Harold Hall
Metalworking
Workshop Set Ups
Dial Indicator and Dial Test Indicator, Setups . Harold Hall
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Photograph of the rear of a DTI
To be added
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All pictures can be clicked on to provide a larger view
First let us clarify the main difference between a Dial Indicator(DI) and a Dial Test Indicator(DTI). A dial indicator has a plunger which moves in and out to detect the measurement being taken Photo 1, whilst the dial test indicator has a swinging stylus to make the test, Photo 2. Also, the dial indicator has a much larger measuring range, typically 10mm compared to 1mm. Dial indicators are therefore used mainly to measure distance whereas dial test indicators are used to set position.
The method of mounting a DI is by gripping the barrel,
in which the plunger moves, photograph 1, or a lug on its rear, Photo 3. A DTI has a small dovetail on its rear on which an adaptor (usually provided) is fitted. Photo 4.
Often the problem with using a DI or DTI is getting it into position for the test and having a method of securing the assembly at the non working end. The photographs that follow(except photograph 8) all use my DI/DTI accessories for the purpose. LINK
Often the jaws of a machine vice set up on the milling machine table require to be accurately in line with either the X or Y axis, Photo 5 shows this being done for the Y axis.
When setting parts accurately on the faceplate, suitably placed toolmakers buttons, assisted by a DTI, can be used, Photo 6. Much easier though is to position the part whilst the faceplate is horizontal and this can be done using my faceplate balancing fixture, Photo 7.
Photo 8 shows a DTI being used to position a round bore central below the milling machines spindle. This assembly uses the DTI mounting facility provided with a Wiggler workpiece positioning kit.
If a part needs to run perfectly true on the lathe the four jaw is used for this as the three jaw cannot be guaranteed to give the accuracy required. Photo 9 and Photo 10 show methods of setting up the DI for checking the result.
An angle plate is being check to see that the top edge is parallel with its base, Photo 11.
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