Solder Ninja Tweezers

USB-Powered Soldering Tweezers compatible with Weller RTW Tips

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Surface mount devices (SMD) have now become common in the world of hobbyist electronics where soldering is often a key step in making ideas and projects comme to life. But they often require more appropriate tools than the amateur soldering iron.

Among them, soldering tweezers allow reworking most of passive components (resistors, capacitors, inductors, leds) by heating both pads at the same time. However, current products on the market are both bulky and expensive.

By combining the remarquable quality of Weller RTW tips, and the flexibility offered by USB power supplies, my intent is to create an affordable, durable, and portable product for makers and professionals.


  • Portable
  • Compatible with Weller RTW tips
  • USB Powered (BC 1.2, Quick Charge, Power Delivery)
  • OLED display and buttons


I am intent on creating and selling a robust product. This leads to quite specific design choices and to manufacturing techniques that not everyone has access to. One perfect example is the body, milled from a single piece of aluminium.

For me, open source really makes sense when the majority of people can actually make use of the published resources, with the least amount of extra steps as possible. That is why I will be releasing here slightly modified files that anyone can use. In particular:

  • A 3D-printable enclosure with corresponding PCB under CERN-OHL-S,
  • A firmware under GPL v3.

  • 1 × Main PCB
  • 1 × Connector PCB
  • 1 × 3D-Printed Top Half-Enclosure
  • 1 × 3D-Printed Bottom Half-Enclosure
  • 2 × 3D-Printed Buttons

View all 7 components

  • Figuring out the inside

    Nicolas Schurando08/08/2023 at 10:00 0 comments

    I have an initial shape I'm happy with, but now comes the difficult task of figuring out the inside. The tip will be dictating a lot of the design as its insertion distance is almost 3 cm long.

    I'm favoring a mostly uni-body design. The main aluminum part will have its opening closed by a plastic piece where the tip mates; I'm hoping for plastic to provide a smoother insertion of the tip.

    Because of the mating connector only existing in a vertical configuration, the electronics are composed of two boards, at a right angle, joined by solder. Routing of the boards is next, stay tuned!

  • Giving it a shape

    Nicolas Schurando08/08/2023 at 09:21 0 comments

    Taking into account the dimensions of the tip, and the curvature of it's grip, I settled on 85mm for the length of the body.

    I printed in resin a first prototype and was seduced immediately. It feels great in the hand and although somewhat far, buttons are still accessible when needed. Unless I need to shift components on the PCB, I'll stick to this design.

    Photos below.

  • Reverse engineering the connector

    Nicolas Schurando08/08/2023 at 04:53 0 comments

    Weller RTW tweezer tips seem to mate with the handle through a 5-pin connector from Binder.

    A bit of reverse engineering gives us the following pinout:

    1. right heater,
    2. right thermocouple,
    3. ground,
    4. left thermocouple,
    5. left heater.

    As with regular RT tips, the thermocouple shares one pin with ground.

View all 3 project logs

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Nicolas Schurando wrote 09/05/2023 at 08:37 point

Hi :). For the USB Power Delivery specifically I'm using the FUSB302. For other types of chargers, I'm using  the PI3USB9281, and some bit banging for HVDCP (Quick Charge).

Yes, I'm using an adjustable buck to ensure it doesn't exceed the amount of power negotiated. I could have probably gotten away with a pwm-ed mosfet, capacitors and a smoothing inductor, but effectively re-inventing a dc-dc converter while stressing software.

I've made a change since last image, I'm now planning on using only one dc-dc for the two heating elements and redirecting power with individual mosfets for each element.

Thank you for your interest in the project!

  Are you sure? yes | no

CentyLab wrote 08/31/2023 at 17:10 point

Hi, I just wonder what IC you will be using for your USB Power Delivery negotiation. And are you running some kind of buck or boost with the inductors?

  Are you sure? yes | no

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