3D Printed Thermal Insert Press




Introduction: 3D Printed Thermal Insert Press

In this instructable I will walk you through how I designed and built my own thermal insert press using readily available parts and my Prusa i3 MK3 3D printer.

As quick background a thermal insert is a metal, usually brass, cylinder that has threads on the inside wall and knurling on the outside wall. They are designed to be pressed into thermoplastics (PLA, PETG, ABS...) with a hot iron (usually a soldering iron), so that the plastic part can accommodate a metal fastener. For more about thermal inserts and how they are used refer to this video:

As you can see in the video above you don't need a press to add thermal inserts to your project, but by using a press you maintain better vertical alignment, better control over depth and speed.

There are a handful of other thermal insert press designs available: some DIY and some industrial machines; most less complex than mine and some wildly complex and expensive. When I was looking at the array of available options for presses I noticed a large gap between the small 3D printed DIY offerings and the large $2k+ industrial machines, my instructable aims to bridge this gap for those who want a machine closer to the form and function of the big industrial machines that can be made for less than $100. Here is a list of the thermal insert presses I found when researching this project:

Yardley Press - $2,450: https://www.yardleyproducts.com/product/thermal-in...

Sonitek Press - $3,495: https://www.sonitekstore.com/heat-staking-arbor-pr...

Adafruit DIY Press - <$50: https://learn.adafruit.com/heat-set-rig?view=all

Matter Hackers DIY Press - <$50: https://www.matterhackers.com/articles/how-profess...

I also want to encourage everyone with a 3D printer to stop relying on solely on 3D printed parts, these thermal inserts provide a low threshold of entry to start doing that. I designed and built this press not just to have a thermal insert press to use for future builds, but to teach myself how to incorporate metal parts into my 3D printed designs. This design was way out of my comfort zone, this was my first 4 bar linkage, first time using a bearing, first time using a linear rail, first time using square nuts and my first design that used a thermal insert. I tried to keep the design simple, by making it a derivative of other similar presses and focus all of my efforts on the implementation of hardware I had no prior experience with. This way when I go into future designs I can have all the uncertainty around these mechanism components taken to zero and focus more of my energy on the creative aspects of the new project. Now lets get to the nuts and bolts ;)


Press Max horizontal reach: 5.4"

Press Max height: 5.92"

Cost of parts (not including Iron and Filament): ~$50

Number of unique 3D Printed Parts: 11

Filament Used: 494g

Printer: Prusa i3 MK3 (need the entire print bed)

Soldering Iron: Hakko 888

This iron is discontinued, but the very popular replacement the 888D used the same iron hand-piece (PN: FX8801-02)


Step 1: Printed Parts

All parts were printed in PETG, I would have made this out of ABS, but I don't have an enclosure built for my 3D printer right now to deal with the ABS fumes. I expect that the frame would me much stiffer if I made it out of ABS.

I have attached screen grabs from Pusa Slic3r to capture all my settings, which are pretty standard, almost everything got printed at 0.15mm layer heights with 20% infill.

When printing the handle make sure to use a raft, otherwise it will fall over.

Step 2: Installing Bearings and Linear Rail

This project uses 8x 608zz skateboard bearings in total and all are press fit.

The linear rail I used for this project is about the cheapest one you can buy, so don't be surprised if it needs a little oil the first time you use it.

Step 3: Installing the Heat Shield

After fiddling around with an early prototype of my design for a few days I realized just how easy it is to accidentally bump the hot iron, so I made a little protective shield to cover it. I also use the opportunity to make my first flexture design, the heat shield clamps itself to the main bracket with no fasteners or adhesive.

Step 4: Installing Thermal Insert ......by HAND

So while I was finishing up the latest revision of this press I realized that there were a few location where I was using nuts that could easily get replaced by thermal inserts to improve the design, so in this step we will install a handful of thermal inserts by hand in order to build the thermal insert press.

When installing the inserts for the iron flexture clamp I found that I was getting clumps of plastic behind the insert which kept me from being able to feed a screw into it when in comes time to clamp the iron. My fix was to run a screw thew it while the insert was still warm to clear out the plastic.

Going forward I am going to be switching to tapered thermal inserts, because I suspect this will not gum up the back of the hole as bad.

All inserts are M3x4x5mm

Step 5: Installing the Springs

You will see two different versions of the yellow depth adjustment bracket in this instructable, I started with the smaller version and switched to the larger one to allow me to increase the return spring mounting height. As you will see in the photos the soldering iron was hanging lower than the heat shield when fully retracted and I wanted to pull it up higher to keep it out of the way of my fingers.

The springs are attached to the soldering iron clamp and the depth adjustment bracket via M3x4x5 thermal inserts, M3x8 screws and M3 washers.

Step 6: Installing the Base

The base and main bracket are bolted together by 5/16" threaded rod, this is the same rod that we will use shortly to bolt the arms together.

While I was designing this project I stumbled on this Kickstarter for Pact Plate a modular base plate system that has a matrix of threaded inserts for building jigs. Pact Plate uses a 25mm grid of M4 fasteners, so in addition to supporting their Kickstarter I also designed my press base around their hole pattern. If there Kickstarter is successful and I receive my plates I will swap out the piece of birch ply I am using now for Pact Plates. This will allow me to use the Pact Plate hole pattern to mount clamps and jigs to hold my parts that are having thermal inserts installed.

Step 7: Installing the Iron

The slots I designed into the main bracket are sized for the zipties that come with the Prusa MK3 3D printer, so if you have a Prusa you can go through you bag of spare parts to get your zipties.

Step 8: Installing the First Section of the Arm

Step 9: Installing the Second Section of Arm

The yellow stand-off on the 4 bar linkage turned out to be an important and accidental design feature. When I was sizing the lengths of the 4 bar linkage I found that if the lengths were sized correctly I could have the yellow spacer bottom out against the main bracket exactly when the linear rail reached the bottom end of its travel. This feature keeps the linear rail from sliding off without having to incorporate an additional stop block in the bottom of the rail.

Step 10: Attaching the Arm to the Iron Clamp

Step 11: Install Handle

Step 12: Install Depth Gauge Rod

You can adjust the maximum depth the iron will travel by adjusting the red thumb screws at the top, just like a drill press.

Step 13: Lessons Learned

Overall I was pretty happy with this project and expect that I will get a whoe lot of use out of the press and the techniques that I gained while designing it. I did however have a few lessons learned I wanted to share:

1. Use tapered thermal inserts, not cylindrical. I had a very difficult time getting my cylindrical thermal inserts to seat straight.

2. I constrained myself to using the springs I had on hand, but I suspect I am overextending the return springs slightly. I might replace these down the line to ones that are better suited for this length of travel.

This instructable is being entered in the Metal Contest, so if you like what you have seen, please Vote! Thanks

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Tip 2 years ago

This is a fantastic design for a self-built tool that is a joy to use! Thank you to the designer!!
Here is a link to my bill of materials for anyone interested: https://docs.google.com/spreadsheets/d/1wolEa3MVAE...
I have included some information in the notes column that may help with where I used certain fasteners, cut lengths, etc. My total build cost, including sales tax, was $46.87 in July/August 2020. This excludes the printed parts needed for the build, a piece of plywood for the base, and the soldering iron.


3 years ago

I had to sink 300 6-32 inserts for a design project at work. The surface was at an angle and the resulting inserts in groups of four had to align with holes in a metal cylinder. For me I used a Weller solder station to sink the inserts initially and then to reach through the holes in the aluminum to fine tune the alignment.
I like your design. It's quite clever.
The most interesting part was the psychological aspects you disclosed, initial trepidation and happiness on a successful outcome. We have all been there.
Thank you for sharing that.


3 years ago

Great idea!


Question 3 years ago

I would like to know if this project is easy to make? Does hot iron or soldering work better?


Tip 3 years ago on Introduction

I like the thinking behind",more for less" This a good project for the beginner, who wants to design one for themselves. The key aspects:
Thermal Insulation:
Maintaining better vertical alignment.
Control over depth, as well as speed.
The options of Brass or metal cylinder threads.
THERMO PLASTICS(PLA, PETG, ABS) w/ soldering iron or hot iron.
The affordablility of DIY , The smaller size vs~ the price of Industrial sizes.
The research, and aim to bridge the gap between smaller 3D printers and the Industrial size 3D Options. For less you can achieve your design.
The step by step instructions, parts, and components.
The benefits as well as the challenges of using Thermal inserts vs. not.
The range of choices from Complex to Wildly Complex.
My Summary is, this is a great option for anyone who desires to DIY on a smaller, more attainable design. The closer to form function made for less.
Thank you my vote is for John Culbertson.


3 years ago

When I had to do my brass inserts, I just threaded them onto a long bolt and heated them up with a propane torch. Then I could precisely press the thing into the plastic. If the back side was open, I could put the bolt through the plastic, then screw on the insert, heat, then pull it through. Doing it that way means that the threads never get covered with plastic. I've heard a lot of people saying to just jam it in there with a soldering iron, but I could never get that to work right. Your rig would certainly help if people want to do it that way.