How do you measure the INSIDE of a bottle?

[J Tiers]

Softtail has it.

One arm into the "bottle", and the indicator on the other. Make so the indicator zeros on the arm

[BCRider]

That's the same idea I was suggesting too. But with an angle or more open radius on the bend for the elbow if needed to get in through the opening.

But so far we still don't know if the aim is to check inside diameter, inside length or wall thickness.

[rzbill]

There is a tool out there called a Magna-Mic. Uses a small ball bearing and a magnetic coil. Calibrated to measure thickness or the gap between the ball and the coil on non-magnetic stuff. Glass, plastics etc. Got one at work. We use it to measure the wall thickness of plastic bottles we mold.

There are also Ultrasonic versions, but I have no experience with them.

Greg has identified the common standard in the food packaging industry for measuring wall thickness of containers that are otherwise difficult to access in an NDT manner. Unfortunately, they are grossly expensive for the hobbyist or small business owner. Interesting post from Wombat that suggested making one using root principles. Try to keep that one in the back pocket for the future. However, I have never used them on a metalic container, only plastics so I do not know how the Magna-mic would work with a conductive container.

On other machined parts that were difficult to access, we used a comparator and a double probe. One end of the probe went into the part and the other end stayed out in the open where it could be shadowed against a profile placed on the comparator screen.

[Dan Dubeau]

I'll back that idea too. Every Patternmaker I've ever worked with had gauges like that. 2 arms, a tooling ball for the anvil, and an indicator zeroed on the ball. You can vary the shape of the arm depending on what you want to measure, and how you need to get in there to do it.

[Joel]

If it will work for you, here is a cheap .7 to 1.5" dial bore set for $43 shipped:
https://www.amazon.com/0-7-1-5-Dial-...Dial+Bore+Gage
It may only go about 6" deep, though.

A .7 to 6" set for $100:
https://www.amazon.com/Anytime-Tools...Dial+Bore+Gage
Starrett:
https://www.amazon.com/Starrett-3089...Dial+Bore+Gage

[boslab]

A measuring pin can be made of rod, think Allen key, fit into or onto height guage, stick offending pipe on a vee block, insert the measuring pin touch where your interested, you get the idea.
I have done the same measuring inside rollers you can access the bottom of the roller outside, then you have the height inside, one subtracted from the other.
There's other ways too, two ball bearings and slips between for recesses was handy, similar to internal tapers.
Mark

[PStechPaul]

First thing I thought of was using capacitive sensing:

https://en.wikipedia.org/wiki/Capaci...acement_sensor

[3 Phase Lightbulb]

I gather a Genie could measure the inside of the bottle for you.

[3illmesmart]

Old school...
https://www.generaltools.com/12-in-inside-caliper
I'm going to guess you could measure the outside caliper left sticking out with this, might need a bigger set...
http://www.timberbits.com/robert-sor...tside-calipers