Hi Dalboy you can also remove the anvil and screw and use it to measure step size from a face to diamiter or flat face.

David

A tube micrometer will do the job. The fixed anvil is not a blade but a cylinder at right angles to the axis of the work to be measured.

Andrew

Can you elaborate on "behind the piece" and "in the lathe"

To me you could be describing the back of a disc held in a chuck and wanting to measure to it's front which would be the thickness of the disc in which case a standard mic would do.

Or is the back of the piece pushed up against a chuck face and you want to measure how much is sticking out? in this case a depth micrometer would do the job with it's flat foot on the outer face of the work and moving anvil extended to touch the chuck face.

Digi calliper will also do both and have a flatter blade to fit down between two chuck jaws to  the back of a small piece of work. If there is enough gap between the jaws then an interchangeable anvil mic may do as less room is needed due to it's flatter shape than the usual curved so the frame won't hit the chuck face so easily

Edited By JasonB on 03/05/2023 18:53:20

Edited By JasonB on 03/05/2023 19:04:17

Hi, in my No. 64 Starrett second edition catalogue, there is one shown which is almost identical to the one that DC31k has linked too, they had eight variations depending on which anvils were required, and in May 1968, the price range was from £7.90 to £9.00, but if you wanted a case to keep it in, it was 15p extra. (prices converted to todays decimal coinage) extra anvils were available, and you could make your own anvils of any shape, to suite special jobs.

Regards Nick.

Edited By Nicholas Farr on 03/05/2023 19:23:37

Dalboy

Have a look at paper thickness micrometer, this might be what you are describing. They have a disc anvil of approx 25mm dia.

If you are wishing to measure how far the work stands out from the face of, say, the chuck, or a chuck jaw, you may be looking for a Depth Micrometer.

Beyond the Thimble, there is failry long blade (Which is the Zero datum ). Rotating the Thimble causes it to move forward and a rod appears from the datum blade.

The graduations on the Thimble and barrel show how far bthe rod protrudes.

Unscrewing the cap at the end of tthe Thimble allows the rod to be changed for a longer one, so instead of measurinh 0-1" it can then measure 1-2", 2-3", depending which longer rod has been inserted.

I find them less easy to read than a conventional Mic, but with care, it is a very buseful tool, essential for measuring dpeths accurately

HTH

Howard.

…often called 'Uni-mic' (or 'Uni-mike'…). Possibly a name originally used by Mitutoyo.

Out here , we call them blade micrometers . A 0-25mm is in a frame size of a 25-50.

Some people look for thread micrometers , and then make up the blades or the forms that are needed. I recently bought a blade micrometer 0-25mm from Aliexpress. I am very happy with it. I got it for measuring the taper on crankpins. Mine came with very thin blades of 0.8mm wide.

As I have a nice non rotating barrel analog 25-50 thread micrometer, if I need a very thin or a radiused blade, I can make them for that micrometer too, and use the extra length, to get by the flywheel side.