Overview: The Dial Indicator
The dial indicator is a must-have item for the on-site machinist. They accurately indicate small distances and angles and ‘amplify’ them, making them easy to read. Typical applications for the in-situ machinist include flatness and ‘run-out’ on items before and after machining, or as part of the machine set up process.
Dial indicators work by using a precisely geared mechanism driven by a plunger and display tiny increments in either metric or imperial format on the dial face (for metric: typically, 0.01mm or 0.001mm).There are 2 main dials on the clock face; the metric dial indicator shown above includes outer increments of 0.01 of a millimetre on the main scale, with each 10th increment numbered for easy reading. The smaller dial shows the number of complete turns of the larger needle, with each number representing 1mm.
Using a dial indicator when setting up an ID mounted flange facer
When setting up an internally mounted flange facing machine, the magnetic mounted type of is recommended. (Some flange facing machine manufacturers, including Mirage supply these as standard with their machines). The dial indicator plays an important part during the machine set up procedure described below;
Setting up the flange facer base assembly
- Measure the flange bore diameter which will enable you to choose the most appropriate base and leg assembly.
- The machine base and leg assembly is inserted within the bore and positioned using the based setting straps.
- When using one of the larger flange facing machines such as the MM1000i and above, some machinists like to it check for concentricity between the base and the flange bore. This can be carried out using a dial indicator attached to a clocking tower, or using a metal rule when an approximate measurement is sufficient.
- If the base position needs fine adjustment, this is done using the jaws on the base legs and rechecking using the dial indicator.
- The machine is then offered to and bolted onto the base.
Using a Dial Indicator to check the facing arm is level with the flange surface
- Attach a dial indicator with a magnetic back to the tool post.
- Position the dial indicator with the plunger positioned 90 degrees to the flange face and with the plunger approximately half way between its range.
- Rotate the machine’s facing arm slowly. You will see the needle moving, telling you that the surface is not exactly level.
- Adjust the jaws on the base legs, retighten and keep rechecking to minimise the amount of needle travel.
- When the machine is level as possible, position the tool at the required point on the flange surface and apply a depth of cut.
- Remove the base setting straps and turn the power on to commence flange facing
- After the flange face has been machined you can check for flatness by offering a straight edge to the flange. If a feeler gauge of 0.05mm cannot be inserted between the straight edge and the flange surface this is an acceptable level of flatness.
Need equipment for an on-site machining project? Get in touch with your regional Mirage contact.