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[Reply #15 on:]

I can't use that type of things you just mentioned because the wood is always "runing" on the machine...

[Reply #16 on:]

Something like this (but better) perhaps?  http://media.digikey.com/pdf/Data%20Sheets/Sharp%20PDFs/GP2Y0AH01K0F.pdf

[Reply #17 on:]

Yes, that's the kind of thing I was thinking of.

[Reply #18 on:]

A webcam to measure thicknesses??

yup - u would need to do some image processing...
the machine parts (in the background) should have a much different color than the wood pieces...
how fast do those pieces pass the sensor? less than 25Hz?

[Reply #19 on:]

That Sharp sensor would work form me the minimal distance is the problem, i need 0.8 mm and for what i've seen they don't have that kind of sensors.
Do you think that this would work?
http://www.baumer.com/int-en/products/product-finder/presence-sensors-measuring/#pfinder_sensor/scripts/level2.php?language=en&header=&country=CH&cat=CONFMyAppli&psg=madynGrundfunktion2|1993482997,madynPGGrundfunktion|Optisch&pid=&ptk=&viewmode=&filterViewMode=&perpage=  

Check the ZADM 034
(ParCon, analog output)

Please

[Reply #20 on:]

the specs look good...
the accuracy is much better than u need: 50um...

[Reply #21 on:]

Yes i know but do you think it is hard to connect it and make readings with arduino?

[Reply #22 on:]

it seems to b easy:
1. connect 12V to it...
2. connect wires for the output like this:
GNDsensor-----------------------wire#1-------------------100R(or similar)-----------------------wire#2-------------------OUTPUTsensor
3. calibrate the arduino (i would use the INTERNAL ADC ref, which should give u reproducible results at the same temperature/voltage):
http://arduino.cc/en/Reference/AnalogReference?from=Reference.AREF

[Reply #23 on:]

It has a current loop output so you need to calculate your load resistor cairfully. Also there is a 4mA output minimum so you will get a fixed offset voltage. Given that you might have to do some messing about withan op amp to give you the full range of the A/D.

However have you looked at the price of this? I can't see one which is never a good thing. I would expect this to be in excess of £200.

[Reply #24 on:]

I've send email today requesting price still waiting for response.

[Reply #25 on:]

Check the ZADM 034

I was about to mention these - they are basically close range LIDAR devices. I can guarantee you they -will not- be cheap. Grumpy Mike is probably right on target (if you can even find a distributor that will sell to the public and only sell you one of them)...