Quick answer
Install a depth base on your 6-inch caliper to measure the depth of slots, steps, and grooves. The base slides onto the caliper blade and locks with a nut for repeatable readings.
Why add a depth base to your caliper
A standard 6-inch caliper measures outside dimensions, inside dimensions, and step distances, but it cannot directly measure depth without an attachment. The depth base converts the caliper into a depth gauge, letting you probe recesses, grooves, and blind holes. This is especially useful for bench top machinists who need to verify slot depths in milled parts or check the depth of a drilled hole without removing the workpiece.
What to watch for during installation
The depth base has a locking nut that secures it along the caliper blade. Over-tightening can distort the blade or bind the slider, while under-tightening lets the base shift during a measurement. The base must sit flat against the caliper's reference face for the depth rod to remain perpendicular to the surface being measured.
Installation steps
- Step 1: Prepare the caliper: Close the caliper jaws fully and zero the digital readout. Wipe the blade clean of oil or debris so the depth base slides freely. A dirty blade can cause false readings or make the base stick.
- Step 2: Slide the depth base onto the blade: Orient the base so the depth rod points downward, away from the caliper body. Slide it onto the blade from the back end until it is flush against the caliper's reference face. If the base is reversed, the rod will not contact the surface squarely.
- Step 3: Tighten the locking nut: Hand-tighten the locking nut until the base is snug against the blade. Do not use a tool—overtightening can distort the blade or bind the caliper slider. Check that the caliper still slides smoothly after tightening.
- Step 4: Verify zero and test: Place the caliper on a flat reference surface with the depth rod touching the surface. The display should read zero. If not, loosen the nut, reposition the base, and retighten. A non-zero reading means the base is not fully seated or the rod is bent.
- Step 5: Take a depth measurement: Lower the depth rod into the slot or hole until the caliper's reference face contacts the top of the workpiece. Read the depth on the display. Rock the caliper slightly to ensure the rod is at the deepest point before recording the value.
Product facts
-
Depth Base for 6" Caliper: This depth base attaches to the blade of a 6" caliper for depth measurement and has a locking nut to secure along the blade. It turns a standard caliper into a depth gauge, letting you measure the depth of any shape with a step, slot, or groove without buying a separate tool.
Depth Base for 6" Caliper