# Week #7 COMPUTER CONTROLLED MACHINING

## Week workflow

This is how I see my week

• SolidWorks
• Rhino
• Rhino CAM

## Decide what do I want to make

### A vermi-composter

I decided to use an already designed model for a vermicomposter designed to be made from a single sheet of wood with CNC-routable. AKER.me, proposes the sources files on Github . This wormhouse will be very helpful for cultivating worms or black flies to feed the fish in the aquaponics system.

## Parametrisized the 3D model

Having the 3D and Nesting model from Github was not suffisant since the files were for a certain thickness of a certain kind a material (i.e. plywood). At the Green Fab Lab we had to use OSB, so I had two choices

:
• Restart the design from scratch, taking into account the thickness of the material
• Having a good fabacademy friend knowing how to parametrisized a 3D model
• ### STEP 1: Mesure the thickness of the material

Fig.1: Mesuring in different parts to ensure we have an homogeneous thickness

Fig.2:Our OSB is 15 mm

For the parametric design I will need:

• Thickness
• Mill bit diameter
• Clearance gap
• ### STEP 2: Find out the right clearance gap for our joints using GrassHoper

We want to make sure that our hole is a little bit larger that the thickness of the other part of the joint.

`Definition: Clearance : space between male a female part of of joint`

To find the right clearance, Gregoire (another Green Fab Lab academy student) generate with Grasshoper a file with several tests that increase the clearance value of 0,25 mm delta from -0,25 mm to 2 mm

Fig.3:Generating a clearance gap increase of 0,25 mm delta from -0,25 to 2mm

Fig.4:Identifying the 0,25 mm clearance

```Result:
With a clearance gap of 0 mm or 0,25 mm, our jointr fit nicely.
As the joint system of the wormhaus model is made with dowels, the 0,25 mm seems to be the most adapted.```

Fig.5:Worhaus joints with the right clearance gap

### STEP 3: Using Solid Works to parametrisized the 3D model

As I still don't have Solidwors, Gregoire (another Fab Academy student) helps me to parametrisized the wormhaus using the following parameters.

Fig.6:Variables used for the parametric design

We then exported a .dxf that I will be able to work on with Rhino.

Fig.7:Solidworks.dxf file imported on Rhino

### STEP 4: Import Nesting in Rhino

Create differents layers that will serve as the strategy to follow in the CAM process.

```Layers terminology
- Pocket Xmm: is a zone where you need to mill an extra layer and this As there is many different depths, a good tips is to associate one color / one layer = one depth >>> create a layer called "10 mm pocket"
- Inside Profile:The edge of the millig bit is from inside
- Outside Profile:The edge of the millig bit is from outside
- Engraving:The edge of the milling bit goes along the line indicated. Good to know for engraging.
- Screw: They help to ensure that you plywood is flatten. Put them on a separate layer >>> The more pin down the better to ensure you have a flat surface. Always good to triangulate the screw. Othgerwise you buy a vacum machine
- Tabs: Help to avoid flying parts
- Peck drilling: Drilling zone```

#### Starting by defining the stock perimeter

We will work with an 15 mm OSB sheet of wood of (width: 1250mm x lenght: 2500mm. This is the first part we need to draw for our nesting.

Fig.8:xxx

#### Profile - inside // Dog Bones

How to make rectangular hole ? The milling bit can't do a 90° corner, so we need to design what we call "Dog Bones" by creating put a curvature in the corner.

Fig.9:xx

To do them properly, you need to consider the mill bit diameter (in our case it's 6 mm), the right strategy is NOT to put the circle center on the corner but the extremity on the corner to enable the milling bit to pass

Fig.10:xx

Fig.11:Profile inside

Fig.12:xx

xx

#### Pocket 7.75 mm and 9 mm

Fig.13:xx

Fig.14:xx

Our local guru, recommends to do pockets a little bit larger than the edge "offsetting the pocket" so that after during the "outside profile" you will get a nice / plan oustide cut.

Fig.15:xx

Fig.16:xx

#### Screw

Triangulation

Fig.17:xx

#### Make sure every curves are closed

`Use "Selopencrv" command`

Fig.18:xx

#### Make sure every curves are on z = 0

Fig.19:xx

`I think we are ready to go !`

### STEP 4: Using Rhino CAM to generate tool path and export as Gcode

Before doing the entire job, I will do a first test milling only one stackable level to test if all the joints are OK

Fig.20: Joint 1, Joint 2, Joint 3

```Workflow
1. Open Rhino CAM
2. Defining the Bounding box strategy
3. Defining Pins downs strategy
4. Defining Inside profiling
5. Defining Pocketing strategy
6. Defining Drilling strategy
7. Defining Outside profiling strategy
```

#### Defining the Bounding box strategy

```Stock
- Indicate the size of your stock /  copy model Bounding box
- Indicate the thickness of your sheet wood stock
- Press generate ```

Fig.21: Bounding Box

#### Defining Pins downs strategy

```Pins down layer
- Go to Machine operation
- Select 2 axis
- Select reference "select drill points // Select drill points & circle```

Fig.22

`Go on Pins down layer // select  objects  // press OK`

Fig.23: Selecting Pins Down layer

`Select tool / drill bit / 6 mm`

Fig.24/legend>

`Check Speed // Check sense of mill bit Clock-wise // Change speed to 20 000`

Fig.25

`Clearance : how heigh you want to go passing from one point from another one + press generate`

Fig.26:xx

`Sorting // Select minimum distance`

Fig.27 Selecting minimum distance option

` Press "Generate" `

#### Defining Inside profiling

`Go to Machine operation // Select 2 axis // Select Profiling `

Fig.28

```        Select "control geometry" /  remove all
Select "Select Drive / Containment Regions"
Go on your "Inside Profile" layer
Select objects
Press OK
Edit / Create / Select tool / Flat Mill
Check Speed
Cut parameters / "cut start side"
Check use "outside/inside...." / check "inside"
Cut levels
Total cut depth= 16
Rough depth = 5
Rough depth cut= 3 (to indicate that we will do 3 rounds)
Finish depth=1 (to finish)
Finish depth cut= 1 (to indicate that we will do 1 round)
```

Fig.29

```        Entry / exit point :
- Select None on the two sections ( VERY IMPORTANT to avoid error entry and exit offset and destroy the material + !!!)
Avanced cut parameters " Bridges/Tabs"
- Check "Create Bridges"
Sorting
- Minimum distance
```

Fig.30

`Press "Generate" `
`Add a picture of dark blue line and another one to show how to`

Fig.31: Dark Blue line

Fig.32: Option to resolve this problem

`Add a picture with resolution`

Fig.33: Option to resolve this problem

#### Pocketing

```        For Pocketing layer
Go to Machine operation
Select 2 axis
Select "control geometry" /  remove all
Go on your "pocketing layers" and "select  objects"  layer / press OK
Select your tool >  Edit / Create / Sellect tool:
Check Speed
Check sense of mill bit Clock-wise.
Cut parameters
Total cut depth=7.75
Rough depth = 6
Rough depth cut= 2 (to indicate that we will do 3 rounds)
Finish depth=1.75 (to finish
Finish depth cut= 1.75 (to indicate that we will do 2 rounds)
Entry / exit point :
- Select None on the two sections ( VERY IMPORTANT to avoid error entry and exit offset and destroy the material + !!!)
Sorting
- Minimum distance
Press "Generate" ```

Fig.34:xx

#### Outside Profile

```For "Outside Profil"
Go to Machine operation
Select 2 axis
Select "control geometry" /  remove all
Select "Select Drive / Containment Regions"
Go on your "Profiling" and "select all objects" on your holes layer / press OK
Select your tool >  Edit / Create / Select tool:
Check Speed
Cut parameters / "cut start side"
Check use "outside...." / check oustide
Cut levels:
total cut depth=16 (if stock thickness = 15mm)
Rough depth =12
Rough depth cut= 6 (to indicate that we will do 2 rounds) !!! If you have a 6mm drill you can go  to 6 mm rough depth) !!!
Finish depth= 4 (to finish)
Finish depth cut= 2 (to indicate that we will do 2 rounds)
Entry / exit point :
- Select None on the two sections ( VERY IMPORTANT to avoid error entry and exit offset and destroy the material + !!!)
Avanced cut parameters " Bridges/Tabs"
- Check "Create Bridges"
Sorting
- Minimum distance
Press "Generate"
```

Fig.35:xx

### STEP 4: Shopbot

```Workflow:
- Open software
- Turn on the key + button
- Check Emergency button
- Retry control
```

Fig.36:xx

Fig.37:xx

Fig.38:xx

Fig.39:Setting z=0

Load Gcode file // last check in the Gcode // Change MS speed

Fig.40:Changing the Milling speed directly from Gcode

Putting pins down // Make sure there is no gap between your sheet of wood and the sacrificial board

Fig.41

#### Results from test 1

The joint #1 and joint #2 (i.e. Fig.20) are fitting well.

Fig.42

However, the joint between X1 part and X2 part was to stretch

Fig.43

I will have to do another test increasing the pocketing value

I decided to give another function to thus stackable with my laptop

Fig.44: Creation of a new pocketing strategie with 8.6mm

#### Results from test 2

From test 1 results, I've done two changes in the pocketing and inside profiling value

`Change Pocketing value (to adress problem illustrated in Fig.43): From 7.75 mm width to 8.6mm width`
`Change the inside profiling from 15mm to 17 mm to ensure  `

Fig.45:

#### Final cut

To clean up every edge, a very usefull tool is sand paper

Fig.46: Your best friend to clean up your CNC object - sand paper

Fig.47: Every piece are ready to be assembled

Last surprise, an error of 4mm on the horizontal square avoiding me to assemble correctly the stackle. To adress this issue I decide to use an XXX

Fig.48: Adjusting the 4mm error with a XXX

And after this long week, and multiple surprise, here we go !! a vermi composter

Fig.49:

Fig.50: The aquaponic system welcome it's new friend.

### Final Project evolution

Fig.51: After installing the LED lighting system + build a shelve structure from CNC left-overs

• 50 DIGITAL WOOD JOINTS
```Measure the material thickness at the beginning