DIY Metal Casting Information and Home Metal Casting Info

October 6th, 2008

Metal Casting

Casting can be defined as a process of manufacturing, which implies pouring of a ‘liquid’ material into ‘A Mold’ containing a desired shaped hollow cavity, and then made to solidify. What needs to be done to finally complete the process is to take out the casting and break it apart so you can see your finished project. The use of casting is ‘forming hot liquid metals’ or numerous metals that are cooled after having the components like clay, plaster, concrete, and epoxies mixed. A lot of times, you will find complex shapes being casted because casting allows you to do this. Casting came into being around 6000 years ago. ‘Copper Frog’ is the most ancient casting existing till date since 3200 BC. The process of casting has two distinct subdivisions: non-expendable and expendable mold casting.

‘Non-expendable’ mold casting: This technique is inclusive of at least 4 distinct methods: continuous, centrifugal, die, and permanent casting.

Continuous casting: Continuous DIY Casting can be defined as a refined process of casting for high-volume, continuous production of ‘metal sections’ with constant cross-section. The pouring of molten metal into a water-cooled, open-ended copper mold takes place. This allows a ‘layer’ of ‘solid metal’ to be formed above the ‘still-liquid’ center. Continuous casting is widely accepted due to its cost-effectiveness. The metals continuously cast are aluminum, copper, and steel.

Read the rest of this entry…

TwoKads:

What is G-Code?

October 5th, 2008

cnc tutorials

G-Code is the common name for the programming language of CNC Machines.Somewhat of a general, catchall term for CNC programming language.  Very few machines adhere to this standard today.  There are as many varations as there are manufacturers.

This is how I think of G-Code.  It is a simple language built off of the Cartesian Coordinate System for motion control.  That is a mouthful.  I don’t know if that is exactly right, but you will get my meaning in a second when we go through some code line by line.  You will remember your High School Geometry soon enough.  For the real pros out there, you know there is much more to G-Code then that, but it is a good place to start thinking about it.

You will see many variations of the G-Code name like:
Gcode
gcode
G-Code
g-code
G Code
G-Code

Are there other “Codes?”
In a word…Yes.We will get to that information in just a minute.  G-code is also the name of any command in a CNC program that begins with the letter G.  G-Codes generally tell the machine to perform an action.  G-Codes can tell machines to move a certain distance in the X-Axis for example.  Or, make a rapid move to another location.  Or, move in an arcing fashion while milling.  An on and on and on.

Read the rest of this entry…

TwoKads:

My personal CNC tale

October 4th, 2008

cnc programming

One day I knew I had a problem.  I just spent 4 hours with my plasma cutter in my right hand.  I had been cutting out patterns I had traced onto a sheet of metal.These interesting shapes were going to become my coffee table.  Everyone complained to me that I didn’t have a coffee table.  I thought, “I’ll show them” and began to build one.
Why make a coffee table out of metal you ask?  The quick answer is that I wasn’t much of a woodworker at the time.  On the other hand, I used to weld professionally and knew I could make anything out of metal.  That is how it all began, making a coffee table out of metal.

Now if you knew me, you know that I can’t just make something normal.  My brain is the scheming type that has to do things differently then the norm.  I wanted to make a table that would knock people’s socks off.  I thought a funky looking table, made out of metal, with casters and lights would do the trick.  You know what?  It did. 
I really had a ball making this table.  I mean I had serious fun.  So much so that I started to design others.  I began showing photos of my work to everyone I knew.  On top of that, I was getting good feedback.I just came across a new hobby, it was furniture making.  Who would have ever thought I would pick up furniture making as a hobby.

While making this first table a problem arose.  It is the one I mentioned above with my right hand.After cutting out all those parts my wrist really began to hurt.  While welding professionally there was always the threat of Carpal Tunnel Syndrome.Human welders are continually afflicted by this injury and others because of repetitive motion tasks.
If you repeat something over and over and over and over, your body gives out at some point.  After cutting up these table parts, I knew I couldn’t go on doing this for a hobby.  I knew something would have to change or the new hobby would break my body.

Read the rest of this entry…

TwoKads:

how can I learn more about G-Code

October 4th, 2008

learn cnc

In a word, no.  You will probably need to know how to quickly scan your G-Code if you are having problems during your machining simulation.  Other then that G-Code and a CNC program are throwaway programs for the most part.  What do I mean by that?  Let me explain.

Let’s look at a specific design.  Let’s say a 12” by 12” square.  You build your model, run it through your CAM Software and create a CNC Program made up of G-Code instructions to your machine.  Say tomorrow the job requirements change to a 24” by 24” square.  Do you go into your G-Code line by line and change the code?  Most people wouldn’t.  They would go back into their CAD or CAM program and scale the square up to 24” by 24”.Then postprocess the job to get their new CNC Program.

There are some people that would do this editing line by line because the design is simple.  Now think of a complex shape and what scaling it up or down would entail.This would include changes to the G-Code and reviewing it line by line.  We are talking thousands of lines here vs. going back and quickly scaling the model and spitting out some new G-Code.  And that is why G-Code is throwaway.  Use it over and over when you can, but don’t fret over archiving it if something changes.  It is much better to make a copy of the design (CAD File) in its original state and save that somewhere.  That is much more useful.

Post Processing??? - Now you have me worried.  With all the variations in G-Codes and M-Codes, how will I ever keep it straight?

Read the rest of this entry…

TwoKads:

Learn about the basics of Casting Sand, Green Sand, and the uses of Casting Sand

October 3rd, 2008

Metal Casting

Green Sand: Green sand is also called as foundry sand or molding sand. This is utilized for sand Metal Casting . When this sand is oiled or moistened, it has a tendency to pack well and retain the shape. Green Sand is made up of three things: Pulverized Coal, Water, and Bentonite Clay and Sand. Out of these four components, the biggest part is that of the sand.  There are several proportions of these four components. The different ratios are used to adjust the surface finish, moldability and capacity of the hot molten metal to degas. The prime use of this sand is in the Casting . The coal is usually called as sea coal in foundries. The Amount of Sea Coal is just about less than five percent. It undergoes partial combustion when there is molten metal present and this causes offgassing of organic vapors.

Green sand is stored in flasks (as the casters call the container). Boxes without the bottoms or lids are these types of boxes. This box is divided into two half parts and these are connected together. These halves are called as the top or cope and bottom or drag flask.

As per its name, green sand is not green in color. The word “green” is used as it is used in the wet state.

Read the rest of this entry…

TwoKads: