NO vs. NC limit switches?

I’ve done a bit of searching for the Nomad’s limit switches and they appear to be these. The Nomad uses an NO variant with just a plunger, I’m guessing D2QW-C003M (which seems to cost ~$4/piece, Carbide 3D didn’t skimp on these switches!).

However the GRBL docs and more experienced machinists that I’ve talked to say that it’s better to use NC switches, because when something goes wrong (e.g. a wire gets cut), the machine can easily detect that there’s a fault and sound an alarm or fail to start rather than allow something to crash.

Since I’m replacing a bunch of my Nomad’s components anyway, I’m thinking of replacing the limit switches too and D2QW-C002M should be a drop-in NC replacement.

Of course GRBL will need to be updated to deal with the signal inversion but that’s fairly straightforward.

Does anyone have any thoughts? Is there a good reason to keep NO switches?

1 Like

Fortunately, the wires are well routed/protected, so rarely get damaged in operation. Moreover they are only used for homing, not as limit switches in the stock setup.

The big disadvantage for NC switches is that they need to be shielded since they’re more likely to generate false positives, and you’d need to add additional switches to get limit switch functionality at the near end of travel.

1 Like

Proxies > plungers

Wonder what the new Nomad is going to get.