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measuring barrel vibes with strain gauges

Has any one been able to measure barrel vibrations by using 120 Ohm strain gauges
what circuitry is needed to connect the strain gauges to an occiliscope
and where does one get the gear needed
i want to compare the vibes on my .22 target rifles
regards john mc
 
I'm not an engineer, but I would think that measuring vibration would best be done with a piezo style vibration sensor.

Strain gauges measure elastic deformation of materials and might not give you the information you seek...
 
120 Ohm strain gauges
what circuitry is needed to connect the strain gauges to an occiliscope

Standard protocol for instrumenting strain gages is to use an instrumentation amplifier to amplify the signal prior to measurement or display on an oscilloscope. I have good luck using TI instrumentation amplifiers and may still have some standalone IA boards that I used to sell for minimal cost. I will check for the boards if you are interested.

I do agree with Keith on the feasibility of using strain gages to measure harmonics. The other issue is what harmonics are you trying to measure? Some times high speed photography is a good first step to understanding the motion of the barrel after pulling the trigger.

Hope this helps,
 
What is important ( assuming you are seeking data related to accuracy) is barrel position at bullet exit. Microchip accelerometers at the muzzle synced to a high speed video camera should do it. If the muzzle position and velocity( not bullet velocity) is always the same, accuracy will be maximized.

RWO
 
Standard protocol for instrumenting strain gages is to use an instrumentation amplifier to amplify the signal prior to measurement or display on an oscilloscope. I have good luck using TI instrumentation amplifiers and may still have some standalone IA boards that I used to sell for minimal cost. I will check for the boards if you are interested.

I do agree with Keith on the feasibility of using strain gages to measure harmonics. The other issue is what harmonics are you trying to measure? Some times high speed photography is a good first step to understanding the motion of the barrel after pulling the trigger.

Hope this helps,
Hello thank you for your reply i am very interested in obtaining some IA boards -- i live in Mackay Queensland Australia and we some times have big problems obtaining the things that are needed
please let me know how i can get some of these boards
regards john mc
 
strain gauges measure strech use to use them to check 4000 ton DCM's when the auto went out X pattern
 
Hello thank you for your reply i am very interested in obtaining some IA boards -- i live in Mackay Queensland Australia and we some times have big problems obtaining the things that are needed
please let me know how i can get some of these boards
regards john mc

What would I do if I was in Australia trying to solve a problem? I knew one Australia that was wired to solve problems caused by thing he did not have. His first name was MacArthur, I did not ask him how he came up with such a magnificent name but he told me anyhow. I met him at an airport in Houston, TX. I was flattered, he said had heard about me.

If I was interested in determining barrel vibration and had no interest in making the rifle look like it was on life support I would mount a laser on the end of the barrel then use a camera to record the dot on the target. Someone should consider the laser could determine trigger pull and time between firing pin drop and the bullet leaving the barrel.

Finding the camera could be a matter of locating a TV station that was interested in such test.

F. Guffey
 
... His first name was MacArthur, I did not ask him how he came up with such a magnificent name but he told me anyhow. I met him at an airport in Houston, TX. I was flattered, he said had heard about me.
stalker30.jpg
 
Ed Shilen introduced me to amplified head phones with a good mic. You can adjust your tuner or weight until the muzzle is dead.
 
An easy but messy method to see the nodes on your barrel is to do what I used on my BPCR rifles. Simply dust the upper surface of a clean barrel with flour, suspend the rifle barrel down holding the stock and strike the bottom of the barrel with a rubber hammer. The zero nodes can be clearly seen and allow the shooter to position his cross sticks for best accuracy at long range. I'm not sure
if this would work on rifles with much sharper firing impulse.

Rpbump
 
Hello thank you for your reply i am very interested in obtaining some IA boards -- i live in Mackay Queensland Australia and we some times have big problems obtaining the things that are needed
please let me know how i can get some of these boards
regards john mc

I checked my stock and no longer have any boards left but I found some sources:
https://oceancontrols.com.au/KTA-284.html
http://www.tenettech.com/product/2840/loadcell-breakout-board

Hope this helps.

Have you ever done any electronics? I ask because I could draw up a circuit that you could build on a breadboard that will work for this application.
 
I checked my stock and no longer have any boards left but I found some sources:
https://oceancontrols.com.au/KTA-284.html
http://www.tenettech.com/product/2840/loadcell-breakout-board

Hope this helps.

Have you ever done any electronics? I ask because I could draw up a circuit that you could build on a breadboard that will work for this application.
Hello Wade yes i am quite able to run a soldering station - i have built many projects over the years - and have the capability of making circuit boards on CNC router -- a diagram would be great to have -
just as long as it contains components that i can source in Australia -- or get on E-bay
thank you for the offer
john mc
 
I doubt he used a zero input pick up with an old Peavey amplifier but I suppose a light display would also have worked.

F. Guffey
No, just tapped the barrel and adjusted until the muzzle was dead. Guess what? I don't shoot much anymore and haven't pursued it further other than buying the amplified headphones with the mic.
 
Hello Wade yes i am quite able to run a soldering station - i have built many projects over the years - and have the capability of making circuit boards on CNC router -- a diagram would be great to have -
just as long as it contains components that i can source in Australia -- or get on E-bay
thank you for the offer
john mc

I will see if I can find the schematics and design files if I can in the meantime here is a link to some very good reference applicable to your problems by TI. TI has a very nice samples program so you can get many of their products delivered for free for testing purposes and prototyping.

Hope this helps,
 
I will see if I can find the schematics and design files if I can in the meantime here is a link to some very good reference applicable to your problems by TI. TI has a very nice samples program so you can get many of their products delivered for free for testing purposes and prototyping.

Hope this helps,

Hello again thanks for the link to TI sight - it was very interesting -- and the sample offer is also a great way of getting components -- when i get a circuit to follow i will get onto TI and see what they can supply
i have already got a supply of 120 Ohm strain gauges and have ordered some 100 to 1 Amps from Ebay so what i need now is a way to join it all togeather in a bridge -- and then read the results
regards john mc
 
Curious why periodic vibration monitoring equipment would not work. An accelerometer and some fast fourier transform would give you the waveform and that would give you vibration frequency as well as amplitude. You would experience a fast ring down but it could still be captured. I think the issue is direction movement. Most instrument are only reading movement in one plane accurately unless there are more than on sensor. I don't know if eddy current could be used or not . Just rambling.
 

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