Nervous dial gage

[David Ragan]

Hi All,

Both dial gauges that I have, plunger type, not lever, jump around a lot. I mean a lot when measuring things, like runout.

this nerve-wracking effect is most apparent when just moving the instrument a little, 5-6mm. Going over a couple of feet, it's tolerable.

I'm thinking that its because they are cheap.

the surface of the plunger tip is smooth, the surface of, say, my fence is smooth--and although there are irregularities amounting to thousands as we go along the fence/master plate, etc, wont a Starrett dampen a lot of that needle jumping around?

Is this classified as stiction?

I'm ready to spend my $140 if it will remedy this issue-dampen some of the static over shorter distances.

As always, Thanks D

[Al Launier]

What make are your guages? Unless there is some sort of vibration going on, this sounds unusual.

[glenn bradley]

I have a $10 Harbor Freight dial indicator that does not do this. Are you sure it is not just accurately measuring the surface? Try it on a piece of glass or polished tile before you throw money at a problem that doesn't exist. If it is the dial, I would start cheap. For setting up machines where our concern in the delta and not the actual measurement an inexpensive unit should be fine.

[Brian Lamb]

Test indicators or drop indicators? How solid is your indicator stand? If you want good indicators, in the test indicator style, I use Interapid or there is a brand called Fowler Xtest that makes a copy of the Interapid 312-b. If you want a good drop indicator, SPI makes a nice unit, it is what we purchase and sell with our indicator holders that we sell.

This is the Fowler Xtest test indicator, for about $114:

http://www.use-enco.com/CGI/INSRIT?P...PMAKA=890-9980


This is the drop indicator, on sale for $26:

http://www.use-enco.com/CGI/INSRIT?P...PARTPG=INLMK32

[Rick Whitehead]

I think Glenn may be right. Your indicators may well be reading the actual variation in the surface of what you're measuring.
How sensitive are your indicators? Do they read in .001, or .0005? If it's .0005, then they are extremely sensitive and will show a large range of motion for a slight variation.
If you're using your indicators to set up woodworking machines, then an indicator reading to .001 is all you need. As Glenn also said, a cheap one will work just fine for woodworking machine set-up.
Rick

[pat warner]

Rock & roll only with the machine running ((runout check) or vibrating during all measurement?
Asked Starrett about this. They could not resolve. Had suggestions but no solutions.

[peter gagliardi]

Rock & roll only with the machine running ((runout check) or vibrating during all measurement?
Asked Starrett about this. They could not resolve. Had suggestions but no solutions.

I have never checked a machine for runout while its running. I am not a machinist, but something tells me that can't be good for a precision measuring instrument. I measure runout with it indicated in and turn by hand.
A spindle with no runout would hardly matter, but same spindle with , say .007" runout will act like a hammer on the indicator end at several thousand rpm's like on a shaper, quickly destroying any accuracy.
Indicators accurate to .001" are easily capable of registering and showing ANY vibration as well, such as walking across a wood shop floor, resting your body or parts of it on a tablesaw, short of the 2000 lb. variety will show as well.
They are going to be sensitive to work properly.

[Bob Wingard]

At VERY low speeds, I guess it would be possible to check a machine while it's running ... anything above a crawl, and I wouldn't subject even a cheap gauge to that kind of mistreatment. Sounds like an excellent way to tear up the insides of the gauge.

[John K Jordan]

wont a Starrett dampen a lot of that needle jumping around?

My dial and test indicators are mostly Starrett with a few others, some cheap and quite old. None are particularly jumpy, especially when the surfaces are very smooth (polished). I don't notice any indicator dampening the needle movement but can't say I've looked for it. I can imagine poor tolerances or grime or corrosion on the gears or bearings causing a problem. Perhaps a disassembly and cleaning? Kind of like working on a clock.

JKJ

[Brian Lamb]

There is no dampening involved in indicators, they are purely mechanical amplification to the needle, of what the tip follows. If you are getting a lot of vibration, chances are you are using too small of a ball or contact point on the indicator, this will tend to drop into every irregularity of the surface and cause the needle to jump around a bit. The largest contributor of needle movement is a flimsy stand that is holding the indicator.

Over 35 years as a machinist, so been there done that in any regards of indicators....

[David Ragan]

thanks guys,
Am not sure about the brand of them....IIRC, there is no brand.
What I need to do is take a polished surface, and run the indicators over it, and see what happens.
I guess the Starrett will have to wait a while longer.......

[Marion Smith]

I'm curious to see the face of the indicator. I'm guessing it may be a .0001's reading indicator. That will jump around like crazy on wood. For wood lathe, a .001 indicator is the one I'd pick. I'd also use a larger diameter tip with radius.

[pat warner]

"ind of mistreatment. Sounds like an excellent way to tear up the insides of the gauge. "
*******************************************
Not suggesting you run your stuff at 10000 RPM.
Should have said: Those machines with VFD's and other RPM manipulators, a slow spin (<20 RPM) probably has a more accurate reading of the t.i.r.. Whilst slowly spinning, under power, you get to read the effects of gears, belts, pulleys, spindle stress and so on. In effect, the practical runout; one never runs the machine by spinning an armature x hand.

[David Ragan]

"ind of mistreatment. Sounds like an excellent way to tear up the insides of the gauge. "
*******************************************
Not suggesting you run your stuff at 10000 RPM.
Should have said: Those machines with VFD's and other RPM manipulators, a slow spin (<20 RPM) probably has a more accurate reading of the t.i.r.. Whilst slowly spinning, under power, you get to read the effects of gears, belts, pulleys, spindle stress and so on. In effect, the practical runout; one never runs the machine by spinning an armature x hand.

Posting stuff here is always a humbling experience for me.

You all know soooo much way beyond what I do-----it is great to learn (a little) about all the mechanical stuff behind all this-whether it be gages, blades, metallurgy, physics, electronics, etc, etc Maybe even some actual woodworking.

The POS gages are 0.001".

Have not had the energy to get out the camera when I get home from my real job; I could do it this wkd.

I would love to have a Starrett-just looking for an excuse to get one----you all not really giving me one though for my infrequent use.

[John K Jordan]

Posting stuff here is always a humbling experience for me...

Yikes, don't let that bother you!! A forum like this gets hundreds of visitors and there are always people with expertise or experience in any possible topic. Those with interest will read the thread if the message title entices them. Looks like about 500 people have read this thread so far! Some of those are bound to know about gauges, others about flamethrowers, other about llamas and honeybees. :-)

I would love to have a Starrett-just looking for an excuse to get one----you all not really giving me one though for my infrequent use.

I learned my lesson 40 years ago. Not once have I ever been sorry for buying good tools. (I've shopped at Harbor Freight exactly once in my entire life.) You can use a quality dial indicator all your life and pass it on to the kids. And the uses seem to multiply - I use the on the wood lathe, metal lathe, milling machine, drill press. And recently, on a pressed-fit cast iron motor plate to see if my homemade puller was moving it at all or if I needed to stop before I broke something!

You might keep a lookout. I have seen used Starrett gauges on Craigs list; might find one at a yard sale, flea market, or estate sale. I have one that is probably older than I am and still works fine. Brown and Sharpe is another very good brand.

BTW, this is my favorite magnetic base for gauges:
https://www.amazon.com/gp/product/B002K07CTK

I bought one and loved it, then found some far cheaper imitations that seem to work just as well:
https://www.amazon.com/gp/product/B00L5T2ZA8

This type has one knob that tightens all the joints at once for very quick adjustment. I use one to position a dust collector pickup at my wood lathe.

JKJ