New Member with questions

[Sweet Dreamer]

I have limited acess to the web right now so please bear with me as I ask some questions.

 

I would like to get into casting aluminum and bronze.  I would very much prefer to heat the metal using wood as fuel if at all possible.  I would also like to build a permanent stone furnance using fire brick.

 

So right now my main question is where can I find designs specifically for building a wood-fired brick furnance?  Size is not so important as I can scale it up or down to suit my needs.  I just need the main idea of the design.

 

I plan on casting fairly small items most will be small parts for building model train engines in G-scale.   I may cast a few things larger, but most of my castins will be very small pieces.  About the largest object I plan on casting right now will be a large locomotive wheel about 4 inches in diameter and about 1/4" thick.  But I do hope to cast several at a time.   So I'd like to be able to prepare at least 30 pounds of bronze absolute maximum.  I'll probably never need that much in a pour, but it would be nice to have that capacity.

 

Thanks in advance for any help.

[Rich Hale]

Farther down the list of subjects is a casting and foundry section,,,was any of the information there of any help?>

[Frosty]

Welcome aboard, glad to have you. Put your general location in the header and you might be pleasantly surprised to find out how many forum members live within visiting distance.

 

Didn't you find the answers to these very basic questions in the casting section? I'm not a caster and I've answered them more than once.

 

Casting is NOT something a person can figure out themselves without serious risk of severe injuries and property damage. A 30lb. flask of molten bronze has the equivalent explosive energy of something like a case of 60% dynamite just waiting for a little water.

 

Frosty The Lucky.

[Sweet Dreamer]

Thanks for the replies. 

 

I'm on dial-up with a really bad connection to boot.   Surfing around trying to hunt for information just isn't an option for me right now.  I actually drove over to the library last night just to join this forum and make my initial post.  They have wi-fi.   And I had to use it from the parking lot because they were closed.

 

Anyway, I've done casting before many many years ago.  So it's not entirely alien to me.   I'm also a very safety-aware person.  I have a full machine shop and woodshop and I also do welding.  Safety is my number one priority.   I'm retired from a career in R&D where I have also been in highly dangerous situations in steel mills, rolling mills, etc.  Not to mention chemistry labs where I've performed many experiments with highly volatile materials.  I'm just giving a little background to aside any fears that I might hurt myself casting molten metals.  In truth, I'm already a bit apprehensive about it.   When I was at the Library I watched a few videos of some guys casting metals and I was shocked to see them doing this with no gloves, no eye protection or anything, and they even seemed to be doing things using really flimsy equiptment.   I would never cast molten metal under such absurdly unsafe conditions.

 

30 lb's of brass would be an exceedingly large pour for me.  I'm not sure if I will ever need a pour that large. None the less I would like to furnace to have that as the max capability.   Even if I make small parts I might like to prepare several molds and pour quite a few parts in a single run.  So for that I might like to have the extra molten metal.

 

Anyway, right now I'm just concerned with building a suitable brick furnace that can be fired with wood fuel.

 

I was looking at this video.  I REALLY LIKE this oven!  Unfortunately it's just a pizza oven.  But I'm wondering if I could modify it to use as a blast furnace for aluminum and bronze instead?

 

[Frosty]

I understand dial up limitations. The library will order books for you. I don't recall the inter-library lend policy name but it's free and reasonably fast.

 

A lot of Youtube videos are scary from most any safety conscious point of view.

 

You can melt aluminum in a wood fire bronze will require charcoal and an air blast. I'm thinking the best bet for good info is hooking up with a local casting organization. Our local caster holds classes and bronze pours where you can pay for materials and make your molds. He (Pat) pours pretty large weights solo but uses a jib boom crane and a gas melter.

 

He also teaches how to build melters. Sooo, if you live in South Central Alaska it'd be worth your time to attend classes with Pat.

 

If not hooking up with a local caster or the local college extension casting program is your best bet, at least check out a library book or two about making a masonry furnace, they're not highly complicated but there are right ways and wrong ways. Stone isnt a good way for first timers, stone can be really dangerous, you have to know what to select for.

 

Frosty The Lucky.

[ThomasPowers]

Charcoal is what you want to use; so first convert your wood to charcoal and then make a charcoal furnace to melt in.  There is a whole series of books on building a hobby machine shop starting with building a charcoal fueled furnace for making Al.  Dave Gingery wrote the series google him and casting together.

 

Also look into the backyard metal casting sites.

[Bentiron1946]

You can melt aluminum with a wood fire but not much else in the metals that require higher temperatures like brass or bronze, like Thomas says for those you will need charcoal. I have made a number of melting furnaces out of metal 5 gallon buckets, crushed fire bricks,bentonite clay(think cat litter) and portland cement. This holds a small crucible real nice and then I use a homemade propane burner and shop vac as an air supply, melts around 10# of bronze pretty quick.

[Sweet Dreamer]

Lots of good information here.  I'll have to look into making charcoal.  I heat a lot of things with wood so I have a lot of wood stoves that are probably making tons of charcoal already.

 

I never heard of "vacuum casting" so that's something new I'll need to look into.  I'm not too worried about learning all of the details of casting right now.  Right now my main agenda is to build a suitable furnance.  One that looks good and will serve my purposes.

 

I really like that pizza oven.   So I'm thinking of taking that general design and modifying it as a blast furnace.   I guess the main thing I'll need to design around will be the crucibles.

What crucibles will I need for casting bronze?

 

What exactly is bronze anyway?   I always think of it as contaminated brass. (ha ha)

 

And how about casting in pure brass?   Does that require more or less heat than bronze?

 

What are the advantages or disadvantages between casting pure brass and bronze?

 

Also are there different types of "bronze"?    Where do you typically get the scrap bronze to melt down?

[Rich Hale]

Actually I think if you have not done it yet,,,,begin by readin everything posted in this area,,,starting with the pinned post at the top. So many folks have written so much to help anyone willing to sit and study it would be a shame to ignore tham and give you short anwers that will still leave questions. And I used to hav edial up and know wot you mean..but if you have to go to library then make it worth your while,,read and take notes,,,and ask about the library loan,,,ILL they will get you the books suggested above...

[Steve Sells]

limited time to read real research, but wanting to build a foundry. Please read more first.   Some of the questions you ask in your posts tell us you have not reasearched much yet.  Do not give up, but you really need to read a lot more before asking questions on how to build anything, find out what options are, and learning what the various metal alloys are is a good idea, some may kill you from over heating them, and you and others can be killed from some major failures.

[Francis Trez Cole]

http://www.backyardmetalcasting.com/ there is a lot of information here

[Sweet Dreamer]

I love to read books.  I already own quite a few books on metal casting in my own personal library.   And I'll definitely be looking into the books people have mentioned on here.

 

In the meantime I want to BUILD a furnace.   I know it's going to be brick because that's what I want.   I know it's going to be "quaint" because that's what I want. I know it's going to be wood-fired, (or charcoal fired), again because that's what I want.

 

So that much is a given.  I'm a wanton person. B)

 

Right now I'm not really interested in casting anything.  I'm interested in BUILDING A FURNANCE.

 

When it comes time to do the actual casting I'm sure I will have researched that to death and back.

 

In the meantime I want to build a quaint-looking brick furnace that will do the job.

 

I can design it myself, and probably will.  But that's basically the information I am currently looking for input on.

 

No sense in re-inventing the wheel if there already exist plans for cool-looking brick furnance out there that is specifically designed for wood or charcoal fuel.

 

So far I found that pizza oven and that other one where the kids were coming dangeously close to killing themselves in a sea of motlen aluminum.  Sadly they offered no plans for how to build their furnance  though.

 

I really want that modified pizza oven. :wub:

 

Right now that's my current leaning.   Maybe build a firebox under it with a grate leading up to the pizza hut?   :)

 

Most of the books I've seen on casting have really crappy-looking totally-ultiliarian furnances.   Yuck! 

 

I want a really cool furnance.  Then we can talk about casting metal. ;)

[Bentiron1946]

Bronze= copper+tin(traditional) bronze=copper+silicon(contemporary)may contain traces of other metals to improve characteristics
Brass= copper+zinc may contain traces of other metals to improve characteristics
Scrap bronze is harder to come by than scrap brass. Scrap brass is the stuff that a lot of plumbing stuff is made of like hose bibs, shut off valves, unions, stops, tail pieces and in some electrical items like light fixtures. Now it hard to find scrap bronze and that you find in some really high end electrical products where there is a high corrosion factor involved. Most all bronze used today is silicon bronze for it ease of casting. Traditional tin based bronze is almost only used in fine arts casting.
Brass and bronze are very close to the same temperature for casting, so don't fret about that. Silicon bronze is the easier of the two to cast, brass the harder and more dangerous, it off gasses zinc which can be bad for you health. Only do casting in a well ventilated area, preferably outside, watch the temperatures and don't overheat it to the point where you start off gassing the zinc. Brass needs to be degassed with a degassing agent so you don't get a lot of porosity in you metal.http://www.budgetcastingsupply.com/Brass_Degas.php Casting is something one can learn with research at the library, I did, it is possible and it is a fun thing to do but be sure you do an awful lot of reading. Remember if the ancients could do it so can you and the internet wasn't even invented when I taught myself how to do it. Yeah, that was almost back in the Late Bronze Age.

[Steve Sells]

Build a furnace then later figure out how it use it? Rather than learn what you need for your projects and build to make that happen?

[ianinsa]

Just for interest, why wood? I have a charcoal retort and you could melt over the chimeny if you wanted to! but UMO (with propane start-up)is a much better and IMO easier and more effective. The backyard casting books , by Terry Aspin (he has written a few) are a great resource.

 

Ian

[Glenn]

Go to the library during business and ask to use the public computer. It should speed up your ability to access information on the internet.  

 

Safety is always a first priority. If you do not play safe, it will cost you dearly when things go wrong, and they will go wrong at some point. Learn what you are dealing with, what metals are used for what purpose, and their composition and properties. Learn how to load, melt, pour, and do all the steps properly and safely.

[Sweet Dreamer]

@ Bentiron

 

Thanks for the information on the bronze alloys.  I knew there would be issues with that already without having to read any books. ;)

 

I imagine that getting the right bronze scrap and additives is no doubt something that comes with lots of experience.

 

I was originally thinking about just casting in aluminum, but people on the model railroad forum suggest that casting parts in bronze makes for a much higher quality model that will bring far higher prices on the market, so I've decided to think about stepping up to bronze.  I've never done bronze before.

 

@ ianinsa,

 

There are several reasons why I have decided to go with wood fuel.  The main reason is that I have literally tons of it already for free.  Any other souce of fuel would be an additional expendature.  I don't mind doing things the old-fasioned way.  A second reason is that I am in a restort area where many of the crafstman around here do their handicraft using "retro" technology.   There will be people watching me cast metals.  So it's more than just a mundane job.  It's a bit of a theatrical production as well.   I was even thinking about using a very large bellows, but I've decided not to go that route.  So I will be using an electric powered blower.   That's another issue too.  I would really like to find, or build, a quite blower.   I'll have to look into that.

 

You need to understand that my goal is not simply to cast metal in the most efficient or easy way that I can.  Like I say, this is a whole theatrical production type of thing, but at the same time I'd like to cast some really good parts.  I will be using the parts as well.  So I'm killing two birds with one blast furnace here.

 

Oh, by the way, I actually have a Terry Aspin book.  It's called Foundrywork for the Amateur - Workshop Practice Series number 4.   This is a very old book that I've had for many years.  It does have a very simple brick furnance shown.  It's 18" square (outside measurement) with a 9" square cavity for the crucible.  The outside of the bricks are wrapped with heavy sheet iron.

 

That "Pizza Oven" I was looking at actually has two layers of bricks.  The inner bricks are firebrick whilst the outer bricks are just standard red bricks.   I like that design.  Seems like over kill for a pizza oven though.

 

 

Of course this is just the basic idea.  I could even turn that up vertically and have it a vertical cylinder.  It would probably be easiest to build horizontally then I could turn it up vertically after it has cured.

 

I guess when it comes to building the furnance it dosen't really matter what fuel will be used.  The firebox would be seperate anyway.   I think I'll just design my own furnace cavity kind of like this pizza oven on vertical. 

 

 

@ Steve Sells,

 

Yes, I would like to get a furnace up and running so I can start casting.  Nothing teaches better than actual experience.   ;)

 

A furnace cavity is just a furnace cavity.  That really shouldn't be a major factor in the actual process of casting.   I just want something solid, permanent and pretty.   I could even line it on the inside with something modern.   That wouldn't be a problem.   Except if I'm going to do that I better leave room for the liner.

[Rich Hale]

Build your furnace to meet your hearts desire..Lots of folks do this,,,and on this site we have seen one thing resurface again and again. They build wot they envision...then they tear it down,,build another one,,etc. This has held true for machinery, forges anvils, tongs, hammers...almost anything shop related and that includes shops themselves. Esthetics over functionality is a poor match up. After all of my years I have changed my ways,,,  I want to see that an idea works before I build it permanent and final.

That of course in my shop my rules,,,you have those options also.

[Wroughton]

Just for interest, why wood? I have a charcoal retort and you could melt over the chimeny if you wanted to! but UMO (with propane start-up)is a much better and IMO easier and more effective. The backyard casting books , by Terry Aspin (he has written a few) are a great resource.

 

Ian

Ian!

 

less teasing, more showing! The charcoal retort please. 

[ianinsa]

I have that book too - that furnace is meant for coke, so for wood it won't be that sucsessful(not enough space for fuel) (might possibly work for charcoal if you enlarge the firebox)otherwise the book has good solid tried & tested info.His later editions use an angle iron frame rather than the sheet steel. However if you add a second skin of brick(as per your pizza oven ) you can omit the steel. By all means build the pizza oven, make sure that where the fire is you butt joint the brick, the mortar is what fails when exposed to the heat. And then on the remote possibility that it does not work - you can always use it to make pizza(without that pesky eroding mortar contaminating it)


BTW. you don't need their moulds just use damp sand and pack it firmly.


Sorry I don't know how to post the link Wroughton, but the retort is in solid fuel forges under Retort.

[Bentiron1946]

You can purchase bronze casting shot which is the easy way to do it, don't buy an ingot, it will be to cumbersome for small scale casting. I bought a couple of ingots when I first started out and man does it take forever to cut of a chunk small enough to fit into a small crucible, at that time I didn't know about casting shot. When you use wood for fuel what you are actually doing is turning it into charcoal as you burn it, it is therefore more efficient to do that before you start the melting process. Therefore learn to do this before you start the melt, get plans for making your own charcoal retort, it will make your melt go a lot faster and produce a much hotter heat. You need to get a heat of about 3,000 degrees around the crucible to reach a melt temperature of 1,900F and a really good pouring temperature of 2,150F and for that that you need a good supply of charcoal on hand even for a small melt. You just don't want to get your metal to the slushy stage and get no further because you are constantly feeding food to the fire and can't make it past that stage, to get there you need charcoal which will burn hotter than just plain wood. The ancients figured this out, you don't need to, you just need to follow their example.

[Sweet Dreamer]

Thanks Benitron.  Lot's of good infromation in your post there.   I'll definitely be thinking about making proper charcoal when the time comes. It's going to be quite a long time before I'll actually be casting bronze.  I'm definitely going to start out casting aluminum until I get that down really well.  I guess I can get by with just wood for casting the aluminum.

 

On the furnace, what I'm seeing is two basic things.  One part seems to be the insulated high-temperature-resistent cavity in which to heat up the crucible.  The other part would then be the firebox.  Of course, if a person is heating with gas there isn't much need for a fire box since the gas torch basically just blows right into the cativty that holds the crucible.

 

So I'm thinking the real "design information" I'm seeking is information on good ways to build a firebox that will burn wood or charcoal and to be able to direct that heat into the crucible cavity efficiently.  This is probably a lost art due to the availablity and convince of modern bottled gas that will easily produce the desired temperatures without any fuss.  I certainly undestand the attraction to that as well as the practical aspect of it.  For someone who is solely interested in casting metal that's definitely the way to go.  I certainly wouldn't argue with that.

 

I'll just have to keep my eyes open for wood or charcoal furnances and see how they were built.  Maybe a book on the history of casting might help.

[Joe111]

You can melt pretty much any metal with wood.Used to melt a ton of cast iron ingots per 8 hour day in this wood fired curcible furnace. Every part of it was made by hand from materials dug from the ground such as china clay and silica sand. We obtained temperatures in excess of 2900F.

 

[ianinsa]

A nice looking set-up Joe!