7. Computer controlled machining¶
Group assignment:
- Do your lab’s safety training
- Test runout, alignment, speeds, feeds, materials, and toolpaths for your machine
Individual assignment:
- make (design+mill+assemble) something big (~meter-scale)
- extra credit: don’t use fasteners or glue
- extra credit: include curved surfaces
Have you answered these questions?
- Linked to the group assignment page
- Documented how you designed your object (something big)
- Documented how you made your CAM-toolpath
- Documented how you made something BIG (setting up the machine, using fixings, testing joints, adjusting feeds and speeds, depth of cut etc.)
- Described problems and how you fixed them
- Included your design files and ‘hero shot’ photos of final object
What I’ve done this week¶
Group assignment:
Individual assignment:
-
CAD Fusion360
-
CAM vcarve
-
ShopBot
FabLab Kuriyama does not have a large CNC, so we went to FabLab Minatomirai to rent a ShopBot for this assignment!
ShopBot Room
CAD Fusion360¶
Modeled the following in fusion360. This is going to be used as a platform to place a trash discriminator
Parameters were set as follows
In our group work, we found just the right fit for a 15 mm lumber-core, and since I wanted a tight fit, I set the joint clearance to 0.25 mm
used doyo-sensei’s Kerf Check Parts Generator that we used in week03.
Exported the dxf file to be opened in VCarve (CAM).
In this case, there are three types of parts: base part, column part, and joint part, so each part was exported as a dxf file.
This time, instead of mods, I used vcarve-pro
CAM vcarve¶
VCarve display is largely divided into drafting part and toolpath setting
The following is the vcarve settings used in this assignment
First, configure Job Setup
Job SetUp
| Job Type |
|---|
| Single Sided |
Same as group work, I used a lumber core of 1830 mm × 916 mm × 15 mm, so adjust the values to the size of the material
| Job Size | ||
|---|---|---|
| Width (X) | Height (Y) | Thickness (Z) |
| 1830 mm | 916 mm | 15 mm |
| Z Zero Position |
|---|
| Machine Bed |
| XY Datum Position |
|---|
| lower left |
Material SetUp
The default value for clearance is 5mm, so if the material is bent or warped, the mill could hit the material while moving So, set it to 15 mm
| Rapid Z Gaps above Material | |
|---|---|
| Clearance | plunge |
| 15 mm | 5.08 mm |
2D Profile toolpath
Set “start depth” to 0mm because it refers to the position of the surface of the material to be processed.
“cut depth” is set to the thickness + 0.3 this time because it may not be possible to cut the material if it is just 15mm thick, depending on the condition of the machine.
| Cutting Depth | |
|---|---|
| Start Depth | Cut Depth |
| 0 mm | 15.3 mm |
Cutting depth is set at 15.3mm, so 3.825mm can be cut off in one cut, making a total of 4 cuts.
| Number of Passes |
|---|
| 4 |
Tool:
Click “Select …”
| No Flutes |
|---|
| 2 |
As in the group work, I used a mill that consists of 2 flutes, downcut
| Cutting parameters | |
|---|---|
| Pass Depth | Stepover |
| 0.25 | 0.1 inches, 40 % |
The instructor said that “Pass Depth” should theoretically be the same value as the diameter, but it should not exceed this value because if it is larger than this, the material and the machine will be overloaded!
| Feeds and Speeds | ||||
|---|---|---|---|---|
| Spindle Speed | Feed Units | Chip Load | Feed Rate | Plunge Rate |
| 16000 r.p.m | inches/sec, | 0.0047 inches | 2.5 inches/sec | 1.25 inches/sec |
“Feed rate” was set to “inch/min” by default, but changed to “inch/sec” because it is difficult for beginners to understand
“Chip load” is the amount of material that the blade shaves off at one time. “Chip load” is recommended between 0.001 inches and 0.01 inches.
Instructor told that I should rely on the sound of the grinding rather than the tip load
The “plunge rate” is half of the “Feed rate”, which is the recommended value
| Machine Vectors |
|---|
| Outside / Right , Climed |
Standard router bits rotate clockwise. If it moves along the left side of the line, it is a downcut (Climb); if it moves along the right side of the line, it is an upcut (Conventional).
Downcuts are preferred on CNC routers. It is cleaner because it reduces cracking and splitting of the material.
| Add tabs to toolpath | ||
|---|---|---|
| □ | Length | Thickness |
| ☑︎ | 10 | 5 |
Tabs should be set to 1/3 of the material
Edit tabs => Select one edge of the target vector image
When attaching tabs, follow the grain of the wood to make it easier to remove them.
Tabs thickness should be 1/3 the thickness of the material thickness
| Add tabs to toolpath | |
|---|---|
| Length | Thickness |
| 10.0 mm | 5.0 mm |
Next, created a toolpath
Following the same procedure as the group work, “Profile Toolpath” was selected for the rack parts, and “Drilling Toolpath” was used for the drilling of the screw markers.
If there is a pass in the area where the screws are fastened, it will lead to a serious accident.
Need to make sure it’s done right.
ShopBot¶
Same procedure as group work, cut with shopBot
Kamakura Group Assignment Week07
Cut the tabs and sand the surface.
Done🔥
What I learned¶
-
Since it was my first time to use a large CNC like Shopbot, I was worried about whether I could handle it safely, but thanks to the instructor’s careful guidance, I was able to make it successfully.
-
It was very interesting to actually create something over 1 meter high.
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I would like to continue learning about large CNC in order to create chairs and bookshelves for use in the lab at the new Fablab Kuriyama.