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dang
11-09-2007, 04:54 AM
Recently I was experimenting with coremaking and found that baking soda hardens to a rock like state when it's baked in a conventional oven.
My question is, has anyone else used %100 baking soda to build "sand cores"? I'll soon be testing a soda core against some molten aluminum. If you're interested keep your eyes peeled.

ratrace2
11-09-2007, 05:38 PM
WOW, that sounds great, could you send me a picture. Actually, I think you should be careful when you do that pour. Do you think it might explode?:)

dang
11-10-2007, 03:16 AM
Well, there's only one way to find out. I'll test it over the weekend and snap some photos.

jrrdw
11-10-2007, 06:26 AM
Do you ever preheat your sand molds?

dang
11-10-2007, 07:32 AM
I don't use sand molds anymore. I gave up after numerous & constant failures. Now I machine my molds out of steel, which I pre-heat in my stove before using, at least for the 1st pouring. The steel molds cool so quickly that I can unload the finished castings and reload them within minutes. Die Casting is great for production!
The problem I have is that steel cores aren't really effective at all due to thermal contraction of the aluminum during solidification. Any kind of core basically gets stuck inside of the casting. It's a disaster, especially after all that machining. So I'm gonna experiment with the sacrificial baking soda cores.
If this doesn't work then I'm gonna bite the bullet and order some oil bonded sand for the cores and all the one off castings that I wanna do.

jrrdw
11-10-2007, 07:45 AM
i allways thought you just cracked out the cores once the metal was solid. My step father makes his own black powder bullets, i got him 50 caliber mold and oak handles to match for Chrismas. The 1st one allways turns out junk, the rest are nice. He says it's because the mold temp isn't hot enough.

If you don't mind me asking, what are you molding?

dang
11-10-2007, 09:23 AM
Yeah, you just knock the cores out once the casting is finished. Hence the term sacrificial. I was trying to use steel cores, that didn't work.
50 Caliber bullets????????? That firearm must be gigantic!

I build and sell printing machinery. I used to weld the machines together, but found that molding them would be much faster with nearly the same durability. I'll soon be branching out into photography equipment as well, using the same Die Casting process.

I have basically the same results as your father with my 1st casting. Pre heating is really important. Once the mold is warmed up though, it's one casting right after the next.

Robin Hewitt
11-10-2007, 04:48 PM
Sodium bicarbonate? That's like sodium carbonate with an extra hydrogen atom.

It breaks down when you pass 50 degrees centigrade to caustic soda and carbon dioxide

NaHC03 -> Na0H + CO2

Suggest you try very hard not to get the dust it in your eyes when you clean down your parts :)

PS: Also suggest you don't delay casting after baking, it's deliquescent, sucks moisture out of the air.

307startup
11-10-2007, 06:32 PM
I know that a lot of die-cast and permanent mold castings use salt cores. The salt is heated til molten and poured into core molds, and when cooled are stationed in the permanent mold using core pins or registers. I'm pretty sure they use sodium chloride or potassium chloride. No nasty chemical byproducts and because they have a higher melting point than aluminum, they don't sag or shift in the mold.

http://www.diecasting.org/library/cgi-bin/quikstore.pl?search=yes&product=70-062&detail=yes&page=search.html&template=database_list_page&and=

that should be the link to an old paper written about the technology

Conversely, but along the same line of thinking is AquaCore, which I have used and is BEAUTIFUL to use...

http://www.acrtucson.com/products/Aquacore/index.htm

dang
11-11-2007, 04:30 AM
Wow. Thanks for all the advice, especially about Sodium Bicarbonate chemistry. Looks like I'll be using good ol' jupiter blend instead.
Later on of course, I'll try out that salt and alpha alumina core mixture as well.
Thanks all.

Robin Hewitt
11-11-2007, 05:00 AM
chemistry.

One very useful feature of caustic soda to keep in the back of your mind is that a strong solution will dissolve aluminium but not iron.

Handy if you ever need to remove a broken/seized aluminium part from a steel fixture :)

dang
11-11-2007, 05:28 AM
a strong solution will dissolve aluminium but not iron.

Is that to say that a %100 Baking Soda core would in fact dissolve whatever aluminum was poured over it immediately? Wow, what an intensely bad idea I had.

Robin Hewitt
11-11-2007, 05:42 AM
The dissolving is a slow old process and needs water to get it going.

I found out about it some 40 years ago when I tried to push a stuck pellet out of my airgun using mother's knitting needles :nuts:

A buddies father dissolved them out for me in the local university lab :)

JerryFlyGuy
11-11-2007, 02:02 PM
Conversely, but along the same line of thinking is AquaCore, which I have used and is BEAUTIFUL to use...

http://www.acrtucson.com/products/Aquacore/index.htm


WYLD, are you saying you've used Aquacore for casting? I've known of it for a long time and it's use in composite's but I was never sure if it would work for alum. casting.. if it will.. then my worries are over.. I've found my investment casting materials..

Thanks

Jerry

307startup
11-11-2007, 03:51 PM
Jerry

I have used Aquacore Premium to cast with. You will need to contact them directly or use their Information Request Form for the high-temp version. I have used them for 5 different castings, when I was working on a cylinder head that I was designing. It worked great for me. Again, I stress, contact them directly. I have a hydraulic press and also do some composite work, so I had the materials available to me. I'd hate to see someone buy some material only to find it didn't work for them. Their ceramic gel slurry might be best for your application.

jrrdw
11-11-2007, 04:42 PM
Jerry

I have used Aquacore Premium to cast with. You will need to contact them directly or use their Information Request Form for the high-temp version. I have used them for 5 different castings, when I was working on a cylinder head that I was designing. It worked great for me. Again, I stress, contact them directly. I have a hydraulic press and also do some composite work, so I had the materials available to me. I'd hate to see someone buy some material only to find it didn't work for them. Their ceramic gel slurry might be best for your application.

You made your own cylinder head? Howd it turn out? Take long to do the machineing? Hope you don't mind my nosieness, i'm a machanic and these things intrest me. :cheers:

ratrace2
11-11-2007, 05:00 PM
You made your own cylinder head? Howd it turn out? Take long to do the machineing? Hope you don't mind my nosieness, i'm a machanic and these things intrest me. :cheers:

I would like to see it too.........................:)I went to your web site: that is a sweet looking john Deere...did you do that

307startup
11-11-2007, 05:03 PM
jrrdw

Since you're interested, I'll elaborate. At one time I had a Chevy Blazer S15. I wanted a Typhoon clone, but being myself, I had to have a totally custom phantom. My friend owns a Buick Regal T-type that we built a killer motor for. We used a Turbonetics turbo (80mm) and GM Performance Parts Grand National Champion heads. I had a Land Rover V8 block...which used to be the Buick/Pontiac/Olds 215 aluminum block. I also had a Buick 300 crankshaft (longer stroke...the Buick 300 was referred to as the 320/340, which were basically the same engine in iron, but the "size" is referring to hp, not cubic inches), which let me build a 5.0 liter stroker motor with a mild for most engines, .040" overbore...on a Buick 215 .060" overbore is radical, due to core shift. I couldn't find any performance heads for the Rover block, except for a $6000 set of Wildcat heads. Basically the Rover/Buick 215 is like a small nailhead. The Wildcat heads were based on 15* Chevy smallblock heads. They are also irreplaceable and damned hard to find since they are no longer produced. Knowing that the Buick V6 is exactly 2/3rds of the Buick V8, I decided to try my hand at reproducing the V6 heads in V8 versions...basically adding on another cylinder. So I purchased some Grand National Champion heads. 2 sets. Spent about $4000 on them. Cut two cylinders off the extra heads, sectioned away the material on the other heads that would let me graft on the extra cylinders, made a jig out of 3/4" steel plate machined flat with the proper bolt pattern and had a guy TIG 'em up. After remachining the heads to be flat and parallel, I built my engine. It ran great NA. After deciding to turbocharge the engine, I started having problems. My heads warped twice and after having them remachined, I was in danger of having no heads left! The problem was, I didn't have the heads heat-treated after welding, and the welding had left the aluminum a tad soft. Soft enough to creep when "warm", which the exhaust has a tendency to do anyway, and with a turbo manifold made of 321 stainless, it was definitely warmer than it liked. So, I used my custom heads as a template/reference and went about designing heads for the Buick/Rover V8. It took 5 tries and several thousand dollars, but I ended up with two usable sets that needed a lot of machining...just like an as cast head has to be machined for valve guides, seats, rocker arm posts, bolt pattern, etc. Eventually I got tired of fiddling with the Blazer and sold it and a bunch of Typhoon NOS parts. I still have the heads and a Rover "motorsports" block that I've been holding onto. With a good billet crank, you can poke and stroke it to 6.0 liters. Of course, I have an "improvement" in mind for that block...which involves bracing the notoriously weak valley...which involves welding in a billet brace...which involves heat treating...which involves remachining...so it just sits there...mocking me. Now you know...

here's the Wildcat Engineering heads...

http://www.roverv8engine.co.uk/index.htm

ratrace2
11-11-2007, 05:17 PM
he gets set of 6cyl heads cuts them up and makes a set of v8 heads. after that me--tell me if this is right--does an aluminum casting of the old heads so that he now has two sets (4) $4000 dollors heads.......WOW.....I need to see a picture of that..that is great..
by the way it's
(1) Truex
(2) johnson
(3) newman

307startup
11-11-2007, 05:23 PM
RatRace,
Sadly enough, it's true. I loved the tinkering bit. It's the money part that bummed me. I was even thinking of producing a small series run of the heads, but didn't think there was a market for it, except in Europe, and with shipping and tariffs, didn't see a way I could do it for a comparable price to Wildcat. I'll have to dig up my old memory sticks for my camera, we have pictures of the molds we pulled for the water passages and ports, the patterns I made and of us pouring the aluminum. I think I still have some pics of the completed motor turbocharged and stuffed in the Blazer. The cool thing is that I know the guys at the local community college who run the Automotive Technology program and they have a Superflow dyno and flowbench, so I got to do my test and tune for free. :D

ratrace2
11-11-2007, 05:44 PM
RatRace,
Sadly enough, it's true. I loved the tinkering bit. It's the money part that bummed me. I was even thinking of producing a small series run of the heads, but didn't think there was a market for it, except in Europe, and with shipping and tariffs, didn't see a way I could do it for a comparable price to Wildcat. I'll have to dig up my old memory sticks for my camera, we have pictures of the molds we pulled for the water passages and ports, the patterns I made and of us pouring the aluminum. I think I still have some pics of the completed motor turbocharged and stuffed in the Blazer. The cool thing is that I know the guys at the local community college who run the Automotive Technology program and they have a Superflow dyno and flowbench, so I got to do my test and tune for free. :D

All we have to do is build you a great CNC operation to build those heads, with my knowledge of fiberglass and composites and my new 14' x 8' x 6' gantry cnc for the carbon fiber body we can be the next Mclaren, ferrari....I did a ferrari 390 spider last summer. Let's get it on................Thinking, have you ever considered doing a version of wire EDM for the cavities of your heads? You probably couln't do it all but you could do alot...maybe.

307startup
11-11-2007, 05:59 PM
All we have to do is build you a great CNC operation to build those heads, with my knowledge of fiberglass and composites and my new 14' x 8' x 6' gantry cnc for the carbon fiber body we can be the next Mclaren, ferrari....I did a ferrari 390 spider last summer. Let's get it on................

If only you knew how close you are to the truth...It's because of my automotive interests that I got into machining. Everything I have done at school and in the working world since leaving the army has been to establish the skill base needed to produce an automobile from scratch. I took several art classes for casting metals just to learn how to cast properly. I actually recieved grades for my "hobby"! While other people were doing bronze castings of arty stuff I was casting intake manifolds and cylinder heads. I recieved my AAS in Machine Tool Technology just so I could learn to use the Haas CNC mill & lathe. From there, my prof got me a job with a local shop that builds high-performance steering components...they make the steering racks for the top teams in Nascar, Sprint cars, Trophy trucks, the Saleen S7 and the Mosler MT900. I then went to work for a company that makes Jeep suspension kits, here in town. Now I am a one-man shop for my company that specializes in hydraulics. I push myself to learn every day and take on some projects that other people won't touch. I'm piecing together my shop bit by bit. Soon I'll have a Tormach mill and then hopefully a Tormach lathe if/when they introduce it. I have worked closely with two engineers to design and produce a transaxle for mid-engine use in high-hp applications. My CNC teacher's brother is Bud Brutsman, the producer & director of Rides & Overhaulin'. It is through him that I was introduced to Chip Foose. If only my dreams weren't so expensive and I had been born a trust-fund baby, instead of a working stiff, I'd be on my way. :D Actually, I enjoy the hard work and effort. Most people watch TV before they go to bed, I take online courses in metal working and watch technical DVDs. This is a sickness...

ratrace2
11-11-2007, 06:13 PM
If only you knew how close you are to the truth...It's because of my automotive interests that I got into machining. Everything I have done at school and in the working world since leaving the army has been to establish the skill base needed to produce an automobile from scratch. I took several art classes for casting metals just to learn how to cast properly. I actually recieved grades for my "hobby"! While other people were doing bronze castings of arty stuff I was casting intake manifolds and cylinder heads. I recieved my AAS in Machine Tool Technology just so I could learn to use the Haas CNC mill & lathe. From there, my prof got me a job with a local shop that builds high-performance steering components...they make the steering racks for the top teams in Nascar, Sprint cars, Trophy trucks, the Saleen S7 and the Mosler MT900. I then went to work for a company that makes Jeep suspension kits, here in town. Now I am a one-man shop for my company that specializes in hydraulics. I push myself to learn every day and take on some projects that other people won't touch. I'm piecing together my shop bit by bit. Soon I'll have a Tormach mill and then hopefully a Tormach lathe if/when they introduce it. I have worked closely with two engineers to design and produce a transaxle for mid-engine use in high-hp applications. My CNC teacher's brother is Bud Brutsman, the producer & director of Rides & Overhaulin'. It is through him that I was introduced to Chip Foose. If only my dreams weren't so expensive and I had been born a trust-fund baby, instead of a working stiff, I'd be on my way. :D Actually, I enjoy the hard work and effort. Most people watch TV before they go to bed, I take online courses in metal working and watch technical DVDs. This is a sickness...
You got it bad, too, huh? Do you have a cnc machine that could do the machine work on those heads?

307startup
11-11-2007, 06:24 PM
You mean bad as in good right? ;)

The great thing is that I make a good living doing what I do and I'm constantly meeting people in my field who contribute to my knowledge base. I even have some of the old timers ask my opinion about setups or how to solve problems they are having. It helps that I'm almost 30 and not fresh out of HS, but still there are times when there is an age discrimination thing from the guys who have been doing this for 30-40 years. After I show them what I'm capable of, they treat me with respect and start swapping war stories. I love the 'zone because it allows me to check out other peoples projects and ideas, and contribute when someone has a problem or question. I am far from omnipotent, but far from ignorant. I drive my own learning curve and am far harsher on myself than any shop owner or foreman ever has. Even when we butt heads, I take the time to listen to their comments or suggestions & find that they listen to my comments as well. I find that generally it works out for the best.

Sorry to DANG for hijacking his thread. :D Hope your casting cores do the trick for ya!

ratrace2
11-11-2007, 06:32 PM
You mean bad as in good right? ;)

The great thing is that I make a good living doing what I do and I'm constantly meeting people in my field who contribute to my knowledge base. I even have some of the old timers ask my opinion about setups or how to solve problems they are having. It helps that I'm almost 30 and not fresh out of HS, but still there are times when there is an age discrimination thing from the guys who have been doing this for 30-40 years. After I show them what I'm capable of, they treat me with respect and start swapping war stories. I love the 'zone because it allows me to check out other peoples projects and ideas, and contribute when someone has a problem or question. I am far from omnipotent, but far from ignorant. I drive my own learning curve and am far harsher on myself than any shop owner or foreman ever has. Even when we butt heads, I take the time to listen to their comments or suggestions & find that they listen to my comments as well. I find that generally it works out for the best.

Sorry to DANG for hijacking his thread. :D Hope your casting cores do the trick for ya!
Well, while we are waiting for "pics" from dang about his casting we can talk about the end game for this cnc stuff; I mean, that's what we are here for: cnc mold making stuff--my molds just happen to be of composites and about 14' x 8' x 6'
But Dang has gotten alot of good advice, I hope his pour went well. I mean, I have never heard of salt as a core material, but I am from the composite world...where every thing is bigger, simpler and more boat or car like. Ya know what, build those heads, brand them, own them, and never look back.....

307startup
11-11-2007, 06:58 PM
I have another one for you...water molds. There was a process called freezecasting where you made molds for your cores using ice. These were then coated with a gel slurry and left to set up. When you baked the cores to set them, the water melted and you had hollow core molds. In fact you could do the whole casting with one lost pattern if you were clever enough to figure out how to assemble your multi-piece mold and cast the ice so when you put it together for slurry coating they would be trapped in position. Whew...talk about a run on sentence. I think I'll try to track it down, so you can view what I described.

http://en.wikipedia.org/wiki/Freeze_casting

http://www.freshpatents.com/Freezecast-dt20051117ptan20050255290.php

ratrace2
11-11-2007, 07:05 PM
I have another one for you...water molds. There was a process called freezecasting where you made molds for your cores using ice. These were then coated with a gel slurry and left to set up. When you baked the cores to set them, the water melted and you had hollow core molds. In fact you could do the whole casting with one lost pattern if you were clever enough to figure out how to assemble your multi-piece mold and cast the ice so when you put it together for slurry coating they would be trapped in position. Whew...talk about a run on sentence. I think I'll try to track it down, so you can view what I described.

http://en.wikipedia.org/wiki/Freeze_casting

http://www.freshpatents.com/Freezecast-dt20051117ptan20050255290.php

You could do your assembly in an "ice cream" freezer.......hahaha.
Have you been drinking??????

307startup
11-11-2007, 07:15 PM
Actually you would only need a cold table...like they use at ColdStone Creamery. That way you don't have to freeze your ass off. Just your fingers. :D If I ever decide to do a production run of castings from my house, that's the setup I would use. All of my cores and molds would be prepped and I'd just keep my furnace fully charged. Running a one-man shop can be a bit stressful, but if you plan correctly, you can get a lot done...and you're not paying anyone else.

ratrace2
11-11-2007, 07:25 PM
Actually you would only need a cold table...like they use at ColdStone Creamery. That way you don't have to freeze your ass off. Just your fingers. :D If I ever decide to do a production run of castings from my house, that's the setup I would use. All of my cores and molds would be prepped and I'd just keep my furnace fully charged. Running a one-man shop can be a bit stressful, but if you plan correctly, you can get a lot done...and you're not paying anyone else.
That is right "if you plan correctly, you can get alot done" that is what it is about. So, plan correctly, produce your "heads", brand your heads--fame is only one user away--and don't look back. You don't know anything about "branding" do you? Do so reading about that, you got everyting else. In the mean time, take a look a the TAURUS cnc clay modelers, that is what I'm about......

ratrace2
11-11-2007, 07:28 PM
Dang, are you done yet??????????????????????????????????

307startup
11-11-2007, 07:49 PM
RatRace2

Actually I have had quite the schooling on branding...Chip Foose is an incredibly enthusiastic personable individual. He has so much going on and does so much that it's really amazing he finds the time to talk with me at all. He is definitely a renaissance man. That being said, I have some other projects that come before cylinder heads. Once I have my Tormach mill up and running, I will be going full steam to produce my transaxle and finishing the castings for it.

Thanks for the tip on the Taurus clay modelers. Where on earth would I put that thing?!?!

ratrace2
11-11-2007, 07:56 PM
RatRace2

Actually I have had quite the schooling on branding...Chip Foose is an incredibly enthusiastic personable individual. He has so much going on and does so much that it's really amazing he finds the time to talk with me at all. He is definitely a renaissance man. That being said, I have some other projects that come before cylinder heads. Once I have my Tormach mill up and running, I will be going full steam to produce my transaxle and finishing the castings for it.

Thanks for the tip on the Taurus clay modelers. Where on earth would I put that thing?!?!
Fine: get going. Don't worry about where you put the Taurus because it prototype is going to be in my shop, thank you.....hahahahha.
Call me if you need a new body style.............I'm from the same town in Itlay as Versace..........That makes me geneticaly predisposed to Italian Car design......

307startup
11-11-2007, 08:00 PM
duplicate post

jrrdw
11-12-2007, 06:15 AM
That mid 60s John Deere restore was done by a friend of mine that i've worked for on and off since i've been 15.

Ice casting, holly ice cubes! Thats outragous, who thought of that???

dang
11-12-2007, 03:03 PM
Uhh,

After all the bad feedback I got about my baking soda idear, I had decided not to test anything, let alone photograph it. I suppose though, if ya'll want some foundry porn, who am I to say no.
In classical Mythbusters style I decided to try out the baking soda. It didn't work out, didn't even harden in the oven at 500 F for 2 hours.
I tried again, this time with crushed together lathe chips to act as an internal webbing of sorts, still it didn't work.
At this point, I'll classify the baking soda core myth as being totally busted. It didn't even make it into the foundry test.

Afterward, I tested my unfinished die, without any bench work done to it, using a steel core, and with none of it's inserts.
It worked as expected, except that the steel core popped right out after I opened the mold, taking a weak portion of the casting with it. After I find a suitable core material, I'll ad all of the inserts and the casting should have a lot more character to it.

If anyone can tell me where to get some aluminum oxide, for the salt core, I'd appreciate it. Thanks for all the advice everyone.

ratrace2
11-12-2007, 03:33 PM
HOW ABOUT USING PLASTER AND JUST WATER JETTING IT OUT?
Is that the broken part in the upper left hand picture?


Uhh,

In classical Mythbusters style I decided to try out the baking soda. It didn't work out, didn't even harden in the oven at 500 F for 2 hours.
I tried again, this time with crushed together lathe chips to act as an internal webbing of sorts, still it didn't work.
At this point, I'll classify the baking soda core myth as being totally busted. It didn't even make it into the foundry test.

Afterward, I tested my unfinished die, without any bench work done to it, using a steel core, and with none of it's inserts.
It worked as expected, except that the steel core popped right out after I opened the mold, taking a weak portion of the casting with it. After I find a suitable core material, I'll ad all of the inserts and the casting should have a lot more character to it.

If anyone can tell me where to get some aluminum oxide, for the salt core, I'd appreciate it. Thanks for all the advice everyone.
Ya know, I was thinking that you could tig/machine something like that a heck of alot easier than molding it...

JBV
11-12-2007, 03:34 PM
Have you tried sodium silicate (water glass) and sand? It hardens when you pass CO2 trough it :)

http://myhomefoundry.com/casting_info/Co2cores-moulds.pdf

ratrace2
11-12-2007, 03:48 PM
Have you tried sodium silicate (water glass) and sand? It hardens when you pass CO2 trough it :)

http://myhomefoundry.com/casting_info/Co2cores-moulds.pdf

I read most of this and it sounds like a good idea....I'd try it.....But I like my plaster idea, though it might blow up when it comes in contact with that hot aluminium.....:confused:

dang
11-12-2007, 03:53 PM
Yeah, that's the broken bit up there in the 1st photo. I usually MIG all of my parts together, but I really, really wanna expand into some other products, so that's why I wanna cast everything nowadays. Also, I need repeatability, and don't have access to any high end machinery, yet.
Gravity Die Casting is my process of choice. I like the fast work it makes of molten aluminum. That test took all of 2 minutes after I poured the alum. When the mold is done and has the spring loaded open/close system on it, I'll finish one product every 10 minutes or so. It's pretty quick, and I need the time to machine new molds.

dang
11-12-2007, 04:06 PM
WOW! This is one of the craziest threads I've ever participated in. The amount of ideas for core mixing here is just astounding. Thanks everyone!
I just read that myhomefoundry page and I think I'm gonna try out the corn starch recipe early this week.
It'll take me a while but I'll try and wade through as many of these recipes as I can.
Hey look the capital letters are back!
Also, I had no idea that ANYONE had a router that big. What materials do you use on that? Any photos?
Ya know, I think I'll try out that plaster idea as well. Simple is best!

ratrace2
11-12-2007, 04:37 PM
"Ya know, I think I'll try out that plaster idea as well. Simple is best!"
________________________________________________________________

Take a coffee can, drill a 3/4 hole in the bottom. now, take a 3/4 roll of candle wax--use a real candle--stick it in the hole and let about 1" left in the can.
Now fill the can with plaster up to the top of the candle--leave the candle just slightly visible.:banana:
Let the plaster dry
take a hair dryer and melt away the wax candle
Cap the bottom of the can.
pour in aluminum. 1/2 about plaster.
Rinse repeat
bolt both side together and you have an aluminium wheel with axles...(nuts)

dang
11-12-2007, 04:40 PM
Alright, but if the coffee can explodes and kills me, we all know who to blame. JK! :)

dang
11-12-2007, 04:45 PM
Anybody check out the Epoxy/Granite thread over in
General Mechanical/ Engineering Design?

ratrace2
11-12-2007, 05:30 PM
(nuts)
Alright, but if the coffee can explodes and kills me, we all know who to blame. JK! :)
BIG BABY

307startup
11-12-2007, 08:47 PM
Plaster of paris works excellent for both cores and as sacrificial molds. That is what the majority of bronze art castings are made with. A wax figure is produced and has plaster poured in to support the hollows and is then trapped in a cylinder of sorts, with plaster poured around it. The plaster is generally reinforced with bits of burlap or small bits of welding rod, what have you. The plaster is cured by baking in a kiln, this is called calcining the plaster. This melts the wax and makes the plaster hard as a rock. You pour your melt, and break away the plaster after the casting has cooled.

ratrace2
11-12-2007, 09:28 PM
Plaster of paris works excellent for both cores and as sacrificial molds. That is what the majority of bronze art castings are made with. A wax figure is produced and has plaster poured in to support the hollows and is then trapped in a cylinder of sorts, with plaster poured around it. The plaster is generally reinforced with bits of burlap or small bits of welding rod, what have you. The plaster is cured by baking in a kiln, this is called calcining the plaster. This melts the wax and makes the plaster hard as a rock. You pour your melt, and break away the plaster after the casting has cooled.
That's what I'm taling about: "we got'ta have an understanding, we got'ta have an understanding" (Kelly's Heros).:)

ratrace2
11-12-2007, 09:38 PM
WOW! This is one of the craziest threads I've ever participated in. The amount of ideas for core mixing here is just astounding. Thanks everyone!
I just read that myhomefoundry page and I think I'm gonna try out the corn starch recipe early this week.
It'll take me a while but I'll try and wade through as many of these recipes as I can.
Hey look the capital letters are back!
Also, I had no idea that ANYONE had a router that big. What materials do you use on that? Any photos?
Ya know, I think I'll try out that plaster idea as well. Simple is best!

YOU BUMPED INTO SOME VERY CREATIVE PEOPLE HERE.....YEA BABY

jrrdw
11-13-2007, 05:40 PM
"YOU BUMPED INTO SOME VERY CREATIVE PEOPLE HERE.....YEA BABY"

It's incredibule what people can make work!

ratrace2
11-13-2007, 06:59 PM
Alright, but if the coffee can explodes and kills me, we all know who to blame. JK! :):withstupi
That's OK. I'll come to your funeral. "I crack me up"......

Serious question: How do you get that alum. to melt like that.
Do you have a furnace, it it expensive. Can I do it.
What grade of aluminium can you get. Can you buy ingots, or just use junk.
I'm mean, I was starting to think about the price of finished aluminium stuff, car heads, valve covers, steering wheels etc. .. Ya know, every time you turn around somebody is saying "billet" this "billet" that, it makes you sick. If the whole world is in love with this "billet" thing so much then let's get on the train.
When I finish my cnc machine I'll have all kinds of machining capacity for aluminium. Imagine going to the car show and selling your own custom valve covers, or just trading them--better yet, take orders for new ones--Uh, Uh, better yet, make some for really hard to get "can't find no where" parts for people.....that's what I'm talking about........Oh my God......:)

307startup
11-13-2007, 07:24 PM
www.budgetcastingsupply.com

You can purchase flasks, furnace components, sand (PetroBond), sodium silicate, degassing tablets, ingots, crucibles, basically everything you need for a casting setup.

Enjoy!

ratrace2
11-13-2007, 07:29 PM
:)
www.budgetcastingsupply.com

You can purchase flasks, furnace components, sand (PetroBond), sodium silicate, degassing tablets, ingots, crucibles, basically everything you need for a casting setup.

Enjoy!

Really!.....But is it hard, expensive. Is it going to cost me $1000 for a rim that I can buy for $500...
I like the idea, WoW, it seems like the thing to do.
What I'm thinking is that, there are all kinds of grade of aluminium, right: 80/20. I once saw an aluminium ingot pressed over and over by a 200 ton press for some kind of diving bell/suit for deep see diving.
Usually, the good stuff is so out of reach that it don't make sense to compete; but, if--for car stuff--it don't matter, I'm not making diving bell suits that sustain life a 500 ft below sea level, then OK.:)

dang
11-13-2007, 07:33 PM
Serious question: How do you get that alum. to melt like that. Do you have a furnace, it it expensive. Can I do it.

I bought my furnace off Ebay. It's because I'm not all that smart. It came with some green sand, and a little toy soldier that you can use for a test mold. Knowing what I know now, I'd have saved alotta money and just built it myself. The fixins, that is the refractory can be bought from http://www.budgetcastingsupply.com . In fact everything can be pretty much bought there. My crucible is made of a steel tube with a bottom welded onto it, and some holes for lifting and otherwise manipulating the HOT crucible.
There are plans everywhere for foundries, including ones built of coffee cans. Mine runs off of propane.
Now, as far as aluminum stock go, I can pretty much melt any kind of aluminum. Cans, sintered blocks, scraps, anything. Aluminum can be expensive. I've spent some time looking for a cheap solution and found someone willing to sell me 300 lbs of scrap per month for $1.50/lb. That's about as good as it gets around my way for price. I hope to use every ounce of that 300 lbs!
Another great site for casting is http://www.backyardmetalcasting.com/
There are plans all over this site, it even has a forum.
If you want to go into production ASAP there are a number of things you'll want to look into.

Just off the top of my head:

Vibratory Finishing
Core and Pattern Making
Anodizing

It's fun. Days like today, when the core you've built works make it worth while. For anyone still reading this exhaustive post, the Corn Starch core worked. It worked! it washed right out of the casting but left some burn marks in it's absence. I'll have to clean all my castings with pool acid, not such a big task. It works, thanks all for your advice!

ratrace2
11-13-2007, 07:36 PM
NEED PICS asap.........................................
Dang: you are awake...... JK:)
WOW, you are in business. That is great, man, go get it........
I think I might be going there too, save that recipe. I might need it.
This thing is getting really good, I mean, Gee, think of the possibilities.......
That "billet" stuff is ours.................WOWOWOWOOOO:)
So the corn starch added to the "something form the fundry.com home page worked......cool
But, Question: aren't there grades of aluminium that you have to use for certain projects/parts, i.e. for car rim, let's say, do I need "blank bank" What??????
Where are you, I got'ta see this........I'm in New Jersey.

dang
11-13-2007, 07:40 PM
Rims aren't cast. I believe they're formed using "Semi-Solid" forming techniques. Basically, their core material is heated until it's nearly liquid, stretchy, like umm, candy is during it's creation. After that it's placed via worker, not machine, (China), into a 200 ton press where it's acted upon by a cylinder with a die on the end. Then it's finished.
Castings have the lowest strength rating of any type of metal, especially those not injected under pressure. It's best to stick with non critical parts for castings.

ratrace2
11-13-2007, 07:50 PM
Rims aren't cast. I believe they're formed using "Semi-Solid" forming techniques. Basically, their core material is heated until it's nearly liquid, stretchy, like umm, candy is during it's creation. After that it's placed via worker, not machine, (China), into a 200 ton press where it's acted upon by a cylinder with a die on the end. Then it's finished.
Castings have the lowest strength rating of any type of metal, especially those not injected under pressure. It's best to stick with non critical parts for castings.
Got, ya..OK, I understand......

ratrace2
11-13-2007, 07:57 PM
Rims aren't cast.
___________________
Ratrace says: what about the rims the make on all Those hot-rod shows, Uh,
American hot rods with Boyd Coddington...those are CNC aluminium...right. It has to be of a certain grade, then they TIG it into a stock metal? Rim.....I Think..That is what it looks like:confused: Right
____________________________________________________





I believe they're formed using "Semi-Solid" forming techniques. Basically, their core material is heated until it's nearly liquid, stretchy, like umm, candy is during it's creation. After that it's placed via worker, not machine, (China), into a 200 ton press where it's acted upon by a cylinder with a die on the end. Then it's finished.
Castings have the lowest strength rating of any type of metal, especially those not injected under pressure. It's best to stick with non critical parts for castings.
How about Boyd Coddington?????

ratrace2
11-13-2007, 08:03 PM
Do you have any CNC equipment??
That is what you need--in my opinion.
That way you could just produce the core dimensions and then machine the final part to perfection..........that would be nice....:)

ratrace2
11-13-2007, 08:08 PM
Rims aren't cast. I believe they're formed using "Semi-Solid" forming techniques. Basically, their core material is heated until it's nearly liquid, stretchy, like umm, candy is during it's creation. After that it's placed via worker, not machine, (China), into a 200 ton press where it's acted upon by a cylinder with a die on the end. Then it's finished.
Castings have the lowest strength rating of any type of metal, especially those not injected under pressure. It's best to stick with non critical parts for castings.

So, it's--what do ya call it--stamped......

ratrace2
11-13-2007, 08:12 PM
[
Just off the top of my head:

Vibratory Finishing
Core and Pattern Making
Anodizing

It's fun. Days like today, when the core you've built works make it worth while. For anyone still reading this exhaustive post, the ...Corn tarch ........
core worked. It worked! it washed right out of the casting but left some burn marks in it's absence. I'll have to clean all my castings with pool acid, not such a big task. It works, thanks all for your advice![/QUOTE]
Off the top of your head, what was the complete corn starch recipe........Just for future reference, and anyone jumping into the middle of this mele of ideas.......................Lay it out for us......Details, details...we like em....

ratrace2
11-13-2007, 08:16 PM
We want foundry porn
We want foundry porn
We want foundry porn.....................:)

dang
11-14-2007, 06:42 AM
Corn Starch Core Recipe

%97 Sand ($5 Home Depot)
%2 Corn Starch ($1 Mal Wart)
%1 Water (Old Fashioned Tap Water)
Mix well
Bake for 1 hour at 450 Degrees

So I filled up my core form with sand, then I sprinkled some magic fairy dust (corn starch) on top of that. Lastly I sprinkled some water into it and transferred it all into a mixing bowl where I mixed it with a fork. When it was nicely mixed I transferred it back into the form and packed it tightly with that same fork. Then I had a beer and watched Chuck for an hour, alright, several beers.
After an hour of drinking, err, I mean waiting for my core to bake, I lit my foundry candle, set up half of my mold and poured this incomplete casting.
There is some filth left inside the casting from the core. This is why I'll need to clean all my castings with a nice acid bath. Hopefully, those baths will evolve quickly to anodizing. I'll also have to build a core box for baking smoother cores.
On the whole, I consider this core recipe to be successful. After I got the core out of the oven, it was so tough that I could, and did, saw parts off of it with a bread knife.
This pouring took all of 2 minutes. The next one will be prettier.

ratrace2
11-14-2007, 10:47 AM
:)I was looking into anodizing, you said it was the next step, if seems to be best suited for pure 6061, 1000 to 7000 grade aluminium. And, it--the anodizing process--seems to like pure aluminium.


http://www.focuser.com/atm/anodize/anodize.html

And I quote: "anodizing cast aluminium is the hardest due to the high silica levels".

This is the money shot: :)
http://homepages.pavilion.co.uk/nickfull/chrome.htm

dang
11-14-2007, 11:09 AM
Ahh, so you're correct. It can be done, just not with very good results. Apparently the anodizing process does indeed favor non-porous aluminum. Mostly, I'm just feeling around in the dark. Feel free to go ahead and skip any step I've prescribed.

ratrace2
11-14-2007, 11:41 AM
Ahh, so you're correct. It can be done, just not with very good results. Apparently the anodizing process does indeed favor non-porous aluminum. Mostly, I'm just feeling around in the dark. Feel free to go ahead and skip any step I've prescribed.

________________________________________________
Yea, sure it can be done, I'm just not sure how much it is in demand.
At one time it was all the rage, anodized car parts--like you see on the guys web site--but it seems to have a fashion that has moved on to some extend.
And, the mechanical properties don't offer that much to the finished product, a little hardening is all.
On the other hand, Chrome is always in style, and it has the ability to get supper hard and hold a machined/ground surface.....supper durable and lowerst coefficient of drag of all metals...:)
________________
Oh, by the way: you need 2024 aluminium alloy for Truck Wheels....
http://pages.prodigy.net/larryhoy/RaceAluminumQualities.htm

ratrace2
11-16-2007, 02:39 PM
Question: If I go down to the local truck junk yard and get an aluminium truck rim and melt it down, and pour it into a block--making something like a billet...something like 10"x10"x10" square, would it machine OK. I mean, would it still be 2024? Would I have to put it into a 200 ton press and "compress" it.
What would I have. Have I lost my mind?:devious::idea:

dang
11-16-2007, 05:39 PM
That's alotta metal to melt! There are so many things which could go wrong melting that much material into a single mold that I'd recommend just biting the surface to air missile and paying the ridiculous cost of getting a milled block of aluminum.
Fresh, or machinable aluminum is pressed together using megaton press rollers in a metal milling facility. That is to say that it's melted, cast into a form and then run under gigantor presses, over and over again, which compact the metal so that it's extremely dense.
Ever notice that when you lathe fresh material that the shavings take up like 100 times the space they did before you machined them? It's because you're affecting the material. When you melt it and re pour it, it'll freeze, or rather solidify into a far less dense form than it was in when you started it.
That's why I like to melt chips and shavings. They take alot less time to liquify than do dense materials.
All that said, you can in fact machine a casting. It'll still be the same alloy it was when you started. It'll have the same ingredients in the same amounts. The same copper or zinc or whatever. It'll just break a whole lot easier do it's lowered density.
Also, it's best to start out small.

ratrace2
11-16-2007, 08:50 PM
That's alotta metal to melt! There are so many things which could go wrong______FORGET WRONG...CHASE RIGHT......._ melting that much material into a single mold that I'd recommend just biting the surface to air missile and paying the ridiculous cost____I CAN'T BITE A SURFACE TO AIR MISSLE_____:) of getting a milled block of aluminum.
Fresh, or machinable aluminum is pressed together using megaton press rollers in a metal milling facility.____OK...WHERE DO WE GOT ONE OF THOSE?____ That is to say that it's melted, cast into a form and then run under gigantor presses, over and over again, which compact the metal so that it's extremely dense.
Ever notice that when you lathe fresh material that the shavings take up like 100 times the space they did before you machined them? It's because you're affecting the material. When you melt it and re pour it, it'll freeze, or rather solidify into a far less dense form than it was in when you started it.
That's why I like to melt chips and shavings. They take alot less time to liquify than do dense materials.
All that said, you can in fact machine a casting. It'll still be the same alloy it was when you started. It'll have the same ingredients in the same amounts. The same copper or zinc or whatever. It'll just break a whole lot easier do it's lowered density.
Also, it's best to start out small.
______________________________
Is that all that is bothering ya? We could, though, if we wanted to make aluminium cases for something like a "can opener", or an aluminium mold for fiberglass car bodies, or door handles for your car, or "billet" knobs for your stereo....................right.............that would work............:)(nuts)

ratrace2
11-17-2007, 01:59 PM
OK, so we got this big tractor-trailer rim of 20/24 aluminium, cheap $30.00, right. Now, we want to turn in back into a solid block of alum. so we can machine it......What next...
OR, we could cut little sections of it off and make smaller blocks of say, 6"x6"x6".......

dang
11-17-2007, 02:33 PM
How much does it weigh? Can you cut it up into smaller pieces? Would it be easier for you to just buy a block of aluminum?

Well, ya gotta cut it up somehow, into small pieces. Then you build, probably a coffee can furnace. You can find the plans at http://www.backyardmetalcasting.com
Then ya gotta build a a steel crucible. The plans should be on the same site.

What do you want to machine this into specifically?

ratrace2
11-17-2007, 03:31 PM
How much does it weigh?
Ratrace2 says: An aluminium tractor-trailer rim weights about 80 lb.

Can you cut it up into smaller pieces?
Ratrace2 says: sure cut it up as small as you want

Would it be easier for you to just buy a block of aluminum?
Ratrace2 says: no, my god the cost of aluminum billet is huge, money

Well, ya gotta cut it up somehow, into small pieces. Then you build, probably a coffee can furnace. You can find the plans at http://www.backyardmetalcasting.com

Then ya gotta build a a steel crucible. The plans should be on the same site.

Ratrace2 says: why not just build a steel box with release pins that allow the side to fall off, then just melt the aluminium in the steel box. TA DA:)
I can get metal plates a Falcon Steel down the street, I just need something
that can get the metal hot enough in the steel box, kind of like a barbeque grill.

What do you want to machine this into specifically?

Ratrace2 Says:
Don't know yet, just want the capacity.

dang
11-17-2007, 03:58 PM
How would you cut a rim that big? I can't do that.

It does seem like a really good deal considering the weight of the rim. That's like 45 cents/lb.

You'd need to wrap some sort of refractory around the steel to hold in the heat. The steel would need to be in the form of a crucible which could be removed from the foundry. Castable refractory is for at
http://www.budgetcastingsupply.com

Think safety, that's alotta liquid aluminum. Check out those links.

ratrace2
11-17-2007, 05:17 PM
How would you cut a rim that big? I can't do that.
Ratrace2 Says: use a Saw-z-all. with a metal blade you can cut up anything.

It does seem like a really good deal considering the weight of the rim. That's like 45 cents/lb.
Ratrace2 says: you need to go to a Truck Junk Yard.......quick(nuts)

You'd need to wrap some sort of refractory around the steel to hold in the heat. The steel would need to be in the form of a crucible which could be removed from the foundry. Castable refractory is for at
Ratrace2 Says: why not just heat up the box until the aluminum melts, then knock out the release pins on the box--let the aluminium cool in the same container that it was melted in. See, you don't have to move the metal, just let it get hot enough to flow into a single slab.


http://www.budgetcastingsupply.com
Ratrace2 says: Yea, that rafractory thing is something that I have to check out, figure out and see how it works.

Think safety, that's alotta liquid aluminum. Check out those links.
Allways, I'll get one of those fire face shield, and leather jacket

ratrace2
11-17-2007, 05:24 PM
We get some steel: we make a box 10"x10"x20"..give it a little depth....right.
Now, heat that steel box until the aluminum melts and form one solid mass inside the steel box.....
Question: how do you heat the metal box sufficiently to melt the aluminum inside. Don't worry about getting the aluminum out of the box...not yet...
What's next?...............................................:)

dang
01-19-2008, 07:39 PM
PROBLEM SOLVED!

C02 Gas and Sodium Silicate mixed with normal home depot sand makes great sand cores. For anyone who's looking to make cores quickly, which don't require any baking, then that's the way to go.

Pres
01-19-2008, 09:11 PM
How do you "mix" CO2 gas with "Sodium Silicate mixed with normal home depot sand"?

How about a step by step to clarify your procedure?

tia,
Pres

JerryFlyGuy
01-20-2008, 12:06 AM
Dang, would you think [your guess is better than mine !] that this would deliver a finish similar to a plaster investment or no?

Curious

dang
01-20-2008, 02:41 AM
Pres, you've got a good point there. I'll explain further.

1 - Liquid Sodium Silicate is mixed (%3 by weight) with Home Depot Sand.
2 - The mixture is packed tightly into a core box for shaping purposes.
3 - C02 (from a pressurized tank, which I get filled at Ace Hardware) is aerated through the core box. Basically I have a hose connected to my tank, I open the valve and "spray" the core with C02.
The core is now hardened. Don't ask me how this happens, I'm no chemist.

FlyGuy,
That's a good question. The short answer is that I ain't sure.
I use Petrobond to cast in. I've not got the patience to wait for a week while my plaster dries out completely. Keep in mind that the process I described is only used for core building.
All that said, I wish I were more patient as I've seen photos of Plaster Investment delivering really great results.

By the by, making cores this way, takes minutes, not tens of minutes, certainly not hours. If you have a core box prepared and all the fixins, it's pretty darned fast. It beats the pants right off of baking soda, which doesn't work at all.

JerryFlyGuy
01-21-2008, 04:48 PM
One last question Dang, where do you get your Sodium silicate? Is it under a brand name at the grocery store or..?? Chemist supply?

Is it pricey????

dang
01-21-2008, 06:04 PM
I got my Sodium Silicate off of Ebay. I did so only because I didn't want to spend too much on an experiment. I bought all of 16 fluid oz for $10 with shipping included. Now that I've seen it work with such success, I wish I woulda bought it from Budget Casting Supply. Not because of price, just because they've been so good to me in the past.

I also traded in my little Argon/C02 welding tank for a straight C02 tank at my welding gas supplier. The two tanks have different nozzles. I then took my tank to Ace hardware where they told me they could refill it. This is a really good thing, since Ace is about a mile away and my Welding Gas Supplier is in another town. Not that it'll matter, I'll be using a whole lot less C02 than I thought, and alot more Sodium Silicate as well.

If you go to Budget Casting Supply to get this stuff, check out some of the other stuff they have. The aluminum casting flux and degassing tablets in particular. I'd like to find out how well those work.

http://www.budgetcastingsupply.com/