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7.computer-controlled machining#

hero shot#

0.preparation#

0-1:assignment check#

group assignment#

For more information, please click here. https://fabacademy.org/2025/labs/kannai/Weekly_Group_Assignment/week07/

individual assignment#

individual assignment

  • make (design+mill+assemble) something big (~meter-scale)
  • extra credit: don’t use fasteners or glue
  • extra credit: include curved surfaces

0-2:process#

1. Concept and visual design#

I needed a desk at home, so I thought I would make one.

Requirements#

A desk that is easy to sit at and does not interfere with environmental functions.

Conditions#

Since it will be placed next to the freezer, the desk top needs to be partially foldable.

2. I drew a simple picture.#

3. Modeling.#

I added a lot of features to the desk. It’s the ultimate desk I came up with! This desk is designed to ensure strength and flexibility without joining with bolts. Therefore, it is easy to disassemble.

  • A. “Mortise and tenon joint,” “miter joint,” and “rabbet joint” are used to reinforce the joint between the support column and the legs.
  • B. The colored parts can be stored so that they stick to the other leg with hinges.
  • C. The left top board can be removed, and the left leg can be stored on the right side.
  • D. A stopper is set so that the left leg does not stick out too much when it is extended.

This time, we will cut a 2m lumber and cut out each part. Therefore, it was helpful to be able to decide on the placement in advance.

4. Prototyping with a 3D printer#

A small prototype was created in advance using a 3D printer to examine whether there were any problems with operation or construction.

  • Normal: The desk will be 70cm wide.

  • It can be expanded to become a 120cm dining table.

  • Normal state(back side)

  • When expanded(back side)

    the panel in between can be expanded and contracted to support the expanded top board.

5. Securing materials#

1. Call Cainz#

There was no wood in stock that met my requirements, but it turned out that I could get it in time by ordering it from the online store.

The wood I purchased is from the following sources
![](../images/07_week07_image/cainz_mokuzai_en.webp)

Pine laminated wood 2100 x 500 x 25mm (16kg) x 2 = 32kg ! So heavy...

2. Simulation of the day#

Purchased a dolly for transportation.

https://www.amazon.co.jp/dp/B0BM9K1GFX?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1 -

1.CNC on the day#

1-01:Preparation#

  1. Output the data in SVG using Shaper Utilities.

  2. Convert SVG to AI file

    Warning

    SVG files can be read into cam tools, but the size will be changed, which requires a lot of processing. Therefore, it is better to handle it as an AI file.

    Ai files are available in different versions; since the PC OS on which CNC is running is WindowsXP, it is recommended to use the oldest version possible.

    Note

    that ai(ver2) was only rewritten from ps(PostScript) to ai extension. Therefore, by converting svg to ps file and rewriting the extension from ps to ai, users who do not have Illustrator can also convert.

    How to convert SVG to AI file (assuming you are a mac user)

    1. install Inkscape. 

      brew install --cask inkscape

      Warning

      Only Inkscape installed via command can be operated via command. If you already have Inkscape installed via something other than the command, uninstall it and then run the install command.

    2. run the command. 

      inkscape input.svg --export-filename=input.ps
mv input.ps input.ai

      Note

      The first time you run the command, Inkscape may run a validation. Therefore, it will take a little time only the first time.

  3. Search for CNC tool parameters for wood

    • What we will do is create a 5cm square inside a 10cm square and cut it out. The inner square remains connected to the outer square by tabs.
    • Measure the cut wood and check the wood’s specific karf and clearance.
    • Adjust the drill parameters and drill operation taking into account the karf and clearance at this time. The modeling may also need to be changed parametrically as necessary.
      • Example: 6mm drill cut at 6mm > 6.03mm (karf_0.03)

6. Check the dimensions of the wood#

Measure the length, width, and thickness of the wood.

Even if the store cuts it for you, there may actually be some errors. Also, be sure to check for any warping that may occur due to humidity, temperature, season, or material.

Note

It is convenient to write the length in mm with an arrow when doing CNC work.

See arrow 1 in the image for a specific image.

1-02:Create a G-code file with cut2d#

Use software:cut2d 1. Load the target data and decide on the placement of the target.

Note

If you are not used to it, it is better to cut out each part separately. This is because if the drill breaks, the screw comes off, or an unexpected operation occurs, it will be difficult to start over from the middle.

  • Adjust the cutting depth

    Adjust the cutting depth

  • Determine the drill path

    Warning

    Be careful not to place the screws on the drill path. If the screw and drill collide, the drill may break.

1-03: CNC operation#

  • Used CNC control software: mach3

  • Place the material on the CNC

  • Align the Y, X, and Z axes to the left edge of the material.

    • It is best to set the X, Y, and Z axes to the Zero point at this time.

  • Adjust the tilt of the material

    • Raise the Z axis slightly and use only the X axis to bring it to the right edge of the material.
    • Adjust the tilt so that the position of the material at the right edge is equal to the drill on the X axis with the left edge of the material fixed.

  • There is wood underneath the CNC for fixturing, and we’ll secure the material here with screws.

  • Secure the material to the CNC table. The proper fixturing method directly affects machining precision.

CNC machining fixturing method

  • First, load the G code to drill the screw holes.

  • Operation screen

    • Load G-code
    • Movement speed can be adjusted
    • Rotation speed can be adjusted

  • Check the material fixation method. Make sure the material is securely fixed.

  • During processing. The drill makes contact with the material and cutting begins.

  • You can see the actual machining process in this video. The drill movement and cutting progress are visible.

Warning

    • If you make complicated movements with the drill moving at high speed, the drill may break. Slow down the movement speed when complicated movements occur.
    • The drill may break if the drill moves too fast. Be careful.
    • If the drill rotation speed is too high, frictional heat may cause the sawdust to ignite. Set the speed carefully, taking into account the hardness of the material.

  • Check that there are no materials other than the material on the table before running

    • Take NG and OK patterns
  • Make sure to put the cursor on “stop” immediately after starting so that you can stop immediately if something happens.
    • If you press the reset or emergency button, the operation will stop, but you will not be able to restart from the middle.
  • Once the CNC work is complete, tighten the screws.
  • Load and run the G-code to excavate the material.
  • A large amount of sawdust will come out. Clean it up with a vacuum cleaner from time to time to prevent fire.
  • Remove the screws and clean up the sawdust with a vacuum cleaner.

Outer edge processing#

  • Remove the tabs with a chisel.
    • If the convex surface is large, the filling work afterwards will not go well. Try to remove the convex surface at this point.
  • Remove the burrs with a file. Since you will be filing again after this work, it is enough to remove the burrs to the extent that you will not get injured when holding it.
  • Use a router to fill
    • Use a router fence to assist with straight lines.

A. Router fence

B. Router

C. Power switch

  • Touch it with your hand and sand any areas that feel rough.
  • Since there are some places where hinges will be attached, install them with a screwdriver.

  • Assemble and you’re done!