Self-check

Passing this is part of the sign-off. Answers are under each question; think before you open them.

1. The file is loaded, you clicked OK on the spindle prompt and the gantry is moving toward the stock — but the spindle is silent. What do you do in the next two seconds, and what went wrong?
   Answer

   Spacebar now; E-stop if the bit is already in the stock. You clicked OK before pressing START on the pendant (or the key/output 1 was off). See the start sequence and E07, E09.
2. You press the E-stop halfway through a job. Which of X, Y and Z zero can you trust afterwards, and what must you do before restarting?
   Answer

   None. Release, pendant Reset, C3 to rehome, jog to the recorded job-origin coordinates and Z2 again, C2 for Z, then FG from a line before the stop. See Stops, E30.
3. C2 ran and reported Z zero, but the first pass cuts 2 mm too deep across the whole sheet. Name three possible causes and the test for each.
   Answer

   Wrong plate thickness in the settings (staff measure the plate and check TS); zeroed on the wrong surface for the file's &PWZorigin (read the header); bit slipping in the collet (witness mark on the shank, staff check after correct tightening). E05, E10, E32.
4. The second profile pass is 1 mm to the left of the first. The alpha drivers did not alarm. Why could they not have noticed, and where do you look?
   Answer

   The loop is closed around the motor shaft: a pinion that jumps teeth or slips on its shaft, or packed chips in the rack, move the gantry without the motor knowing. Look at rack teeth, pinion set screws, motor spring tension, roller wheels. E16–E19.
5. Your CAM file has Z0 at the material top; the lab convention for through-cuts is Z0 on the bed. What happens if you zero on the bed and run it anyway?
   Answer

   Every rapid and retract runs inside the stock and every cut goes a full sheet thickness into the spoilboard: crashed clamps, broken bit. Match &PWZorigin to the surface you touch, every time. E32.
6. You want 0.15 mm/tooth with a 6 mm two-flute at 14 000 rpm. What feed in mm/min? What plunge?
   Answer

   14 000 × 2 × 0.15 = 4200 mm/min; plunge at half or less, ≤ 2100 mm/min, ramped if possible. Feeds.
7. You pressed the spacebar to pause and want to check the cut. What must you confirm before your hand goes near the bit?
   Answer

   A spacebar stop is not isolation. Before reaching near the bit, confirm that the spindle has stopped, the interlock key is OFF and removed, the keypad is closed and no file is loaded or paused. Keep clear before re-engaging the key or restarting. Stops.
8. The part you are cutting out is 300 × 200 mm. List three ways to keep it from flying on the last pass, and the drawback of each.
   Answer

   Tabs (hand finishing); onion skin 0.25–0.75 mm (hand finishing, needs accurate thickness); screws through the part into the spoilboard (holes, must be clear of toolpaths). E22, E23.
9. What does the alphaStep driver's closed loop see, and what does it not see? Give one failure from each category.
   Answer

   Sees rotor position vs command: a stalled motor from a clamp strike alarms (E01). Does not see anything downstream of the shaft: a slipping pinion, a creeping bit, a moving sheet (E17, E10, E22).
10. After the job: name five things you do before you walk away.
    Answer

    Finish or stop the file and stop the spindle; raise Z and jog clear with everyone outside the cutting area; close the keypad, end the loaded/paused file and remove the key; clear and clean the deck and stow the bit; report faults. Leave the machine powered for lab staff. Users never power down the machine; E-stop is for emergencies.
11. Name the three buttons on our pendant and what each does.
    Answer

    Reset re-enables the drives after an E-stop (twist the E-stop to release it first); green Start starts the spindle (when output 1 and the key allow it); E-stop cuts spindle power at once and motor power about 5 s later. Stops.
12. Where does the Z-plate's clip go, and where does the plate go back to?
    Answer

    Nowhere new: the clip stays clamped on the aluminium carriage plate; the circuit runs through plate → spindle → collet → bit. The plate goes back in its holder on the YZ car with the lead coiled. Never put the clip on the bit or nut: the spindle whips it off.