zero a depth micrometer

[mikecwik]

a glitch in the matrix lost this thread.

if we could go back in time, which i am the only one capable of doing so...alien technology and what not it was an interesting thread. so if everyone can go ahead and redo their post as best they can especially pixman for pointing out something id not considered in the adjustment process.

i have the good fortune to have some depth micrometers though ive never felt the need to get that critical. then i was thinking since i have it why not use it. i was sort of thinking how to zero one of mine out and what i came up with was pretty ridiculous but it is actually what has to be done to do it as i found out later. by the way its not an easy search to find the procedure.

a lot of people might need to take an accurate measurement that have nothing to do with the machining world and they are not going to have a surface plate or a gage block set. heck, im willing to bet a huge number of machinists do not own a set.

the procedure is not super difficult to understand but would you like it if someone came in and twisted all the adjustments on a 6" set and how long would it take one to get it back proper? its just not very user friendly.

im on my way to the airport.........highjack my own thread begin.


nothing photographed twice and i do have more.

[PixMan]

To calibrate a depth micrometer start with the most-often used rod, the 0-1" one. Find a perfectly flat surface, such as a suface plate. I good quality parallel or other piece of flat ground stell will also work.

1. Wipe the surfaces of the plate, the end of the meauring rod and base of the micrometer all clean using a lint-free, oil and chemical free cloth or paper.
2. With the of secure in the micrometer's thimble, back off the micrometer to minus a few thousandths tenths of a millimeter.
3. Bring the thimble down to touch the plate, check the reading. If not zero, just make a note of how much the error is.
4. Using 1" (or 25mm if a metric micrometer) increments of gauge blocks under the micrometer, make the same check with each length rod. Note the error.
5. Compare error measurements. If all exactly the same, make the adjustment to the thimble body. If any one rod is good, make that your "zero" error rod and adjust all other rods using the little open-end wrenches until all read zero. Note that the "heads" of the rods will be very snug, and you may need to use a brass-jawed vise to hold it while you make an adjustment. The threads are relatively coarse pitch, so a TINY tweak of the adjustable head is all it takes to move it a few thousandsanths at a time.

That's about it!

HTH

Ken

[sasquatch]

MikeCwick Thanks for the great pics.

[Sunset Machine]

I bought a cheapo last spring to set up a planer. Zeroed it against a ground flat, although for this I was comparing the four corners to each other and the actual measurements didn't matter. The green stuff is grinder fluid just for visibility.