Posts tagged Troubleshooting from the G-Code Sprint team.
A CNC lathe cutting a taper on a part that should be straight is usually a code error, tool or part deflection, or tailstock misalignment. Here is how to find which.
A CNC router cutting air almost always means the Z zero, the work origin, or the units are wrong. Here is how to diagnose each cause and fix it before you waste stock.
M30 means end and rewind, so a machine stuck there has a file-format or mode problem: missing EOB, missing percent marker, DNC streaming, or a setting.
A skipped tool change has five usual doors: block delete active, a T without M06, staging conventions misread, a restart that jumped it, or magazine logic.
Dry drilling inside a canned cycle is usually an M8 placement problem: the command arrived late, landed in the wrong mode, or asked the wrong system.
When Fusion 360 outputs wrong G-code, the toolpath is almost never the problem: the post processor is. The four mismatch types and the fix ladder.
A cutoff nub has three parents: tool above or below center, an X endpoint that stops short, and centerline speed physics. The fixes, code and setup both.
A macro alarm is a message your own shop wrote: a programmer put that check there deliberately. How to read it, what is safe alone at 3 a.m., what waits.
Mastercam posts wrong G-code when the machine definition, control definition, and post do not match your actual machine. The triad, and the fix order.
Night-shift troubleshooting is daytime troubleshooting plus a boundary question: what is safely yours to fix alone, what waits, and how to decide fast.
On a PrintNC you are operator and machine builder at once, so G-code trouble has three suspect layers: the program, the post, and the configuration you wrote.
Most VCarve G-code problems are post processor mismatches: the wrong .pp file for your controller. The symptom table and the air-cut habit that ends them.
A moving feed with a dead spindle is a code or override mismatch: an M05 that fired early, a missing spindle-at-speed wait, or independent feed and spindle controls.
Air-drilling means the machine's idea of Z disagrees with reality: a missing G43, the wrong H number, a stale work offset Z, or the cycle's R-plane math.
A lathe that cuts exactly twice as deep as programmed is almost always a diameter vs radius mix-up. Here is the X rule, the four places it hides, the fix.
When a CNC halts waiting for the spindle while it is visibly spinning, the control is missing a confirmation signal: at-speed, orientation, or gear state. The hunt order.
Fanuc alarm 010 means an improper G-code: a code that does not exist or is not enabled on your machine was commanded. Here are the common causes and how to find it.
Fanuc alarm 021 means an arc was commanded with an axis outside the active plane. Here is why plane selection causes it and how to fix the offending block.
Fanuc alarm 007 means a decimal point on an address that does not allow one, or two decimals in a word. Here is which addresses take a decimal and which do not.
GRBL has two different number-1 messages: error:1 is a malformed G-code word, ALARM:1 is a tripped hard limit with position lost. Here is how to fix each.
Conversational programming still generates G-code underneath, so it can still alarm: bad inputs, undefined tools or offsets, or a missing software option.
G02 cuts a straight line when the arc is not actually defined: missing I and J words, a firmware without arc support, the wrong plane, or a huge radius.
A CNC moving in inches when you expect millimeters is running G20: left active by a previous job, a power-on default, or a program that never states units.