Gunaseelan Murugesan
Bridging is arguably one of the most powerful tools at your disposal as a 3D printer user. Not only can it help you save some time and money by utilizing fewer supports, but it also helps make it possible to print features that would otherwise be unachievable. It gives you the flexibility to access a whole range of new design possibilities when 3D printing.
However, If a 3D printer isn’t correctly calibrated and maintained, it can lead to disaster – bridges that look like stringy messes instead of what was intended. When these structural prints are not successful, the integrity of the finished product is compromised.
In order to save filament, time, and effort during the construction process, as well as in the post-processing phase, this article will show you how to minimize improper bridging in your 3D printer creations.
What Is Bridging in 3D Printing?
Bridging, in 3D printing terms, refers to segments in which the extruder releases filament over a gap between two supported positions in the same layer with no extra filament below it. This eliminates the need for support under bridges as well as reduces overall material costs and production time. But what is good bridging and what is bad bridging? How can someone make sure their prints come out the best they can?
Bad Bridging & Good Bridging
Good 3D printer bridging means that the printed object looks as good as it does in the slicer – flat and smooth with no gaps or unsightly strands. Achieving this level of printing isn’t easy – it involves having the perfect filament temperatures, speeds, and infill settings for your particular printer to get just the right amount of material at exactly the right time. Also, the first layers need to have correctly adhered for strong bonding and no loose filament strings.
On the other hand, Bad bridging in 3D printing refers to the operation when the filament is laid on a newly printed layer, connecting it with the previously completed layers. An obvious sign of bad bridging includes strands or layers of filament that never seem to finish bridging the gap, while in more extreme cases, no bridge will be created at all.
Reason for Poor Bridges?
Several reasons may contribute to an inadequate bridge, such as:
- The print head temp is too high: The process of bridging depends on the filament cooling after extrusion. If not, the still-molten filament will droop.
- The extruder filament isn’t cooling quickly enough: Bridging problems could also be caused by not enough cooling. If the fan doesn’t cool the filament quickly enough, the molten filament will have time to drop before it hardens.
- Too much material is being extruded at once: The filament should extrude out of the 3D printer at the same speed that it moves. If the 3D printer puts out too much filament, it will physically push the bridge down. This can happen when the extrusion multiplier on a printer is set too high.
Furthermore, while some materials can bridge easily, such as PLA, others like PETG can be quite challenging due to their tendency to string and absorb moisture from the air. To ensure successful bridging with PETG or any other filament, it’s important to make sure it’s completely dry before use.
SLICER SETTINGS & SOLUTIONS
First, you should know that different filaments will bridge in different ways. Successful bridging depends on more than just the slicer settings you choose. With that in mind, it’s important to look into your filament manufacturer’s recommended slicer settings when experiencing bridging issues. Doing this allows you to unlock the full potential of the filament you are using and get the best results from your prints. Most of the time, you can find these settings on the box of filament or on the website of the manufacturer.
You may have previously attempted these settings, but your 3D printer still isn’t bridging well. All you need to do is adjust some slicer settings according to the guidelines offered and then experiment with them until you get the perfect bridging. Although it might take some trial and error, eventually careful tinkering with the layer height, width, and speed should do the trick. Just make sure to save your initial slicer settings in case something goes wrong; that way it’s easy to start over without as much effort.
If this is your first time making adjustments, it might be wise to go to the official website of your slicer program. There are great resources and tutorials available there so you can find out exactly how to make changes like these in your own specific slicer program.
Reduce the Print Head Temperature
Lowering the print head temperature is one of the first steps to take when troubleshooting bad bridges or other issues with filament cooling and bridging. When an extruder is too hot, it can create a situation where the filament flow moves faster than expected, and there isn’t enough time for it to cool properly. Temperature towers for 3D printers are a great way to test different temperatures and figure out which ones work best for avoiding bridging.
Try a test print that will produce a bridge but lower the printing temperature by 5 °C to determine if the temperature is affecting bridging issues. Try reducing the temperature by a further 5 °C if the test print doesn’t bridge properly (as long as the temperature stays within the manufacturer’s limits). If the printer is still not bridging properly, then another aspect of the 3D printer is probably the culprit.
Additionally, keep in mind that different filaments have various ideal temperatures.
Increase the Cooling Fan Speed
If the filament doesn’t move, sagging in low temperatures or you prefer printing at higher temperatures for cleaner layer lines, increasing the cooling fan rate of your 3D printer can help minimize sagging. This cooling process works by allowing increased air to be blown onto the extruded filament via the fans, aiding in rapidly dissipating the heat from the filament and allowing it to solidify quickly and reduce sagging.
It might be a good idea to add a specialized part cooling fan to your 3D printer if it doesn’t already have one.
Reduce the Extrusion Multiplier Values
If you’ve already reduced the extruder temperature and increased the cooling rate of your 3D prints but the result is still not up to your standards, it might be time to adjust the extrusion multiplier. This proportion determines how much filament is extruded while printing and when this number is too high, globs can gather on the filament as a result, resulting in unsatisfactory prints.
This extra filament will press down on the bridge while printing, perhaps leading to bridging problems. To help reduce the risk of bridging failures, it is recommended to decrease your extrusion multiplier by no more than 10% from the default setting.
Reduce the Printing Speed
High Print speed may also be a factor in determining the quality of your 3D prints. When your nozzle is moving too quickly, it can cause problems while bridging and filling gaps as the filament won’t have enough time to bond with the previous layer as it’s pulled along by the machine.
Decreasing your print speed in 10 mm/s increments is a great way to start. Experiment with different speeds and you’re sure to find one that works for you, but take caution not to go too slow. If you do, the filament will be suspended in the air and tend to droop creating waste and inconsistencies in your build.
Physical Reasons & Solutions
The solution isn’t always in the software, especially when it comes to 3D printing.
One of the main points to remember with 3D printing is that it’s a two-part operation: software, and hardware. The software (slicer) needs to be well-tuned to the printer, but it’s equally important that makers take extra steps to ensure their filament and printer are properly cared for in order to achieve optimal prints. If the printer isn’t clean and well-maintained, it won’t matter how finely tuned your slicer is – you’ll still have trouble getting prints that meet your expectations.
Use High-Quality Filament
Investing in a higher-quality filament with a tighter tolerance is an important consideration for any 3D printer, especially those trying to achieve complex and intricate prints. A tighter tolerance means less variation in the filament’s cross-sectional area, leading to extrusion that is more consistent and reliable, reducing the possibility of sagging bridges and other unwanted defects.
Bridging in 3D printing can be approached in a variety of ways, and there are also many different ways to get desirable outcomes. In addition to bridging, you may repair a wide variety of other quality concerns with your 3D printing by fine-tuning the settings of your slicer.
Learn more about this no-cost strategy for better print quality by reading our advice on optimizing your 3D printer.
Use Dry Filament
If you want the best results when 3D printing, using a dry filament is key to avoiding bridging issues. Wet filaments will cause the extrusion of your printer to be uneven and inconsistent, resulting in an ugly print with visible “bridges” of material joining the main body of the object.
Using a filament dehydrator or taking measures to keep your filament dry from moisture in the environment can significantly improve the quality of your prints by ensuring that you are using consistent and dry filaments for your creative projects.
Last Option: Add Support Structures
3D printing can sometimes be tricky as it requires bridging over gaps, and some printers just don’t have the capability to do it. If you’re noticing your printer is struggling with bridges that are far too long or not forming correctly, manually-added supports can help provide an additional underpinning for the bridge. This will lessen the strain on your printer by breaking up a single, long bridge into shorter segments that your 3D printer has a better chance of completing nicely.
Cheating on bridging may seem counter-productive, but it has its advantages. A few supports placed in strategic locations can be the difference between a successful print and a huge headache. The basic rule is to support a bridge when the gap between structures is more than the nozzle diameter, or if you’re feeling unsure, just add one or two supports that can easily be removed after printing.
Gunaseelan Murugesan
Experienced Project Engineer with a demonstrated history of working in the field of Product Design & Development industry in Mechanical Engineering. Skilled in 3D Printing and Re engineering Technologies with CATIA V5 , Materials Science, Finite Element Analysis (FEA), Mimics, ANSYS Workbench and Casting Simulation software. Strong engineering professional with a Master’s Degree focused in Industrial Metallurgy from PSG College of Technology, Coimbatore.
