08. Into mechanics

So the basics for the Arduino + CNC shield + G-code are under control to get the stepper motor moving. I now need some mechanical thing to move.

The following video is good source of inspiration:



Quite smart. Yet my constrains are different from a CNC: the axis should move faster and they don't need as much strength. Still the linear guidance could be the same...

After browsing the Internet for almost a whole week end, I end up with the following ideas:

1. Linear guidance: 
1. Use an aluminum T profil + 624vv bearing on one side
2. Plain bearings as wheel on the other side
2. Linear motion: use toothed belts by the meter + pulley + clamps

Suppliers found:

• Bearings; on ebay for around 0.50 EUR per bearing
• Toothed belt & co: http://www.tridistribution.fr/fr : it's way more expensive and I still need to get some details sorted out to choose the right features.

07. Plug my stepper motor and test it

Now it's time to plug my stepper motor onthe CNC shield.

I read this tip: "Do NOT connect or disconnect a motor while the driver is energized. This will cause permanent damage."  -- Sparkfun

As per the specification of my 42BYGH47401A stepper motor, the wiring of the 4 leads are ordered as:

• RED Phase: A
• BLUE Phase: A Return
• GREEN Phase: B
• BLACK Phase: B Return

Not fully explicit to me as my CNC shield shows A1, A2, B1 and B2 for each

As per http://www.selene.co/Articles/WiringConfigurations.aspx, "Bipolar motors are the simplest of the configurations presented here. Bipolar motors have 4 leads and two windings. Only one configuration is possible with a bipolar motor, as shown to the right. What is important for a bipolar motor configuration is the polarity of each winding. The windings must be symmetric (A+ and B+ winding leads must be connected to the same end of the winding."

So I decided to wire it as

• B2: black wire
• B1: green wire
• A1: red wire
• A2: blue wire

This is how it looks:

So I am now ready for my first test:

1. Switch on the main alim
2. Plug in the USB cable into the Arduino

Here is my stepup:

In the Arduino IDE, I open a serial monitor (under Tools / Serial monitor):

1. I type in $$ + send, to check that I am properly connected: I get my default parameter setup
2. Now I can type in my first G-Code command:

It means "move x-axis by 4 mm at a feed rate of 25 mm per minute". And it works !!

Now the same in video: yeah !! :-)

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As a recap, this video is also a pretty good introduction by John to getting started with Arduino CNC Shield.