Ok… so that was our very first workshop, course, introduction… did it work? Yea, kindof… would we do it again the same way? Possibly not.
Firstly, thank you, thank you, thank you to the people who turned up… and thanks for helping us through what was (for us) a learning experience.
We knew we didn’t want to do formal courses on CAD, but didn’t really know where the people attending the tutorial were at in terms of ability or aspiration etc… and really, as this entire endevour is about sitting in a circle and collaborating, rather than instructing from the front… that’s what we tried to do. There were eight people in attendance – as well as Lee, Steve and me… and I think this was a pretty good size. If we’re going to do actual physical stuff in future, rather than a show-and-tell session, then I think we’d need to split into two groups. I think a good workshop working-sub-group size is 4.
So we tried not to make it about sitting at the front and talking… but wound up doing a whole lot more talking than we ever imagined we would. I think future events of this type need to be a lot more hands-on… with a lot more doing, than showing-and-telling. To be fair, we were kind of hobbled by DHL Couriers, smashing our laser-tube AGAIN… so the main bit of kit that we’d like to have work-shopped on, was, as ever, a blue box sitting against the wall… and our 3D printer was trapped in a delivery van, somewhere in the midlands as well.
Aye well… we will live and learn, and improve with mighty quantum leaps.
Everyone who attended said “see you next week”… which was wonderful, because to be 100% honest, this utterly experimental approach to sharing/teaching has been one of the scariest things we’ve ever done.
Anyhoo… here are some notes of what we covered in terms of basic theory, a PDF of which is available here, the HTML below. This contains links to the various applications and resources that we said we’d provide links to
Thanks for coming.
Summary – Week One
For a digital machine to cut out, build up, or etch a shape… first we need a picture of the shape… a digital file that you make on your computer. These files come in various shapes and sizes, many of which you will have seen before… a laser-cutter for example, can reproduce (as an etching), pretty much any image you can find on the internet… with varying degrees of success. To do more finely-tuned work though, we need to create special files.
(Firstly, a bit about file types…
To identify file type look at the end of the file name, for example this document is titled “Introduction to Design 1.pdf”, showing that it is a PDF type of file. Or right-click on the file and select “properties”)
2D Image files – What are vector & raster files?
Vector files are drawings made up of straight lines, rather than shaded areas. They use simple shapes (known as geometric primitives) such as points, lines, curves to represent a design. Each of these primitives is defined by points in the x and y axes. Vectors can be used to control the laser-cutter or CNC router to cut out shapes (“profiles”), or etch a design. The tool/laser follows the vector like a pathway… so it is a very fast way of working.
Programs which produce vectors; Adobe Illustrator, CorelDRAW, Inkscape, AutoCAD, Solid Edge 2D.
All of these export or save as .dxf file format, which is the most useful for taking 2D designs to CNC machines.
A Raster image, or bitmap, is a rectangular grid of coloured or grey pixels which represent an image. A profile cannot be cut using a raster image, though a vector could be traced from a high resolution image with clearly defined edges… so if you have a complicated black and white shape, often you can just photograph it, import into your drawing app, hit “trace”, and it will draw an outline for you.
A vector can be also manually traced using a raster image as a guide. A raster or bitmap can be used to etch images on the laser cutter, or engrave on the router.working
Example file types; .bmp, .png, .gif, .jpeg (poor), .psd, .tif.
Programs which can produce & edit raster images; Adobe Photoshop, Corel Painter, MS Paint, GIMP.
An image resolution of around 300dpi (dots per inch) should give good results.
3D model files
These can be built in 3D modeling software or ready made models can be downloaded from the internet. These are a mesh of polygons & triangles which define a 3D form. 3D model files can produce components on the 3D printer, or forms for the CNC router to machine from a block of material.
.stl (STereoLithography) files are the most useful for taking designs to our machines, STL files describe only the surface geometry of a three dimensional object without any representation of color or texture.
.obj can also be used by converting them to .stl files.
Example 3D modelling programs; Autodesk 123D, SketchUp, Tinkercad, DAZ Studio 3D, Rhinoceros, Solid Works, 3D Studio Max.
Tip- when looking for a model on google, search for file type too, for example; “Horse 3D model stl”.
Digital Machines (CNC)
CNC means Computer Numerical Control. This means a computer converts the design produced by Computer Aided Design software (CAD), into numbers. The numbers can be considered to be the coordinates of a graph and they control the movement of the cutter. In this way the computer controls the cutting and shaping of the material.
Different machines require different file types in order to produce cut profiles, 3D prints or etched & engraved images.
Laser Cutter / Etcher
Laser cutters/etching machines are capable of very accurate work as a laser is used to etch or cut material precisely. The pathway of the laser is defined by a vector for profile cutting or etched linework (text for example). When etching an image a raster image can be used, the results depending on resolution of the image.
Our laser cutter can cut up to 18mm Acrylic or wood.
Capacity: 1400mm x 900mm.
Required file type: .dxf for profile cuts or etched linework, .bmp for etched images.
3D designs produced in CAD software (or downloaded from the internet) can be sent to the 3D printer software. The software then controls the printer building the model by calculating where to deposit material one layer at a time. The printer automatically manufactures an accurate and realistic model by adding a layer of resin to the model at every pass of the print head.
Our machine’s capacity: 140mm x 140mm x 135mm.
Required file type: .stl, .obj.
Routers can cut profiles from a .dxf file, or carve 3D models from an .stl file. All designs require setting up for machining in a tooling setup program prior to machining. Larger 3D forms can be made by splitting a form into layers the same thickness as the material and re-assembling these after machining.
Our machine’s capacity: 2440mm x 1220mm x 120mm.
Required file type; .dxf for profile cuts e.g. cut plywood shapes, .stl for 3D forms e.g. sculptures & moulds.