Sample Package v1.3

Purchase list

1. Copper rod stock

   Superconducting 101 copper rod, Diameter = 1.5"

   https://www.mcmaster.com/8965k75

2. Screws for fastening (4 for each)

   #4-40 Brass socket head screw, Length = 5/8"

   https://www.mcmaster.com/93465a111

3. Screws for mounting (2 for each)

   #4-40 Brass Pan Head Phillips Screws, Length = 1"

   https://www.mcmaster.com/94070a115

4. Nuts for mounting (2 for each)

   #4-40 Brass hex nut, Width = 1/4", Height = 3/32"

   https://www.mcmaster.com/92671a005

5. Screws for thermalization (1 for each)

   #4-40 Brass socket head screw, Length = 1/4"

   https://www.mcmaster.com/93465a106

Milling procedures

These G-code files are generated in a certain order. Particularly, I assume that the milling procedures are performed before the drilling ones.

The way I name the files:

1. The first letter:

    x: Stands for the top part
    y: Stands for the bottom part
   

2. The second letter:

    t: Stands for the topside of the part
    b: Stands for the bottomside of the part
   

3. Letter "c" indicates that this file is for center drills

4. The numbers indicats the tool to use.

Top, Topside

1. Pockets: 3/32" End Mill

    xt332.txt
   

2. Center Drills

    xtc43.txt (Z = -0.015")
    xtc32.txt (Z = -0.135")
    xtc3mm.txt (Z = -0.135")
   

3. #4-40 tapped holes: #43 Drill Bit

    xt43.txt (Z = -0.620")
   

4. #4-40 close fit: #32 Drill Bit

    xt32.txt (Z = -0.620")
   

5. #4-40 mounting holes: 3mm Drill Bit

    xt3mm.txt (Z = -0.620")
   

Top, Bottomside

1. The pocket: 3/32" End Mill

    xb332.txt
   

Bottom, Topside

1. Open pocket: 3/8"" End Mill

    yt38.txt
   

2. Pockets: 3/32" End Mill

    yt332.txt
   

3. Center Drills

    ytc45.txt (Z = -0.015")
    ytc43.txt (Z = -0.055")
    ytc2p3.txt (Z = -0.105")
    ytc3mm.txt (Z = -0.055")
   

4. Post pockets: #45 Drill Bit

    yt45.txt (Z = -0.0667")
   

5. #4-40 tapped holes: #43 Drill Bit

    yt43.txt (Z = -0.300")
   

6. Coaxial holes: #42 Drill BIt

    yt40.txt (Z = -0.300")
   

7. #4-40 mounting holes: 3mm Drill Bit

    yt3mm.txt (Z = -0.300")
   

Bottom, Bottomside

1. Pockets: 3/32" End Mill

    yb332.txt
   

Guidelines for CNC machining (Bridgeport EZTrak)

Workflow

1. Design the part using SolidWorks.

2. Generate the toolpaths using the built-in SolidWorks CAM.

3. Generate the G-code files using a post processor named "EZTRAK_G.ctl". One G-code file corresponding to one toolpath only (without tool change operations).

4. Use the python scripts to modify the generated G-code files.

Compatibility

The machine is old, which means certain G-code commands are not recognized by this machine. The known examples include:

1. Drilling commands like G81, G83

2. Tool radius compensation commands like G40, G41

In order to bypass these commands, we use python scripts to modify the G-code files generated by the default "Drill" and "Center Drill" operations in SolidWorks CAM.

Milling

We do both roughing & finishing procedures.

1. Spindle

    Spindle Speed = 2400 rpm
   

2. Feedrates:

    XY Feedrate = 8 in/min
   
    Z Feedrate = 4 in/min
    
    Leadin Feedrate = 4 in/min
   

3. Side parameters:

    Allowance = 0.01 in
    
    Stepover = 80%
   
    Wedge Machining: True
   

4. Depth parameters:

   a. For roughing

    Bottom Allowance = 0 in
   
    Island Allowance = 0 in
   
    First Cut Amount = 0.02 in
   
    Max Cut Amount = 0.02 in
   
    Final Cut Amount = 0.01 in
   

   b. for finishing

    Allowance = 0 in
   
    First Cut Amount = 10 in
   
    Max Cut Amount = 10 in
   
    Final Cut Amount = 0 in
    
    (The value "10 in" can be as large as possible)
   

5. NC

    CNC Compensation: OFF
    
    (This prevents the program from producing G40 and G41 codes.)
   

Drilling

We do centering before drilling. G-code file for both procedures are modified by the python script "modify_gcode.py". Spindle and feedrate parameters are the same as used in the milling procedures.

1. Center Drill

    Center Drill Depth = 0.015 in
   

2. Drill

    Add Tip Length: True
   

3. Pecking (This parameter is defined in the python file "gcode-tools.py")

    Pecking Depth = 0.050"
   

Related projects

1. A new sample rack and a new copper bucket for our new fridge