The Power of Multiple Tools
No tool alone is revolutionary. For example, a waterjet becomes transformational once you have a press brake for bending sheet metal. Similarly, a 3D printer with a laser cutter can become a very powerful combination.
A fixture we recently designed is a great example of rapid prototyping with a combination of tools. In this case, a laser cutter and an FDM 3D printer. The requirements of the fixture were to hold and allow rotation of a device under test (DUT) at precise 5 degree increments. It had to be designed and fabricated quickly and use as many off the shelf (OTS) components as possible. The entire design, fabrication, assembly and test time took around 1 FTE day. Everything else were OTS parts ordered off McMaster Carr.
One neat thing to highlight is that McMaster Carr’s wonderful CAD library can be used to your advantage if you have fabrication abilities. In my case, I couldn’t find the right OTS knob to fit the rotary shaft that I specified. So instead of wasting time looking further or buying a non-standard knob from elsewhere, I simply took the CAD of the closest knob that would work, modified it in SolidWorks, and then 3D printed it.
Combining prototyping techniques can lead to better, faster results and this was one great example to showcase. Stay tuned for more interesting content!
ABS parts with heat set inserts
Heat set inserts are a great way to make a strong, reliable thread in 3D printed parts (FDM specifically). These make a big difference if you need better pullout force, or if you’re regularly removing and/or adjusting threads.
Pay attention to which kind of insert you use though - there are various different types, but the best use polymer flow to their advantage when inserting to create a strong lock.
Bearing block with spring plungers
This is a closeup shot of the bearing block. This holds a press-fit bearing for the rotary shaft and also provides mounting for the spring plungers which lock into the ball detents and provide a satisfying click at every 5 degree interval.
Rotary shaft & knob
This is the back of the fixture showing off the rotary shaft mounted in the bearing and the custom (not custom) 3D printed knob which was “stolen” off McMaster Carr.
Fully assembled fixture!
This is the fully assembled fixture (without the DUT mounted). Using 8020, 3D printing, and laser cutting allowed this assembly to be built incredibly quickly. The ball detents on the main mounting plate work well with the spring plungers to hold the DUT firmly in place, but still allow the operator to adjust and click every 5 degrees.