Printing FAQ

Every feature adds something the printer can get wrong: patterns add thin strips and pointed tops, lettering and symbols add small details, scoops add curved overhangs, notches and stacking lips add steps, and dividers add thin walls. Each one is usually fine by itself, but the chance that something goes wrong grows with every feature you add to the same print.

• Use only the features you need. A plain container with dividers almost always prints well.
• Before a long print, print a small test container with the same features, or the same container cut short in your slicer.
• If a print fails, take features away one at a time to find the one that causes it.

Do not use a nozzle larger than 0.4 mm for any print with text, symbols or patterns. A larger nozzle draws lines too wide for the small letters and the strips between openings, so they come out filled in, blobby or missing.

• A 0.4 mm nozzle, the usual size, works for everything CoolBox makes.
• A 0.6 mm or 0.8 mm nozzle is fine for plain containers and dividers with no text, symbols or patterns.
• Set Nozzle width in CoolBox to the nozzle you will use. The narrowest strip a pattern may have depends on it.

• Make the text taller. Small text loses its shape first; letters 6 mm tall or more read much better than the 4 mm minimum.
• Use a layer height of 0.2 mm or less, so the depth of the lettering is several layers.
• Use a 0.4 mm nozzle or smaller.
• Pick a simple symbol with few fine details. Detailed ones may not print well at small sizes.
• Print slower for the outer walls, where the lettering is.

• Use a 0.4 mm nozzle or smaller.
• Make the strips wider and the openings smaller. CoolBox already keeps them within safe limits, but wider strips are stronger.
• Turn the part cooling fan up, especially for PLA, so the pointed tops of wall openings set before the next layer.
• Print slower. Patterns have many short moves, and fast printing makes strings between openings.
• Turn on retraction in your slicer, or raise it, to stop strings.

• Raise the stacking lip's Tolerance a little, for example from 0.2 mm to 0.3 mm, and print again.
• Check the first layer for elephant's foot: the step under a container is the first thing to spread.
• Print all the containers of a stack with the same printer, material and slicer settings.

Every printer, nozzle and filament prints a little larger or smaller than the design, so a lid that is snug on one printer can be loose or stuck on another. The lid fit test finds the right fit for yours before you print a full-size container and lid.

• Choose your lid style, then use Export lid fit test in the lid settings. Each style has its own test.
• It saves one small print: a test piece and four test lids, each at a different lid fit, with its fit cut into its top.
• Try each test lid. Pick the one that goes on without forcing and stays on when you tip it over.
• Enter that number as Lid fit. Every lid you design then uses it.

Print the test again if you change your printer, nozzle or type of filament.

A hinged lid is joined to its container by a pin you add after printing: a piece of ordinary 1.75 mm filament. The lid settings say how long to cut it.

• Cut the filament to that length with flush cutters, so its ends are square.
• Close the lid, so the knuckles line up.
• Push the pin into the hinge from the right-hand end, as you look at the back, until it stops. The hole is closed at the left end, and the right-hand knuckle grips the pin.
• If the pin is hard to push, twist it as you push. If it still sticks, run a 2 mm drill bit through the lid's knuckles by hand.
• If the pin ever works loose, pull it out a little, melt its end briefly with a lighter or soldering iron so it mushrooms, and push it back. To take the lid off, pull the pin out with pliers.

How tight a lid fits depends on your printer and material, so print the lid fit test first (see above) and set Lid fit from it. If a lid still fits badly, raise Lid fit if it is too tight, and lower it if the lid falls off.

• A lid that sticks only at its top edge usually has elephant's foot: lids print upside down, so that edge is the first layer. Turn on elephant's foot compensation in your slicer, or lightly sand the edge.
• Print the lid and its container with the same printer, material and slicer settings.

To make a pog, open the Pogs designer. A pog prints in two parts: a frame, and an insert that snaps into it from the bottom, sticker side first. The frame has a narrow ledge around its top that stops the insert, and a thin ridge inside its bottom that holds it in.

• Print the snap fit test once: use Export snap fit test in the Pogs designer. It saves one small frame and five test inserts, each with its fit cut into its bottom.
• Try each test insert. Pick the one that snaps in firmly but still goes in by hand, and set Snap fit in the Printer settings to its number. It is saved with your account, so every pog you design uses it.
• Then export your pog. It saves two files: the frame and the insert.
• Glue a printed sticker to the insert's face, or give the pog text in the Face group instead, then push the insert into the frame from the bottom, face first, until it snaps in.

Print the test again if you change your printer, nozzle or type of filament.

Set Thickness in the pog's Shape and Size group, or on the 3D view. A pog starts at 3.8 mm (6.8 mm double-sided) and can go up to 10 mm.

• On a pog with one insert, the extra goes into the insert, so it is thicker and the frame taller.
• On a double-sided pog, it goes into the ledge in the middle; both inserts stay as they are.
• Either way the snap ridge and the insert's edge do not change, so your Snap fit and the snap fit test still apply.

Thin strings are plastic oozing from the nozzle while it moves from one place to another without printing. They come mostly from the slicer and the filament, not the design, but some pieces make them more likely:

• Pieces with an open center, such as a pog's frame. On every layer the nozzle can cross the hole, leaving a string across it. A double-sided pog's frame is about twice as tall as a single-sided one, so it has twice as many chances.
• Narrow bands with many short moves, such as the steps near a pog frame's faces, where the nozzle stops and starts often.
• Several pieces on one plate, where the nozzle travels between them on every layer, often over a piece that is still open.

What to try in Bambu Studio, most likely fixes first:

1. Turn on Avoid crossing walls, so the nozzle goes around an opening instead of across it. This alone often stops strings across a hole.
2. Dry the filament. Damp filament, PETG most of all, strings much more. A few hours in a filament dryer often makes a large difference.
3. Lower the nozzle temperature by 5 to 10 °C. Hotter plastic oozes more.
4. Check the retraction length and speed, and turn on Wipe while retracting. The defaults are usually good, so try this only if the steps above do not help.
5. Print the piece on its own, or set the plate to print one object at a time, so the nozzle does not travel between pieces over it.

Strings across the center of one piece point to the first two steps; strings between pieces point to the last.

A 3MF file says which filament (AMS slot) each part prints with:

• A piece, and its lid, print with filament 1.
• With Lettering color on, its text and symbol are a part of their own on filament 2, in the lettering color.
• A pog's frame prints with filament 1. Its insert prints with filament 2 when you give it its own color, or filament 1 when it is the frame's color. The insert's lettering, with Lettering color on, takes the next filament: 3, or 2 when the insert is on filament 1.

In Bambu Studio you can change the filament of any part after opening the file. An STL file has no filaments: each part is its own file, so load them together as the parts of one object and choose each part's filament in your slicer.

Plastic shrinks as it cools. If the first layer does not hold on to the bed, or the print cools too quickly, that shrinking pulls the corners up.

• Bed adhesion. Clean the build plate with dish soap and water or isopropyl alcohol; oil from fingers stops the first layer from sticking. Level the bed, and check that the first layer is pressed down onto it, not laid loosely on top. A textured plate, or a glue stick on a smooth one, helps the first layer hold.
• Build plate temperature. A plate that is too cool lets the first layer let go. Use the temperature your filament maker recommends, usually around 55–65 °C for PLA and 70–85 °C for PETG, and let the plate warm up fully before the print starts.
• Cooling too fast. Turn the part cooling fan off or down for the first few layers; most slicers have a setting for this. Keep the printer away from drafts, open windows and air conditioning, and use an enclosure, or a cardboard box over the printer, for PETG and ABS.
• Add a brim in your slicer, especially for large containers, so the corners have more to hold on to.
• Use PLA, which warps the least. PETG and ABS need more care, and ABS needs an enclosure.

PLA is the easiest and works for almost every container and card divider. PETG is tougher and bends before breaking, but it strings more, which shows on patterns and lettering. Avoid flexible materials: thin walls and dividers will not hold their shape.

• Layer height: 0.2 mm, or 0.12–0.16 mm for fine lettering and symbols.
• Walls (perimeters): enough to fill the wall thickness, so thin walls and dividers print solid. With a 0.4 mm nozzle, a 2 mm wall is about five lines.
• Supports: off.
• Look at the sliced preview layer by layer before printing. Gaps or missing strips there will be missing in the print too.

• Make them a little thicker; very thin dividers snap at the tab.
• Keep the pattern border and text clear of the edges, as CoolBox does by default.
• If they curl at the corners, clean the bed and add a brim.
• Lettering cut right through a divider leaves thin bridges in letters; cut part way instead if the letters tear.