Measure distances in mm

[nmlfreitas]

Hello guys
I'm not new with arduino and electronics, but i have a question that i need to ask to people that know a lot more then me.
I want to use a sensor with arduino to measure from 0.8mm to 6 or 8mm. I have a machine that is always working with wood sheets and i need to read the thickness of the sheets with the machine working, do you think it can be done with CNY70 optical sensor?
If not is there another sensor that can do it?

Thanks guys

[CrossRoads]

Got a link tothe CNY70 datasheet?

[pylon]

What accuracy do you need/expect? Is the surface of the sheets always the same (color, smoothness, etc.)?

[nmlfreitas]

Thanks for the quick reply.
The sensor datasheet http://www.vishay.com/docs/83751/cny70.pdf
I need an accuracy like 0.8mm to 0.82 or 0.85 more less.

Thanks

[CrossRoads]

Spec shows output will very from 0.1mA to 1mA, you'll have to take that use an op amp like this
http://www.dipmicro.com/store/index.php?act=viewProd&productCode=TLC279IN
to convert it to a 0-5V signal that the arduino can measure.
From Figure 11 the change in current between 0mm and 1mm is quite small.

[nmlfreitas]

From Figure 11 the change in current between 0mm and 1mm is quite small.

So that means if i want to detect changes from 0.8mm to 0.85 or 0.9 it will be hard or almost imposible right?
Any other sensor that it's possible for me to use?

[Grumpy_Mike]

Yes you are asking too much from this sensor.
I assume you want a non contact sensor? It is quite difficult to do this and I don't know of any off the shelf sensors that will do this.
It might be possible to use a reflection of a laser onto a linear CCD sensor but it is not an easy setup.

[CrossRoads]

You might be better with a mechanical dial kind of tool with digital output. Not sure what that is called.

[Grumpy_Mike]

You mean one of these
http://engineerblogs.org/2012/02/awesome-tools-for-every-mechanical-engineer-by-sam-feller/

[CrossRoads]

No, I mean something digital like one might find on an incoming-inspection table, or perhaps a calibraton table, for automatic recording of results.

[RIDDICK]

what about a webcam (properly affixed with screws or so... connected to some stable USB box... like an OLinuXino...) that looks at the piece from the side?

[nmlfreitas]

You mean something like this

http://www.microsense.net/products-position-sensors-selector-thickness.htm

?

A webcam to measure thicknesses??

[RIDDICK]

nope
not capacitive but optical...
or is it impossible to look from the side?

[nmlfreitas]

yes i can be measured from the side if that is what you are asking.
But your are saying that the capacitive is not going to work for me?

Thanks

[Nantonos]

No, I mean something digital like one might find on an incoming-inspection table, or perhaps a calibraton table, for automatic recording of results.

This sort of thing?
http://www.tormach.com/store/index.php?app=ecom&ns=prodshow&ref=31761
plus USB interface
http://www.tormach.com/store/index.php?app=ecom&ns=prodshow&ref=31865