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Internal and external
Installation of spindle speed sensor
This is part 653-EE-SB5V from mouser.com. It is an amplified microsensor with built-in LED and receiver which operates at 5mm distance from the trigger which is basically a whiter spot,strip or contrast change surface.
I'm intending to mount this sensor to use as an rpm indicator and for coordinated threading with MACH2's Turn threading feature soon to be implimented.
How would I best wire this? Where does the 5V come from? Through the parallel port 5+v because of low current?
Has anyone else installed a similar device? Where might it be physically mounted and what kind of reflective tape does one use to generate the signals?
I have the Shoptask 3 in 1 Bridgemill and will be mounting one of these on both the Lathe spindle and the mill spindle.
The machine is set up with servos, three gecko 320s, 39V power supply from Camtronics, and of course Mach2.
Thanks for anyone who can help here..
John
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Last edited by Bloy2004; 01-27-2004 at 03:25 AM.
schematic
Internal and external
Last edited by Bloy2004; 01-27-2004 at 02:54 AM.
Precautions
Will the current limiting resistor be necessary? And what is that external sensitivity adjustor for? I suppose it will depend on where the 5+v source comes from?
Last edited by Bloy2004; 01-27-2004 at 03:04 AM.
terminals
My guess here is:
0V(-) ..goes to any one of the grounds on the breakout board.
5V+(Vcc) ..Is supplied from inside computer using one of the power supply connectors used for drives that has both 5V and 12V.
OUTPUT ..goes to the Mach2 terminal for "Spindle Pulse".
L ..not used because current is minimal.
Last edited by Bloy2004; 01-27-2004 at 03:56 AM.
Bloy:
Your guesses about 0 and +5 are correct. Be sure that your computer ground is also provided to the breakout board.
You NEED a current limit resistor to prevent damage to the LED. Something in the neighborhood of 1k ohms (but this will affect sensitivity to some degree and may need to be less or more).
It looks like the circuit will produce a pulse out for any transition (light-to-dark or dark-to-light) so for one white marker you will get two pulses (but you need to verify this).
robotic regards,
Tom
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"In the blue grass region,
A paradox was born:
The corn was full of kernels
And the colonels full of corn."
- - John Marshall, the first Chief Justice of the Supreme Court
Tom..Thanks loads!
the device is a LIGHT-ON type so I believe there is only a signal when it detects a contrast from the normal dark. This was a bit confusing for me.
It brought the question...How thin does the white tape need to be? I may use multiple reflectors to give two or more pulses per revolution of the spindle. This will depend on how Art sets up the Mach2 software. I've read that having multiple pulses per rev will allow Mach2 to better average the spindle speed and thus accurately control threading passes. Does this make sense?
The initial pulse also tells Mach2 Where the spindle is to coordinate the return passes and find the thread entry.
Just a thought...this thread probably should have been placed in the "CAD/CAM, DNC and CAD Software" section under the "ArtSoft software" forum.
John(bloy2004)
Or, how thin can it be, i.e., how fast does the sensor respond to a change in input conditions.It brought the question...How thin does the white tape need to be?
For a CNC application there are two considerations: the hardware - what is the minimum tape width that will produce any output; the software - what is the minimum pulse width that will be seen 100% of the time.
If the hardware and software are very fast you might be able to set up so that there are 100 pulses per revolution.
robotic regards,
Tom
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"Better a jerk that knees than a knee that jerks."
- - William Safire
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