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Help! how to use sensor to detect gap 0.2mm?

Mon, 23 Jun 2008 22:05:54 -0700

Hello all,

currently I have a problem with the gap of my project. My project compenent have gap btw the motor and chassis. It supose to be no gap (<0.2mm). So my question is how to
design the sensor that detect the gap. thank you.

Re: Help! how to use sensor to detect gap 0.2mm?

Tue, 24 Jun 2008 08:30:11 -0700

laser sensor?

Re: Help! how to use sensor to detect gap 0.2mm?

Sat, 28 Jun 2008 07:01:37 -0700

I dont think you will get cheap sensors for such high precision.

Re: Help! how to use sensor to detect gap 0.2mm?

Thu, 26 Jun 2008 23:16:33 -0700

omron smart sensor? but it will cost a lot. i want a cheap and easy to develop sensor which can detect gap between 2 metal. thank you.

Re: Help! how to use sensor to detect gap 0.2mm?

Sat, 28 Jun 2008 11:17:35 -0700

@saloi
You could probably use an LDR attached to a 0.2mm shim or feeler gauge and arranged like this...

If the gap is more than 0.2mm more light would fall on the ldr,which after a certain threshold would trigger a gap violation condition.
A high sensitivity ldr would be needed.The physical arrangement,ambient light conditions,proper sealing of the ldr from ambient light etc would be critical.Even with all this the repeatability and precision would have to be seen after construction.

Re: Help! how to use sensor to detect gap 0.2mm?

Sat, 28 Jun 2008 11:29:41 -0700

go u only want to detect gap or measure it??

Re: Help! how to use sensor to detect gap 0.2mm?

Sat, 28 Jun 2008 19:31:41 -0700

hi saloi,

you also can try using a Peizoelectric wafer between the motor and the chassis to know if there is any deviation. Peizo element inside any buzzer can be inserted and if the motor is too close and hits the peizo element an AC pulse is generate from it which can be used to trigger the gate of a sensitive mosfet which connects to a micro........

Arun

Re: Help! how to use sensor to detect gap 0.2mm?

Sun, 29 Jun 2008 00:26:19 -0700

great arun clever solution