How Do I Measure the 1mm Diameter Hole?

I would think some sort of optical measuring instrument would be your best bet.
Like a microscope that rests on the item being inspected which has a scale and vernier incorporated into the optics... I've seen that sort of many years ago. Prob get similar with a camera that sends pics to a PC these days.

I might have a browse around with my tea and toast!

I did a search for 'measuring microscope' got some good stuff, some were so expensive they didn't bother putting the price, but some good E-bay stuff from graticules to a travelling microscope for about £126 which was in India and looke like a useful bit of kit.

It all depends on your budget!

Good luck.
Del

Nice find!

Pin gauge sets

http://www.meyergage.com/wp-content/uploads/2012/09/Individual-Gage-Pins.pdf

The X type has the tolerance that you need.

Thank you for your post, but this pin gauge measurement will suit only if we know the exact reading.

I understand that you do not yet know in which range is the diameter you obtain.

How do you manufacture or want to produce the hole ?

This could be a hint in which direction the tolerance field would move.

One way and the most probable could be the mentioned "pins". You can order and use several "pins" with diameters in steps.

The problem is more complex than at first view since the hole has a depth and any optical measurement at the edge level can give an information not any more valid in the deep and can be "polluted" by a chamfer. Of course it is possible to displace the focus and try to make measurements in the depth at different levels but you do not have the safety to measure all around at same level.

This is the reason I suggest to have several calibrated pins and define where the diameter is. A series could be 0.995/1.000/1.005/1.010/1.015/1.020/1.025/1.030...

You can also couple 2 dimensions on same pin making a "go-no go" pin to define the interval. I would also recommend to make the measurements from the 2 sides in order to see if the hole is straight or tapered. With the pin you can check if the tool went straight or not (curved bore).

You could also look at capacitive or inductive measurements although I think that the diameter is too small. For 3 mm I remember to have seen such "heads".

Try to find at a college a chair for fine mechanics, micro-mechanics or watches, they could help you better since such dimensions are their daily bread.

Also manufacturers of nozzles for big diesel engines are confronted with similar problems. Those could be directions you should look for information and help.

I wrote my text before the suggestion of the Chinese device. If you are only interested in the diameter at the surface you can help your self in a first approach in a much more simple way: use a high resolution photo camera with at least 12Mp and make a picture in the macro range. You can calibrate the picture with a plane thickness gauge. And after this you analyse the picture taking the coordinates in number of pixels. If you have the x-y pixel coordinates for 3 points you can compute the circle diameter passing through. For the calibration it is good to have same distance and place the reference in 2 orthogonal positions. It will not be as accurate but will not cost so much. And once you have the data you can order the "go-no go" pins for series control.

Used for 18 mm diameter accuracy under 0.01 mm

Thank you "nick name",

Your comments are added more value to my questions.

How large is your product run, how many holes do you have to inspect? And what is your yield expectations, or failure rate? A 100‰ pass rate is only in pipe dreams. As mentioned before, you might consider machining your own "GO-No GO" gauges, especially if it's a large production run.

Use an eraser to remove one of the zeros in your tolerance..

...after which a kit of precision twist drills with diameters either side and including <...1mm diameter...> should suffice as a test device.

All,

I have done this measurement by using 0.5mm probe in the SWISS made CMM machine.

Thank you guys for your comments and posts!

Conceive a tapered rod, 0.95mm diameter at one end and 1.05mm in diameter at the other end as a test device. When it is inserted into the hole, the diameter of the hole can be inferred from the distance the rod passes into the hole, as a proportion of the length protruding divided by the length of the rod.