Patricia Samudio :: Fab Academy 2023 ::

Computer-Controlled Machining

On the CNC space exploration day, the instructor gave an orientation on safety rules and initial handling of the ShopBot PRSalpha machine, which is available for large jobs. In the same isolated space, another machine is also available for small jobs, such as PCB boards. In this case it is a Roland Modela Pro II MDX-540.

Safety recomendations

When working with the ShopBot, it is recommended:

Wear earmuffs
Wear eye protection
Wear a face mask
Wear tight-fitting clothing and closed shoes
Wear gloves when inserting/removing material
Use the machine with the cabin closed (because of the noise)

What to avoid:

Use scarfs, earrings, collars, nothing pendant
Put your hands inside the work bed when the machine is working
Use the machine alone, always with an instructor present
Use the machine tired, in a hurry, ill or in a bad mood

For the general characterization of the ShopBot, we relied on information from CIDI FabLab's 2022 generation website.

To operate the machine, first activate the air compressor by placing the handle in the vertical position. Then turn it on. Next, adjust the cutter by removing the key from the machine. To do this, turn the red knob and activate the key (turn them off). Remove the key.

Task

Link to the group assignment page.

Document how I designed my big object.

Document how I made my CAM-toolpath.

Document how I made something BIG.

Describe problems and how I fixed them.

I include files and 'hero shot'.

Challenges

Grupal:

Complete your lab's safety training.
Test runout, alignment, fixturing, speeds, feeds, materials and toolpaths for your machine.
Document your work to the group work page and reflect on your individual page what you learned.

Individual

Make (design+mill+assemble) something big.

Big Object. Process of desing and production

To realize my "big" object, I decide to design a piece of furniture, including a small seat or stool. This piece of furniture will be part of the furniture in the workspace I have in my house.

First I take the measurements of the space it will occupy, and then I move on to CAD processing of the sketches using Fusion 360.

Sketches.

As this is my first experience designing and producing, myself, a 'big' object, I decide to start with the production of the simplest object: the stool 😅. Use 12 mm thick MDF type wood, available from FabLab. Below you can see the process developed in the chosen application. To realize it, I relied on some videotutorials (view Side bar menu).

Once the drawing is finished, I generate .dxf files for each part (three: two legs and a seat), I use DeepNest to prepare the nesting of the parts for cutting.

After generating the file, I determine the parameters for processing in a VCarve software, indicating type and thickness of material, type of milling cutter, the passes and speed, as well as the depth of cut.

Toolpaths

To manufacture the stool, I used the following toolpaths:

Milling cutter: 6.35 mm
Number of slots: 2
Depth of pass: 1 mm
Spindle speed: 10 000 rpm
Feed speed: 2500 mm/min
Number of tools: 1

As for 2d profile toolpath:

Depth of cut: 15.0 mm.
Machine vectors Inside/Left with conventional direction activated.
I added tabs with a thickness of 3 mm to prevent the parts from moving when cutting.