i did a bit of sand casting in my 9th grade metal shop class. that and sheet metal where my favorite things to do. i've been curious about sand casting parts such as valve covers and especialy intake manifolds. i might even have some done depending on the cost. i've been doing some searching on the net and found a little info but i'm hoping the vast knowledge of the HAMB will come through once again and someone can explain the process, especialy for parts like an intake manifold. what could a guy do at home to save on some of the labor involved in the process of casting an intake?? what if a guy built a prototype from steel or some other material, what would be the next step?? how was it done back in the day when Vic Edelbrock and men of that ilk where doing it in the days of hot roddings infancy??? also, where would one go to have the actual casting done?? any recomendations?? thanks in advance for your time.
i guess you should start with a hardwood model as first nad it have to be a 2 piece style ,you need accdes to the inside because you also need formsand ,heayvy to complain in english ,sorry
Being a woodcarver by trade, I've been hired to do pattermaking for folks at various times. The patterns are first carved in wood and then pressed into sand. sometimes the patterns are female molds so that a "core" of sand can be fashioned (think runners on an intake) . Hollow molds require good casters. Shrinkage is another concern and must be calculated. Both good casters and good carvers are a dying breed Casting sand is unbelievable stuff. It is not "crumbly" and a core has amazing structural strength. If you've got a serious project in mind , I'd be interested in helping out. I've always wanted to explore casting further, but found little time. Most my carving is ornamental nowdays as it seems to pay the bills.
I have been fooling around with doing casting at home. There are quite a few websites that explain how to build your own furnace and make your own sand. Search google for "homemade sand casting" It has also been discussed on here several times. I took a 55 gallon drum, cut the top 3rd off and lined the remaining 2/3rd and bottom with fire brick. I put a 3" dia tub in the bottom to blow air into using a furnace fan. I set the crucible in the bottom and fill around it with charcoal. Then light it and stand back. It actually works quite well. The only thing that I have made is some ingots. I am at the point now that I need to find a good source of foundry sand. Apparently the correct foundy sand is expensive and I am too cheap to buy it. Budget Casting Supply sells the chemicals for making cores. Apparently you mix this chemical with the sand, mold it to the shape you want and let it cure in a co2 rich environment. It reacts with co2 and get like sandstone. I would be interested in doing something with you guys if you wanted.
Found a table for factoring shrinkage at this sight: http://www.efunda.com/processes/metal_processing/sand_casting_table.cfm Had some other good info as well
i dont think sand casting has changed much in 100 years other then the process is automated, i worked in a small foundry for about a year where we cast survey marker tops, it was a simple one sided match plate, when you have internal openings you need to make a core first out of a different kind of sand that has a glue in it that burns out when you do your pour. if you have a simple project like a one off emblem then a frendly foundry guy might do it with out a match plate. heres this other thread to, http://www.jalopyjournal.com/forum/showthread.php?t=224026
You're gonna have to find a real foundry to pour it for ya, and aluminum is preferred for lower overall cost due to improved workability. Steel is much more of a beast to work with during casting, and afterward repairing casting flaws. And there will be casting flaws. The reason you won't be melting yourself is a 20lb intake is gonna require something like a 35 lb pour. Being a low production piece, you'll "over-riser" the part when figuring your gates and risers. It's cheap insurance against casting flaws, minimizing gating is something that should only be done with higher levels of production, and some experimentation to understand how that specific casting fills. As mentioned, you'll need several sets of tooling. One to form the outer shape (probably bolted to both sides of a match plate), another set to form the runners, another for any water manifolds or exhaust crossovers. Runner tooling is often 8 individual tools assembled together. The runners will definitely be chemically bonded sand, the outer can be the same, or "green" sand (clay/water bond). Something like a valve cover is much more attainable. 2 piece mold with maybe an insert for personalization. The foundry at my college made scale engine blocks about 5 inches long, HUGE hit. So popular they did several different engines as the tooling kept wearing out. I personally spent countless hours slaving away over scale iron dukes who's tooling should have been scrapped 100 molds ago. If you have access to a kiln, look into investment casting. You can work with 5-gallon pails of sand and slurry to make much larger molds. The molds are stable for months after kiln firing, probably fitting into the educational timeframe a little better. Resin bonded sand is very stinky, Investment mold materials aren't. If you made tooling for some kind of "blank" wax pattern, adding wax details to personalize each one becomes a big art project. Investment wax molds are just assembled with soldering irons or heated tools of any sort. Very student friendly, and wax can be recaptured to reuse for gating. Good luck
I had an aircleaner that I made out of wood cast by a foundry out of Washington state. I will have to track it down. Make sure you do your research well as there are many things to consider even with a simple project vs. what you are wanting to do. Shrinkage is number 1 issue. Also draft, so that the mold can be removed as in the method I used. Plenty of gating. Maybe Dennis from O'Brien trucking can lead you to the right people on this. This is the aircleaner I had cast. The bottom design was an experiment to see how well it could hold a design. It was done to fit a 4 barrel but look like a Thickstun shape.
ok, so let me know if what i was thinking is a bad idea and why. i was going to fabricate the intake from steel and then use duraglass and bondo to give it the shape of a cast (and not a fabricated) part as well as thickin up the side walls of the runners. i was then hoping that that part could be used to make the outer shape (this would take the place of the wood form i guess). what research i have done has shown making molds for the runners out of fiberglass. check it out here http://www.hotrodders.com/forum/journal.php?action=view&journalid=2439&page=6&perpage=5&reverse= and let me know what you think. is there a better or easier way i should go about making the runners?? what about my idea of the steel and bondo pattern?? thanks for all the input. this is something i want to research fully before i get too carried away.
With all due respect I think you're on track to spend 300 hours and 600 dollars to make a manifold that flows unevenly runner to runner. Thus creating mixture distribution issues. In the case of a manifold, you're not just taking on the casting engineering, you're taking on something fundamental to engine performance. I'd stick to dress up and accessory items. But if everyone had my attitude, nothing new would ever get done. Good luck.
Here's a thread with video, some of the others here may like to see how it looks being poured. I plan to do some casting this winter. http://www.jalopyjournal.com/forum/showthread.php?t=187300&highlight=casting+session
Wood pattern making is a dying art. Items are noe designed in 3D on a computor and the information is fed in to a machine that does "stereolithography". I think that's what it's called. Look it up.
man i sure do miss doin that stuff in high school. i still have an ingot somewhere from that class. i just came across a small aluminum sail boat i cast in class too. it's sittin in the garage.
Generally speaking,tooling is made out of wood,metal or resins for patterns. With that said, we'll talk about the nuts & bolts of parts making. You can make a master (Double Shrink)pattern, which actually gives one 2 patterns. The master and then the production tooling. The production tooling generally goes by the 1/8" shrink rule.(meaning that the pattern has to be 1/8" larger in every aspect in order allow for shrinkage when casting/cooling). Match plate,Flask or mounting area, The pattern is is mounted to this, The gating,runners, sprews and vents all play a vitally important role here, Gasses need to evacuate, aluminum needs to be poured at the correct flow in order to insure complete penetration of all vacancies in the pattern (that had previously been placed and hard packed with sand all around it,in the sand packing process). If you are doing an intake, then you'll also have to have core boxes and they need to fit the core print of the production pattern.(vitally important so that the inside goes with outer,if not careful core shift can occur). It is best to get this all done @ a capable foundry that is willing to work with you through all of your tooling teething woes. The above posts address the sand type whether it may be synthetic or natural refined casting sand,Same goes for cores,they need binders to maintain their structural integrity. It is alot of work to perform this type work, you really gotta love it. machining it is a whole other animal. Nuff said!
I love this topic. I have been wanting to do some of my own stuff.and I have a few links NOW i have a few more thanks guys. Watching with Wide EYEs With having two mills 1 smithy Drill /mill /lath. and Now a much biger drill/mill with a 32in table.Mig welder and a Tig in the works to buy. I thought casting would be Great to start doing. I did it in High school. So learning that all over again I luv it
there is also lost form where you carve a part out of foam, the form part is placed in the sand and when the hot meta l hits the foam is evaporates, the parts i have seen done this way were a little rough though.
For a period of time after I got out of the hospital I worked for a Mag and Aluminum casting foundry. We made the castings for the Viper intake and water pump housings. Also they did the castings for the intakes on the Chevrolet Nascar engines. It's a complex and dirty process and requires mastering some fairly complex operations to sucessfully pull off a finished process. Cyclone Kevin knows well the drill. First, if your going to do an intake you've got to do your homework as far as flow which means having a knowledge of the engine your dealing with, the air requirements needed to make it perform in whatever application your aiming for, the physical limitations,if any depending on environment (engine bay/chassis) it's going to be installed in, and the list goes on. A flowbench is critical for this research. All of this just scratches the surface and magnifys the effort that companies like Edelbrock expend on a continuing basis to bring a product to market. I suggest that you find a local foundry doing similar types of casting and see if they will give you a detailed tour by someone who understands what your trying to accomplish. I assure you it will be an eyeopener. Frank Frank
Maybe the thing to do is make a wood or metal prototype larger (see 1/8" rule above) and figure out a way to make a negative mold out of it (2 pieces would be best, but more complex molds can be made. Pull the positive gently out of the new negative mold, put negative mold back together, place in bucket surrounded by supporting structure (loose sand) and fill with wax and let cool. Remove negative mold and toss (you can always make another from your original blank). Clean up your wax positive, ensuring all your tunnels and portals are clear and smooth, clean all casting seams and smooth it out (lighter fluid and the flat edge of a knife work well). Personalize it if you want to. Then sprew the bejesus out of it and consider making a couple main sprews (1" square wax) and graft a wax cup on the ends. I suggest a couple with the idea that you could conceivably pour into both main sprews at the same time to cut down on premature cooling and fill all your extremities. Then get dirty (wear goggles and a respirator, powdered glass is no fun) and make a couple dozen coats of slurry till it looks like a intake pretending to be a snow man. After everything is cured, use a rosebud torch to melt the majority of the wax out and you'd be ready to pour. At least, this is how I've spent my time laying awake at night imagining how I would do it.
The manifold tooling is expensive from a foundry. So far the cheapest I've come across for a 3X2 that I designed for a 350 Olds has been around 25K. At that price me and the ten other guys that might want one would have to pay quite a lot. Thats not counting the casting cost or the machining.
There are absolutely no secrets. I have bought about 4 books and there are plenty more at the library. Go to a few places in the industry, they spill their guts like drunk parrots. My efforts were pre middle ages "literally" before seeking professional help. In order to make anything more complex than a plaque, plan on working VERY hard. My first prototype of a functional part is in the machine shop and even now I want to tweak the pattern a little more. My foundry is in my backyard though. I suppose I could of hired a woodpecker to make the pattern and hired a foundry to do the rest but then I would lose interest.
i hear that. the main purpose of doing this would just be to do it. i loved this stuff when i was a kid and would like to take it to the next level. i've been dreaming of having a little foundry in my back yard for years. i'll most definately start with a simpler part than an intake if i even get around to it at all. so little time and so many damned ideas!!!
I too have just recently begun the journey of the backyard metal caster. I ran across the www.backyardmetalcasting.com website, now I'm almost ready to melt aluminum in my second furnace. there will be plenty of naysayers- but hey- it CAN be done- by YOU in YOUR environment, if you are commited. try it- I bet you'll get hooked. I did.
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