Advanced 3D Printing

If under-extrusion is too little plastic, over-extrusion is too much — and it brings its own set of problems: rough, bulging surfaces, parts that come out larger than designed, blobs and 'zits' on the walls, and elephant's foot at the base. The good news is that over-extrusion is one of the most directly fixable defects, because it almost always comes down to calibration. Here's how to dial it out. What Over-Extrusion Looks Like Watch for: walls that look swollen or rough rather than crisp, top surfaces that are bumpy or 'over-filled', dimensions coming out oversized, blobs and pimples (zits) on the surface, stringing combined with excess material, and elephant's foot — the bottom layers bulging out wider than the rest. Fix It in This Order 1. Calibrate Flow Rate (Extrusion Multiplier) The number-one cause. If flow is set too high, every line puts down too much plastic. Run a flow-rate calibration and reduce the multiplier until walls come out crisp and dimensions are accurate. This single step fixes most over-extrusion. Our flow test guide and the two-pass method in the Orca Slicer calibration guide walk through it. 2. Check Filament Diameter Setting Your slicer assumes a filament diameter (usually 1.75 mm). If that figure is wrong — or your filament is inconsistent and actually runs thicker — the printer pushes too much. Confirm your slicer's diameter matches your filament. Consistent filament matters here: our Spain-made filament holds ±0.05 mm tolerance, so the 1.75 mm setting is accurate spool to spool. 3. Lower the Temperature Printing too hot makes plastic runnier, so it oozes and spreads more than intended — contributing to blobs and rough surfaces. Drop the temperature in 5 °C steps; a temperature tower shows the cleanest setting. 4. Tune Pressure Advance / Linear Advance Blobs and zits often appear where the nozzle starts, stops, or changes direction — pressure builds in the nozzle and releases as a blob. Calibrating pressure advance (linear advance) evens out that pressure for clean corners and seams. The Orca Slicer calibration guide covers this step. 5. Enable Coasting and Wipe In your slicer, 'coasting' stops extrusion just before the end of a line to release pressure, and 'wipe' moves the nozzle over the printed line to clean off excess. Both reduce blobs and zits at the seam. 6. Fix Elephant's Foot Specifically If only the base bulges, it's a mix of over-extrusion and a bed that's too hot or a nozzle too close on the first layer. Lower the first-layer flow or bed temperature slightly, and use your slicer's 'elephant's foot compensation'. Our first-layer guide covers Z-offset, which interacts with this. Quick Diagnostic Symptom Most likely cause First fix Walls swollen, parts oversized Flow too high Calibrate flow rate Blobs/zits at corners and seams Pressure advance / coasting Tune PA, enable wipe Rough, over-filled top surface Flow too high / temp too high Lower flow, then temp Only the bottom bulges out Elephant's foot First-layer flow, compensation Dimensions consistently too big Flow or filament diameter Calibrate flow, check diameter Over vs Under: The Same Calibration Solves Both Over- and under-extrusion are two ends of the same dial. If you've read our under-extrusion guide, you'll recognise the tools — temperature tower, flow test, pressure advance — because dialling them in correctly is what keeps you in the sweet spot between the two. Get the calibration right once on consistent filament and both problems disappear. Start With Filament You Can Trust Accurate flow calibration depends on filament that's actually the diameter it claims. Our PLA, PETG, TPU, ABS, and ASA are made in Spain to tight tolerances, so once you calibrate flow, it stays correct. Fighting blobs or oversized parts you can't tune out? Get in touch and we'll help.

Under-extrusion is when your printer lays down less plastic than the model needs. You'll see it as gaps between lines, thin or missing top layers, weak walls that pull apart, and a generally starved, patchy surface. It's one of the most common print-quality problems — and because several different things cause it, the fix is about working through them in order. Here's how. How to Recognise It Under-extrusion shows up as: visible gaps between adjacent lines, layers that don't bond and split apart, holes or thin spots in the top surface, stringy or skipped infill, and parts that feel brittle. If walls look starved and you can see through to the infill, that's the signature. Fix It in This Order 1. Check for a Partial Clog The most common cause. A partially blocked nozzle restricts flow — the printer tries to push plastic but can't get enough through. Signs: clicking from the extruder, inconsistent flow, or it gradually worsening over a print. Do a few cold pulls (atomic pulls) to clear debris, or run a cleaning filament. If a nozzle is worn or stubbornly blocked, swap it — nozzles are consumables. Keeping filament dry and clean prevents most clogs. 2. Dry Your Filament Wet filament foams and spits at the nozzle, disrupting steady flow and mimicking under-extrusion. If the spool's been open a while, dry it (45–55 °C for several hours) and store it sealed with desiccant. Our Spain-made filament ships sealed and dry, with tight diameter tolerance — thin spots in cheap filament are themselves a cause of under-extrusion. 3. Raise the Temperature If the nozzle isn't hot enough, plastic can't melt fast enough to keep up with the flow rate — especially at speed. Raise the temperature in 5 °C steps. A temperature tower finds the point where flow becomes consistent. 4. Calibrate Flow Rate If flow is simply set too low, every line comes out thin. Run a flow-rate (extrusion-multiplier) calibration and set the correct value in your profile. Our flow test guide walks through it, and the Orca Slicer calibration guide shows the two-pass method. 5. Slow Down (or Lower Max Volumetric Speed) Every hotend has a limit to how fast it can melt plastic. Push past it and the printer physically can't extrude enough — under-extrusion at high speed even though slow prints are fine. Lower print speed, or calibrate Max Volumetric Speed to find your hotend's real ceiling. 6. Check the Extruder Itself A worn extruder gear, weak idler tension, or a slipping drive can fail to grip the filament. Look for chewed filament or gear marks. Check tension and that the gear teeth are clean. See our extruder calibration guide to confirm it's pushing the right amount. Quick Diagnostic Symptom Most likely cause First fix Gets worse over a print, clicking sound Partial clog Cold pull / clean nozzle Spitting, popping, inconsistent Wet filament Dry the filament Fine slow, bad fast Speed exceeds melt rate Slow down / Max Vol Speed Uniformly thin everywhere Flow rate too low Calibrate flow Chewed filament at extruder Extruder grip/tension Check gear & tension The Filament Factor Cheap filament with loose diameter tolerance causes intermittent under-extrusion that no amount of tuning fully fixes — thin spots simply deliver less plastic. Our PLA, PETG, TPU, ABS, and ASA are made in Spain to ±0.05 mm (±0.08 mm on TPU) and sealed dry, removing two of the biggest causes before you start. Once you've ruled out filament, the settings fixes above will hold. Still under-extruding? Tell us your printer and material and we'll help narrow it down.

Those fine wispy threads stretched between the parts of your print — stringing (or oozing) — are one of the most common and most fixable 3D printing problems. They happen when molten plastic leaks from the nozzle while it travels across open space. The good news: it's almost always solved by tuning a handful of settings. Here's how to fix it, in the order that actually works. Why Stringing Happens Inside a hot nozzle, filament is molten and under slight pressure. When the print head moves between two points without printing (a 'travel move'), that pressure can push a little plastic out — it cools mid-air into a thin string. The fix is about controlling that leakage: pulling filament back before travel (retraction), not running hotter than necessary, and keeping moisture out of the filament. Fix It in This Order Work through these in sequence — each step removes a cause, and doing them in order stops you chasing the wrong fix. 1. Dry Your Filament First This is the most overlooked cause, and on PETG, TPU, and nylon it's often the whole problem. These materials absorb moisture from the air; when that water hits the hot nozzle it turns to steam, spitting and oozing plastic everywhere. If your filament has been open for weeks and you're getting sudden stringing with little popping sounds, dry it (a filament dryer or a low oven, 45–55 °C for several hours) before changing any other setting. Storing filament sealed with desiccant prevents the problem returning. 2. Lower the Nozzle Temperature Hotter plastic is runnier and oozes more. Drop your nozzle temperature in 5 °C steps and watch the strings shrink. The cleanest way to find the sweet spot is a temperature tower, which prints the same shape at several temperatures so you can see exactly where stringing stops without sacrificing layer strength. 3. Tune Retraction Retraction pulls filament back before a travel move, relieving nozzle pressure. The two settings are distance (how far) and speed (how fast): Direct-drive extruders: 1–2 mm distance, 25–45 mm/s speed. Bowden extruders: 4–6 mm distance (the long tube needs more), similar speeds. Increase distance gradually until strings disappear — too much causes jams and gaps. A retraction test print dials this in fast. 4. Enable Travel Optimisation In your slicer, turn on options like 'combing' / 'avoid crossing perimeters' (keeps travel moves inside the model so any ooze is hidden) and 'wipe before retract'. 'Z-hop' lifts the nozzle during travel and can help, though it slightly slows printing. 5. Increase Travel Speed The faster the head crosses open space, the less time plastic has to ooze and the less the string can form. Raising travel speed to 150–200 mm/s often visibly reduces fine stringing. Material-Specific Notes PETG is the classic stringer — it's naturally prone to it and very moisture-sensitive. Expect to dry it, run slightly cooler, and tune retraction carefully. See our PETG/TPU/ASA settings guide. TPU strings because it's flexible and hard to retract. Minimise retraction, print slow, and keep it dry — long retractions just snarl flexible filament. PLA rarely strings badly; if it does, it's usually temperature or moisture. ASA/ABS ooze less than PETG but still benefit from drying and tuned retraction. Quick Diagnostic Symptom Most likely cause First fix Sudden stringing on filament that printed fine before Moisture Dry the filament Popping/crackling sounds while printing Moisture Dry the filament Fine consistent strings everywhere Temperature too high / retraction too low Lower temp, tune retraction Blobs and zits on surface Retraction / coasting / wipe Enable wipe, tune retraction Strings only on flexible filament Over-retraction of TPU Reduce retraction, slow down Consistent Filament Makes This Easier A lot of "random" stringing is really moisture or inconsistent diameter. Our filament is made in Spain to tight ISO/REACH tolerances and sealed with desiccant, so it arrives dry and prints consistently. Once you've dialled in your settings on a good spool, they'll keep working. Still fighting strings after all this? Tell us your material and printer and we'll help you troubleshoot.

PLA is easy. The moment you move to PETG, TPU, or ASA, the same printer that produced flawless PLA starts stringing, warping, or refusing to stick. None of these materials are difficult once you know what they need — they just need different settings. This guide gives you reliable starting points for each, plus the why behind them, so you can dial in your own filament and printer quickly. A note before the numbers: every printer and spool is slightly different. Treat these as starting points, then fine-tune with a temperature tower and a flow test. Our own filament is made in Spain to consistent ISO/REACH standards, which removes one big variable — spool-to-spool inconsistency — from the equation. Quick Reference Table Setting PETG TPU (flexible) ASA Nozzle temp 230–250 °C 210–230 °C 240–260 °C Bed temp 70–90 °C 30–50 °C 90–110 °C Print speed 30–60 mm/s 15–30 mm/s 40–60 mm/s Cooling fan 30–50% 0–30% 0–20% Enclosure Optional No Strongly recommended Retraction (direct drive) 1–2 mm 0.5–1.5 mm 1–2 mm Retraction (Bowden) 4–6 mm Avoid / minimal 4–6 mm PETG: Strong, Glossy, Slightly Sticky PETG is the natural step up from PLA — tougher, more temperature-resistant, and great for functional parts. Its quirk is that it's sticky: it adheres so well it can tear chunks off your bed, and it strings if over-retracted or printed too hot. Temperature: Start at 240 °C and run a temperature tower from 230–250 °C. Too hot = stringing and blobs; too cool = weak layer bonding. Bed & adhesion: 80 °C is a reliable starting point. PETG sticks too well to smooth PEI — use a textured plate, or a glue stick / release agent as a barrier to protect the sheet. Our Magigoo Original both improves adhesion and acts as that release barrier. Cooling: Some cooling (30–50%) improves overhangs and reduces stringing, but too much weakens layer adhesion. Balance is key. Stringing: PETG's signature problem. Tune retraction and temperature together — see our retraction test. Shop our PETG filament, or the certified UV-resistant PETG for outdoor parts. TPU: Flexible, Forgiving on Warping, Fussy on Speed TPU is flexible filament — perfect for phone cases, gaskets, and grips. It barely warps, so it needs little bed heat, but it's sensitive to speed and retraction because the filament is elastic and compresses in the extruder. Temperature: 220 °C is a good middle. The softer the TPU (lower Shore hardness), the more it benefits from slightly higher temps for flow. Speed: The single most important TPU setting. Print slow — 15–30 mm/s. Flexible filament buckles if pushed too fast, causing under-extrusion and jams. Retraction: Minimise it. On Bowden setups especially, long retractions cause the elastic filament to snarl. Direct-drive extruders handle TPU far better. Cooling: Low to moderate. TPU doesn't warp, so cooling mainly helps detail. Bed: 40 °C is plenty. For flexibles, our Magigoo Pro Flex is formulated specifically to hold flexible prints without over-bonding. We stock TPU in several hardnesses: TPU Flex 93A (most flexible), D53, and the D60 UV-resistant for outdoor flexible parts. ASA: The Outdoor Workhorse (That Needs an Enclosure) ASA is the go-to for outdoor and automotive parts — UV-stable, weather-resistant, and tough. It behaves like ABS, which means one thing dominates everything else: it warps, and it needs a stable, warm environment to print reliably. Enclosure: Strongly recommended, arguably essential for anything beyond small parts. A stable, warm chamber prevents the layer-separation and corner-lifting ASA is prone to. This is exactly why enclosed printers like the Flashforge Adventurer 5M Pro or Bambu Lab P1S make ASA so much easier. Temperature: 250 °C nozzle is a solid start. Hotter helps layer bonding, which matters for ASA's strength. Bed: 100 °C, with an adhesion aid. Magigoo Original works well for ASA. Cooling: Minimal to none. Part cooling causes warping and cracking in ASA — let the chamber do the work. Ventilation: ASA produces fumes. Print in a ventilated space, ideally with a filtered enclosure (HEPA + carbon). Shop our Spain-made ASA filament. The Universal Workflow: Dial It In Whatever the material, the same tuning sequence gets you to perfect prints: Temperature tower first — find the temp with the best layer bonding and least stringing. How to print one. Flow / extrusion multiplier next — get dimensions and wall thickness accurate. Flow test guide. Retraction last — eliminate stringing once temp and flow are right. Retraction test guide. If you're also calibrating the extruder itself, see our extruder calibration guide. Filament Made in Spain Consistent settings start with consistent filament. We manufacture our PLA, PETG, TPU, ABS, and ASA in Cantabria to ISO and REACH standards — tight diameter tolerance and repeatable properties spool to spool, so the settings you dial in today still work on your next order. Not sure which material suits your project? Ask us.

The aim of the retraction test is to achieve a "cleaner" part without material residues in the movement areas of the hotend. The slicer parameters that influence this test are mainly speed and retraction distance.

This test should be carried out every time you print with a new material, as it provides one of the main printing parameter parameter of the filament i.e. the extrusion temperature. This test consists of a staggered part, in which the extrusion temperature will be varied progressively by 5 degrees. As each material has an optimum temperature, this test has different parts for different materials. These parts are practically the same, only the temperature range is different for an easier reading.

The purpose of this test is to adjust the amount of extruded plastic, that is to say, that the deposited material is the one we want at any given moment. It is performed to correct small variations in the diameter of the filament. The parameter that influences the flow is the so-called extrusion multiplier, with a calibration of this parameter you can solve the typical problems of under-extrusion or over-extrusion.