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Author Topic: Spindle RPM feedback, not low enough.  (Read 14644 times)

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Offline Katoh

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Re: Spindle RPM feedback, not low enough.
« Reply #50 on: February 13, 2013, 05:38:51 PM »
Hi Peter
That's Ok, this time of year with school holidays and everything else, life gets a bit crazy.

I'm using this switch "recommended in a prior thread"
http://au.element14.com/optek-technology/opb916bz/opto-switch-slotted/dp/1217280?Ntt=121-7280
My wiring I have described in the thread.

hope this helps.

Cheers
Katoh
Cheers
Katoh
Re: Spindle RPM feedback, not low enough.
« Reply #51 on: February 13, 2013, 06:27:00 PM »
Hi Katoh,

Looking at the datasheet for the  OPB916B sensor, it  has an open collector output with a 10Kohm pull-up resistor.   When activated, the open collector transistor pulls the output line  (blue wire) to 0V.

So you MUST have the MB-02V6 inputs pull-up jumper set to 5V (pos 2-3).  Is this the case? If, not it won't work.

Cheers,

Peter.

----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com

Offline Katoh

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Re: Spindle RPM feedback, not low enough.
« Reply #52 on: February 14, 2013, 12:07:06 AM »
Hi Peter



So you MUST have the MB-02V6 inputs pull-up jumper set to 5V (pos 2-3).  Is this the case? If, not it won't work.



That's where I have the input set to, to 5v.

I can get the signal from the opto to the BOB and it does reach Mach, The problem is to get low RPM, under 100 I need an index Debounce of 80, but for high  rpm 2000 the index debounce is set to 8, but wont give me a reading under 1500.
If I bypass the BOB which I have done now the index debounce is set to 1 and I have stable rpm reading's from 40 to 4000 rpm. The little led next to pin 15 that I used, flash's without fail every time the switch is triggered, without fail be it 1 rpm or 1000rpm, just something goes wrong sending the signal to mach.
Everything thing else works fine, I have 12 other inputs on that board all are good, maybe its loosing a bit through the board, enough just not to give a good reading.

Thanks
Katoh
Cheers
Katoh
Re: Spindle RPM feedback, not low enough.
« Reply #53 on: February 14, 2013, 01:26:33 AM »
Hi Katoh,

Is the opto exposed to fluro light?

If so can you test it in the dark?

Cheers,

Peter.
----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com

Offline Katoh

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Re: Spindle RPM feedback, not low enough.
« Reply #54 on: February 14, 2013, 04:35:43 AM »
No the Opto is the lathe gearbox / pulley box. Covered with the steel door.

Katoh
Cheers
Katoh
Re: Spindle RPM feedback, not low enough.
« Reply #55 on: February 14, 2013, 06:09:26 AM »
Hi Katoh,

Try changing the 220ohm resistor with a 180ohm or 150ohm one as the MB-02 has 1K strong pullups on the inputs.

Cheers,

Peter
----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com

Offline Katoh

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Re: Spindle RPM feedback, not low enough.
« Reply #56 on: February 14, 2013, 06:33:54 AM »
Hi Peter
I will give that a go, but please bare with, it will take me a couple of days to test at the moment.
Thanks
Katoh
Cheers
Katoh
Re: Spindle RPM feedback, not low enough.
« Reply #57 on: February 14, 2013, 03:28:43 PM »
Hi Katoh,

OK. In the meanwhile I'll see if I can get a few of the optos and do some teting myself.

Cheers,

Peter
----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com

Offline Katoh

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Re: Spindle RPM feedback, not low enough.
« Reply #58 on: February 16, 2013, 04:53:05 AM »
Hi Peter
Just had a chance to test now, went out today and bought a new 180Ohm and a 15Ohm resister and replaced  the 220Ohm.
Had to go through pin 13 is pin 15 is now a direct input to the computer via the cable, I was really hoping for good news but it did the same as before. There was no difference in readings whatsoever. The same scenario, again bypass the BOB and I get stable readings.
Again the little led corresponding to pin 13 flashed every time the switch  was activated without fail, but for some reason the message to mach was scrambled eggs.
The funny thing here is even through the board if I turn the spindle by hand and the index light gets triggered on the diagnostic screen, but only if I turn slowly (something to do with  screen refresh rate as pointed out by Hood), It works exactly the same when you bypass the BOB. But still the readings are everywhere through the BOB but stable without it.

Got me beat!

Cheers
Katoh
Cheers
Katoh
Re: Spindle RPM feedback, not low enough.
« Reply #59 on: February 16, 2013, 07:03:51 PM »
Hi Katoh,

The only thing I can think off is that the BoB has 1Kohm pullups on the input lines which may be too strong for the sensor to pull to ground.

I should receive my sensors on Monday or Tuesday so I'll test it out using a Scope and see what is going on.

Cheers,

Peter

Cheers,

Peter
----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com