A Probe Safety Clip for the MicroMag 2900 AGM

A Probe Safety Clip for the MicroMag 2900 AGM

This is a little project I finished some time ago to address one recurring problem with the PCM MicroMag AGM. The AGM probe is held to the transducer by a 7 pin connector (Amphenol/WPI 126 Series Miniature Hexagonal Connector), as shown in the picture.

Initially, the pins sit snug in the receptacle and hold the heavy probe in place. However, frequent plugging and unplugging, as common during use, leads to the pins becoming less tightly fit. The probe is then prone to easily detach from the transducer and fall to the bottom of the instrument, crushing the sample carrier.

I found that the single screw seen above the connector could be put to use. The idea was to design some kind of clip that prevents the probe from falling by providing additional support. I went to several design stages and manufacturing methods. The first iteration of the safety clip was made by 3D-printing of a model built with Autocad Inventor. I was excited by the possibilities of additive manufacturing at first. However, it turned out that the printed object was quite brittle and did break quickly under stress.

So, after additional design changes and a switch to conventional machining techniques, I came up with the current design that seems to do the job quit well. Due to the requirement of lightweight design some kind of plastic material was necessary. I chose Delrin, a well-known and easily machinable material.

The clip consists of three parts, the upper part is permanently attached to the AGM transducer, the middle and lower part slide out of the upper part to make insertion of the probe easier. The third picture shows the complete assembly with clip and probe and transducer base plate.


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