Can't Buy Sensor for Stirling-Steel CNC Conversion

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ken572
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Re: Can't Buy Sensor for Stirling-Steel CNC Conversion

Post by ken572 » Mon Jul 14, 2014 8:35 pm

SteveHGraham wrote:The only kind of induction I've heard of is magnetic, unless you count being drafted.
Steve, :D

These are some helpful examples and explanations.

http://www.chaski.org/homemachinist/vie ... 44&t=99416

Ken. :)
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Re: Can't Buy Sensor for Stirling-Steel CNC Conversion

Post by SteveHGraham » Mon Jul 14, 2014 9:18 pm

My degree is in physics. I sat through a whole lot of E&M, and nobody ever mentioned induction without mentioning a change in magnetic flux through a current-carrying loop. If there is another kind, I have not heard of it.
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ken572
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Re: Can't Buy Sensor for Stirling-Steel CNC Conversion

Post by ken572 » Mon Jul 14, 2014 10:00 pm

SteveHGraham wrote:My degree is in physics. I sat through a whole lot of E&M, and nobody ever mentioned induction without mentioning a change in magnetic flux through a current-carrying loop. If there is another kind, I have not heard of it.
Steve,
I agree 100%

Ken. :)
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Re: Can't Buy Sensor for Stirling-Steel CNC Conversion

Post by larry_g » Mon Jul 14, 2014 10:48 pm

http://old.turck.us/illustrations/M_B1008-Specs.pdf

Searching around the Turck site I found the above which has some good information in it. Reading through what you have posted it sounds like the flag is for a single position sense, not for position in degrees, as a single flag is more like a home switch. So I'm assuming this may be a home switch or zero location and the rotary position is determined by an encoder on the motor. I used to argue with some of the programers on our automated machines that wanted to use a home switch as home and not the activated home switch to start a homing routine to find the home pulse on the encoder and call that home. It amounts to home at the switch which could be near a whole rotation on the encoder error or more depending on the braking speed of the drive.

on edit Re the flag. since this sensor has a 4mm range you need something proud of the spindle by greater than 4mm to allow the flag to trigger the sensor as it passes the sensor. On the link above pay attention to the section with the trigger wheel and understand how the teeth on the wheel trigger the sensor on and off.

Is there a link to a manual, operating procedure, schematics online you can link to forour review?

lg
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Re: Can't Buy Sensor for Stirling-Steel CNC Conversion

Post by hammermill » Mon Jul 14, 2014 11:14 pm

For non-contact detection of metallic targets at ranges generally under 50mm (2 inches). Inductive proximity sensors emit an alternating electro-magnetic sensing field. When a metal target enters the sensing field, eddy currents are induced in the target, reducing the signal amplitude and triggering a change of state at the sensor output.


The above sums it up as to functiom

LG good reference too

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Re: Can't Buy Sensor for Stirling-Steel CNC Conversion

Post by ken572 » Tue Jul 15, 2014 9:11 am

hammermill wrote:For non-contact detection of metallic targets at ranges generally under 50mm (2 inches). Inductive proximity sensors emit an alternating electro-magnetic sensing field. When a metal target enters the sensing field, eddy currents are induced in the target, reducing the signal amplitude and triggering a change of state at the sensor output.


The above sums it up as to function

LG good reference too
hammermill, :wink:
Very Well Said.

Ken. :)
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Re: Can't Buy Sensor for Stirling-Steel CNC Conversion

Post by SteveHGraham » Tue Jul 15, 2014 9:48 am

Last night I was thinking that this must be yet another example of how physicists fail to teach anything practical. When I was in school, they taught us how moving magnets and charges could induce current, but the idea that a simple piece of steel could do it doesn't really fit in with the teaching. I assume the flag must have a small magnetic field, since even iron that isn't deliberately magnetized may have a little bit of magnetism, or maybe it has some charge on it, relative to the sensor. This is the kind of thing an engineer would know, since they have to deal with real objects instead of stuff drawn on chalkboards.

It's my understanding that traffic light sensors are inductive, but I don't think of vehicles as magnets.

Maybe someone else knows what's happening. Anyway, if it works, it works.
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Re: Can't Buy Sensor for Stirling-Steel CNC Conversion

Post by DICKEYBIRD » Tue Jul 15, 2014 8:06 pm

Here's what I use on the spindle of my lathe & mill. I don't have the knowledge you guys do but for less than $30 this works well & has everything you need...no circuit designing or building. It has an opto sensor which (I think) lessens the chance of attracting stray ferrous debris like a magnetic sensor may. Just a satisfied user. :D

http://www.cnc4pc.com/Store/osc/product ... cts_id=129
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Re: Can't Buy Sensor for Stirling-Steel CNC Conversion

Post by dly31 » Tue Jul 15, 2014 8:42 pm

Some magnetic sensors have both the magnet and pickup device in the same unit and the proximity of steel alters the flux strength for detection. I think traffic sensors operate the coil in an oscillator and the presence of metal in the field of the coil changes the frequency of oscillation, similar to a "treasure finder". Some other sensors also work that way.

I seem to recall the word "induction" also used in regard to inducing a static voltage charge and I am pretty sure some of the machines were called "induction machines".
Don Young

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Re: Can't Buy Sensor for Stirling-Steel CNC Conversion

Post by juiceclone » Tue Jul 15, 2014 10:12 pm

research "hall effect sensor"

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SteveHGraham
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Re: Can't Buy Sensor for Stirling-Steel CNC Conversion

Post by SteveHGraham » Tue Jul 15, 2014 10:36 pm

I already have the sensor.
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Re: Can't Buy Sensor for Stirling-Steel CNC Conversion

Post by hammermill » Tue Jul 15, 2014 10:44 pm

It my not work for you truly do not believe.. hi hi

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