This is how I see my week
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.
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:
For the parametric design I will need:
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
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.
As I still don't have Solidwors, Gregoire (another Fab Academy student) helps me to parametrisized the wormhaus using the following parameters.
We then exported a .dxf that I will be able to work on with 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
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.
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.
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
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.
Use "Selopencrv" command
I think we are ready to go !
Before doing the entire job, I will do a first test milling only one stackable level to test if all the joints are OK
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
Stock - Indicate the size of your stock / copy model Bounding box - Indicate the thickness of your sheet wood stock - Press generate
Pins down layer - Go to Machine operation - Select 2 axis - Select your type of strategies for your layer - Select reference "select drill points // Select drill points & circle
Go on Pins down layer // select objects // press OK
Select tool / drill bit / 6 mm
Check Speed // Check sense of mill bit Clock-wise // Change speed to 20 000
Clearance : how heigh you want to go passing from one point from another one + press generate
Sorting // Select minimum distance
Go to Machine operation // Select 2 axis // Select Profiling
Select "control geometry" / remove all Select "Select Drive / Containment Regions" Go on your "Inside Profile" layer Select objects Press OK Select your tool 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)
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
Add a picture of dark blue line and another one to show how to
Add a picture with resolution
For Pocketing layer Go to Machine operation Select 2 axis Select your type of strategies for your layer > "pocketing" 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"
For "Outside Profil" Go to Machine operation Select 2 axis Select your type of strategies for your layer > "Profiling" 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"
Workflow: - Open software - Turn on the key + button - Check Emergency button - Retry control
Load Gcode file // last check in the Gcode // Change MS speed
Putting pins down // Make sure there is no gap between your sheet of wood and the sacrificial board
The joint #1 and joint #2 (i.e. Fig.20) are fitting well.
However, the joint between X1 part and X2 part was to stretch
I will have to do another test increasing the pocketing value
I decided to give another function to thus stackable with my laptop
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
To clean up every edge, a very usefull tool is sand paper
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
And after this long week, and multiple surprise, here we go !! a vermi composter
You access and download all the files generated during this week from my google drive:
Measure the material thickness at the beginning Do several tests on your joints playing with different clearance before doing your final cut Parametric Design is key with CNC