Measuring Diameter of Large Quartz Tubing

If this is to verify diameter, you could make a series of certified go-no go gauges to pass your material through. If the tube is too large, it will not pass the first gauge. If it passes the second gauge, it should not pass the third gauge.

what is the accuracy required? 0.1mm, .05mm, 1 mm. I suspect a machine vision system would work fine. Cognex and DVT might have something reasonable and quick to set up. Also, mounting the laser and moving it across the object while monitoring an encoder or stringpot and laser output may be good enough. Two laser micrometers on each side of the pipe located at known points, just add both mics plus the reference distance. You could have multiple points across a linear slide to pin the mics for different sizes. Just a few quick thoughts

I suspect that the key to solving the diameter part is the use of highly accurate metal tape measures that measure the outside perimeter of the tube. This will give the OD. Samples of the wall thickness should derive the ID. This method will not measure eccentricity of the ID/OD. Hope this gives you a few ideas.

We used to get accuracy to within a few thousands with string pots. Maybe, a rotory encoder you roll around the circumference. Are you measuring inner or outer diameter? Good luck.

Thanks for the ideas.... Usually, anything that touches the tubes leaves a mark so the go/no gages, the tape measures and the rotary encoder probably wouldn't work. The tubes have a .5 to 3.0 mm tolerance but we print the exact size on the labels for the customers. Something with a RS232 output would be good. I think we need to go with a non-contact type of unit....