As printed plastic parts cool the different areas of the object can cool at different rates. 1 Depending upon the parts being printed, this effect can lead to warping and curling. Although PLA has a much lower shrinkage factor than ABS, both can warp and curl, potentially ruining a print. There are some very common ways to deal with this potential problem, the most notable being a heated build platform. However, sometimes that might not be enough.
- Use a heated build platform. A heated build platform helps keep the lowest levels of a print warm as the higher layers are printed. This allows the overall print to cool more evenly. A heated build platform, sometimes abbreviated as HBP, helps tremendously with just about any ABS print and large PLA prints.
- Print with a raft. Rafts are a printing option in ReplicatorG and Skeinforge. They’re basically a large flat lattice work of printed material underneath the lower-most layer of your printed object. They’ll also help reduce warping and curling by allowing your printed object to adhere better to your flat build surface. Other variations on this are to print with a larger raft and/or a thicker raft comprised of more layers.
- Calibrate your starting Z height. A good first layer makes all the difference. If your starting Z axis height is too high, the extruded filament won’t be able to make a good bond with the platform. If you think your Z axis starting height is too high, try lowering it by 0.05mm increments until you find a good first layer.
- Get the right build surface. Some people have experimented with different surfaces such as steel, titanium, glass, different kinds of plastic, different kinds of tape, and foam board. However, I find both ABS and PLA seem to stick really well to hot or warm Kapton tape.
- Clean your build surface. ABS and PLA stick better to a clean build surface. Keep it clean of dust, pieces of old prints, and any other debris.
- Print slower. Printing slower allows finer detail, better adhesion to the build surface and lower layers, and gives the printed part more time to cool evenly.
- Print cooler. Printing at a lower temperature isn’t always an option. Ideally, you should be printing at the lowest temperature required for extrusion and that allows good interlayer adhesion. However, trying lower temperatures isn’t for the faint of heart. Printing at a too low a temperature could cause harm to your extruder motor or extruder.
- Eliminate drafts or enclose your robot. Forrest Higgs found that having his 3D printer too close to an open window caused very uneven heating across his build surface. This in turn caused the side of his prints closest to the window to curl. Since keeping the window closed wasn’t an option for him, he compensated for the window drafts by adding a heat lamp. Cupcake and Thing-O-Matic owners might have an easier time of eliminating drafts by simply enclosing two or three of the sides of their robots. It will also have a fortunate side effect of helping to control fumes.
- Design with mouse ears. Zach Smith’s solution was to add little discs to corners of an object to help those corners stick to the platform. These essentially serve as “mini-rafts” to give those corners more surface area and better adhesion without having to print an entire raft.
- Design with aprons to hold down corners. Forrest Higgs suggested adding “aprons” around an object to be printed, while that object was being printed on a raft. These low thick pieces of plastic help keep the raft flat and help prevent any curling or warping from affecting the desired printed object itself.
- Design with surrounding thermal walls. While Forrest Higgs’ apron approach provides a mechanical advantage of essentially holding down corners with a chunk of plastic, Nophead has added thin surrounding walls to his designs to act as baffles to keep warm air around the printed object as it moves around. He’s postulated that a very thin surrounding wall could have the same beneficial effect as printing inside an enclosed build chamber. Interestingly, it seems that Nophead suggests that designing objects with more rounded corners might also help avoid curling and warping at those corners.
- Reduce infill. When printing a model you can chose to print it hollow, completely solid, or some percentage between zero and 100. However, as Nophead points out even the plastic inside a model exerts a force on the entire printed object as it cools. It stands to reason that the more plastic you have, the more those pieces of plastic will pull against themselves and the build surface as they cool. By reducing infill there will a reduced amount of internal tension as the object cools. Reducing these internal forces by printing with a lower infill ratio can help reduce curling and warping as well.
- EDIT: Sand the Kapton. Charles Pax has suggested that sanding a Kapton tape build surface will increase the surface area, making it easier for the molten plastic to stick.
- EDIT: ABS surface. Some have suggested essentially painting the build surface with liquid ABS.2 This is has the same effect of laying down a big flat raft.
If you’ve got some suggestions, tips, or tricks that you use to fight warping and curling, please leave a comment below!
|Tagged with||curl, curling, draft, forrest, forrest higgs, hbp, heated build platform, higgs, hoeken, mouse ears, nophead, R&D, randd, research and development, warp, warpage, warping, zach smith||9 comments|