CNC Mill Introduction

This is the content required for an introduction to our CNC router - reading this does NOT replace the mandatory session with a tutor! It will make it a lot quicker though ;-)

If you need this introduction, please reach out to the following tutors: Patrick, Martin, Johannes

Before you get this introduction, please make sure you already have the Handheld Router Introduction, this will help you understand the machine much better and is required before using it.

Let's begin! First off, make sure you have read the machine's manual, if available (check its "InfoBox" in the wiki for instructions how to find it).

Safety

Personal protection:

Dangers	Precautions
sharp, fast spinning bits (end mills or - rarely - certain router bits)	stay clear of the CNC router when in operation unplug the router when changing a bit or touching the chuck for any other reason insert your mill as far as you can afford for maximum strength
strong forces acting on the workpiece that might make it move	secure your workpiece properly - see CNC router workholding
the machine has no live sensors and will execute its code regardless of what gets into its way heat generated during improper use can even set the machine on fire	home the machine (set its absolute maximum positions) before executing any movements reference the machine to the workpiece (relative maximum/starting positions) before starting the router monitor the CNC router closely when in operation keep an eye on the cables that come from above - are they securely out of the machine's paths?
hitting "pause" or "stop" in a control program will still let at least the current line be executed	push the emergency shutdown button if anything goes wrong
lots of dust that could harm your health or settle down on machine parts, possibly hindering movements	use the shop vac (with cyclone separator for collecting waste and dust shoe to connect to the router) as well as the room's air extraction (for fine dust) when using the room air extraction, make sure the vent next to the door is open so replacement air can flow in

Suggested Reading

Besides these safety notes, you should read about the different end mills (and router bits, if you want to try those) to know what you're doing! Different materials usually require different mills, and the feedrate depends on the mill as well as the type of material.

• our list of milling experiences - please also share what you find out!
• top milling tools for new CNC machinists
• G-Code fundamentals
• Interfacing with Grbl (Please take special notice of the "Other Grbl Messages" section)
• Our list of G-Code senders

Recommended Watching

• CAM, virtual setup: how to prepare your model and place it in a virtual workpiece in Fusion 360 (DE)
• machine setup: how to set up a job on the WorkBee CNC

Demonstration

The tutor will show you these steps in detail:

1. at the machine
   • selecting the right bit
   • inserting a bit
   • turning the machine on and off (easy to forget!)
   • homing the machine (setting absolute "0" positions)
   • setting the relative "0" position on your workpiece
   • connecting and turning on dust extraction
     • paper trick: go down until a piece of paper is just held in place by the mill's tip
2. on a computer
   • generating G-code from a design in Fusion 360
   • Using CNCjs for uploading the code to the CNC router

You should then be able to do a small practice cut together with the tutor.

Interfacing with the CNC Router

General

Grbl provides a serial interface via USB. The baud rate needs to be set to 115200.
As mentioned in the suggested reading section, it is a good idea to make yourself familiar with the fundamentals of interfacing with Grbl.
In any case, if you want to start a job with the CNC router, you have to execute these steps:

1. Make sure the router is off
2. Insert your desired bit into the router
3. Turn on the CNC Control Unit
4. Make sure the emergency stop is not pushed
5. You should hear howling. If you don´t, please push the emergency stop and release it
6. Use CNCjs to connect to the machine.
7. Perform a homing cycle ($H). You might have to release the machine first ($X).
8. Use the manual controls to bring the machine to the X/Y origin of your job.
9. Use the manual controle to bring the machine to the Z Origin of your job
   ATTENTION: Nothing prevents you from driving "into" the spoilboard or your workpiece now. So make sure you move carefully and slowly!
10. Zero the machine
11. Move the router up a bit on the Z-axis
12. Turn on the router with your desired speed
13. Start your job
14. Carefully watch your job. Use the Shop Vacs to get rid of dust during your job.
    If anything goes wrong, push the emergency stop!
15. Once your job is done, turn off the router, home the machine and clean up.

Different G-Code Senders

Since our CNC router is based on Grbl, there are multiple software options for G-Code senders.
In the CoMakingSpace, we are using CNCjs for interfacing with the CNC Router.

Waiting List

This introduction takes longer than many others and usually can't be done spontaneously during regular opening times. If you would like to receive it, please add yourself to >> this list << and we will find a good time once a few members are on it!