Reposted from my work blog.
Dial Indicators are great! They’re very precise, easy to read, and have a standard form factor. They’re also really easy to use as a building block for larger gages.
Mueller Gage is the name brand for these types of gages, and their catalog is full of inspiration. They also make super nice commercial gages that you should just buy if they are within your budget.
I used to work in a shop where they used gages made from bar stock and dial indicators extensively, so I set out to build one of their style gages from memory. (Shout out to Tom Sidloski and Will Perry from Valley Manufacturing!)
To use this style of gage, you need to create a gage setting master. In 35-125 we have several sets of gage blocks, and a couple sets of gage block clamps.
To create a master, select a set of gage blocks that add up to your desired nominal dimension. You should be able to “wring” them together, rubbing clean gage blocks together so that they stick to each other. Stack them up to create the total size you need and place them in a clamp. There are a couple different kinds of end caps that will allow you to create inside or outside diameter setters, or location gages.
Using your master setter, set the zero on the diameter gage. This is done by moving the gage clamp and turning the bezel. When properly zeroed, the gage should stop moving and change direction at zero on the dial when placed in the gage setter.
This gage will now give you a very repeatable and precise measurement for an arbitrary size. When measuring large parts or diameters where roundness variation is large, be sure to take multiple measurements and average the results.