Anyone ever done a custom casting?

[bkubisht]

Hey you inventors or manufacturers out there, I want to know what's involved from an idea for a custom auto part, to having 2-5 of them churned out for testing.

Wish I could say what it is, but I might want to patent it or something. It is a replacement for a stock part that is cast, and my part would probably also be cast. Probably only slightly more complicated than an aluminum bellhousing, and will be a single component with no moving parts.

What does a small-run manufacturer need? Like a handmade piece mocked up and welded together, or a clay model that they can make a mold from, or detailed autocad drawings or what?

I figure my time is cheaper than theirs, so what things can I do myself to save some money? Basically I'm looking for experiences and tips, and how mucho dinero I should expect to spend to create a ?mold? and get a few prototypes.

[bk005]

For sheap might try a techincal college or a college with like an Industrial Technology program. When I was in school we did small work for local companies and locals. Made molds for plastic injection parts and such, and small runs of production parts.

[Kc J]

BK005 is right , local university or college is what you should try .
ASU East at Gatway Airport has a foundry program .
When I went there and talked with the instructor , he seemed more than happy to help .
I haven't finished modeling up my part , but when I am done I plan on them casting a couple parts .
They can cast aluminum or brass only and the going rate is about $12 an hour .
Try searching U of A on the net , they may have a program also .

[sceep]

stereolithography protos are realatively cheap, depending on the size of the part, and the amount of detail you want in your prototype. $500-$2500 ea. Then you can have the mold cast directly off the proto.

Keep you part simple. learn a modeling progam so you can do all your own design. Talk with local Universitys about doing the machining at a reduced rate.

Don't forget your lube when you go to the foundry. Steel molds are NOT cheap.

I just completed a single cavity plastic mold. Part is roughly 3 x 2 x .5 the mold alone was $4500.

[fj40guy]

Usually casting is done to save cost in manufacting*. 1000's of identical parts.

When you need just a few parts, they are fabricated. So CNC machining would be the first thought for an item. Or two or more parts machined, then welded (picture a tube 4" diameter with a 12" disc attached... prototype is machined & welded together.... once done, casting would be done for production)

Sceep -- you got a deal! Those molds were about $25,000. That was for a plastic connector that went onto a computer cable. EDM work that was nice. Alas, lot of that work has been shipped off to China. :(

*noticed the cast replacement spindle holder for my riding lawn mower. The bolt holes are not threaded, as you use a self threading bolt! Little things to save cost like that add up!

Tom :usa:

[res0zvle@charter.net]

I have heard that this place is pretty good with limited production parts:
http://www.emachineshop.com/
Hope it helps.

[bad booger]

I was watching some show on cable a couple of days ago. It was some Discovery show of some sort where they were trying to see who would win a fight between a lion and a crocodile. They had the sculls of the two predators and used them to build Styrofoam models. They cut Styrofoam form blocks to match the sculls.

It was probably a pain to do everything was rounded. The teeth were cut out separately and the attached to the sculls with glue "I think". Once they had that completed they buried the sculls in sand. Though I am sure it is special sand. Then they poured molten aluminum into the sand and it melted away the Styrofoam and formed the shape of the skulls. Once it was hardened they broke apart the mold that had held the sand in place and they had the skulls.

After they cleaned them up they set them up with hydraulics and made the jaws come together with the same force an animal of that size would be capable of. The lion had about 1500 psi and the croc was supposed to have 4000+ but the steel I beams that the rams were attached to started bending at 2000psi so they didn't have but about 1500 or so psi out of it. Anyway the castings looked really good and were pretty stout to do the things they did with them. Basically what I took away from this show was that I'd like to know more about the trick's needed to make the casting. Maybe you'd like to know too.

[morpheus]

Check this guy out, He casts quite a few things at home:

http://www.frugalmachinist.com/

[Urban Wheeler]

http://www.backyardmetalcasting.com/

[MC]

If you want a cheap way to cast a nice part to a internet search for Lostfoamcasting its a process where teh foam is haped to your part, sprayed with silicone , set in sand and then the media or metal is poured into the foam. Its a super cheap way of casting items extremely accurately.... +/- .007 is teh better average. This technology has been around a long time but only really been utilized in the last 15 years. Its auto mfg's make their changes so fast and also how saturn car company got into the car market without having to make alot of specialized molds and tooling.


Good stuff

[chumly2071]

also, for several good references on DIY casting and small (5 gal can size) foundries, check out Lindsay Publications books. don't forget, casting can be dangerous. moist sand in a mold will explode when you pour molten aluminum in it. read up on it, learn it, and try it. just be careful.

[Poley]

If you are thinking of a patent than you should look :) here http://www.uspto.gov/ and do a search to see if it already has a patent and also look for a cetified Patent Agent in your area, I use Mrs. Joanna Robertson she is a very good Patent Agent. Also be aware that to secure a patent it takes alot of time, it is a very long process. But hopfully worth it in the end. hope this helps :)

[wheelsup]

You forgot, EXPENSIVE
I just sat thru a few hours of a guy talking about patents and such.
he holds several (more than half dozen) and spent 10,000 of thousands of dollars getting each. Plus the cost to defend one if the need arises. A patent is only as good as your ability to defend it. There are other ways to rpotect your ideas, much cheaper. he talked of a few, and had used them a lot with success.
probably google search and find how. It was pretty involved, had something to do with having people sign off they had read a paper writtne on your idea on a certain date and understood what the idea was, and they could make it from the drawings and description on the page, plus some other stuff.
Brian.

[bkubisht]

Everyone, you've been most helpful! Those links were awesome, but they made me realize that for my part, building with machinist processes on steel is going to be much easier and less expensive than casting aluminum. That emachineshop site is the schiznit, I'm going to spend some time with their design & cost estimate software.

I wonder how tight of a radius 1.5" tubing can be bent? And when does corrosion become a problem if you bolt aluminum parts to steel parts?

[Rockrat]

Everyone, you've been most helpful! Those links were awesome, but they made me realize that for my part, building with machinist processes on steel is going to be much easier and less expensive than casting aluminum. That emachineshop site is the schiznit, I'm going to spend some time with their design & cost estimate software.

I wonder how tight of a radius 1.5" tubing can be bent? And when does corrosion become a problem if you bolt aluminum parts to steel parts?

I think 3" radius with a true mandrell bender, but not 100% posative. And yes disimiliar metals due corrode. when mated together.

[randii]

Stereolithography is the best way to go from CAD to reality, and CAD is the best way to uniformly plan for mold shrinkage and provide relief for good release. Sceep must now somebody in the business for those prices! Lost foam casting is pretty good, too, or you can skip the middleman and just machine a block of foam. Here, *you* gotta plan for shrinkage, relief, and release, without help from CAD plug-ins.

You can do short-run sand-cast in your backyard, with a homebilt blast furnace, but to get any real consistency or repeatability, you'll want a better process. Some 'arts-and crafts' metal-works will take in side work casting, or you could go *way* upscale and pay an industrial shop to work your molds/casts.

Remember, the cast result is only as good as your mold, which is only as good as your original... and errors have a way of snowballing through iteration.

Randii