SMD LED tester tweezers

Wanhao Duplicator i3 V2

Yes

50%

supports "everywhere" are necessary inside the battery compartment if you print the tweezers as a single part

Isn't it annoying to try to touch SMD LEDs with the tips of your multimeter in order to see what color they have, what the correct polarity is and how bright they might shine? Admittedly there are tweezers available which you can connect as test leads to a multimeter, but still, you might not get all the answers you wish for.

Research

I found two suitable models on Thingiverse which I thought could be easily enough modified:

• Tweezers for SMD by Ruslan_Kulibin
• SMD Test clamp by Tom20170

which I both printed yesterday. They are both quite nice designs, I especially like the spring in the second one, but I felt that both were simply too short for my hands and since they were only available as STL files modifying the design wasn't so straight forward.

A 2032 button cell is a very versatile tester for all kinds of single LEDs, from infrared to blue, ultraviolet and white. No additional resistor is necessary as the internal series resistance of the battery will limit the current to a safe value.

The design and assembly

From the included OpenSCAD source you can print the tweezers either in two halves or in one piece. When printing it in one piece make sure that your slicer does not put support into the long and thin channel because it will be impossible to get it out, while you need to have support in the battery compartment for it not to collapse.

Apart from the plastic parts you will need

• two sewing pins, preferably nickel coated ones without a plastic tip
• some length of single-core wire
• a soldering iron and solder
• optionally but recommended two colors of heat shrink tubing
• a 2032 lithium button cell

And here are the detailed assembly instructions:

1. print the tweezers
2. drag the wire through the arms
3. solder the wire to the pins
4. attach the pins in the openings of the arms
5. bend the wire to form battery contacts

Optionally you can print the tweezers in two identical halves which you glue together.

If you use sharp pins then you can even test LEDs which are still inside the manufacturer's tape strip by pinching holes through the clear plastic top film.

Custom Section

Optional holster

Since 2018-11-12 the OpenSCAD-file also includes the option to create a matching holser to keep the sharp tweezers in your shirt pocket. I recommend to print the holster standing up, opening down with brim. No supports are necessary.