Best sensor for quantifying magnitude of vibration?

[NeverDie]

I have a small CNC for etching PCB's by isolation routing. The process creates vibration in the machine, which gets worse if there are lose bolts.

I am wondering: what sensor could I attach to it that would let me measure the magnitude of vibration? If the amount of vibration seemed unusually large, perhaps it could notify me that I should tighten the bolts again.

At the moment I'm imagining that maybe attaching a microphone to the CNC might provide this kind of magnitude information (which might be represented as loudness). However, is that the best I can do, or is there actually a better sensor that I might use?

[gohan]

I can't think other than an accelerometer, the fun part will be to figure out what is the direction of the vibration in order to mount the sensors accordingly or use a 3 axis one

[Nca78]

As @gohan says, this is the job for an accelerometer.
Search "accelerometer machine vibration" or "accelerometer CBM" in Google and enjoy :)

[JohnRob]

While not specifically answering your question... would loctite help?
Or possibly nuts with self locking features (castle etc).

[NeverDie]

@johnrob said in Best sensor for quantifying magnitude of vibration?:

While not specifically answering your question... would loctite help?

Yes, I think it would help. Not very easy to apply in this situation though, because most connections are t-nut without much thread pushing through to the other side.