ShopBot PRSalpha 144-60Prototyping Lab · University of Iceland
06 Something’s wrong
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06Something’s wrong

Something went wrong

Start from what you see. Stop first, diagnose second.

The machine stopped
Red LED on the box?“location no longer accurate”
Driver alarm E01clamp strike · packed rack · cable
Software frozen?controller disconnected
E-STOP now E02only it still kills the spindle
Spindle fault codeon the VFD?
Overload / overcurrent E36record the code
Position is lost after any alarm or E-stop.Staff clear the cause → Reset → C3 → re-zero (Z2 from your notes, C2) → FG from a line before the stop
Driver alarm · any VFD code · smoke · snapped or pulled bit → stop and call staff
Index

Start from what you see

Find what you see, not what you suspect. Each card names the most likely causes in order and links to the fault card (E-numbers in the next section) and, where the figure can act it out, to the figure key that plays it.

Everything stopped dead, red LED on the box, "location no longer accurate"
Alpha driver alarm. Stop and call staff; do not open the cabinet. Staff check the driver alarm and cause (clamp strike, packed rack, cable). After recovery, rehome and re-zero. → E01 · figure key 1
Software froze or says the controller disconnected; spindle still running
USB dropped: the PC went to sleep or the cable was knocked. Press an E-stop: the software can no longer stop the machine and the E-stop is the only control that kills the spindle. Then fix the cause, Reset, C3, C2, resume with FG. → E02 · figure key 8
C2 drives the bit into the plate and keeps going
Input 1 not seeing the touch: clip off, dirty plate, open lead. Spacebar; if Z still moves, E-stop. The circuit test (input 1 lights on contact) before C2 is the only guard against this. → E05 · figure key 2
C2 touches once and then stops with an error
Plate moved before the second touch; or (staff: check the C2 settings) a zero Safe-Z pull-up. → E06
C3 runs into the end of the table, or nags "move off prox"
Stop and call staff. Staff check switch gap, input polarity and wiring; do not adjust or disable the limits. → E04 · figure key 3
Spindle did not start but the axes move
Interlock key, output 1, pendant START not pressed before OK, VFD in LOCAL. Spacebar before the bit reaches the stock; E-stop if it already has. → E07, E09 · figure key 4
Typed a new RPM, nothing changed
Enter not pressed in the Spindle RPM Control window, window closed, or RPM controller not talking to the VFD. Read the rpm on the spindle controller's display, not in the software. → E08
Cut gets deeper every pass; the last pass goes through the spoilboard
Bit slipping in the collet. The motors cannot see it. Stop and call staff. With the spindle stopped and key removed, staff inspect the tool and collet; re-zero Z after recovery. → E10, E11 · figure key 5
Snapped bit
Was the spindle turning? Then: chipload too high or too low, straight plunge too fast, dull cutter, or it hit a clamp/screw. → E12, E21, E39
Loud bang, bit broke mid-cut
With the spindle running, the bit hit metal: a hold-down screw or a clamp on the path, or a clearance height below a screw head. Spacebar, spindle stopped, key OFF and removed, tell staff; the bit and possibly the collet are scrap. Before the next run, check every screw and clamp position against the toolpaths in CAM. → E39, E21, E28 · figure key S
Melted plastic, aluminium welded to the flutes
Feed too slow for the rpm, chips being recut. Faster feed, shallower depth, single flute for plastics. → E13
Frayed plywood veneer, fuzzy edges
Up-cut tooling on the top face, dull bit, wrong direction. Compression or down-cut bit, climb finishing pass. → E14, E24
Burn marks, smoke, hot dust
Rubbing, not cutting: too slow, dull. Stop and check the dust under the brush for embers. → E15, E25
Second pass offset from the first; circles come out oval; sides not square
Position creep: packed rack teeth, worn pinion, loose pinion set screw, tired motor spring, or roller wheels wrong. → E16, E17, E18, E19, E38 · figure key 7
Ticking or a bump at the same place every time
Debris on the V-rail or in the rack at that spot. Clean it; do not grease over it. → E16, E20
Part lifted, moved or flew; sheet wandered
Hold-down failed as the profile cut through: no tabs/onion skin, bowed stock, too few screws. → E22, E23 · figure key 6
Right shape, wrong place on the sheet
Job zero not where CAM thought: wrong corner, wrong Z surface (&PWZorigin in the file header vs the surface you touched), zeroed with Z2 before homing. Air-cut first next time. → E26, E32
Everything is 25.4× too big or too small; feeds absurd
Inch/mm mismatch between the file and the software (VD). → E27
Rapid move hit a clamp
CAM clearance height below the clamp. → E28, E21 · figure key 9
"Z limit" or "table limit" message
Retract height exceeds usable Z travel, or the job runs past the table limits (VL). Stop and have staff check the setup. Never disable limits. → E29, E35
Preview plays, nothing moves
Software in Preview (SP) instead of Move/Cut (SM), or no controller connection. → E33
An axis moved when I touched the keyboard
The keypad window still had focus. Close it when you are done jogging. → E34
Spindle stopped with a code on its controller display
Overcurrent/overload. Stop the file, record the code, find the cause before resetting. → E36, E37
I stopped the job and need to continue
Decide whether position survived (spacebar stop: yes; E-stop or driver fault: no → Reset, C3, re-zero). Then restart from a line with FG, spindle started by the start sequence. → E30, E31

Stop and call staff when

Stop (E-stop in an emergency). Before reaching in: spindle off and stopped, key OFF and removed, keypad closed, no file loaded or paused. Get a signed-off staff member before continuing if you see any of these:

  • A driver alarm (red LED, "location no longer accurate").
  • Any fault code on the spindle controller's display.
  • C3 nags "move off prox" or runs into the end of the table.
  • Input 4 keeps flashing after Reset; input 1 does not light in the circuit test.
  • A damaged, pinched or hot motor or spindle cable; the dust hose off the foot or split.
  • Smoke, embers, burning smell, or hot dust under the brush.
  • A bit that pulled out, snapped, or hit a screw or clamp.
  • Anything in the glossary marked staff only (VN, VL, SF, ZT, TS offsets, eccentrics, pinion re-engagement, VFD parameters).
Reference

All 39 failure modes

Open a row for what you see, why, and what to do. Faults the 3D model on The machine can act out show their key (1–9 or S) and are bold in the index.

  1. E01Alpha driver fault — “location no longer ACCURATE”[1,22,30]key 1
    What you seeAbrupt stop, driver-fault dialog, red LED on the box; coordinates untrustworthy.
    WhyObstruction or excessive load, chips in the rack, a struck clamp, a damaged motor cable; AS drivers also trip on heat, voltage, speed and sensor faults.
    What to doStop and call staff. Staff check the driver LED and cause; students do not open the cabinet. After recovery, reset, re-home (C3) and re-zero. Reduce feed or depth if it was the cut.
  2. E02USB disconnect / communications failure[7,55]key 8
    What you seeSB3 loses the controller mid-file; spindle keeps running.
    WhyPC power management (USB selective suspend, sleep), long or damaged cable.
    What to doE-stop first and call staff. Staff check PC power settings and the direct USB cable (under 3 m, no extension). Rehome and re-zero after recovery.
  3. E03Dust hose off the foot / skirt torn[13]
    What you seeChips everywhere, dust in the air, the brush not sweeping.
    WhyHose pulled off the foot by a long move; brush skirt torn or lost.
    What to doStop, spindle off, refit the hose or tell staff; never cut without the foot on.
  4. E04C3 homes early, fails, or asks to “move off prox”[2,6,49]key 3
    What you seeWrong zero, stop before the target, or a nagging prox dialog.
    WhyMisaligned target, swapped input polarity, bad switch or cable, dead input channel.
    What to doStop and call staff to check inputs 2/3, target alignment and wiring. Do not disable limits.
  5. E05Z plate not detected[4,6]key 2
    What you seeInput 1 stays dark; the bit keeps descending.
    WhyClip knocked off the carriage plate or on paint/dust, a dirty plate or bit, dirty contact, open lead or connector.
    What to doTest input 1 before every C2; it must light on contact and clear on separation. If it fails, do not run C2. If Z fails to reverse at contact, spacebar; if Z still moves, E-stop. Call staff.
  6. E06C2 touches but stops[4,6]key 2
    What you seeFirst touch registers, routine halts.
    WhyPlate moved before the second touch; or (staff: check the C2 settings) a zero Safe-Z pull-up.
    What to doLeave the plate until both touches finish. If C2 halts, stop and call staff; students do not change pull-up settings.
  7. E07Spindle will not start[4,21,24,25]key 4
    What you seeAxes move; spindle stays still; a still bit snaps instantly.
    WhyInterlock key off, no output 1 / pendant Start, VFD in LOCAL, or a drive fault.
    What to doStop the file. Check the key, output 1 and pendant Start sequence with everyone clear. If it still fails, call staff; do not change VFD parameters.
  8. E08RPM will not change[4,6,52]key 4
    What you seeTyped value ignored; speed stays as before.
    WhyRPM window closed, Enter not pressed, wrong VFD selected, RPM-board USB lost, legacy keypad-only VFD.
    What to doOpen TR, type the required rpm and press Enter; confirm on the VFD display. If it does not respond, stop and call staff; do not change drive settings.
  9. E09Wrong spindle-start order[4]key 4
    What you seeFile starts with a still spindle.
    WhyPendant green START pressed after OK (alpha wants it before), or not at all.
    What to doAt the spindle prompt: pendant START, hear it reach speed, read the rpm on the VFD, then OK.
  10. E10Bit slips in the collet[4,13,16,31]key 5
    What you seeCuts get deeper pass by pass; Z zero seems to drift.
    WhyDirty or worn ER25 collet, nut not snapped onto the collet first, wrong torque, wrong shank size.
    What to doClean taper/collet/nut; collet into nut first; use the tightening method demonstrated during induction, not a torque for another nut; replace collets after 400–700 h or any incident.
  11. E11Tool pull-out read as axis drift[1,13,16]key 5
    What you seeDepth changes while coordinates look right; witness mark on the shank has moved.
    WhyInadequate grip; the motor encoder cannot see a bit sliding.
    What to doCompare Z zero before/after a test cut; replace suspect collet and bit; don't clamp on the flutes.
  12. E12Broken bits — chipload, plunge, ramping[10,11,25,26]
    What you seeSnapped cutter, chatter, spindle bogging.
    WhyWrong feed/rpm/depth, aggressive straight plunge, dull cutter — or a spindle that was never running.
    What to doMaker's chipload chart, ramped entries, reduce depth; distinguish VR acceleration ramping from CAM entry ramps.
  13. E13Plastic melts / aluminium welds to the cutter[11,35]
    What you seeGummed flutes, fused chips, repeated breakage.
    WhyFeed too low for rpm, recutting chips, heat.
    What to doMake chips not heat: faster feed, shallower depth, proper evacuation.
  14. E14Plywood tear-out[11]
    What you seeFrayed veneer, rough edges.
    WhyCut direction, dull or wrong geometry, grain, feed.
    What to doSharp compression or down-cut tooling, test both directions on scrap; don't slow down until it burns.
  15. E15Burning in hardwood[4,11]
    What you seeScorched edge, smoke, hot dust.
    WhyToo slow, rubbing with a dull tool.
    What to doSharp tool, correct chipload; stop and check for embers; never leave a running job.
  16. E16Dust packed in rack teeth[13,32]key 7
    What you seeTicking, uneven motion, erratic Z.
    WhyChips filling the gear mesh.
    What to doBrush racks and pinions clean, then light grease (schedule: BB-sized blob every 6 in, run the axes, wipe excess).
  17. E17Worn rack or pinion[13,15,16,33]key 7
    What you seeOval circles, Z notches at certain heights, reversal play.
    WhyWorn teeth or poor mesh.
    What to doPush-pull test, inspect full travel, replace pinions as a set; CC circle test separates mechanics from bad CAD.
  18. E18Loose pinion set screw / tired motor spring[2,13,15]key 7
    What you seeClunks, sudden registration loss, backlash.
    WhyPinion moving on its shaft or not fully engaged.
    What to doStaff task: tighten set screw and key, set spring preload and full-width engagement; rehome afterwards.
  19. E19Roller bearings loose or over-tight[13,16,18,19]
    What you seeLateral Z slop, bad fourth pocket wall, binding, axis faults.
    WhyEccentrics wrongly set, contamination, worn bearings.
    What to doStaff task: adjust eccentrics with drives disengaged; replace worn bearings rather than overtighten.
  20. E20Debris on the V-rails[13,16]
    What you seeBumps that repeat at one spot.
    WhyBuild-up on rail edges or rollers.
    What to doScotchbrite + WD-40 on rails, brass brush on rollers, every 40 h.
  21. E21Crash into a clamp or screw[1,4,12]key 9
    What you seeBang, broken cutter, alarm, shifted cut.
    WhyToolpath or rapid intersects hardware.
    What to doStop, inspect tool/mount/drives, fix clearance, rehome and re-zero; plan screw zones.
  22. E22Part lifts or flies[4,12,29]key 6
    What you seeSheet rises or a cut-out catches the bit and is thrown.
    WhyPoor hold-down, bowed stock, no tabs.
    What to doScrews in the waste, tabs or 0.25–0.75 mm onion skin, never reach in.
  23. E23Clamps or shims let go[12,11]key 6
    What you seeSheet shifts after the first passes; parts come out the right shape in the wrong place.
    WhySpring or pistol-grip clamps creeping, shims loosening as the sheet relaxes, too few screws, screws only at the edge.
    What to doScrews into the spoilboard through the waste, at least every 300–400 mm and near every freed part; re-check clamps after the first pass; shim bowed stock flat before screwing.
  24. E24Climb vs conventional[11,12,16]
    What you seeOne direction chatters, the other is clean.
    WhyEdge engagement changes with direction; looseness compounds it.
    What to doVerify mechanics and hold-down first; climb on the finishing pass often helps, test on scrap.
  25. E25Fire in the dust path[4,36,43]
    What you seeSparks, smoke, smouldering dust.
    WhyFriction heat, screws hitting the impeller, hidden fasteners.
    What to doNever unattended; keep fasteners out of the intake; extinguisher within reach.
  26. E26Wrong XY zero / origin corner[4,26,42,47]
    What you seeRight shape, wrong place.
    WhyJob origin differs from the CAM origin; jogging confused with zeroing; Z2 and C3 mixed up.
    What to doHome with C3, move to the chosen origin, Z2; verify the CAM corner; air-cut first.
  27. E27Inch/mm or SA/SR mismatch[10,11,27,54]
    What you seeToolpath scaled or offset; speeds absurd.
    WhyActive units don't match the file; wrong distance mode; edited unit values.
    What to doCheck units in Values → Display before loading; the Autodesk post's CN,90 header only checks units, it doesn't set them.
  28. E28Retract height too low for clamps[10,12]key 9
    What you seeTraverse hits a clamp though the contours clear.
    WhyCAM clearance below fixture height, or Z reference changed.
    What to doClearance = tallest fixture + margin; preview rapid links.
  29. E29Retract beyond Z stroke[1,2,10]
    What you seeZ-limit message, top-stop approach.
    WhySafe height + offset + tool length exceeds usable Z travel. Have staff check that the setup fits before running.
    What to doRevise fixtures/toolpath; don't disable limits to reach the unreachable.
  30. E30“Stop button pressed” / won't resume[4,11]
    What you seeStopped dialog, no motion.
    WhyInput 4 still active, E-stop latched, driver not reset.
    What to doClear the cause; after an electrical E-stop rehome and re-zero — positions did not survive.
  31. E31Restarting a broken job by line[10]
    What you seeHalf-cut part; restarting from line 1 recuts or collides.
    WhyRestart point lacks speed, spindle, offset state.
    What to doRe-establish zeros, FG (File Load in Goto mode), pick the line, approach at verified safe Z.
  32. E32Table-surface vs part-surface zero[4,13]
    What you seeRapids and retracts run inside the stock, cuts go a sheet thickness into the spoilboard (bed zero, top-zero CAM) — or the whole job cuts air (the reverse).
    WhyC2 zeroed to one surface, CAM assumed the other.
    What to doMatch CAM zero option to the touched surface at every setup.
  33. E33Stuck in Preview[10,34]
    What you seeAnimation, no motion.
    WhySP active instead of SM; or no controller connection.
    What to doCheck connection, then SM; never toggle with hands in the envelope.
  34. E34Accidental keyboard jog[4,47]
    What you seeAxis moves when an arrow key is pressed.
    WhyKeypad window has focus.
    What to doExit keypad when done; Fixed increments for fine approach.
  35. E35Table limit trips mid-cut[2,10,11]
    What you seeLimit warning near an edge.
    WhyReal limit, wrong base offset, VL/SF/VN settings, false input.
    What to doCheck coordinates and switch state; limits use the base system, not Z2 zero.
  36. E36VFD overcurrent / overload[24,30,39]
    What you seeSpindle stops with a drive code; gantry may keep moving.
    WhyLoad, acceleration demand, short, loose motor wiring.
    What to doStop the file, record the Yaskawa code and call staff. Staff clear the cause before resetting; do not open the cabinet or change parameters.
  37. E37Motor/driver overheating, spindle fan dead[2,13,22,41]
    What you seeAS code 1, thermal stop, no fan noise.
    WhyDriver heatsink at ~85 °C, blocked cooling, failed 24 V fan.
    What to doStop and call staff. Cooling-system and fan-cable checks are staff tasks.
  38. E38Gantry out of square[2,13,16]key 1
    What you seeDiagonals differ; corners not 90°.
    WhyGantry reset with sides misaligned; unequal mesh; table shifted.
    What to doStop and call staff for gantry alignment and diagonal checks; validate squareness before cutting again.
  39. E39Bit hits a hold-down screw[1,4,12]key S
    What you seeA loud bang mid-cut with the spindle running; the bit breaks off and a screw head in the waste is chewed up.
    WhyA screw placed on or too close to a toolpath, or the CAM clearance height set below the screw heads so a move between cuts runs into one. Carbide shatters on steel.
    What to doSpacebar (E-stop in an emergency), spindle stopped, key OFF and removed, tell staff; the bit and possibly the collet are scrap. Screws only in planned safe zones of the waste, drawn in CAM and checked against every toolpath and rapid; clearance above the tallest screw head.
Driver and controller alarms, in detail
  • If an obstruction or heavy cutting load makes a closed-loop alpha driver fall behind, it tries to correct, then raises an alarm, stops the machine and shows an alarm message.
  • Typical SB3 wording: "Driver fault! (location no longer ACCURATE)".
  • What to do:
  1. Stop. Do not restart the file. The displayed coordinates can no longer be trusted [QS 17].
  2. Make the spindle safe: off and stopped, key OFF and removed, keypad closed, no file loaded or paused [UG 5; QS 13].
  3. Record the screen message and tell staff which axis faulted. Staff read the red LED blink pattern on the driver; students do not open the control cabinet.
  4. Staff find and remove the cause: a collision, clamp, bound axis, too deep or too fast a cut, or damaged cable. Motor and driver faults can show only during movement.
  5. Never unplug a motor cable with power on. It can destroy the driver [UG 64].
  6. Reset the drivers. A software spacebar stop does not need this; a driver or E-stop event does [UG 47].
  7. Rehome with C3 and re-zero Z with C2, then resume with FG if appropriate [CR 39; CR 11].
  8. Do not reset repeatedly into the same fault. Report it to staff.
  9. If an axis is not powered or locked after reset, stop and call staff. Connector and driver checks are staff tasks [UG 69–70].
  10. Drivers and motors run warm. Excessive heat indicates a fault; report it rather than touching electrical equipment [UG 64].