Practice Test Geeks(CNC) Computer Numerical Control Machinist Technical Practice Test
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CNC Mill Setup & Operation Flashcards

7 cards from real CNC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 CNC Mill Setup & Operation flashcards as text

  1. A part drawing calls for a slot tolerance of ±0.001". After milling, measurement shows the slot is 0.003" too narrow. Which corrective action is most appropriate?

    Answer: Adjust the cutter diameter offset (wear offset) to remove additional stock

    Increasing the wear offset value by half the total error on each side allows the control to reposition the cutter path outward to widen the slot.

  2. What does the M08 miscellaneous function command do?

    Answer: Activates flood coolant

    M08 turns on flood coolant; M09 turns it off, and M07 is typically mist coolant.

  3. When tramming a CNC mill head, what condition are you correcting?

    Answer: Spindle misalignment (tilt) relative to the machine table surface

    Tramming aligns the spindle axis perpendicular to the table by sweeping a dial indicator in an arc and adjusting head tilt until the reading is consistent.

  4. What is the purpose of a G28 command in a CNC milling program?

    Answer: Returns all axes to the machine home (reference) position

    G28 commands the machine to travel through an intermediate point and then return to the machine reference (home) position.

  5. Which cutting parameter most directly controls surface finish quality in CNC milling?

    Answer: Feed per tooth (chip load)

    Feed per tooth determines the theoretical scallop height; reducing chip load generally improves surface finish, especially on finishing passes.

  6. In CNC milling, what does SFM stand for and how is it used?

    Answer: Surface Feet per Minute — used to calculate proper spindle RPM for a given cutter diameter and material

    SFM (Surface Feet per Minute) is the recommended cutting speed for a material; RPM = (SFM × 3.82) / cutter diameter in inches.

  7. A program block reads: G91 G01 X1.5 Y-0.75 F10.0. What positioning mode is active?

    Answer: Incremental positioning from the current tool position

    G91 activates incremental mode, so X1.5 Y-0.75 moves the tool 1.5" in X and 0.75" in the negative Y direction from wherever the tool currently is.