# Dial Test Indicator VS Dial Indicator?



## R.G. (Mar 23, 2012)

Sorry - beginner question.

What's the difference?


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## Tom Griffin (Mar 23, 2012)

The difference is access and range.

Dial test indicators are good for indicating vises, aligning the edge of a workpiece, finding the center of a small hole, centering a part on the lathe, etc. They are versatile and easy to get into tight places, but they have limited range. 

Dial indicators can have a much greater range and are good as carriage stops on the lathe and for comparing the height of parts on a surface plate, but they are big and bulky and therefore work better for dedicated applications.

Tom


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## R.G. (Mar 23, 2012)

OK. Makes sense. 

Is there a difference in the motion of the measuring arm? One type has an arm that measures axial motion, the other has a pivoted arm. Do both types (DI vs DTI) come in both arm styles?


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## Tom Griffin (Mar 23, 2012)

Dial test indicators have a pivoted arm, dial indicators have a plunger. 

Because of the pivoting arm, dial test indicators do not read accurately throughout their travel, only near the center. That's why they are normally used to check relative change like indicating a vise or centering a part on the lathe. If you want to measure accurately over a large distance, a dial indicator is the way to go.

Tom


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## Redirish (Mar 23, 2012)

Tom is right in his explanation. I have 3 DTIs, 2 expensive ones, and one I loan out. I think I have 6 DIs, 2 are set up to zero work in the 4 jaw and set up the taper attachment. 2 are on mag bases and the others are loaners. Now, mind you I sure didn't get all of them the same time, took 32 years. And remember this, the only stupid question is the one you don't ask!


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