Test indicators

[TRA]

I didn't say they worked the same way, I said it was the best analogy I could think of (that is, relating something that is clearly not understood (why that middle ground isn't really usable) to something that is (wall clocks). I stand by what I said. The dial _is_ movable, but you're only going to move it to a point at which the needle sits at rest.

GsT

What you are describing is more like how a digital works. At a certain point a digital jumps to the next number. Most .0000 digital indicators or measuring devices are in .0005 intervals. Analog indicators are direct drive so to speak, and the needle movement is directly related to the movement of the stylus.

The analog clock that has tics, works on a geneva drive process.

 

[CMaier]

AND WHAT HAPPENS WHEN I ROTATE THE DIAL???
how does a mechanical thing KNOW where the hash marks are or what i am doing ?

none of this make any sense.

No magic, it's just how they work. The "transmission" is designed around the marked increments (the hash marks). The best analogy I can think of is the second hand on a wall clock. You can see it move from second to second, but the middle of that space between one second and the next is not 0.5 seconds. It's simply calibrated to start moving soon enough to 'arrive' at the next second, or hash mark, at the appropriate time.

 

[TRA]

AND WHAT HAPPENS WHEN I ROTATE THE DIAL???
how does a mechanical thing KNOW where the hash marks are or what i am doing ?

none of this make any sense.

All you are doing is setting the incremental zero when you rotate the dial. Indicators only have so much range and you set the zero by rotating the dial once you find that point regardless of where it is. Digital calipers have an "Inc" or "Abs" set button. when you press it you set the incremental or absolute zero. Absolute measures the part, incremental measures the tolerance. Dial Indicators are incremental.

If you are reading a stationary point on your indicator, you have probably run out of travel. Some indicators may only have .010-.015 travel. The higher the resolution the less travel you have to work with.

To answer your question about moving the dial, it's just like moving the hands of a clock. The clock has no idea what time it is, it only measures the duration of time. An analog clock is incremental.

 

[Boyd Allen]

" Dial Indicators are incremental." I disagree completely. In the case of an analog clock, the gear train is advanced by an incremental input. This is not the case with a dial indicator. IMO your simile has lead you astray.

 

[CMaier]

naw boyd,
i was asking the guy that insists the indicator only works at the marked increments...
i have been using fine measuring tools way too long to buy his story.
i have a 4 groove bbl and i decide to dial in on the tops of the lands.
when my indicator says i have between .0002 and 0003 ( as in between hash marks, but not high or low,
in the middle) on all 4, i think i am pretty well dialed in.
i preload the stylus, i rotate in a single direction,
i mark the chuck and measure the same spot on the land.

or on the bottom of the groove. or a 6 groove bbl...
the indicator does not know where the hash marks are,
nor if it is indicating 0.0001, .0003 or 0.0002.

 

[Boyd Allen]

I understand. Just couldn't let his statement go unchallenged.

 

[TRA]

I understand. Just couldn't let his statement go unchallenged.

-

If you were referring to my statement, please tell. You offered no reasoning, just your assumption and it's wrong. An indicator only measures the distance from a user set zero to the actual position of the workpiece. Same as a caliper measures either ABS or INC. Absolute would be `actual size of the bore, in this case. Incremental is the amount out of round (in this case) the bore is, or out of position. BUT, do you know which it is??? Out of round or out of position?

 

[jackie schmidt]

-

Incremental is the amount out of round (in this case) the bore is, or out of position. BUT, do you know which it is??? Out of round or out of position?

That's easy enough to figure out.

Of course, we can always throw another variable in the mix. How true does the machine's spindle run in it's own bearings?

 

[coyotechet]

I have a few of the 1.5" dial Interapids and some of the #74.111958 (2.75" long) with the 0.080" carbide ball. You will find the larger ball is best when indicating an irregular surface like a rifled barrel bore..

Thanks Jerry but I am still looking for a .0001 with a long stylus. Interapid does not make a a Dial test indicator that reads .0001 with the 2.75" stylus according to Rene at Long Island Indicator Service. I really don't need one just want one of any good brand.

I contacted Rene with long Island indicator about the #74.111958 and this is his reply.

Graduations_______Range______Dial______Point Length________Model________Catalog no.___________P.O. Price
__0.0005"________0.060_______1.5"________2.75"__________312B-15V_______74.111958___________$389.00
__0.0001"________0.016"______1.5"________.687___________312B-3V________74.111957___________$369.00

Your answers are shown above.
Thanks for Asking.

Rene Meyer
Long Island Indicator Service
14 Sarah Drive
Hauppauge NY 11788

 

[CMaier]

chet
if you look at all the data, it should be pretty obvious,
that the typical .0001 is aprox 1/2-5/8 arm length.
to get a .0001 at about 3" the indicator would actually have to be
.000001x or so indicator to start with using 1/2 to 3" as a 6 factor.

 

[Butch Lambert]

Thanks Butch but I am still looking for a .0001 with a long stylus. Interapid does not make a a Dial test indicator that reads .0001 with the 2.75" stylus according to Rene at Long Island Indicator Service. I really don't need one just want one of any good brand.

I contacted Rene with long Island indicator about the #74.111958 and this is his reply.

Graduations_______Range______Dial______Point Length________Model________Catalog no.___________P.O. Price
__0.0005"________0.060_______1.5"________2.75"__________312B-15V_______74.111958___________$389.00
__0.0001"________0.016"______1.5"________.687___________312B-3V________74.111957___________$369.00

Your answers are shown above.
Thanks for Asking.

Rene Meyer
Long Island Indicator Service
14 Sarah Drive
Hauppauge NY 11788

I believe you are quoting Jerry and not me. I just wanted to know if a .080 ball would touch the bottom of the groove.

 

[geo.ulrich]

Chet look up federal LT- 2 1 5/8 probe .0001 resolution, I have been looking at this with some amusement as always a lot of bad info. and some good. If you change probe length if you want to know or care what the resolution is it needs to be checked. To use an indicator for measuring it must be a finer resolution than what you are checking ie. you can not use a .0005 to check a .0005 tolerance. this is where hysteresis comes in. I attatched a picture of my indicator calibrator if you really want to know what you are reading they need to be checked. after years in gage labs the only thing I can tell you is few are good .... also for whoever mentioned Geneva stop works on watches it has nothing to do with running a watch only in winding so mainspring won't be broken.... it hasn't been used since the 1880's

 

[coyotechet]

Butch I am sorry I did go back and correct my mistake. looks like I can not even read the bold letters that Jerry used in his name.
As for the long stylus .0001 indicator if one was ever made the cost would be more than I would most likely pay. Still I would like to have one, until then I will just use my Mitutoyo 513-504 (.0001) and the Interapid 321B-15 .0005 2.75"stylus.and be happy.

Chet

 

[Butch Lambert]

Butch I am sorry I did go back and correct my mistake. looks like I can not even read the bold letters that Jerry used in his name.
As for the long stylus .0001 indicator if one was ever made the cost would be more than I would most likely pay. Still I would like to have one, until then I will just use my Mitutoyo 513-504 (.0001) and the Interapid 321B-15 .0005 2.75"stylus.and be happy.

Chet

Chet,
Too many internet smiths talking about tolerances that they can not really understand and hold. Not encouraging sloppy work, but more attention to learning to read conditions. That would help more than a .0005 closer tolerance.