What to cast first??.......

That is the question....

This weekend I want to try a proper casting; something useful that looks more like a "thing" than just a blob of metal. I wanted to start off easy by building a lathe. However there is so many things I'll need for that become a reality, not to mention the various failures on the castings that I will inevitably suffer.

I decided I'm going to try for a 4 jaw chuck as a first attempt, as this will be useful in both the lathe and as the chuck for the 4th axis on my CNC machine. Another good reason to start off with it is that it's quite a complex piece with many slots, pockets, bearing cups and such.

The method of lost foam casting is one very predominantly used in industry today. It basically involves cutting a desired shape out of normal EPS foam (Styrofoam) then dumping that "blank" in some ceramic material to create a smooth surface around the blank, then pouring in the metal, the metal will burn out the foam and fill the resulting cavity with metal and voila you have a metal part the shape of the original blank.

I will use my CNC (Computer Numeric Control) machine to cut out the blanks in foam. I built this machine about a year ago from two old dot-matrix printers and a few bits of MDF wood. It's not the most accurate thing on the planet, but it saves me a lot of effort in creating the blank.

This is the design for the chuck main body I have in mind.

Designed in Rhino 3D
















Hope this gives you some idea of what I'm aiming to do.











Here is a few shots of my MDF CNC machine... this will be used to cut the foam patterns for now.



I'm in the process of building a much bigger and way more rigid machine than this one, but for the moment, and seeing as I work with a very soft material Styrofoam, This cheap and easy machine will do.










Starting the first outline cut for what will become the lathe chuck.

You will probably need to click on the picture to see a bigger one if you can't see the circle being cut out.









My trusty old laptop. This poor thing have really been through the wars. I use it regularly to prop up stuff when grinding, or as a coffee cup coaster, since it's surface is about the cleanest thing on my workbench... Despite it being held together by self tapping screws and coffee stains it still keeps on working.

It's running TurboCNC v4.0 which converts the g-code language to pulse signals to drive the motor electronics.


In a later update I will go through the steps involved more thoroughly. We will also be building the BIG machine together.

Here is a short video clip of the router cutting out the foam blank.