Micrometer - 80 mm with Vernier

This is great while working at your desk measuring small things that you need to draw and print.

The top and bottom “teeth” measure inside and outside dimensions.  The pointy extension on the right end measures hole depth.

The hash marks on the bottom (0 and vernier scale) did not indent very well.  Read the first indent on the bottom hash marks as the “0” point.  That is shown with a single pencil line in the last photo.  It is indicating a little more than 16 mm on the photo.

When the “0” reading is to the right of an adjacent mm hash mark, as in above, you can use the vernier to add the number of 0.1 mm's to the reading.  I read it as 0.4, as indicated by the pencil-marked arrow in the last photo.  So the measurement is 16.4.

My digital calipers read 16.66 mm for this measurement.  

So, the printed micrometer is - 0.26 mm of actual, which is better than what I had anticipated.

There are three each .stl and .gcode files.   One file supports printing both parts of the micrometer at once.  The other two files support changing filament color, so you can make the numerals show up better.

I also found that printing in white and making the numerals with black ink was perfectly adequate.

There is a spring in the middle of the back that is designed to put pressure on the mating part and retain it in position.  You have to twang this with a blunt object, such as a screwdriver, in order to release it and allow it to flex.  There is also a bump on the tail pin that adds pressure for the same reason.  Probably over-kill.

After printing several test pieces, I found that a design clearance of 0.3 mm between the sliding parts provided a reasonable slip fit.

if your print is too loose or tight, drop me a note and I will add a couple new files with more ore less clearances.  Advise if loose or tight