We all know what the CNC Milling Machine spindle is used for - to hold the tool. But it is old and boring. Everybody does that.

Here are the 6 interesting and maybe less common ways to utilize machine spindle, increase productivity and solve some problems you never thought you had.

Use your Spindle as a fan to blow chips and coolant off of your work-piece, table and fixturing.

I saw this little gadget at a local IMTS show and it was quite cool. It is installed into a tool holder like a regular cutting tool would be and at the end of the program you can call the it up and run a little table-cleaning program to make your work a lot cleaner!

Did you know there are three ways you can touch off your tools?

Because of how Machine Offsets add up, there are several ways CNC machinists can set their Tool and Work Offsets.

This is especially true for Tool Length Offsets.

Tool Offsets can be either Positive or Negative.
Depending on your Machine Shop equipment you should use one or the other.

Regardless of how you set your tool length offset, you apply it the same way.
Right after the tool change and after turning on your spindle and moving to your X Y position above the part.
The very first absolute Z movement should be the line where you apply the tool length offset.

Positive Tool Offsets (gage line tool length offsets)

In the case of Positive Tool Offsets, the offset represents the Length of the tool measured as a distance from the Gauge Line of the spindle (typically spindle nose) to the tip of the tool. The longer the tool, the larger your Tool Length offset will be.

Before we run any G-Code program, we need to tell the machine where our part zero is.
A Part Zero is simply a bunch of numbers that offset the axis to give the machine a new coordinate point to work from.

Work Offsets is one of the most basic pieces of knowledge any machinist must-have.

Let us account for all the basic coordinate systems and definitions, available in a generic CNC machine

• Machine Home and (Absolute) Machine Coordinates
• Work Offset Coordinates
• Tool Length Offsets

Machine Home and Machine Coordinates: G53

Machine Coordinates (or Absolute Coordinates) is the absolute and constant representation of the machine axis position.
These coordinates never change between Machine Restarts and must remain such. In fact, there is often no way for an operator to adjust the Absolute Machine Axis Home position.

Machine Home is simply that magical place where all Machine Coordinates should become Zero.

To Home the Machine is to start a machine operation, that will move all Axis to their soft limit position where X, Y, and Z-axis reading will be set to zero.

Homing must be done every time you restart your machine. Without it machine does not know where is the position of its table or spindle.

When homed your machine coordinates will read X=0 Y=0 and Z=0 and it is going to look like this:

The point where Machine X and Y intersect is called Table Home Position and the one where the Machine Z-axis starts from is called Spindle Home.

Now, there is no agreement between machine tool manufacturers on where the machine home should be.

In this tutorial we are going to explore different options and techniques when programming cutter movement.

Lets begin with a simple part shown in a drawing below.

Basically it is a rectangular piece 4.00x2.00
For the purpose of simplicity lets make the depth of our profile (z- dimention) 0.75"

We are going to use a 0.5" dia endmill, again because it is a very common size and is easy to do basic math with.

I took a liberty of puting locations for our part/toolpath, so it is easy to extract numbers from the drawing just by looking at it.

Notice the green rectangle. This rectangle represents the path that the center of the tool will have to take to produce the part with required dimentions.
The thing is: because endmills have certain diameter, the center of the tool must be always offset by its radius.

There are two ways of doing that.

Renishaw OTS tool probe cycle for HAAS can set both length and diameter offsets.

Too bad there is no choice: it only puts absolute measured diameter of the tool into D- diameter offset and makes wear offset=0

But if your programming is done with the center of the cutter, then you actually only need the difference between actual and programmed diameters of the tool.

I.E.: When probing 5/8Dia end mill, we get D=0.6248. You would normally have to subtract 5/8 from it and leave the -0.0002 difference.

But there is an easier way