Showing posts with label The Giant Book Of Metalworking Projects. Show all posts
Showing posts with label The Giant Book Of Metalworking Projects. Show all posts

Wednesday, March 7, 2018

The Shell Molding and Casting Process

So casting methods generally start with green sand molding and consumable or foam casting. For greater accuracy and repeatability you can move up to match plate molds.

For best accuracy and finish, shell molding, die casting and investment casting among others come to mind. All are capable of producing very accurate and near finished castings. Most require only light finishing and polishing for use. Exceptions of course would be surfaces requiring a machined fit such as mating surfaces, bearing housings etc., though items in this category are generally larger and not suitable for these processes, Shell molding and casting, covered in this article, will produce accurate and consistent castings, turbine blades have been produced with this method, an item normally produced by the investment process.

Shell molding and casting requires more equipment, a larger investment in materials and skill levels than green sand methods but if you require accurate small castings, once you are set up and comfortable with the process production can go quick.The most expensive part of the equipment would be the curing and heating oven, an inexpensive alternative is a toaster oven which can run at temps of 500-600*F, right were you want to be for non-ferrous work. For large work you can use the kitchen oven ( your partner might have you in the dog house for that one though, lol). Next would be the patterns, if you can make match plates you should be able to make these. Resin coated sand and silicone release agent are available at foundry supply sources.

So if you are interested here are two articles from "The Giant Book Of Metalworking Projects" on the shell molding and casting process.

Click to expand, click again for best view.

Sunday, March 4, 2018

Copper Plating Nonmetallic Items

As promised here is another interesting article from "The Giant Book Of Metalworking Projects". Did you know you can copperplate nonmetallic objects? Home diy'ers have been doing it for a long time, it is relatively simple. Copper sulfate and sulfuric acid are easily sourced and with care relatively safe. It's been said many times before, but I will say it again here, when mixing acid and water always slowly add the acid to the water, never the other way around.

Preserving baby shoes for posterity by copper plating has always been appealing to me, you can do this and many other things as pictured in the article.

Click to expand and click again for best view.

These pictures would have looked much more spectacular in full color, unfortunately I don't think Tab ever published a full color book, lol.

Saturday, March 3, 2018

Cracks In Castings And Aluminum Flow Characteristics

So I assembled a couple of articles from "The Giant Book Of Metalworking Projects". These are good examples of the kind of info this book is chock full of. There will be much more to come.

The first article concerns finding fine cracks in castings such as engine blocks. I can think of at least one situation where this info would have come in handy for me.

The second article is an experiment on the flow characteristics of silicon aluminum alloy.

A very telling experiment. For melting recycled aluminum, if you are casting thin sections and require good flow characteristics it only makes sense to choose similar recycled aluminum. Transmissions, small engine and compressor blocks, cooling fins from electrical equipment all have higher silicon content and will give better flow characteristics than chunky castings that did not require those flow characteristics to begin with.

If you like this kind of thing, keep an eye out for more posts from this information rich volume.

Friday, March 2, 2018

Production Molding Patterns

It's been a while since we posted anything on the casting process so here's an article some will find useful and most will find interesting.

So you have built a functional small foundry, developed a nice tool or product, built a prototype and worked out all the kinks. You have determined that there is enough demand to make it worth your while to produce and sell. You may decide that selling a casting set for the diy'er is more profitable or a partly machined set will be in greater demand. Either way you will need to set up accurate and interchangeable casting production. For small to medium sized castings aluminum match plates is a reasonable way to go. There are more accurate methods and I will post some of them in later posts from this book, but for most castings, match plate molds are quick and inexpensive to produce.

"The Giant Book Of Metalworking Projects" published by Tab Books Inc. in 1983, (yes you have seen this in at least one previous post) is cover to cover full of great projects and metalworking information. Picture quality is not that great, but that applies to most Tab books. Quality has improved since McGraw Hill bought them out years ago. There are other casting methods outlined, with plans, in this book, such as the shell molding process. The book covers a huge number of metalworking methods with lots of plans sprinkled throughout the book, to demonstrate these methods. I will be sharing many more articles from this volume in future posts.

So back to our small casting kit business. You can produce a lot of accurate interchangeable castings using durable match plates in a non-ferrous operation. For iron and a small cupola it would be folly to try without a couple of staff to help out.