Can I use ping to read .001 of inch?
Speed of sound?
About 1100 feet per second.
13200 inches per second
13200000 thousandths of an inch per second.
Trying to use this to operate stepper motors to adjust an axis within tight tolerances
roytownsend:
Can I use ping to read .001 of inch?
Very unlikely. 1" is about 74 microseconds; divided by 1000 is 74 nanoseconds, which is not much more than a single clock cycle on a 16MHz Arduino - way too short to be able to measure correctly.
You may try a ping on a faster system, but I'll bet good money that the circuits of the range finder itself are not nearly that accurate.
What do you think the closest I might be able to come to .001"?
What is "ping"? Generally speaking precision cost $$$, so how much you got to spend?
Maybe a third of an inch (about one wavelength)
roytownsend:
What do you think the closest I might be able to come to .001"?
Well, the upper limit should be in the sensor's datasheet (assuming it's an expensive, serious sensor, not a nameless eBay bargain). Then there's the problems of the physical world (noise, echoes etc.) and the limitations of your own system. All in all, I will be happy [edit: extremely, unbelievably happy!] with 0.1 inch... if you need really good accuracy, you probably need a different kind of sensor altogether.
[Added: AWOL is right, there's the physical limitation of the sound frequency as well - again, check the datasheet]
What do you think I should use? This could work .01" if that is a better # to learn how to change the programming to use decimals.
Thank you
How do you use "ping" to read less than an inch?
You don't.
You use a suitable technology. I suggest capacitive sensing with a disc probe.
On a mill which I use to an accuracy of 0.0005" you determine position by turning threaded bar. if you have a 40 TPI thread, and turn it one turn that is 25 thousands of an inch a turn. You can get a rotary encoder that can take that down to 1 thou.
That said what you need to do is look up how DROs work and it isn't with ultrasound.
ChilliTronix:
On a mill which I use to an accuracy of 0.0005" you determine position by turning threaded bar. if you have a 40 TPI thread, and turn it one turn that is 25 thousands of an inch a turn. You can get a rotary encoder that can take that down to 1 thou.That said what you need to do is look up how DROs work and it isn't with ultrasound.
an encoder with 200 steps per rotation would divide that 0.025 by 200.
dave-in-nj:
an encoder with 200 steps per rotation would divide that 0.025 by 200.
Which would more than meet the OPs requirements.
Thank you for all of the information. Now I know that I will have to find a different way.
AWOL:
Speed of sound?
About 1100 feet per second.
13200 inches per second
13200000 thousandths of an inch per second.
In air that's about right. If the medium were changed to Xenon, however, there would be 7 007.87402 thousndths of an inch per second. This is getting closer to possible. If the clock speed of the arduino were ramped up to 20Mhz it might even just be doable.
KenF:
In air that's about right. If the medium were changed to Xenon, however, there would be 7 007.87402 thousndths of an inch per second. This is getting closer to possible. If the clock speed of the arduino were ramped up to 20Mhz it might even just be doable.
Now that's how an engineer solves a problem! 
That reminds me of a bonkers physics exam question I once saw, that was something like
"A cathedral is one hundred metres long, with the organ at one end and the entrance at the other.
If the organist strikes a key connected to a 3 metre organ pipe, how long after will the verger, at the entrance, hear the note, and what will the frequency be, if the organist is playing in an atmosphere of coal-gas? (you may assume standard temperature and pressure)"