Home > Aluminum Foundry > Sand castings and patterns

Look at those castings gleam!

These are some Gingery Lathe parts that were just shaken out of the molds. They are still in the rough, as you can see, and the sprues and risers need to be cut off. The shiny surface is the result of carefully selecting the right pouring temperature.

Dremel router attachment castings in the rough

These castings were poured with the metal definitely too hot. They did clean up quite nicely, however. The mold is formed from wooden patterns that exactly match what is to be cast. The patterns for these castings were made from 1/4" thick lauan plywood. The shapes were drawn with DeltaCAD v3.0, printed out at 1:1 and then traced onto the wood. The shapes were then cut out and nailed together where necessary. Filleting was formed with clear packaging tape applied to the inside corners to provide a rounding effect. Now I much prefer making patterns with bondo and then painting them with high gloss spray paint.

Dremel router attachment

Here is the finished project. Notice the patterns sitting to the right. I used clear packaging tape to cover the patterns instead of shellacking them. The packaging tape also forms the fillets on the bracket and the base. The ribs on the base pattern are formed from wire and the knob bosses are formed with washers. I purchased the black knobs at ACE hardware and also the screws that hold them on. Some time in the future, I may improve the patterns with auto body putty and a coat of paint, but I'll have to see what the probability of making more of these really is...

There are holes drilled from the bottom of the router base up into the bracket casting. Boy was that a trick. And then the holes needed to be tapped to accept 8-32 screws. The straps that hold the Dremel tool onto the bracket are just 18 guage galvanized sheet metal.

The attachment has several advantages over conventional routers. The low mounting profile of the knobs allow precise control. Also, there are more varieties of bits available for the Dremel tool, and thus expand the capabilities of it.

Cast aluminum grill for my '85 Buick Lesabre

You know the story...a deer jumps out in front of you, and before you have time to say 'sand-casting,' your vehicle has been inflicted with some serious cosmetic damage. Well, I don't know how much cosmetic damage an old station wagon can really sustain, as these old beasts aren't too much into cosmetics as most vehicles (and their owners) are concerned.

At any rate, I wasn't going to spend a couple hundred dollars on cosmetics for an 85 model with well over 100k miles on it. The molten metal ideas began to flow...

Top view of cast aluminum auto grill

The grill is actually 2 castings, one a mirror image of the other. Each required a full one and a half quart crucible full of metal. The pattern was made of styrofoam, and cut with hot wire foam cutting process.

For the molds, I used sharp silica sand, with a 2-part air-setting resin binder. (Sorry folks, I don't know the name of the stuff, it was delivered to me in 2 coffee cans by a friend from a foundry making parts for GM!) The foam patterns were removed (chipped and broke out) before pouring. The molds were very heavy, each half weighing 30 or 40 pounds.

My friends used to kid me that I should have cast some long, barbed spikes on the grill, so that the next time I hit a deer, it would stay lodged, and then I would have "venison on the grille!"

Hydraulic lever bracket in the rough

Breakdowns are especially bad when it's borrowed equipment. My dad loaned me his log splitter a while back, and I was merrily splitting away when *pop* a bracket on the hydraulic spool valve snapped. It was the bracket that steadies the control lever linkage. So I epoxied the broken part (right), 'reinforced' it with some bondo, and used it for a pattern to cast the replacement.

Hydraulic lever bracket finished

Now with all the holes drilled, flash and other imperfections filed off, and ready to be bolted in place. This casting was a bit tricky because of its irregular shape and lack of good parting line. The trickiest part was the setting the core that formed the hole in the center.

Hydraulic lever bracket installed

So there you have it. I don't know how much this part would have cost, or even if it is available, but now it doesn't matter. The home shop foundry has won again! (Note melting furnace, sitting proudly in the background.)

Corn Mold Project

One of my readers had a little project for me to do...here's the chronicle of this ongoing project. Whatever in the world does aluminum have to do with corn? Here's a case of a pattern being made of a mold, then a mold being made from the pattern! More...