Hobby Foundry
Casting Session - September 2, 2006
My grandfather had a foundry business here in San Diego. I worked there from time-to-time and learned how much you can do.
This is a photo of my grandfather's foundry and pattern shop on the corner of Kettner Blvd and Nutmeg Street here in San Diego--he's on the far left.. Taken in 1957, you can see the bags of plaster my grandfather used for patternmaking and the woodstove used for heat (with a rusted-out firebox). We still have the bandsaw that's sitting next to my grandfather. Seven feet tall and all cast iron, they don't make them like that anymore (the bandsaw, not my grandfather). Not long after this picture was taken, the moved the business to Armour Street which at the time was a new industrial area.
Here is a picture of the home-made foundry. The furnace is a modified Gingery Design and runs on Natural Gas taken right from the same supply as is used by the water heater.
Here's the furnace running. We're melting down some rejected cases from some IV Pumps. A356 Alloy
The furnace is open and getting ready to remove the crucible.
Here some patterns for the Gingery Dividing Head.
Mold open and patterns removed.
Close up of the Drag.
Two mold poured.
Four molds worth of castings.
A couple of Patterns and Castings I did for a machine that simulates human breathing. The spider is 13" across. Patterns are made from Hardboard and Basswood scraps that I had stashed in the garage, the castings are A356 aluminum obtained from scrapped parts from the R&D department of a local company.. Everything in the picture made from recycled material.
Here's a couple of shots of the finished castings mounted in the machine. Usually, after the castings are machined I sandblast them and give them 2-3 coats of clear semi-gloss lacquer. For indoor applications it's as good as anodizing and a lot less expensive. I anodize parts when the customer requires it or if it's going to be outdoors.
Casting Session, September 2, 2006
Here's the patterns I'm planning on casting today. The small one with the core box is for an adapter to mount a NEMA 32 sized servo motor on a device that normally accepts a 23 size motor.
I made several cores, just in case. The sand is a mixture of Silica Sand, Sodium Silicate (aka Water Glass) and ordinary Molasses. When this mixture is gassed with CO2, it hardens instantly.
The open mold for the Motor Adapter.
Mold with core installed.
Click HERE to see a short video of pouring the molds.
Mold Shake out.
I'm building an automated test fixture at work and as always, they want it right now. Many of the parts are simple, I sent those off to a local machine shop for fabrication. One part is ideal for a casting so....
Here's a model of the finished part, done in Solidworks.
I need to make 20 of them, a matchplate is in order:
Matchplate in flask ready to mold
Open mold
Furnace charged and ready to light, all metal used is recycled, most from obsolete castings generously provided by my company.
Pouring mold
4 poured molds, 5 total were needed.
Mold shakeout.
20 parts de-gated and ready for machining.
Fixtured for machining.
Before Cut.
After Cut, the difference in the sheen in the cut area is just due to lighting. Some will say that machining A356 aluminum without heat treating it first is impossible, looks possible to me. Just like any metal, you need to use sharp tools, proper speeds, and a good lubricant coolant.
All the milling is done, now comes drilling and tapping.
Video of tapping the 10-32 holes. Only dry steric acid is used as a tapping lube.
All machine work is done, now they're off to the plater for anodizing.
