RAMBo 1.4 + Marlin controlled via MacBook

Hi everyone,

im doing a little diy project with my students and we built a mpcnc burly, using a RAMBo v1.4 with Marlin and dual endstops. during the last months we’ve invested a lot of time and money to make the machine meet our expectations. its not as advanced as some of the axamples ive seen made by the comunity, but it fits our requirements.

the machine runs perfectly fine using a sd card by exporting gcode from fusion360, using the RepRap postprocessor. (allmost - we still have to delete line N20, because otherwise the tool would scratch throug the workpiece… didnt figure out, whats the problem here - but that shouldnt be the topic here)

My question is: is there a “straight forward” way of controlling the RAMBo by using a MacBook via usb? (didnt find one yet) if yes, which software do i need and which postprocessor would be used therefore?

Anyways thanks to @ryan and the whole comunity - it is a great project so far for our students and we love the product!

kind regards from germany

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For years, Guffy’s post processor was the PP of choice Fusion 360 users. Earlier this year Don Gamble forked Guffy’s project and made substantial improvements. See this forum topic for Don Gamble’s work.

Note that last October, Fusion 360 made changes in the personal licence version of their software that broke using Guffy’s postprocessor. In particular, it resulted in the lead-screw-driven Z axis being moved too fast. This problem can be mitigated by executing the following g-code once (i.e. the change is persistent).

M203 Z8    ; Limit Z feedrate
M500       ; Save the setting to EEPROM

As for driving the MPCNC over USB, there is a Mac version of Repetier-Host. Repetier-Host is the primary way Window’s users driver the MPCNC over USB. Here are the V1 setup instructions for Repetier-Host. Note that I’m not a Mac user, so I’ve never tried the Mac version of Repetier-Host.

I’m not sure how old your students are, but beyond USB control, there are other control solutions that you may want to explore with them. The MPCNC can be controlled wirelessly using a Raspberry PI. Not something I’ve done, but here is a link to some instructions and a firmware image.

Personally I stuck to the SD card, but created a pendant to make setup easier. While my pendant is custom, here is a Thingiverse link to a MPCNC pendant project that provided the knowledge in how to build the pendant.

What age are your students? What are they making?

Edit to clarify: The g-code a post processor generates is independent of the platform/tools used to send the g-code to the control board, so you don’t need to change your post processor if you are using a Mac to send the g-code vs. using the SD card.


that is exactly the information density ive been searching for. :slight_smile: thank you many times for your help. repetier is running as expected. (just that i got you right - i still have to flash the two lines of gcode to the board, in order to get correct results even with the v2.1 of the pp done by don gamble? and what if we use a commercial license? no problems there?)

i read about the optionalities of controlling the board via bluetooth, membrane, ipad etc. and that could be an interesting next step. our students are from different fields of study but all located in the subject of design (industrial design, interaction design, communication design, IoT…) and theyre between 20 and 30 years ol i would guess. we’re using the machine for all kingds of projects ( cutting foam, wood, kappa and right now, were even doeing PCB milling to build our own arduinos) the machine is a lot of fun and much more precise than expected. we also have a industrial portal milling machine in our workshop, but with that one, youre not allowed to make any mistakes, due to the extremely expensive tools and parts that are installed. the mpcnc is the perfect approach to get in contact with cncmilling. were allowed to leran from our mistakes, without wasting too much money.

best regards


Don’s v2.1 postprocessor addresses the problem, and a commercial license removes the reason the problem is occuring, BUT it hurts nothing to run the g-code just to make sure that the Z axis never moves too quickly and therefore may lose steps. Consider it a safety belt.

Fusion 360 removed Rapids from the personal/free version, so the Z axis ends up moving at the same rate as X and Y and is folded into the same movement. Given that X and Y are belts and Z is a lead screw, Z just cannot move as fast as X and Y without losing steps.

It is cool to see the MPCNC used in an environment like yours. Most of the people on the form are hobbyists with the MPCNC as their personal CNC machine.

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