Dial Indicator

[pepi]

If this is a dumb question so be it, have no other place to ask. Is there some difference between a Dial Test Indicator and a Dial Indicator? 

The Indicators look the same trying to figure out if I am missing something.  

Greg

[Highpower]

GENERALLY....  Dial test indicators (DTI) are smaller in size and have a very limited range of measurement. But they have very fine graduations so they are used for very fine measurements, sometimes down to .0001 inches. (One ten-thousands of an inch.)

Dial indicators (DI) are usually larger in size and can have a much longer range of movement. An indicator with a one inch range is probably the most common one found. You can get one with a two inch range as well for example. And they are usually graduated in .001 inch increments. I'm sure you can find dozens of both types in different sizes and ranges & graduations as well.

[Mayhem]

Cost is another difference

Just so you know, there is no such thing as a stupid question - only stupid answers.

[pepi]

Good show, thanks helps me to understand the usage for the two types of indicators.

[Sunset Machine]

There's a gotcha in using them. Depending on the type, the tail must be either tangent or parallel to the ways if you're looking for accuracy. The pic shows a head being set to 45 degrees.

Note the vertical position of the dial indicator as it measures the rise on the chuck face when the table travels side to side.  Exactly 90 degrees to the ways/table, not the chuck. If it were tangent to the chuck face, the indicator would only show half of the actual rise.

[TomG]

Dial test indicators also have small pivoting arms, so they can be used to indicate small holes or slots.

Tom

[pepi]

(02-16-2016, 11:37 AM)Sunset Machine Wrote: There's a gotcha in using them. Depending on the type, the tail must be either tangent or parallel to the ways if you're looking for accuracy. The pic shows a head being set to 45 degrees.

Note the vertical position of the dial indicator as it measures the rise on the chuck face when the table travels side to side.  Exactly 90 degrees to the ways/table, not the chuck. If it were tangent to the chuck face, the indicator would only show half of the actual rise.

That's a good point and understood ^

(02-16-2016, 12:40 PM)TomG Wrote: Dial test indicators also have small pivoting arms, so they can be used to indicate small holes or slots.

Tom

  Can it be said that both of the indicators pictured can be:

 A. Dial Test Indicator or B. Dial Indicator. 

And that the accuracy and range of the indicator will determine if it is A or B, that sound right?

I see these indicators sold on eBay and not sure if they are using the correct name, or throwing in the word TEST to hype the price.. 

Hope I am not giving folks a headache with this.... 

[Highpower]

The small gauge on the left is normally referred to as a DTI. (Dial TEST Indicator.) Again, that is the type used for fine / extremely accurate measurements. Because of the increased resolution built into those indicators, there is a definite increase in the cost to manufacture them as Mayhem noted above.

The larger gauge on the right is what most people think of as a DI. Just plain old "Dial Indicator". Very common and import versions can be purchased very cheaply. High quality name brand versions that are built to a higher standard can be quite costly as well. "You get what you pay for" as they say.

To add to Tom's point about measuring inside of holes or slots with a DTI, I will add that you can purchase accessory attachments for a standard dial indicator (DI) that will allow you to perform the same task. Just not quite as accurately as using a DTI.



To add to the mix there are back plunger indicators too! The measuring stem is attached to the back side of the dial housing instead of coming out of the bottom of the dial housing. It is a very popular item with lathe users.



Clear as mud, right?  

[pepi]

Ok thanks

Willie,
I originally had it in my mind the way you describe the two types. After reading post 2, and seeing the pictures. I mistakingly thought the left picture had 2 styles of the DTI,  and the one on the right was a DI. That is how I got off into the weeds, read to much into the post.
 

[TomG]

If you are trying to figure out what to get, a dial test indicator would be first in line. You would use it all the time for things like indicating a vise, indicating a part in a 4-jaw or faceplate on the lathe or tramming the head on a mill. Dial indicators are used for things like soft stops on the lathe, or precisely positioning the table on a mill if you don't have a digital readout.

Tom