Week 8:

 Computer-Controlled Machining


I have this week worked with computer-controlled machining and completed the following:

  • Test-cutted parts for a small scale mockup.
  • Test-cutted parts for a full scale prototype.
  • Contributed to the group assignment with observations about:
    • The kerf - what is removed
    • The runout - difference kerf and tool size.
    • The alignment - skewing og abnormalities.

Safety Incident:

A wrong z-zeroing position in the material setup in VCarve caused contact between the collet/spindle head and the material, which caused friction and a spark that ran through the exhaust tube - which of cause made med press the safety bottom that stopped the job. I corrected the setup error and reran the job 15 minutes later, during which the dust collector caught fire (more about this at the bottom of the page).

Using the ShopBot Milling Machine
Preparing Toolpath for the Milling Machine

Preparing Toolpath In VCarve

I used my parametric design created in Fusion 360 - which I adjusted to the thickness of the material and exported as a .dxf-file. I then completed the following steps in VCarve:

  • Create new file.
  • Setup Material (Size, Z-zero, X/Y-datum).
  • Import and arrange design-files (.crv, .dxf, .dwg, .esp, .ai, .pdf).
  • Use toolbar to modify design (Add fillets etc.).
  • Select and setup desired toolpath type (Profile, Drilling etc.).
  • Preview and save toolpaths (.sbp).
  • Place the toolpaths on computer attached to the milling machine.
The error that cause the above mentioned incident was related to the Z-zero in VCarve (more about this at the bottom of the page).


I modified the tool path by adding fillets - as Dog-Bones with a radius of (1/4"/2 = 25,4 / 4 / 2 =) 3,1mm and Tabs - and the used the following setup for the tool paths:

Settings: Profile: Drilling:
Tool: 1/2" Straight, End Mill 1/8" Tapered Ball Nose
Code: (48-072) (77-102)
Flutes: X X
Cut Depth*: 1/2" 1/8"
Spindle Speed: 12.000RPM 12.000RPM
Feed Rate: 3"/s X
Plunge Rate: 1"/s 1/8"
Calculated Chip Load: XX XX

*Neil pointed out one should think about both about tool, collet and spindlehead when setting the maximum cut depth.

When saving the toolpath VCarve informed me about the presence of '14 Unsuitable Open Vectors and 5 Duplicate Vectors'. I decided to groom the imported files by joining unintentional open vectors and deleting duplicate vectors. Afterwards the tool path saved without any warnings.

Grooming the File
Preparing the Maschine

With the software side of the preparation complete it is now time to setup the machine to execute the job:

  • Level, square and clean the sacrificial layer.
  • Place and fix the material (I used MDF).
  • Inserting Tool (check that the collet is clean).
  • Reset safety buttoms inside, turn maschine and extraction on.
  • Close door, Reset Door/Safety, Reset Shopbot.
  • Update X&Y axis, then update and raise the Z-axis.
  • Set appropiate user X&Y axis.
  • Warm up spindle (takes 9 minutes).

Running the Milling Machine

I decided to make my first machined piece a scaled version (1:2,5) of my idea for the final design - which I had previously fabricated on the lasercutter in smaller scales (1:10 and 1:5). My first cut worked like a charm. I thus decided to prepare a toolpath for full size prototype of my idea for the final design.

  • -

Correcting Z-Zero Error i V-Carve
Latest Edition in the Prototype Development
Beginning to look like a Final Project!

See more

Read about the milling process in my weekly assignment about Molding & Casting.

Safety Incident

Consequence of Erroneous Z-Zero Setting
Smoke from Fire In Dust Collector
Fire Fighters Arriving
The fire was confined to the dust collector. The room with the ShopBot is sooted.
Made it to the Local News