Dimensional accuracy of your prints will be important to assure better fit, function, and tolerance. Especially in articulated parts and designs, you will have to maintain a certain level of accuracy to keep the parts functional. People experience tolerance issues with their print and sometimes don't even notice that it is entirely a dimensional accuracy problem.
What Causes Bad Dimensional Accuracy?
Bad dimensional accuracy is such a broad subject that it might be hard to troubleshoot it as quickly as some other problems you might have. Everything from the slicer software you are using to mechanical problems in your 3D printing can affect the accuracy and precision you are going to achieve.
We suggest our users first print a calibration cube and use a digital caliper to measure the dimensions of the cube to put a finger on how bad the problem really is. After you have an idea of how off the calibration of the machine is you might get a step closer to solving the problem. Some of the common causes for subpar dimensional accuracy are;
- Design mistakes
- Belt tension problems
- Bad first layer adhesion
- Printing too fast
- Temperature problems
- Bad calibration
- Wrong object sizes
- Flow rate issues
- Bad filament quality
These are not the only causes of bad dimensional accuracy but will be a good start for you to explore the issue and solve the problem.
How to Get Better Dimensional Accuracy?
While the subject is complicated, solving the problem might be easy by using the process of elimination. You need to consider the most common problems and apply the solutions to those problems until the issue is resolved and you start getting better performance from your 3D printer.
Evaluate the Problem and Take Measurements
The first step of solving a problem is admitting that there is a problem. The second step would be evaluating the problem and finding its cause. As we have said before, we advise our users to print a calibration cube and take measurements of it using a digital caliper. Measure different axis and how bad the problem is on different planes. If the margin of error is higher than the acceptable range, you can start implementing solutions.
Design with Dimensional Accuracy in Mind
While this might be a temporary solution to a permanent problem, compensation for shrinkage and a margin of mistake during the design process might eliminate the issue entirely before it even starts. There is already a margin of error that is acceptable for most 3D printers that change depending on the device and material you are using and designing with these margins in mind can be the solution to your problem.
Recalibrate Your Device
The smartest thing to do from the hardware aspect would be to calibrate your device again. Make sure the calibration on all axes is on point and there is no problem. Dial in the first layer perfectly to ensure better first layer adhesion, then adjust the stepper motor calibration. The calibration process will change for different segments of 3D printers and it is the most reliable way of solving a lot of problems you might experience while using your device.
Change the Printing Speed
Too fast of a 3D printing speed can cause a number of problems from bad details to subpar tolerance. To avoid this issue, hop on the user interface of your 3D printer and adjust the printing speed to the optimal point. Nobody wants to wait longer than they have to for a print, so you will need to experiment with different speeds to find out the maximum printing speed you can achieve without negatively affecting the quality of the prints.
Be Mindful of the Temperatures
Heat has a way of altering the state of materials. The effect it has on the material will entirely depend on the filament you are using, but dimensional issues can be caused because of imperfect temperatures in any material.
First of all, you will need to adjust the extruder temperature. To find the best temperature for the specific device and filament, you can print a temperature tower and evaluate the results. This method will allow you to observe the different temperatures’ effects on your prints.
The other thing you need to be mindful of would be the chamber temperature. This will only be an issue for 3D printers with enclosures but the temperature you are printing with might be way too hot for the filament you are using. PLA, which is one of the most popular filaments on the market, is notorious for not responding to heat very well and losing its structural integrity. For this issue, we suggest increasing the fan speed and maybe even leaving the lid of your 3D printer open.
Check the Flow Rate
Flow rate dictates how much filament gets extruded through your nozzle in a given time period. It will have an impact on several aspects of your 3D printing, such as the surface smoothness, printing time, and of course, dimensional accuracy. If it is set too low, you might experience gaps in your layers and get different dimensions than you want to and if it is set too high, you might experience zits and bubbling on the surface of your prints which will also affect the accuracy and tolerance.
Try changing the flow rate and test it out on a couple of prints. Aim for a change in 5% increments until you achieve the perfect flow rate. The flow rate will also be affected by extruder heat, so keep that in mind.
Adjust Your Belt Tension
Belt tension will control how your print head moves on the X and Y axis. Making it too tight will restrict the moment of the print head and adjusting it too loose will cause dimension problems. The perfect tension will change depending on the 3D printer but as a rule of thumb, it should not be loose enough to have a visible sag. It also shouldn't be so tight that you can't move it with your hand. You can adjust the belt tension using a hex key on the bolt that is designated for it. The process might change depending on the device you are using so make sure to check the user manual of your 3D printer.
Experiment with Different Filaments
As you know by now, different materials interact with heat differently. While some filaments are very comfortable to print with, some others don’t respond too well to high temperatures. If the material you use is not essential to the function of the print, you can always experiment with different filament types and see if it has a positive effect on the dimensional accuracy of your prints.