SRX Mag Encoder Mounting Kit Grommet Alternative

Hello everyone!
If you have ever tried to use the SRX Mag encoders with the Toughbox Micro, you might have noticed that the grommet’s height that comes with the kit is not enough to tune the encoder’s distance from the magnetic shaft.

The most common solution to this (that I have seen while researching!) was shortening the shaft in a lathe. However, for teams like us who don’t access to a lathe right away, our mechanics lead found a much simpler solution. He simply grabbed some Lego Tires that were sufficient enough in height and diameter. (I don’t remember the exact size, but I can check it if anyone is interested!) We simply swapped the original grommets with lego tires and it was perfect. To be honest, it was very sturdy and reliable.

Overall; for teams who are having a similar issue and do not have a lathe/don’t want to machine the shaft, this is a great solution as far as we have experienced.

Here are some photos:


You know LEGO nerds only need to see the markings, right? :wink:

A glance at the picture says these are 30.4 x 14 VR tires, which are retired parts (last released in 2006) but still available new for less than a dime plus shipping. That they’d be sturdy enough is hardly a shock to me.

The bigger question is why the AndyMark grommet wasn’t sufficient adjustment range; I don’t remember hearing any such reports when I worked there. Have you tried pinging their support email?


This is a good find and thanks for sharing. I have used the AndyMark grommets in the past but could never get quite enough spacing to get a steady green indicator. It was always an amber that might flicker green, but needed to be spaced just a bit further. It looks like this would solve that.

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We’ve had this same issue in the past with SRX Mag Encoders on the Toughbox Mini. Last season, we 3D printed the mount available on AndyMark’s website and it worked really well (Here’s a download link to reduce clicks). If your team has access to 3D printing capabilities, I would highly suggest giving these a try. If they don’t work, you can always adjust the model height.

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Strange; I actually recall that we cut some grommets down the first time, though they were from the local Ace and not AndyMark. If they had been too thin, probably the first thing I’d have tried was an extra half grommet.

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Interesting! In our case it was mostly amber and sometimes flickering green like @chadr03 mentioned. I assume there would be differences per product due to the production process. Also, we noticed that some encoders had to be closer than others to give us the green light, so I think that is the case here. (Also, as an international team, it is very hard (and expensive) for us to ship spare grommets in a short period of time. That is why we had to find a cheaper and faster solution :sweat_smile: )

I haven’t sent them an email yet but it is on my to-do list! Thanks for the tires’ link by the way! I assume all encoders need custom spacing and grommets might not be enough sometimes. (Well, none of them was enough in our case :thinking: ) Yet, we found out that this solution was sturdy enough just like you said. So, not complaining about the undersized grommets! :grin: