Your First Diagnosis

Diagnosis vs. guessing

Guessing:

"The print has stringing. I'll increase retraction." → "Still has stringing. I'll increase it more." → "Now there's under-extrusion." Three hours later, you have different problems than when you started.

Diagnosis:

"The print has stringing. Are they fine hairs everywhere, thick strings, or blobs at the seam? That tells me the cause."

Five minutes later, you know exactly what to fix.

Diagnosis is not harder than guessing. It's faster, cheaper, and produces results that last.

The three categories

Every print problem belongs to one of three categories:

Calibration — Your printer is mechanically capable but the parameters are wrong. The most common category.

Hardware — A physical component is worn, broken, or insufficient.

Material — The filament has an issue — wet, degraded, wrong grade. Often overlooked.

Before you change any setting, identify which category the problem belongs to.

How to read a symptom

Stringing:

Surface quality:

Extrusion:

Your first real tool

CN3D has 12 interactive diagnostic flowcharts — one for each major symptom.

Each flowchart works like a conversation. You describe the symptom, it asks specific questions, it narrows to the exact cause, you get targeted fixes.

Try it now: Open the Stringing flowchart and walk through it — even without a real problem. Notice how two printers with the same symptom can have completely different causes.

The 4 diagnostic questions

Before you change anything, ask:

1. What exactly is the symptom? (Not "looks bad" — "regular horizontal bands every 2mm")

2. When does it appear? (Always? Progressively? Only after 10 min? Only at corners?)

3. What changed recently? (New filament? Changed speed? New slicer version?)

4. What is the simplest possible cause? (Don't assume hardware failure when calibration is more likely)

These four questions take 30 seconds. They save hours.