MDF Rose Engine Lathe 2.0
Build Instructions – Stepper Controls
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Option 2: Alternative Stepper Motor Drivers
The printed circuit board was developed to use either
•
the DM542T external drivers outlined above, or
•
the Pololu DRV8825 stepper motor drivers which would be attached to the board using header sockets.
Advantages to Using the Pololu DRV8825
1.
DRV8825s are about 1/3 the cost of an external driver (i.e., the DM542T).
2.
Having the DRV8825s mounted to the printed circuit board makes for a smaller physical footprint, enabling it to be
installed easily inside the lathe’s bed carcass.
3.
The power draw for this configuration is lower, so a different (& potentially less expensive) power supply is possibly
available.
4.
There is less cabling to be done.
Disadvantages of Using the Pololu DRV8825
1.
DRV8825 chips are limited to a max 1.5 A (vs. 4.2 A for the DM542T drivers).
a.
This can necessitate the need for different, more expensive stepper motors. The cost of these different motors can
erode the savings for not using the external stepper motor drivers (DM542T).
b.
It is easy to overload the DRV8825 chips and cause them to fail.
c.
It is easy to overload the DRV8825 chips and they in turn can cause other components to fail (e.g., the Teensy).
2.
DRV8825 chips get hot when used, so fans must be attached to them to ensure they do not overheat. And the user will
need to replace the fans when they fail.
3.
Future deliverables (e.g., a curvilinear slide and a spherical slide) for the MDF Rose Engine Lathe 2.0 will be tested to
ensure compatibility with the design from above. If the add-on devices do not work with the changed configuration, the
owner/builder will be responsible for accommodating the necessary changes.
Recommendation
Unless you are an electrical / automation engineer or have substantial experience in this space, the design outlined with external
stepper motor drivers will be easier to implement over the long term.
