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Curran919

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Reply with quote  #16 
Quote:
Originally Posted by Walt Strong
Curran,
"Have you had luck with cutting the disk into a ring, breaking the ring, wrapping it around the shaft and gluing it on (e.g.) the outside of a coupling hub? Is the butt unnoticeable?"

I have an older version of this Infrared sensor (IR) without the fancy package:

https://monarchinstrument.com/collections/remote-sensors/products/infrared-sensor-with-8-ft-cable

The specifications indicate 0.039" or 1-mm for a minimum target size. Try getting a laser beam to do that! I have cut and pasted an encoder disc with okay success. Try cutting disc at an angle so that the splice joint may have a good spot to align the sensor with. A black felt marker can mask over the splice (butt), as necessary. Field installation can be have many issues including limited down time and access. Remember that the encoder method measures angular velocity or displacement that can be minimal (torsional node) near the coupling!

Walt



Thanks Walt. I'm hoping to present at a f***upnight soon about my first time field installing a torsional telemetry kit on a coupling. The transmitter had a nice flight across the room when my mag base holding the ring antenna shook off.

If the coupling spacer is flexible enough, we should still be able to get a useful disp. signal at the hub methinks, at least for frequency identification.

I dont understand the point of making the cut at an angle. The tach is only going to sense the splice at a single radius, so whats it matter if that spline changes position at different radii? My torsional polytech laser also recommended an angled splice for the reflective tape, but I didn't see any effect of that on the signal (and it made no sense to me).

Just thinking out loud here... if the disc is installed eccentric, this will give a artificial 1x signal, but it shouldn't give any harmonic components, whereas zebra tape with a nonuniform butt will lead to a spike in the rpm signal 1/rev, which WILL lead to harmonics. Right? Any tips on reducing eccentricity, or is the effect generally slight?

RustyCas

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Reply with quote  #17 
Ted, I can't ever remember the 198F not working in any kind of light.  The only times it won't trigger are when I go brain-dead and don't adjust the tach setup in my meter.  It doesn't like a low sensitivity.  I set it to 2 volts and it does fine.  I've used the PLT-200 a few times but it just wouldn't hold up to being banged around.  I don't baby my equipment (as I probably should) and my 198F's just keep going and going.  I always have spare AA batts in the case, so power is never a problem.


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Walt Strong

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Reply with quote  #18 
We have two branches of discussion for the OP laser tach and torsional encoder.
Curran,

"The tach is only going to sense the splice at a single radius, so whats it matter if that spline changes position at different radii?" This might allow you to move the optical sensor radially and pickup a path that has less error with the splice. The idea is to avoid/minimize the harmonic city cause by the 1xSS pulse created at the splice joint.

"Any tips on reducing eccentricity, or is the effect generally slight? There is minimal effect. A larger error can be associated with vibrations of the optical sensor and support.

A good target is needed for the optical encoder method. I print encoder wheels of various diameters and number of targets. 

I have Codewheel Generator 1.1.1 6/10/2018 software by Jack Lackamp that runs on Win Vista and XP (and Win 7 with XP compatibility mode) and tested on Win 10 (with some issues but saves to Bluebeam and then prints)

http://www.societyofrobots.com/robotforum/index.php?topic=4338.0

Available free download here:

https://www.softpedia.com/get/Others/Miscellaneous/Codewheel-Generator.shtml

Print encoder with inkjet printer on Hammermill Card Stock-White 110-lb 8.5"x11"
Cutout the code wheel encoder and attach with brush-on contact cement to face of coupling or engine flywheel or hub. An encoder wheel printed on multiple pages can be spliced together using a lot of patience. I use the Copp-Tek frequency to voltage converter with the Monarch IR optical sensor or a magnetic sensor or CAT diesel flywheel magnetic sensor.

Walt

Barry

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Reply with quote  #19 
 Yes Walt it appears a clear case of hijacking has occurred.  😜
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RustyCas

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Reply with quote  #20 
Quote:
Originally Posted by RustyCas
Ted, I can't ever remember the 198F not working in any kind of light.


Shouldn't have said that!  Couple days ago I was balancing a fan late in the afternoon.  Tach was facing away from the sun, but sun was bright on the shaft... no signal.  Got a sunshade out of the truck for the reference run, but with no way to really keep it in place, I moved the tach to the opposite side.  Accounted for the 180 phase change and calculated my trial weight position.

Did trial run.  Jeepers... how did I get my weight 180 degs from where it needed to be?  Oh well... then it dawned on me that I hadn't changed the phase angles in FastBal to account for the 180 shift.  Saved me a lot of embarrassment because I actually had the trial weight only 5 degs from the final position.

So, no, I'm not sure they make a laser or optical tach that is immune to bright sun.  I might rig up a Noga indicator holder with a large piece of cardboard as a sunshade. 

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MachDiag

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Reply with quote  #21 
Rusty,

I'm headed to a rooftop exhaust fan balance job this weekend.  I've got my 198F lasertach ready to bring along for comparison.  And hey... I don't play a fiddle, but if I did, I'd bring that along too (Fiddler on the Roof).
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