Week 7: Computer Controlled Machining

The assignment:

1. Group assignemt: LINK

2. Individual assignment: Make (design+mill+assemble) something big

Designing a bedside table in Fusion 360

The material, a plywood board, that was given to us had these dimessions: 2500x1250x15

To demonstrate that I can design something with dogbone joints I designed a bedside table in Fusion 360.

I wanted the design to be mostly parametric, so I set up these parameters:

1. The thickness of the material = 15mm.

2. The height of the seat = 457mm.

3. The diameter of the seat = 355 mm.

4. The width of the legs = 100mm.

5. How far the outside of the legs are from each other. (Footwidth: half of the seat diameter + 1/8)

6. And the tool diameter for cutting out the dogbones: 6mm

First I made a construction plane in seatheight where I made a sketch of the seat that I then extruded and added fillets to make it less sharp.

Then I made a new component for leg 1. With the line tool I drew the leg and added vertical constraints and made some of the lines colinear with the ground and the seat and added some of the dimensions from the parameters. At last I mirrored the leg to finish the sketch.

Then I started a new component and sketched the other leg on top of the first. At last I rotated it and used the combine function

The I used the joint function to lay out the components

and added dogbone joints using the dogbone feature in Fusion 360.

The Fusion file is here

……I exported it as *dxf to open it in RhinoCam to setup the machine and get it ready for milling.

The DXF file is here

Why CAM/CNC

Keywords are: - Automation - Accuracy - Flexibility

In the Lab we have a CNC Raptor XLS .The machine is setup with a router bit that is held in the router with a collet. We are using plywood for our BIG design, but you can also use other materials like mdf, cork, hard wood or polycarbonate, acrylics, nylon, wax etc.

When preparing the file it is a good idea to nest the different shapes in order to optimize the use of material and the production time. I use Deepnest.io and RhinoNest for this.

Setting things up in RhinoCam

In class we where instructed to use RhinoCam for the CNC Raptor XLS. As I had to work from home (Denmark) for this weeks assignment I used a evaluation version of both Rhino and RhinoCam. RhinoCam comes with these limitations:

In order to learn more about the software I set up the machine and the tools for the drill and milling procedure in this version.

To get started there are 2 things to set up.One is drilling of the markings for the screws that hold the material down and the other is the actual milling process of the design.

This is how I set things up for marking the drill holes:

Set the origin of the tool and insert the size of your board/ material

First place the holes for the screws to hold down the board (in Rhino use Points and then place them)

Then use “machining Operations” to tell the machine where to drill

Create a new tool and set the properties

Feeds and Speeds

Note that the speed is 1800 RPM and cut is set to 3000

Clearence Plane

By setting this to 30 you should be on the safe side.

Cut parameters

The depth is set to 3mm for every pass.

Sorting

At last click “Generate”

Next choose “ Machine Operations” and profiling to create a toolpaths for cutting along the outline

Control Geometry

Here you select the curves or faces that you want to mill.

Cut parameters

Here you set the cut direction where you can choose between upcut or downcut. I use downcut for plywood. In general you can say that upcutting is better for getting out the chips and for roughing, while downcutting is better for getting a cleaner surface finish You also choose wether you want to cut on the outside or the inside of the vector.For my design I will use both cuts – outside the closed vector for the body and the wings and inside the closed vector for the eyes, the shapes in the wings and the holes in the body. I am not going to cut on the line, - but I think this possibility could be useful for engravings.

Cut levels

For the total cut depth I go for 15,4 as my material is 15mm and I want to make sure that it cuts all the way through.

Entry/Exit

Advanced Cut Parameters

Here I choose 3 bridges/tabs and a rectangular shape.

I will continue documenting the rest of the process when I get back to the Lab

Back in the Lab I set up RhinoCam and one of the instructors looked through the G-Code together with me

Ready for milling

First we used the broom to clean the surface of the machine

Find the right drill

Tip: turn the drill clockwise and notice the reflection in the rotation. This one is a downcut drill.

Insert the drill with the tools for it.

Now set X,Y,Z – same as the Roland milling machine Make the drill for screws. Stop and screw down the material Set the Z axis again. Now the material is lying flat.

Fire!!

After assembly this is what the bedside table looked like

Another design idea (old stuff)

I designed a new version of the visualization of a bee that I might use for my final project. First I made a design in Inkscape using the techniques I learned week 2 Inscape

I wanted to make a front, a back and the wings in between. 3 layers. I might need the wings to move later – you never know. As we were told to go big the dimensions of the bee will be height: 100cm and width: 100 cm Then I saved it as an *.dxf and imported it into Lightburn to make testcut on the lasercutter.

First I cut out a small version in cardboard so I could get a hands-on feel for how I could assemble it.

I made some adjustments on the wings in Inkscape to reduce weight of the big version and make it look more interesting. Then I went for 6mm plywood and cut it out using these settings.

The size of this version is 180mm x 270mm

For assembly I used glue because at this point I still didn’t know which solution for assembly I was going for. (First idea is to use a roundstick (when going big) to go through the 3 layers using the holes in the cut-out to hold everything together that way.)