Calibrating a Starrett 98-4 Level

Just got a used Starrett 98-4 precision level which is accurate to
.005" per foot. How do I calibrate the level? It has a screw on one
end that holds one end of the level and a threaded stud on the other
that hold the other end of the level. The level is held captive on the
stud in between the nuts on the threaded stud. Mine was loose when I
got it and I need to know how to get it back in trim and check it for
accuracy. Thanks, Steve
Reply to
Steve
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Not really "calibration", but more "zeroing".
What you do is find a good stable flat surface (a surface plate would be nice) and set up a reference stop for one edge of the level to be against so your angle is repeatable.
Then place the level against the stop, and note how many lines it is off of center. Then reverse the level end for end, and check again. It should be the same number of lines off for each orientation. Make your adjustment until you have that consistent. Once that is done. you can be assured that if the bubble is in the center, the surface is level (at least, within the capabilities of that particular instrument).
Note that there are far more sensitive levels. Starrett's "Master Precision Level" (No. 199) is 0.0005"/foot, and thus is much more touchy to adjust.
Good Luck, DoN.
Reply to
DoN. Nichols
Hi, Find a flat, stable surface that is reasonably level. A surface plate or smooth machine table will work. Place level on the surface and mark location or place some heavy parallels around it so you can remove the level and put it back in the same exact location. Adjust the level until the bubble is reasonable centered. Reverse the level (swap ends.) Continue to refine the adjustment until the bubble reads the same when the level is reversed. Really does not take too long.
Mill
Reply to
MP Toolman

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