woensdag 9 december 2009

Some time ago I became the proud owner of a TAIG CNC mill. As you can see in the next pic, it has quite an oversized motor to drive the spindle: Even though the z-axis stage has no problem lifting the weight of this motor, there were several reasons why I wanted to have the option to put on another one:

1. Tool rotational speed
While you can change the spindle rotation rate by repositioning the belt, the tool still rotates quite fast at the highest reduction ratio. For milling low melting point materials like PMMA, this can be a problem. The new motor is a DC motor used in servo systems, it generates a torque even at very low speeds.

2. Vibrations and noise
The original motor is pretty quiet, but still generates a bit more vibration than desirable for late night milling in a 4th floor small appartment. :-)

3. Mains voltage
To operate the 110V motor from 230V, a bulky transformer is needed. It generates a hum that can be annoying and takes up valuable tablespace.

4. Oversized
I'll use the mill to make small parts, not to mill 2 inch slots in heavy steel. So I hardly ever need the power of the original motor. If I do at some point, I can always put it back on as needed.

5. Wear
Having less (off-centered) weight on the z-stage will help to prevent wear on its slideways, bearings and drive spindle.

So enough reasons to let the original motor aid in its own demise and use the TAIG to make a mount for the new one.

First a drawing was made in VCarvePro, and this was used to generate the toolpaths:

After simulating the actions of these toolpaths, this is an impression of what the part will look like: This is what it looks like right in the real world, just after milling:
After cleaning up the chips: Notice the tabs that can easily be added in VCarvePro: Without them the part would come loose on the last pass, which can cause all kinds of trouble.

After having removed the tabs by hand:
The finished part:
With the motor attached:
And on the mill:
At low speeds, the motor is almost noiseless and this allows one to enjoy just the sound of the steppers and the beautiful soft hiss of metal being cut.