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CNC

The CNC machines will be running as usual. We expect they may well be even busier than ever, as they take the place of other more hands-on making. Now is the time to develop and fully realise your digital fabrication skills. There are acrylic screens between machines for your safety, and strict limits on numbers in rooms. So you will need to arrive on time, on the hour, as the doors will be locked at other times. Slots now will be maximum 3 hours. You’ll need to clean keyboards and keypads before and after use with the wipes we provide. But the machines are available and running as always. Do please make good use of them.

ASKING FOR HELP

Mon - Fri 12:00 - 13:00*

If you have read the guide below and you need help please join us in the Open forum to answer any questions you may have about preparing your files. Feel free to listen in so you can pick up some tips from us helping others. Usual rules apply: microphones off unless your speaking; put your 'hand' up if you want to say something. See you there!

 

*We are closed from the 11th December to 4th January

PROCESS

1. Complete CNC Essentials

01

Complete your CNC Essentials. Without this your cannot move farward and use the machines.

2. Create your geometry to machine.

02

Download the template file and model what you want to machine.

3. Program

03

Book into the CAM Lab to program your CAD models in Rhino CAM.

4. Book

04

If you want to use the Mini Mills go ahead and book. If you want to use the CNC Routers send your file for checking and once approved you can book.

5. Come in for your booked slot

05

Come in and use the CNC to machine your work.

CNC ESSENTIALS

HERE'S THE THEORY

WHAT IS A CNC SPINDLE?

A Spindle is a very fast spinning motor that holds an END MILL. The end mill spins at a specific SPEED and the machine that the spindle is attached to FEEDS it through the material to cut away the material in its path. This is what is known as the TOOL PATH. The machine that the spindle is attached to is either a MILL or a ROUTER. The machine is controlled by a computer, hence COMPUTER NUMERICAL CODE - CNC. The computer code is generated out of your Rhino CAD file by using a CAM (Computer Aided Manufacturing) plugin call RhinoCAM.

WHAT CNC SPINDLES DO WE HAVE.

We have 6 CNC spindles:

The MILLS (we have 5)

Peter and Bernard are Mills; in fact they are so small we call them mini mills. These are machines that you will complete the CNC essentials on. They can cut low density foam (The black and cream foams) and Balsa wood.

Rem and Bjarke are larger than Peter and Bernard. They also have an automatic tool change so they can swap their end mill automatically based on your file.

The ROUTERS (we have 2)

Renzo and Norman are routers, unlike the mills their bed stays static and the gantry moves. These are designed for large sheet material but can also cut foam and sectional timber. Norman has an automatic tool change, Renzo does not.

 

WHAT THEY CAN DO.

At a very basic level the End Mill can cut 2 dimensional shapes by using two axis - the X and the Y - it can also create what is called a POCKET by cutting away a set region, part of the way through the material. However, it can also use it’s 3rd axis - the Z axis- to cut simultaneously with the X and Y. This enables complex surfaces to be machined. Here in the Fabrication Lab we can cut low and high density foams as well as sheet material such as plywood, MDF and hard plastics like acrylic and also sectional timber.

WHAT THEY CANNOT DO.

The end mill cannot cut pockets or internal parts smaller than its diameter. The machines are known as 3 axis machines. They can move on the X and Y and up and down on the Z. However, they cannot access undercuts (see the diagram below), this requires a 5 Axis CNC machine. They cannot cut deeper than the specific end mill will allow. Most* of our end mills are designed to cut through 50mm (our thickest stock material).

 

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*There are exceptions, Peter and Bernard will not cut deeper than 40 mm using a 6mm end mill and the 3mm end mill cuts to 10mm in depth.

 

TOOLS

There are two distinct differences in the End Mills we have (remember End Mills are tooling that fits in the spindle). We have Ball Mill and Flat mills. Large diameter tools remove a lot of material quickly, small diameter tools are much slower but capable of a finer finish.

Choosing End mill versus Ball nose will determine the characteristics of the tooling marks, End mills have a flat end and are good for Flat surfaces, while Ball nose have a rounded end and are good for curved surfaces.

Peter and Bernard have each 5 different tools:

WHAT MATERIALS CAN YOU USE?

This is dependent on the machine and its extraction. The mini mills (Peter, Bernard and Rem and Bjarke) have less power so cannot cut denser materials, they also have no extraction which means they can only cut soft materials like balsa and foam. The routers (Renzo and Norman) have a lot more power and extraction so they can cut MDF, Ply, harder plastics and foam.

Inside the template file there is a list (in the layers) of all the materials each machine can cut.

WHAT ARE THE HAZARDS.

The hazards involved with using high speed spindles and moving CNC machines can be great. The smaller machines are less hazardous as they are enclosed. The larger routers are extremely powerful and have more hazards with greater consequences.

HAZARDS:

  1. COLLISION - As the mini mills are enclosed the risk of collision with yourself and the machine is not possible. This is not the case with Norman and Renzo.
  2. FIRE - As the spindles rotate at an extremely high speed friction is created. If the End Mill is blunt then this friction can be much greater causing the material to ignite. Fire is a very real possibility on the routers.
  3. HARMFUL INHALATION -  The end mills remove material as fine chips this can be a fine inhalable particulate. The mini mills are enclosed and the Routers have high power extraction systems however the particulate can still be made airborne when the material is moved.

 

CONTROLS

There are 3 simple rules that must be followed at all times.

1. PAUSE THE MACHINE FIRST. NEVER INTERFER WITH TH MACHINE WHILE IN OPERATION.

To control the risk of colliion we insist that you observe the machine from outside of the machine room. You must in no circumstances interfere with the machine or the material while the machine is in operation.

2. NEVER LEAVE A MACHINE UNATTENDED

To control the risk of fire when using Norman or Renzo, we insist that you observe from outside of the machine room, and you must never lose sight of the End Mill.

3. CHECK EXTRACTION AND ALWAYS VACUUME

Always check the extraction is on and working. When you have finished cutting be sure to vacuum as much as possible before moving the stock material.

THE CHALLENGE

To complete the CNC Essentials, you must produce a part to be cut. This is ‘The Balsa Challenge’.

This must be:

  • A two-part joint cut from one pieces of balsa wood (stock size 65mm x 70mm)
  • Each part can be no bigger than 50mmx20mm
  • Your joint should be designed in a way to have at least 2 different 2 axis operations

You will need to create a 3D model of each part of your joint set out in one template files (Although 2 axis machining only requires curves we do insist you create a 3-dimensional model of your joint, this will help you visualize the final piece). You might find it easier to draw the joint first in a CAD program of your choice and then import it into the template file.

The curve regions

Your 3D model will need to have curves, you will need to have at least a curve for each operation. These curves are known as curve regions and they delimit the region to machine, they go in the 2 axis operation layers. Keep reading it will all make more sense.

For pocketing operations curves consider expanding your curve over the milling area. This will allow you to have cleaner and sharper edges.

THE CAD MODEL

The software - Rhino3D

The CNC machine is controlled by a drawing you create in CAD which you then go on to program in Rhino CAM. To start, Download the template file from the link above. You can draw your object in any CAD software but you must use RhinoCAM to program it, therefore you must be familiar with RHINO. If you are not do a few tutorials first

https://www.linkedin.com/learning-login/ to become familiar with the layout and how to use the layers.

THE DIGITAL MACHINES TEMPLATE

The Template file is extremely rich and includes a host of information in the 'User Guide' layer. It also represents the sizes of the beds on our different machines and the stock material sizes.

Here are a few golden rules:

  • Always work from the latest Template file, which you can download above or in the main CNC page.- Do not change the file, apart from adding your own drawing into the appropriate layers
  • Do your drafting in a separate Rhino file or whatever other software you like, and then copy/import this into the Rhino Template
  • If at any time your Rhino file becomes corrupted or confused, just download a fresh, up-to-date copy and start again.
  • Once you have completed your Essentials, if you have any questions or want your file checking before using up your booked time, come in advance and ask a Technician or Lab Assistant for help.

How to start:

  1. Expand the first layer called '1. CHOOSE A MACHINE' then 'CNC SPINDLES' and switch the light bulb to activate PETER & BERNARD. The bed size will appear.
  2. Next, expand '2. CHOOSE YOUR STOCK' then 'CNC SPINDLES' expand BALSA and activate the layer called 'Balsa Challenge' using the light bulb. This is the size of your stock material.
  3. Now expand the layer called '3. DRAW YOUR PARTS' - 'CNC SPINDLES'. In the layers that you place your work you have seen there are 2 axis operations and 3 axis operations. 2 axis operations require curves while the 3 axis operations require surfaces. In the template file under USER GUIDES you will find more information regarding each operation.

Below is a screen grab of what you should have.

THE CAM PROGRAMMING

Once your 3D model is ready, you will need to book the CAM LAB to program your job with RhinoCAM.

 

 

1. The Knowledge Base.

If RhinoCam is not open, in the menu headings at the top select RhinoCAM and choose Mill (even if you are using our Routers Norman and Renzo).This is a file that loads the particular settings for the stock material you are using.

To load the Knowledge Base go to the CNC section of the website and click on 'Download Knowledge Bases' you will be taken to a google drive. For the Essentials right click on 'PETER & BERNARD - BALSA - 4.8mm' and download.

Click on the icon shown in the image below and load the Knowledge Base you just downloaded. Each operation's nam of the knowledge base contains a series of information. These are the name of the operation (ex. PROFILING - External), The Tool number (ex. T1), the tool diameter (ex. 2mm) and the type of tool (ex. FM stands for Flat Mill).

Now it has loaded delete the processes you do not need.

Each operation's nam of the knowledge base contains a series of information. These are the name of the operation (ex. PROFILING - External), The Tool number (ex. T1), the tool diameter (ex. 2mm) and the type of tool (ex. FM stands for Flat Mill).

2. Setting up the Box Stock

You need to set up the size of the stock material. The template stock material sizes are for you to draw within. They do not inform the machine. Setting the box stock tells RhinoCam the size, thickness and starting origin of your stock.

3. Programing your operations

Double click on the operation. All machining operations require a region to machine. This is your curve. If you have many regions to select, once you have clicked 'select Curve/Edge region', right click on the layer of the operation you need and choose and ‘Select Objects’ then press Enter. Once selected press 'Generate'.

 

For Pocketing, only ​- You will need to click on the ‘Cut Levels’ tab and specify a depth to which the machine will cut.

4. Check tool paths

Now you have programmed each operation. Check each operation’s tool-paths by clicking on each operation and looking at the tool paths in the Top, Front and Perspective viewport to check that they are machining within the material (above 0 and below 4.8mm for Balsa).

Simulation

To help you understand better the tool path  and how your final result will be, try to simulate your job. Click on the simulation tab, select your operation and press play.

5. Time to ‘Post’

To process the CAM file into the G-code that the machine will read you need to 'Post' the file. For Machines that have no automatic tool change (that is Peter and Bernard) you need to Post each process that has a different tool separately. Right click on the Knowledge base operation and click ‘Post’. This will create a file called and NC post – save this onto a USB stick.

Once you are happy with your Balsa Joint, it is all on the correct layers, you have correctly programmed it in Rhino CAM and checked it for errors. Complete the quiz below. Once complete you will be given a link to send your file for checking.

If you want to progress further please register or login first!

For your Essentials practical, once you have had your BALSA Chellenge checked you will be notified that you can proceed. You will be able to book using the button below.

If this button is greyed out then your Balsa challenge has not yet been approved. We aim to contact you with 24 hours of submitting your Balsa challenge. Please be patient.

When you come in for your practical exercise you will be expected to be able to use the machine un assisted. This will include:

  • Inserting the correct tool for the job.
  • Correctly fixing the material in place
  • Setting up the origin of the machine.
  • What to do if something goes wrong.

If you cannot complete this unassisted you will not be able to progress. Watch this video as many times as you need to. Feel free to take notes and take them along to your practical slot.

THE MINI MILLS - REM, BJARKE, PETER AND BERNARD

If you are not able to book a slot (greyed out button) and you have completed your CNC Essentials last term or earlier, please email (Admin@FabricationLab.London) the Lab to get your record updated. 

THE ROUTERS - NORMAN AND RENZO

To book the CNC routers first we must check your file once programmed in Rhino CAM. Once programmed, generate your g-code and  email this .nc file and the Rhino file to cnc@fabricationlab.london. Once we have checked it you will then be able to book your slot. not before. You will not be able make changes after this point. if you want to change the file you will need to resubmit.

If you are not able to book a slot (greyed out button) and you have completed your CNC Essentials last term or earlier, please email (Admin@FabricationLab.London) the Lab to get your record updated. 

CAM LAB

You’ll need to programme your jobs for CNC machining using RhinoCAM. This software is only available in the CAM Lab so we have now also made the CAM Lab available from 30 minute to max 2 hour slots. Please book below.

PROCESS

1. Create your geometry at home.

01

You can download a free 90 day trail of Rhino. You will need to have it prepared in the Rhino template before you come to program it.

2. Book your Cam Lab computer

02

Once you have finished drawing what you want to fabricate book your CAM Computer

Currently due to reduced capacity we can only offer use of the CAM Lab for prcessing Rhino CAM files.

Please log in to book.

REM

Roland Modela MDX-40
MAX MATERIAL SIZE 290 x 390 x 50 mm

ADVANTAGES

A fast, easy to use CNC Mill. Will machine medium and high density foam to be uses as component parts or molds. Also good for flipping the stock for machining both sides.

DISADVANTAGES

Smaller bed size than the CNC routers. Only machines foam.

£3/h

PETER & BERNARD

Roland SRM-20s
MAX MATERIAL SIZE 200 x 150 x 40 mm

ADVANTAGES

Our lowest price CNC.  Will machine medium density foam (Blue and Cream, not Orange foam). Good for machining highly detailed designs. Fitted with our smallest tool (2mm Flat Mill)

DISADVANTAGES

Will only machine Blue and Cream foam. A small bed.

£2/h

RENZO

AXYZ 4008 - ROUTER
MAX MATERIAL SIZE 1220 x 1200 x 50 mm

ADVANTAGES

A Powerful CNC Router capable of cutting foam up to 1220 x 1200 x 50. Good for machining context models.

DISADVANTAGES

There are few disadvantages when cutting foam. Unlike normal it has a manual tool change.So jobs that require lots of tool changes can be slow.

£5/h

TO BOOK, EMAIL e.lancaster1@westminster.ac.uk YOUR RHINO FILE AND NC CODE FOR CHECKING. WE WILL BOOK YOU IN.

NORMAN

AXYZ 4008 - ROUTER
MAX MATERIAL SIZE 1220 x 2440 x 50 mm

ADVANTAGES

Our largest CNC. Capable of cutting Plywood, MDF, foam and Acrylic.

DISADVANTAGES

A popular choice of with a que.

£5/h

TO BOOK, EMAIL e.lancaster1@westminster.ac.uk YOUR RHINO FILE AND NC CODE FOR CHECKING. WE WILL BOOK YOU IN.

FABRICATION LAB
University of Westminster
College of Design, Creative and Digital Industries
35 Marylebone Road, London NW1 5LS
Office@FabricationLab.London

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