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Re: setting up a reflective object sensor for dummy's
« Reply #20 on: January 21, 2008, 12:25:17 PM »
Have you looked at the campbell designs breakout board? the jack for an input is a bit different than yours. Its got a ground, a signal, and a 12V supply. How different would the wiring be for that. I had to get a work around for similar type switches that are used as homing switches on my Mill. Here is the diagram I was given for that. Here is a link to the pdf for the breakout board.
http://campbelldesigns.net/files/breakout-user-guide.pdf
In previouse posts I was given a circuit for a work around for the reflective object sensor but never had any luck with it working. In the end I just used an external 5V DC power supply for the emitter and then just connected the ground and signal wire. I am aware that, that may be the source of my troubles but if there is a way around it, id like to try. I need my breakout board for the speed control function so Im stuck with it.
Chris

Offline jimpinder

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Re: setting up a reflective object sensor for dummy's
« Reply #21 on: January 21, 2008, 12:25:55 PM »
I'm sorry to come to this so late - it just shows - miss a day, miss a lifetime.

What is your problem. If you have the Fairchild relective sensor giving a reading then you are there !! apart from a few adjustments.

The way I did mine was to coat the rim of the chuck mounting plate in matt black paint - note MATT black  since we are dealing with relection.
The chuck plate is about 6" diameter. The Fairchild relective sensor was mounted so that it shines down  on the matt black. From my grand-daughters "box of sticky things" I got a little sticky mirror, about 5 mm wide and maybe 10 mm long. I stuck this on the rim of the chuck mounting plate. I then started the chuck, and adjusted the DISTANCE the sensor was from the rim, until it gaye a reliable reading. Since it comes straight up on the screen this is fairly easy.

The distance is quite critical, though, too near or too far away and the reflection on the rim does not hit the sensor. The other thing is to ensure that the mirror part is clean.

The other thing to do is adjust the index debounce so that it is long enough to trigger only once while the reflector is over the mirror. This is easy - since the mirror is only 1/45th of the length of the rim.

There is a slight problem - and this will occur ( I think) with whatever system you use. My system does not reliably read from 0 to 1000+. I cannot abjust debounce for all speeds. Therefore at very low speeds I do sometimes get odd readings. I can live with that. It is accurate from about 150 rpm to over 1000 rpm ( it has no trouble with faster speeds)

Not me driving the engine - I'm better looking.
Re: setting up a reflective object sensor for dummy's
« Reply #22 on: January 21, 2008, 01:03:18 PM »
thanks jim but I have messed with it and no matter what I do I cant get it to read anything but giberish. I can leave the lathe running and move it  all over with no change. also if I pull up the diagnostic screen I can get the signal light to come on with any object let alone a reflective one. its more of an object sensor than a reflective object sensor if you ask me. I didnt want to mount mine on the front of the lathe as i thought this was asking for dirt problems along the way. I mounted mine inside the headstock where there is a nice cavity. the chuck shaft in there is aproximately 1.75'' . what size would you recommend the reflective material be on a shaft that size. also what would be a recommended debounce setting. Im looking at a speed range of 100-1500 rpm.
 regardless I will continue to mess with it until the other optical switches come but Id rather use something a little more reliable so Im going with those. although ive been reading people have had a share of problems getting those to read accurately enough to do threading opperations. Id like to have a reliable tach first and formost. but Id also like the option to do some threading in the future too. But Ill start with getting the tach working first.
Chris
Re: setting up a reflective object sensor for dummy's
« Reply #23 on: January 21, 2008, 01:04:48 PM »
Hood,
 what diameter and thickness is the disk your using in that photo? size of slot?

Offline jimpinder

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Re: setting up a reflective object sensor for dummy's
« Reply #24 on: January 21, 2008, 01:39:11 PM »
Chris - I'm sorry you are having so much bother. Here are a couple of pictures of mine to show how simple it is.

I take it you are now using a 5 volt feed to power it Ignore the "pull up" resistor on the output, it is not needed.
If you power up the transmitter side, you should, using a multimeter,between the output and 0 volts, be able to detect a sizeable drop in resistance, as soon as the detector picks up a signal from the transmitter. You can check this using a little mirror - and simply hold the chip in your hand and move it towards the mirror and away. If you connect these two leads between your 0v and your index input, this should give a reliable signal.

The only problem I can think of inside an enclosed space you are using is that the transmitter will be sending outputs all round the housing, and some could be bouncing back into the sensor.

Anyway - I really can't say any more - here are the photos. ( P.S. I dont have a problem with dirt - and if I do, it is readily available for the wipe of a cloth.)
Not me driving the engine - I'm better looking.
Re: setting up a reflective object sensor for dummy's
« Reply #25 on: January 21, 2008, 02:42:47 PM »
Chris,
I started to go the way you are going.
I ended up with - http://www.cnc4pc.com/Store/osc/product_info.php?cPath=25&products_id=129
                         http://cnc4pc.com/Tech_Docs/C3_5_WG.pdf
It's all together and works PERFECTLY.
Just a Thought
Re: setting up a reflective object sensor for dummy's
« Reply #26 on: January 21, 2008, 03:34:04 PM »
Overload
wish I had seen this before I bought the other sensors this morning. Look before you leap I guess. :-\ anyhow.

Jim. I did what you suggested already and It does exactly what you sya but when I hook it up Im not getting anything useful out of the DRO.
I will play with it again tonight.

Offline TonyP

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Re: setting up a reflective object sensor for dummy's
« Reply #27 on: January 22, 2008, 06:42:45 AM »
There can be several problems with reflective sensors:
 Remember they work on Infra-red, so what you think of as reflective & non reflective may not be as good as you think.
The operating distance is far more critical if you use a shaft as opposed to a disc - the beam bounces off at odd angles, depending on the shaft diameter.
When using a shiny reflector the same thing applies - unless it's flat with no wrinkles, you may get multiple pulses.
I've used them as tacho's on small engine test beds but given up after a while & converted to the slotted switch type.

Tony

Offline jimpinder

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Re: setting up a reflective object sensor for dummy's
« Reply #28 on: January 22, 2008, 08:27:24 AM »
Chris - If you have it all working that far, the only place you are loosing the signal is when you feed it back into the computer. It does not need any other pull up resistor, just connect the wire directly to the LPT1 input (mine is through a breakout board but is UNPOWERED).

Best of luck

Jim
Not me driving the engine - I'm better looking.
Re: setting up a reflective object sensor for dummy's
« Reply #29 on: February 02, 2008, 03:37:51 PM »
ok well I just got my sensor and slotted wheel hooked up. Im using a four inch diameter disk with about a half inch wide slot in it. I have It wired just like hood said.
Black and green on ground
white and red on the positive terminal 12V on mine with a 220 Ohm resistor on the red lead
and the blue wire on my signal terminal.

The Index LED on my diagnostic screen comes solidly on when I turn the slot to the sensor and is solidly off when I turn the wheel to block the sensor. I am however still getting a useless tach reading. it jumps from the low hundreds to near 20,000 and never holds a reading for more than a second.
I played with the debounce and it seemed to have little effect.
where do I go from here.
do I try reinstalling mach to see if it is a software glitch or what. Have there been any versions with problems with the spindle speed dro.
Chris