PETG is one of the most versatile and practical 3D printing materials available, offering a compelling balance of durability, ease of printing, and chemical resistance. However, PETG is also one of the most brand-sensitive filaments when it comes to temperature. A spool that prints perfectly at 235 degrees Celsius from one manufacturer might string terribly at that temperature from another. Even different colors within the same brand can behave differently due to pigment chemistry affecting melt flow.
The temperature tower test is the most efficient way to determine optimal settings for any specific PETG spool. Rather than running multiple full prints at different temperatures and comparing results, a single temperature tower test reveals the ideal temperature range in under an hour of print time and minimal wasted filament.
What Is a Temperature Tower
A temperature tower is a purpose-built test model that prints identical geometric sections at incrementally changing temperatures. Each section tests the same features (overhangs, bridging, stringing, surface quality) at a different temperature, allowing direct visual comparison on a single print.
Standard Temperature Tower Design
Most temperature tower models consist of a central pillar with identical test sections stacked vertically. Each section typically includes overhangs at 30, 45, and 60 degrees, a small bridge spanning a gap, thin walls for surface quality evaluation, and a text label indicating the temperature for that section. The sections are separated by small gaps or visual markers so you can easily identify which section corresponds to which temperature.
For PETG, the typical temperature range starts at 220 degrees Celsius at the bottom and increases to 260 degrees Celsius at the top, with 5-degree increments between sections. Some towers cover a narrower range with 2-degree increments for more precise tuning once you have identified the general optimal zone.
Where to Get Temperature Tower Models
Temperature tower STL files are freely available on Thingiverse, Printables, and MakerWorld. Search for “PETG temperature tower” and choose a model that matches your printer’s build volume. Some slicer software (Cura, PrusaSlicer) includes built-in temperature tower models with automated temperature change scripting, which simplifies setup significantly.
Setting Up the Temperature Tower Print
The setup process requires configuring your slicer to change temperature at specific layer heights. This is the step where many people get confused, but modern slicers make it straightforward.
PrusaSlicer / OrcaSlicer Method
In PrusaSlicer and its derivatives, add a temperature change command at each section boundary. Right-click on the layer slider at the height where each new section begins and select “Add custom G-code.” Enter M104 S{temperature} where {temperature} is the target temperature for that section. Repeat for each temperature change point.
Cura Method
Cura offers a post-processing script approach. Navigate to Extensions, then Post Processing, then Modify G-Code. Add a “ChangeAtZ” script for each temperature step, specifying the layer height and target temperature. Alternatively, Cura’s built-in calibration tools include a one-click temperature tower generator that handles the setup automatically.
Critical Print Settings
Print the temperature tower using the settings you normally use for PETG, with a few specific adjustments. Use a moderate print speed (40-50mm/s) so speed does not interfere with temperature evaluation. Set cooling fan to your normal PETG percentage (typically 30-50%). Use standard retraction settings. The goal is to isolate temperature as the only variable.
Do not use a brim or raft unless your bed adhesion absolutely requires it. These features at the base can make it difficult to remove the tower for inspection. If adhesion is a concern, a glue stick on PEI or glass provides enough grip for the relatively small tower footprint.
Interpreting Temperature Tower Results
Once the tower finishes printing, remove it from the bed and examine each section systematically. Good lighting and a magnifying glass help identify subtle differences between sections.
Stringing Evaluation
Stringing appears as thin threads of plastic stretching between features. Too-hot sections will show significant stringing because excess temperature makes the plastic more fluid and more prone to oozing during travel moves. Compare the stringing between sections and note which temperatures produce clean, string-free transitions.
Layer Adhesion Assessment
Gently flex each section between your fingers. Under-temperature sections will feel brittle, and layers may delaminate with minimal force. Well-bonded sections will flex slightly before breaking, and the break will tear through the material rather than separating cleanly between layers. Mark any sections that feel weak or delaminate easily.
Surface Quality
Examine the flat vertical walls of each section. The ideal temperature produces smooth, consistent surfaces without blobbing, zits, or rough texture. Over-temperature sections may show glossy, slightly rough surfaces from plastic that flowed too freely. Under-temperature sections may show matte, slightly textured surfaces from incomplete layer fusion.
Overhang Performance
Look at the angled overhang features. Better-cooled (lower temperature) plastic typically produces cleaner overhangs because it solidifies faster. Higher temperature sections may show drooping or curling on steep overhangs. However, if the temperature is too low, overhangs may have poor adhesion to the layer below and curl upward.
Bridging
Examine the bridge spans in each section. Good bridging shows relatively straight, even lines crossing the gap with minimal drooping. Over-temperature bridges droop significantly. Under-temperature bridges may have gaps or uneven lines from inconsistent extrusion.
Finding the Sweet Spot
The optimal temperature zone is the section (or range of sections) that best balances all five evaluation criteria. Rarely does a single temperature win on every criterion. You are looking for the best overall compromise.
If your top two candidates are adjacent sections (for example, 235 and 240 degrees Celsius both look good), consider printing a second, narrower tower covering just that range in 1-2 degree increments. This fine-tuning step is especially valuable for production printing where you want the absolute best quality from a specific filament.
When No Single Zone Is Perfect
Sometimes the best stringing temperature conflicts with the best bridging temperature. In these cases, prioritize the criteria most relevant to your typical prints. For decorative figurines and collectibles, surface quality and stringing are usually more important than bridging performance, since most figurine models have minimal bridging. For functional parts with large overhangs and bridges, prioritize structural criteria.
Documenting and Organizing Your Results
Creating a settings database for every filament you use transforms temperature tower testing from a repeated chore into a one-time investment per filament.
What to Record
For each filament spool tested, record the brand, material type, color, purchase date, optimal nozzle temperature, recommended temperature range (plus or minus 5 degrees around optimal), retraction settings that worked well, any special notes (such as “strings more than other colors from this brand” or “needs lower fan speed than typical”).
Storage Methods
A simple spreadsheet works well for most users. Include columns for all the variables above plus a column for your subjective quality rating. Over time, patterns emerge. You may find that a particular brand consistently prints best at 237 degrees Celsius regardless of color, or that their translucent colors run 5 degrees hotter than their opaques.
PETG-Specific Considerations
PETG has characteristics that differentiate its temperature tower results from PLA.
Higher Baseline Stringing
PETG strings more than PLA at any temperature. Accept that some stringing is inherent to the material and focus on minimizing rather than eliminating it. Post-processing with a heat gun (quick pass at low heat) removes PETG strings effectively without damaging the print surface.
Bed Adhesion Concerns
PETG adheres extremely well to some surfaces, particularly bare PEI. At higher temperatures, PETG can bond so strongly to PEI that it damages the sheet when removed. Use a release agent (glue stick creates a barrier layer) or a textured PEI surface to prevent destructive adhesion.
Moisture Sensitivity
PETG absorbs moisture more readily than PLA. A damp spool will produce popping sounds, rough surfaces, and poor results at any temperature. If your temperature tower shows universally poor results, dry the filament in a dedicated dryer or oven (65 degrees Celsius for 4-6 hours) before retesting.
At 3DCentral, PETG is used selectively for products requiring enhanced durability and heat resistance. Every PETG product in our catalog has been through rigorous temperature optimization on our production printers to ensure the quality matches the high standards of our PLA collectibles. Browse our figurines collection to see the results of this careful tuning in every piece we produce.
Frequently Asked Questions
Q: How long does it take to print a PETG temperature tower? A: A standard temperature tower covering 220-260 degrees Celsius in 5-degree increments takes approximately 35-50 minutes depending on your print speed and the specific model used. This is a minimal time investment compared to the hours of failed prints you avoid by knowing your optimal temperature. The amount of filament used is typically 15-25 grams, making it a low-cost test as well.
Q: Do I need to run a temperature tower for every new spool of PETG? A: Not necessarily for every spool, but definitely for every new brand and every new color from a brand you already use. Colors within the same brand can behave differently due to pigment chemistry. Once you have tested several colors from a brand, you will develop a sense of that brand’s general temperature range and can often get close with your first print. A quick temperature tower confirmation is still recommended whenever quality matters, especially for production prints.
Q: My PETG temperature tower shows good results at two different temperatures. Which should I choose? A: When two temperatures look equally good, choose the lower of the two. Lower temperatures produce less stringing, generate fewer fumes, reduce wear on your hotend, and typically provide better overhang performance. Lower temperature also means the plastic solidifies faster, which benefits detail and precision on decorative objects. Only choose the higher temperature if layer adhesion is specifically better there and you need maximum part strength.
