Eastbots Wiki

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This page is about a kit-built CNC engraving/cutting machine being attempted by Jeff, Steve, and the Eastbots.


====== Frame & Motion Stage ======

Based on the C-Beam Machine kit from Openbuilds.com: https://openbuildspartstore.com/openbuilds-c-beam-machine/

{{ cbeam-openbuilds.jpg?200 }}

Steve and Jeff assembled it following the video on https://www.youtube.com/watch?v=HVR8pABCHXI

====== Electronics ======

We're using a "Mach 3" interface board, which connects to a PC parallel port.
It looks similar to this one:
https://www.hobbytronics.co.za/p/473/mach3-opto-isolated-parallel-interface-break-out-board

The interface board provides enable, step, and direction signals to the three stepper driver modules,
which are M542 units:

http://www.americanmotiontech.com/products/productdetail.aspx?model=m542-cnc-stepper-drive-50v-4.2a

The interface board also has inputs that can be connected to limit and emergency-stop switches.

The interface uses the [[CNC Parallel Port Mapping | parallel "printer" port signals]] to control the stepper motors.

The interface board is cabled to the parallel printer port on a PC.  The parallel port must either be on the motherboard or on a PCI expansion card; USB control is not possible (see the linuxCNC documentation).


====== First Motion ======

The machine first moved its motors in June 2019: https://www.youtube.com/watch?v=QzRUWVw7nxc

(This is from the motor test function in the linuxcnc setup program, which moves one motor back and forth at high speed.  The test is OK if the motion is smooth and repeatable)

====== Control Software ======

The control PC is running centos linux with the CCRMA real time kernel http://ccrma.stanford.edu/planetccrma/software/

We're using LinuxCNC to drive the interface board.  http://linuxcnc.org/

LinuxCNC's job is to take a file containing G-Code instructions, and feed them to the stepper motors to move the cutting tool along the paths specified by the G-code.

====== Simulate before cutting ======

Before running a g-code program on a real machine to actually turn metal into shavings, 
we can simulate that program to make sure that it does what we want.  

[[https://camotics.org/|CAMotics]] is a nice, free g-code simulator that installs easily on windows and recent linux.

====== CAM Software ======
To be determined.

Simple G-code can be written by hand. https://en.wikipedia.org/wiki/G-code

There are simple g-code generator python scripts at https://github.com/LinuxCNC/simple-gcode-generators
The output of these is easy to understand, and will be some of our first trials.

But to really make parts, we need a true Computer Aided Manufacturing (CAM) tool, that takes a 3-d model from CAD and turns it into the long sequence of cutter moves described by g-code.

We can get a free/student version of MasterCAM with a voucher code from FIRST

We might try openbuilds CAM which I think is a web-based thing. https://cam.openbuilds.com/