Threaded spacer/pillar to convert m2.5 to m3

Hi, I use MakerBeam to put together a support structure for my projects ( They use M3 bolts. I need to attach breakouts to these beams, and many suppliers like Adafruit use m2.5 or a similar Imperial size for their breakout boards and Feathers. Sparkfun have larger holes and they work fine with M3.
My question is whether you know of standoffs, spacers or PCB support pillars that are threaded with M3 at one end and M2.5 on the other. They can be M/F or F/F - but I am looking for some kind of way to interface between a structure that is based on M3 bolts and fasteners, and M2.5 for most of the small breakouts.
If you know of a structure prototyping kit like MakerBeam that is based on M2.5 that would be even better.

Hi All, Just thought of a way around this - you could obtain 2.5M nylon standoff (Adafruit manufacture these) that will fit with M2.5 mounting holes for some of the Adafruit breakout boards - and then use sandpaper to file down the head of the nylon bolt/screw to fit into the MakerBeam groove. If it is a bit loose, just add a washer. That should solve this problem of how to interface M2.5 with M3 for mounting components on a structure.


Hi Robert,

There’s not much available in the way of M2.5 to M3 adapters - if you had a drill press and a small tap set you might be able to make something up. You could also get a 3mm drill bit to enlarge the M2.5 holes in the PCB (although the recommended clearance hole size for M3 is 3.4mm, so if you can find a 3.4mm drill bit that’d be better).

The key thing to watch out for is whether that would remove a grounding pad or another important part of the PCB.

Good thinking on cutting down the M2.5 standoff Hex head to turn it into a T nut though! If you had access to an SLA 3D printer you could probably get enough resolution with some high-quality filament to print a fastener too.

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