It is nearing 11.30Pm, on a Sunday night, the rest of the household have gone to bed and I'm tapping away on the keyboard trying to knock this September ezine into shape, yes it is way over due, but time has been short as other commitments and business demands have absorbed a huge amount of time in the last three weeks.
But tonight I am also staying up to watch the F1 Grand Prix from Monza Italy, (Starts around 12.00PM) I have always been interested in F1 motor racing. Wow, now there's a world of extreme technology if ever I have seen it, this is also a world where they speak in very large numbers when it comes to spending dollars, it is hard for the average person to comprehend. Our Australian driver Mark Weber has put his Red Bull car on third spot on the grid, so we wish him luck for the race.
If you are new to metal casting I hope the last couple of ezine issues have helped to spark some ideas to get your foundry projects up and running, there is nothing quite like seeing what other people are doing in their foundries to keep you up to speed, but no two people will have the same needs or requirements and that's what makes this hobby so special, the individuality of the whole thing.
- Build Your Foundry Tools & Equipment.
- Make Your Own Patterns.
- Create The Sand Moulds.
- Melt & Cast Metal.
- Finish Your Castings.
- Plus Lot's More.
Metal Spinning.
Metal spinning can be
employed in the home workshop to create many different types of items
for your metal craft projects.
Silicate Sand
Moulding.
Silicate sand moulding
is an excellent choice if green sand moulding medium is unavailable.
This is one of the oldest methods of shaping/forming sheet metal, and is a relatively simple process in which a circular blank of metal is attached to the spinning chuck of a lathe. As the blank rotates, it is forced into shape by means of hand-operated tools of blunt steel or hardwood, supported against a fulcrum pin The purpose of the hand-tool is to press the metal blank into contact with a former of the desired shape. (See Illustration above)
The former, which is held in the rotating lathe chuck, corresponds to the internal shape of the finished component, and may be made from a hardwood such as maple, or, in some cases, from metal. Formers may be solid; if the component is of re-entrant shape, then the former must be segmented, to enable it to be withdrawn from the finished product.
Adequate lubrication is necessary during metal spinning. For small-scale work, beeswax or animal tallow are often used; whilst for larger work, soap is the usual choice.
Large dished reflectors & components used in chemical plant, stainless steel dairy Utensils, aluminium teapots, copper & brass ornaments, light shades and all kinds of other domestic wares are manufactured using the metal spinning technique.
Metal spinning and forming can be easily performed in the home workshop, but you must have a lathe, even an old lathe will suffice, the tooling is cheap and easy to make, if you are looking for another method to shape metal, spinning may fit the bill. There are many good books available on the subject.
Silicate & Resin Bonded Sand Moulding.
Resins are liquids or gums, natural or synthetic, where the individual molecules polymerise or fuse together to form very long chains.
When this happens the resins harden to form a strong solid block of material that is extremely inert and forms a powerful bond with other materials. This polymerising reaction can be triggered by certain chemical reagents, usually a strong acid, and also by heat.
The possibility that such a material could be used as a sand-bonding medium for foundry work was recognised at a very early development stage. As a result there are now very many resins and resinous mixtures available to foundries that a particular choice becomes complicated.
At this time it is not possible to completely describe all of the many different materials
available but hopefully this overview will provide some introduction to the different types of resin
and resin derivatives.
One of the big disadvantages of resins & resin bonded sands as compared to green sand
is that because they are essentially organic and based on formaldehyde there are considerable environmental difficulties in disposing of waste and used material.
(Green sand does not present such a problem as this material can be recycled over & over.)
The acid catalysts that are used as setting agents also add to these difficulties particularly in atmospheric pollution within the foundry itself when the moulds are poured. Further development has taken these characteristics into account in an endeavour to alleviate them.
Currently resin additive percentages can be as low as around the 1% level by weight of sand and the newer bonds, some coupled with chemically set silicate, mean that reclamation is simpler and environmental impact much reduced. There is no doubt that continuing efforts will be made to further increase the acceptability of sand bonding materials at the same time improving the possibilities and economics of reclaim and re-use of the sand itself.
Once the process and chemistry is well understood by the moulding operator excellent
moulding/casting results can be achieved.
Resin Binders.
There are basically four types of cold set resin binders available, each
producing a range of physical properties. They may be classified as follows:
1. Urea Formaldehyde/Furfuryl Alcohol (UF/FA).
2. Phenol Formaldehyde/Furfuryl Alcohol (PF/FA).
3. Urea Formaldehyde/Phenol Formaldehyde/Furfuryl Alcohol (co-polymers).
4. Phenol Formaldehyde (PF, Furfuryl Alcohol-free).
In the photo above, are shown some very simple items to use when mixing the silicate resin into the dry foundry sand, the particular items from left to right are.
1. Container of sand.
2. Two part core box.
3. Set of digital kitchen scales. (Used to weigh the sand & resin seperately)
4. Container of resin.
5. Small container of reactive catalyst.
6. "T" shaped Wire mixing tool. (Mount in hand held electric drill)
7. Bucket for mixing sand & resin.
At the bottom of the picture is a two peice core box and freshly made resin sand core.
Basic Method: Weigh out quantity of sand for moulding/core job, calculate correct % of resin & hardener, (Ranges between 1.5 to 3%). Place dry sand in plastic bucket, pour resin into bucket onto sand mix with T inserted into hand held electric drill set on low speed to thoroughly mix sand - resin - hardener for about 1.5 mins, core box should be assembled, lightly ram resin coated sand into core box, vent where required, set core box aside to cure, (Around 15 -20 mins). Carefully separate core box and remove hardened sand core. Repeat procedure to produce quantity of cores required.
Drawbacks Of Resin Bonded Sands.
Chemicals are quite expensive to purchase, smallest size container is generally 20 litres. Sand has to be kept perfectly dry, large batches of sand mixes require more complex/expensive mixing equipment, disposal of used foundry sand moulds can be a problem, cured/hardened sand cannot generally be recycled as is the case with green sand. Bench life of some chemicals can be short. And of course like any chemical use, caution and safety first must always be kept in mind, always read the PDS brochure of any product you intend to use.
If you can find solutions to the problems that this system presents your moulding and casting results will be raised to a new level, we have used the system and have achieved great results, understanding the chemistry behind the mixing can take awhile, but it quickly begins to fall into place. This foundry sand system is well worth exploring, but there will be some expense involved to set up.
A Fascinating Project For The Serious Old world Aviator.
WRIGHT BROTHERS Aeroplane Company.
Materials to build your own Wright glider and Flyer replicas.
Check the engine castings out.
Visit:
http://www.first-to-fly.com/Adventure/Workshop/materials.htm
Metal Fatigue.
A phenomenon which results in the sudden fracture of a component after a period of cyclic loading in the elastic regime. Failure is the end result of a process involving the initiation and growth of a crack, usually at the site of a stress concentration on the surface.
Metal fatigue can occur in any mechanical component, sudden failure could be the cause of unexplained automotive & industrial accidents, a good understanding of the causes of fatigue may help you to avoid an accident.
If you have ever wondered why a metal component suddenly fails you may find the answer here.
http://materials.open.ac.uk/mem/mem_mf.htm
Hobby Metal Casting - The Journey & The Exploration.
Involvement in certain hobbies can be due to all kinds of factors, in some cases it stems from a curiosity point of view, with others it can be because a friend insisted on showing you how, but
the urge can also come from a personal need or challenge to create and make something, which you know will be the only way in which you will obtain that certain something.
From the point of view of a raw beginner learning to master hobby metal casting could at first seem to be an impossibility, simply because of the assumption that there is an awful lot to learn about the subject, and if the truth be known, there probably is, but like many other skills you learn throughout life, the more you practice, the better your skills become, a first year trainee surgeon would not be assigned to the task amputating someone’s leg without first studying
and learning about the human body.
Likewise a novice metal caster can't expect to master the art of hobby metal casting with out at first reading, learning and then applying the knowledge you've gained and combine the theory with some solid practice.
If you have just an ounce of practical skill in your body, you will be able to turn that small amount of skill into a valuable resource you'll be able to use for life.
You could begin your metal casting by using the most basic furnace, equipment & tools, many people who started in this way are now experienced metal casters, and know how to create
all manner of things from metal, they have also discovered that sooner or later, other people get to hear about their special talents, and it's not long before the odd paying job comes in,
which helps to make your hobby self sufficient
The type of people that get involved with hobby metal casting range from radio controlled racing car enthusiasts, Go-Kart Builders, antique restorers, vintage motorcycle and car rebuilders,
people who build miniature steam engines & aero engines and parts. Some people have found It is even possible to design and build miniature engines that run on gasoline, there are several
home trained hobby foundry workers who have undertaken to design & build intricate patterns and cores to cast and build miniature 4 cylinder & V8 engines, real engines that have spark
plugs, which run on petrol.
A certain amount of practical skill is required to make the many parts required for these amazing home designed & built projects.
Think you cant do any of those kinds of projects? Well think again, because many of the people who now build these projects started out as a pure novice, they were eager to learn how to cast metal, they found the right knowledge, then learnt by doing, soon they found that the things they once thought impossible were now achievable, that's the power of knowledge, belief in your self, and the commitment & passion to get the job done.
Next Month: Ezine Number 60.
Next months ezine is the sixtieth edition, crikey how did that happen? It does seem like a short period since we launched the Hot metal Ezine, yes it has been an awfull lot of work, but we know from feed back that the ezine has been enjoyed by many many people. So what I would like to do is invite you to submit a special project for inclusion into the 60th ezine, this is not a competition, all you need to do is to send two or three photos plus a short article explaining about your project, what do you think? have you got something to show us? We would love to see something from you.
Until next time.
Enjoy your metal casting.
Col.
PS.
You want help to kick start your hobby metal casting Journey?
This page Is For You