One issue that users experience after 3D printing threads is having them not fitting together properly. This can lead to failed prints and wasted material and that’s why I wrote this article on how to fix this problem.
To fix 3D printed threads not fitting, you’ll need to calibrate the extruder steps and print temperature and ensure proper thread design and tolerances. You can also try using a tap or making some scaling adjustments. Using the “Horizontal Expansion” feature in Cura can also help to fix the problem.
This is the basic answer on how to fix 3D printed threads not fitting, keep reading to find out more details and information about it.
How to Fix 3D Printed Threads Not Fitting
These are the main ways to fix 3D printed threads not fitting:
Use horizontal expansion on Cura
Make scaling adjustments
Calibrate your printer
Use a tap
Ensure proper thread design and tolerances
1. Use Horizontal Expansion on Cura
Another fix for 3D printed threads not fitting is to use the “Horizontal Expansion” feature that is available in Cura.
This feature allows you to adjust the dimensions of the printed object horizontally, which can help fine-tune the thread fit.
Here’s how you can use Horizontal Expansion in Cura:
Open Cura
Access the “Horizontal Expansion” setting
Adjust the Horizontal Expansion value
Print a test and evaluate the quality
To find this feature, go to the Cura sidebar, navigate to the “Material” tab. Scroll down until you find the “Horizontal Expansion” option or use the search bar to locate it automatically.
Increase or decrease the horizontal expansion value to adjust the thread fit. Positive values will expand the model horizontally, while negative values will contract it.
Start with a small adjustment, such as 0.1mm, and slice the model. Print the object and test the thread fit.
If the threads still don’t fit as desired, do the process again and adjust the horizontal expansion value incrementally until you achieve the desired fit.
Horizontal expansion can be used in combination with other methods mentioned in this article, such as adjusting tolerances during design.
One user suggests using the horizontal expansion feature to fix any tolerance issues on the model. Another user stated that he was able to fix this issue by setting his horizontal expansion in Cura to -0.15.
Check out the video below for more information about how to use this setting.
2. Make Scaling Adjustments
Making scaling adjustments is another possible solution to fix 3D printed threats not fitting. Slight scaling adjustments, typically around 1 – 2%, can help compensate for variations in filament shrinkage or expansion.
You can make this type of adjustment in Fusion 360 or any other software you are using to design the threads. One user stated that sometimes scaling the diameter in your slicer is all you need to do to get the threads fitting.
He said that he was able to fix this problem by scaling the diameter of the nut up by 2% and it turned out perfect. Another user suggests increasing the female thread or decreasing the male thread by 5% in the X and Y plane.
One 3D printing hobbyist stated that for a 3D printed thread to fit in you need to adjust the scale in a disproportional way.
He recommends increasing the X and Z dimension by 102% and leaving Y at 100%, especially if you only have the STL file to work with. Another hobbyist was able to solve his issue with threads not fitting in by scaling down his thread on Fusion 360.
Check out the video below for more information about how to scale objects in Fusion 360.
3. Calibrate your Printer
Making sure your printer is properly calibrated is a way to fix 3D printed threads that are not fitting in. This is because an accurate calibration can be very important to achieve precise thread dimensions.
To properly calibrate your printer, you’ll need to:
Level the bed
Check the extruder steps/mm
Fine-tune the flow rate (Cura)
Measure and adjust the print temperature
Calibrate the flow rate
Verify and adjust the print speed
Fine-tune retraction settings
One user stated that after tuning in the extruder steps and properly calibrating his printer he was able to get parts that immediately fit together.
Another user also recommends calibrating the printer, including the flow rate, e-steps, and retraction. He suggests using the Teaching Tech Online Tool to assist with calibration.
Check out the video below for more information on how to calibrate a 3D printer properly.
4. Use a Tap
Using a tap can be another solution to fix 3D printed threads that are not fitting together. Taps are specialized tools used to cut or create threads in materials like plastic, metal, or wood.
They are useful for correcting and refining the threads of printed objects to ensure proper alignment and a secure fit.
Just be aware that taps come in different sizes and thread patterns, so choosing the right one that fits your needs is important.
Here are the steps on how to tap a thread that is not fitting:
Identify the specific threaded hole that is causing the fitting issue.
Choose a tap that matches the desired thread size for the problematic hole.
Position the tap in line with the existing threads of the 3D printed hole.
Begin turning the tap gently in a clockwise direction, ensuring it catches the threads and initiates the cutting process.
Apply consistent clockwise pressure while turning the tap.
Continue tapping until the desired depth or bottom of the hole is reached.
Reverse the tap’s direction by turning it counterclockwise to safely remove the tap from the threaded hole.
Test the thread fit with the mating component.
One user recommends buying taps and dies and stated that you are better off making the threads bigger and then cutting them down to the final size with real tools.
Another user stated that if you are planning on 3D printing a lot of threads then it is recommended to buy a tap and die set. He also said that you can buy a cheap set since plastic won’t break any tools.
Prices pulled from the Amazon Product Advertising API on:
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.
Check out the video below for more information on how to tap a 3D printed model.
5. Ensure Proper Thread Design and Tolerances
Another way to fix 3D printed threads not fitting is to ensure that the design is correct and apply the proper tolerances and clearances.
This may be especially helpful if you are designing your own models. You should make sure that the tolerances and clearances are correct for the thread you want to print.
Tolerance is the acceptable range of variation in the size or dimensions of a part. It determines how much the actual measurements can deviate from the desired or nominal measurements while still ensuring proper fit and function
Clearance is the intentional space or gap between parts to allow them to fit together easily without getting stuck or rubbing against each other.
This method will depend on the software you are using to design the threads. The most recommended software to design your own threads is Fusion 360.
One user suggests setting a parameter for tolerance to 0.2mm and adding/subtracting that from your dimensions. Another user recommends allowing an additional clearance of 0.1 – 0.2mm between parts that need to fit together.
Check out the video below to learn how to design your own threads using Fusion 360.
Michael Dwamena is the founder of 3D Printerly, a platform dedicated to simplifying 3D printing for hobbyists and professionals alike. Owns over 20 3D printers (filament and resin) and has plenty experience 3D printing. Michael has authored over 900 articles, helping millions navigate the exciting world of 3D printing.
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