Back in stock!

The Ultimachine Mini-Rambo Boards are now live in the Shop, as well as an option for the bundles. Here!

The two main reasons for carrying this board is it is extremely high quality and it was built as the refined Ramps 1.4 board we currently use. Meaning it is a more reliable board and it has been designed with more robust safety features built in (harder to destroy these boards by accident). Hopefully this will result in a more pleasant user experience for the newcomers to electronics. These boards are using trusted high quality components and assembled in the US. Johnny R from Ultimachine designed all the Ramps series of boards and this was the next generation from him and his team.  There are many improved features including properly implemented drivers with more efficient heat transfer, replaceable fuses, isolated USB, and a second fan port.

The board is more expensive than the current ramps boards for me but have no assembly required and I am expecting a non existent failure rate. These two factors mean I can have a much lower markup on them than the ramps. These boards also have the driver current that is set in the firmware meaning much less setup and testing time for me as well, again lowering the need for a steep markup.

The downside as compared to the ramps 1.4 the Mini-Rambo has one less extruder driver, meaning no dual extruders with this board, for teh dual end stops or multiple extruders you can use the full sized Rambo boards that are now available.

There is much more information available from the following links.






Using the Mini Rambo

The most common way the Mini Rambo will be used on the Mostly Printed CNC or LowRider cnc, will just be power and the X, Y, and Z steppers. The board is labeled clearly on each port.


If you are using an LCD the header adapter is not needed and you can plug it directly into the board as shown.


Adding an Extruder

To use an extruder you will need to flash the extruder enabled firmware or set the firmware to your appropriate thermistor value (Most commonly 11). You will then need to plug in your extruder heater, Thermistor to port T0, your print fan to port fan 1, and your extruder stepper into E0.


Using a Heated Bed

In addition to all the wires above, you will need to add what is shown in the picture below. Everything else has been removed for clarity. The firmware will need to have the heated bed thermistor value set (Usually to 11). You will need to add the bed thermistor to port T1, power to both inputs A&B, and of course the bed plugs into the heated bed port.



If you have plugs that do not fit the the sockets on the Mini Rambo, you can persuade them to come off and usually your plugs will fit the bare pins.


Formal Details

If you have any doubts or are unclear on anything the wiki page should have all your answers.


Laser Pin

Adam did some investigating and found a suitable laser PWM pin. Forum post.


Driver Math

These can now be set in Configuration-Adv.h,

#define PWM_MOTOR_CURRENT {950, 950, 950} //XY,Z,E

ITripMAX=(As stated Setting the drivers to 70%-90% of max rated amps is a good idea, 70% seems pretty good to me.)

VRef = ITripMAX * 0.8 (this gives you the ideal test point voltage)
Wv = (VRef / 1.66) * 255 (Wv=the pwm value needed (if you are using a rambo stop here I believe))

// Motor current PWM conversion, PWM value = MotorCurrentSetting * 255 / range
#define DEFAULT_PWM_MOTOR_CURRENT  {900, 900, 900}

So Wv/255*2000=DEFAULT_PWM_MOTOR_CURRENT (Values are XY, Z, E)