Incorporating Nuts and Thread Inserts in 3D Prints with Markforged

Design a pocket or cavity in your 3D model where the nut will fit snugly. Here’s how you can do it:

1. Measure the Nut: Measure the dimensions of the nut you want to embed (width across flats, thickness, and height). A vernier calliper is a useful tool for this.
2. Model the Pocket: In your 3D design software create a pocket that matches the nut’s dimensions with a small tolerance for ease of fitting. We usually use 0.125mm each side, which is very achievable and repeatable on Markforged machines.
3. 3D Print the Model: 3D print your model with the nut pocket.
4. Insert the Nut: After the print is complete, insert the nut into the pocket. You may need to press it in firmly or use a bit of glue to secure it.

Note: As with all these techniques make sure when you torque up your assembly you’re loading across the layers and not pulling against just the lamination, it’ll be stronger that way (think about it like the grain in wood).

Markforged 3D printers allow you to pause the print at a specific layer to insert the nut. Here’s how we do it:

1. Design the Pocket: As above, design a pocket for the nut in your 3D model. This time it can be anywhere in your model, and we go on to describe one that’s buried inside the part in this example.
2. Slice the Model: In Eiger identify the layer where the pocket for the nut begins and turn off supports for that area (you can leave supports on and pull them out later if you wish).
3. Set a Pause: Set Eiger so your printer pauses at the final layer of the insert and take a note of the time it tells you to be come back.
4. Start Printing: Begin the print so the pause is at a time to suit yourself i.e. a time when you’re around.
5. Insert the Nut: When the printer pauses, insert the nut into the partially printed model and ensure its flush with the top layer of the print (a little below is also OK, but proud is definitely unacceptable!).
6. Resume Printing: Place your print bed back on the machine and continue the print to encapsulate the nut in the part. Pleasingly Markforged print beds will re-locate reliably, accurately and repeatably so this is an easy thing to do, and you won’t see a witness line in the part wall when it’s complete.

Note: Try not to leave the print too long before resuming, it’ll be carrying some helpful latent heat, which you don’t want to dissipate.

This method involves heating the nut and pressing it into the 3D printed part.

1. 3D Print the Model: 3D print your model with a slightly undersized pocket for the nut. If you’re using a threaded insert the hole size can be found on the insert data sheet on the supplier’s website – think ‘tapping size’.
2. Heat the Nut: Use a soldering iron to heat the nut or insert.
3. Insert the Nut: Press the heated nut into the pocket. The heat will slightly melt the surrounding plastic, creating a strong bond as it cools and solidifies.

Some applications will have higher than normal load requirement, here’s what we do at Mark3D.

1. Eiger: Use the functionality found in Eiger (Markforged enterprise printing software) to select the specific area you’re interested in, by ‘adding a sketch’ to define an area where reinforcing fibre can be added.
2. Choose your fibre: Usually we use Kevlar in situations like this, however High Strength, High Temperature Fibreglass works well too.
3. Re-slice: Once you’ve set you number of layers and how many rings of continuous fibre you’re adding re-slice your part and start printing.

General Tips for Success

• Tolerance: Markforged 3D printers hold very good tolerances, so we usually work as we would in other engineering disciplines. If however you have an entry level printer you might need to allow for slight tolerances in your design to account for print inaccuracies and material shrinkage.
• Material: Ensure the material you are using can withstand the insertion process (some materials are more prone to cracking). Markforged Onyx is a reliable base material for this, and can be further reinforced with continuous carbon fibre if needed.
• Thread Alignment: Make sure the threads of the nut align properly with any bolts or screws that will be used.

By choosing the method that best suits your design and 3D printer capabilities, you can effectively embed nuts in your 3D prints for enhanced functionality and durability.

Note: – this information is given as a guide in best faith and should not be used without your own verification taking place.

Would you like to test the strength of Markforged 3D printing technology yourself? 

We’re happy to provide you with a sample part to try in your own workshop. We know it can be hard to believe that 3D printing has come such a long way in recent years, and that’s why we’re ready to prove it. Simply get in contact with us using the form, and we can get to work creating a 3D printed jig, fixture, prototype, or end use part for you.

We’re Mark3D UK, and we’re the Markforged experts. We deal with Markforged 3D printers day in, day out, and have more experience with them than anyone else in the UK.

We hope this blog on embedding nuts and inserts into 3D printed parts was helpful to you. If there are any other guides you’d like to see, get in touch with us and let us know!