Ball attachments will convert any micrometer into an accurate tool for measuring tubing wall thickness. These will fit on either the anvil or the spindle side of the micrometer (your choice). Be sure to select the size that corresponds to the diameter of your micrometer's spindle or anvil.
Because you will have added the dimension of the ball to the micrometer, you will have to subtract that diameter from any readings you take. Put a tag on your micrometer as a reminder to yourself or anyone else who might pick up the mike and try to use it.
Mitutoyo and Brown & Sharpe ball attachments have a neoprene sleeve.
Starrett attachments are all metal.
Etalon model for Etalon metric micrometers.
If you regularly use your micrometers for these applications, you may want to invest in a Brown & Sharpe micrometer with spherical faces. They have the advantage that you'll never have to make subtractions or other calculations to get your reading.
Brown & Sharpe model with spherical anvil and flat tungsten carbide faces makes this micrometer ideal for measuring convex curves directly without having to subtract the diameter of a ball. Measure wall thickness of tubing with inside diameters as small as 3/8". Straight/line barrel graduations and glare-free satin-chrome finish virtually eliminate .025" reading errors. Convertible "fixed/friction" thimble for a choice in measuring action and ring lock. Graduations in .0001"
Made in U.S.A.
Caution if buying from Amazon: their product images sometimes do not match the product description. Read carefully!
Disclosure: some of the links on this website may direct you to Amazon. Any purchases you make from those links will result in a commission for us. That commission helps to pay for the construction and upkeep of this web site. We are grateful for any purchases you make through those links.