Measure runout on shaft while rotating?
Measure runout on shaft while rotating?
(OP)
I am looking for a method of measuring runout on a shaft while it is rotating. The shaft will be approx 2" diameter, rotating 500RPM, and there may be a film of grease on OD of shaft. There is a small 1/4" dia hole providing access to the shaft from a housing that covers it. For a "static" measurement we are simply putting a dial indicator on the shaft and rotating the shaft by hand to get a reading. The problem is that I think the readings get worse under operating conditions but I have no way of measuring it. I am trying to resolve whether the shaft is running out, for example, .005" or .010", not down to 1 tenth.
Any ideas? The only link I can find is at
http://www.lionprecision.com/targa/index.html
but it looks expensive and not really shop suitable.
Thank You
Any ideas? The only link I can find is at
http://www.lionprecision.com/targa/index.html
but it looks expensive and not really shop suitable.
Thank You





RE: Measure runout on shaft while rotating?
I would think that if you got a good digital indicator gauge you could stick it in the hold and measure. Out side of that I think your best bet would be to re-produce operating conditions on a shaft that is not incased and try to measure off that.
RE: Measure runout on shaft while rotating?
You might want to look into some optical/laser measurement methods.
If the runout is enough to see visually with the naked eye, you might want to try shining a strobe on it. By varying the frequency of the strobe, you can make the shaft appear to move in slow-motion. Alternately you could also strobe your laser sensor for the same effect.
By the way you can pick up a cheap stroboscope on Ebay pretty easily. They come along almost every day.
Don
Kansas City
RE: Measure runout on shaft while rotating?
RE: Measure runout on shaft while rotating?
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RE: Measure runout on shaft while rotating?
http://www.polynetics.com/
Heckler
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RE: Measure runout on shaft while rotating?
Larry
RE: Measure runout on shaft while rotating?
Then measure the scar that the hole leaves on the side of the dowel.
Mike Halloran
Pembroke Pines, FL, USA
RE: Measure runout on shaft while rotating?
the human finger is capable of detecting movement as little as one-thousandth of an inch. i will let you improvise a device that allows the human sensor to determine and quantify movement.
another method is to use proximity probes mfg by BN.
an aside, if you suspect the runout is greater while operating than while safely and properly measuring, then other problems exist with the rotating assembly. that is unless the shaft is poorly designed.
i would definitely check the balance of the rotating assembly and inspect the bearings (support structure). any imbalance may very well cause shaft bending and/or premature bearing failure. if bearings have failed, then carefully inspect the rotating assembly and have the bearings return to mfg for analysis and cause of failure.
good luck!
-pmover
RE: Measure runout on shaft while rotating?
If you only have a 1/4" diameter hole, then you are limited. The solution depends upon how deep is that hole.
Keyence, Pepperl+Fuchs, maybe Turck & others make inductive analog position sensors, but they're not necessarily cheap. But it would certainly have the frequency response and dimensional range to give you the info you want without having to touch the shaft. The grease shouldn't affect the readings. You would also need something to scale/display the readings, and maybe something to log it.
If you want to go cheap, perhaps you could buy some sensor hardware and partner with your local university to use their student labor and laboratory reading gizmos and software.
The next alternative would be laser triangulation sensors from Keyence, Banner, many others. And still not really cheap. But the same readout requirements apply, and then the grease would be part of the reading.
And ultimately you have to ask the question "how much is downtime and repair worth if the shaft fails, versus the cost of finding out the answer quickly" ?
TygerDawg
RE: Measure runout on shaft while rotating?
Bently Nevada, now devoured by GE, and CSI, swallowed up by Emerson a while ago, are two of the bigger players in the vibration analysis market. They have equipment designed specifically for this type of application. The processing of the signal is important, especially bandwidth. Many of the common proximity sensors are bandwidth limited by the electronic signal conditioning they incorporate.
http://
http://www.compsys.com/
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RE: Measure runout on shaft while rotating?
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Measure runout on shaft while rotating?
RE: Measure runout on shaft while rotating?
1) juryrig a wire linkage to the shaft which will be acting like a cam to multiply the radial motion by a factor of say 5. The low speed 500RPM shouldn't bend the linkage.
2) Get a stobe light to "freeze" the motion so that you can easily detect 5x the runout or in your case, if you are looking for .005, then .025 should be easily seen.
RE: Measure runout on shaft while rotating?
RE: Measure runout on shaft while rotating?
one to read displacement, the other set to "see" a once per rev notch in the shaft for phase (notch say 0.030 X 0.030 cut into shaft)
a dual channel o-scope with a sweep of 0.012 sec/div (10 division axis)
channel a being displacement with scale set per 100mv/div (0.001" for prox probe)
channel b being once per rev with scale set at 500mv/civ
RE: Measure runout on shaft while rotating?
I will look into some of the sensors suggested. I don't claim to be an expert in proximity sensors but it sounds like I need to read up.
Thank You All
RE: Measure runout on shaft while rotating?
RE: Measure runout on shaft while rotating?
A wobble, because the shaft is bent would be different. You could measure it with a phonograph needle mounted on a micrometer.
TTFN
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RE: Measure runout on shaft while rotating?
RE: Measure runout on shaft while rotating?
- review your installation procedure for lip seals
- e.g. are they lubricated at assembly?
- radial lip seals with more radial compliance
- radial lip seals with double lips
- auxiliary v-ring face seals alongside the lip seals
Mike Halloran
Pembroke Pines, FL, USA
RE: Measure runout on shaft while rotating?
In my experience specialty lip seal manufacturers do not understand and thus vastly understate or underestimate the heat generation of their products.
RE: Measure runout on shaft while rotating?
I hope this is of some help.