[Metrology] Damage Indicator?

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I have searched here and generally the web and was unable to come up with a conclusive answer. Will tapping (with a hammer) a piece of stock while an indicator is in contact with the stock damage the indicator? For example truing up stock in a lathe chuck.
Is the answer the same for digital and dial, test (lever type) and drop indicators?
Does "shockproof" have any effect on the instrument's survive-ability?
 
The other part of the question might be, is it ok to tap away from the indicator versus toward it??
 
A good question. I haven't an answer but, in general, would think it is not a good practice to jar any piece of mechanically sensitive equipment. It would depend very much on which direction the impact was directed and how strong it was. I would guess that an impact that caused a deflection of a thousandth or two would not damage a well made indicator.

While not having dug into the bowels of various indicators, I would also expect a well made indicator to fare better than a China clone. It would also depend upon the type of indicator. My sense is that test indicators are more fragile than dial indicators.

I did get into my digital test indicator when I hit the wrong key and drove the indicator into the work with enough force to stall the z axis motor. It had shifted some components around and bent a coupling strip but I was able to straighten it out and realign everything and the indicator is working fine.
 
I do not profess to be an expert on this subject but have been a machinist or attached to the machining industry my entire career. I still have and use my first dial indicator, a 1" travel Mitutoyo, that I bought when I was an apprentice in the early 70's. I handle it with care each and every time I use it.

IMO a dial indicator, whether it be a drop style, dial test, or digital, is a precision tool. Any sort of shock is not conducive to a long and accurate life. Another way of looking at it is: would you use your 1" micrometer to tap on the part to line it up? I wouldn't.

I am in no way chastising you for asking the question. That's how we learn. Just offering up my opinion. Hope it is useful information.

Tom S.
 
I concur with the above opinions, I try not to hit my watch with anything, and I have to assume that indicators whether digital or dial are at least as sensitive as my cheap, Walmart watch.
 
I believe the OP is referring to tapping the part into tram, not bashing the indicator with a hammer. Totally different process. One is work, the other is fun! It is completely acceptable and actually standard practice to tap a part into alignment with the indicator needle or point touching the part, that's what they were designed for. It is of course a lot cheaper if you completely miss parts of your indicator.

In a bad year I might repair 300 or so gauges at work with the majority being indicators. The worst thing you can do is drop them - and it happens a lot.
 
I have searched here and generally the web and was unable to come up with a conclusive answer. Will tapping (with a hammer) a piece of stock while an indicator is in contact with the stock damage the indicator? For example truing up stock in a lathe chuck.

You have never worked in a machine shop have you?
For this purpose buy a few cheap import indicators that may be had for $25.00 or less, accuracy is unimportant as you are only measuring runout not actual part dimensions directly, for general lathe work even a cheap indicator will be close enough over a measuring span of only several thousandths and if it gets damaged buy a new one. I keep 3 cheap indicators for this reason, 1/2", 1" and 2" ranges, then use Mitutoyo, Starrett or other expensive tools for critical applications.
 
I usually just grab the stem hanging out the end of the indicator opposite the workpiece, and pull it gently back a little before giving the workpiece a little lead-percussive love to nudge it around. That way I'm not subjecting the indicator to a sudden, sharp shock. The trick is to pull only hard enough to raise the business end of the indicator stem off the workpiece, but no so hard that you move the indicator or it's holder. I mostly use cheap-o Horrible Fright dial indicators. They're cheap, cheerful, and have been plenty enough accurate for what I use them for. They read dead-nuts on when I zeroed them on my poor-man's surface plate, then slipped .5 and 1" standards (B&S) into place to measure. Read .5 and 1" respectively, right on the money. They cost about $15 or so, and while I try my best to not drop them, sometimes my hands just don't cooperate and onto the floor they go. I'd rather bugger up a cheap indicator than an expensive one. I mark the ones I've dropped (up to 3 now) and put them in a drawer. I can cannibalize them for parts if necessary.
 
I always pull the plunger back just as Ogberi describes, just before I give a gentle tap. I just feel it isn't good to subject the indicator to a sudden shock.

David
 
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