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Since I’ve started showing some 3d printing in my projects lately, I’ve gotten LOTS of questions about the process that has to happen before you even turn on the printer. To be honest, that part of the process was what kept me away from 3d printing for so long! So, the other day, I ran across a small need in my shop (in the middle of filming a different project) so I took it as an opportunity to show the whole process of solving that problem, with a custom designed part.

This entire process took me about 45 minutes, start to finish, and I’m the first one to admit that I’m still very new (and clumsy) with the software that I’m using.  At first pass, it still may look a little complicated, but if you follow along with the software in front of you, I assure you.. it’s really simple. Really, it’s just a matter of getting familiar with the tools and where the buttons are that you want.

3d printing has, so far for me, been something that you use to print out little toys that you download from Thingiverse, but through projects like this, I’m starting to get a better picture of the process as an end-to-end problem solving mechanism. Obviously, it’s not for every application (just like wood isn’t, or metal isn’t) but it is becoming a more powerful tool for me, than I expected initially.

So, let’s check out how I made a custom part, with 45 minutes, free software and a 3d printer!

Here’s what you’ll need:

I started by measuring the hex nut.


I also measured the height, including the threaded rod.


In 123d Design, I made a 6 sided polygon with a radius based on my measurements.


Using the same center point, I made a large circle of arbitrary size.


I used the extrude tool to “pull” the circle into a cylinder. It’s height was about 5mm taller than the height measurement.


I used the extrude tool on the hexagon, which removed that shape from the cylinder, making a cavity.


I used the filet tool to roll over the outside edges of the cylinder, to make it more comfortable to use.


To add some knurling, I made a small cylinder.


I intersected it with the knob, so that it just partially protruded from the side of the outer surface.


I used the pattern tool to copy, and evenly space, this cylinder around the parameter of the knob. I just gave it a number of how many copies I wanted.


That’s all of the modeling! I exported all of it, combined, as a single .stl file.


I open the .stl  in Cura, and rotated it 180˚ so the hex cavity was facing upwards. Then saved it to an SD card.


I plugged the SD card into my printer, and hit


About 20 minutes later, there was a perfectly printed knob.


I didn’t do any finishing to the knob, which would have smoothed it even more, since it was perfectly usable right off the print bed.


It slid right down onto the hex nut, and worked great!!


The entire process took about 45 minutes, start to finish!