# need to build a system to measure pull.

#### joewales44

Joined Oct 8, 2017
150
need to instantaneously measure pull from 0 to 10 ounces and record the amount of pull on graph or have some way to see it.
pull will come and go in as quick as 0.1 second.
anybody seen anything like this or know how to build it?
thanks

#### joewales44

Joined Oct 8, 2017
150
would i have to use an oscilloscope to capture readings this quick?

Joined Jan 15, 2015
6,684
Number of ways to go about it. 0 to 10 ounces is pretty light I would likely start with a 1.0 Lb load cell, maybe an S beam type or a tension / compression type to be used in tension. Inexpensive to expensive depending on your desired uncertainty. You could also look in Grams for a 500 gram version. Here is an example of an inexpensive 500 gram (just a little over 1 Lb). Next I would provide a stable excitation and run the output into an A/D converter. Again depending on what you want to spend and what uncertainty. I would buy something like this if you want inexpensive. You can even go much less costly. The merit to this and similar starter kits is they will take a low input mV signal from a load cell and amplify it. They also come with software which you can setup to chart your data however you wish. The software will record a file you can save and playback. You can also very easily scale the software to the engineering units of your choice, in your case ounces of tension.

Since you mention 0.1 second you really want a load cell and A/D converter with a fast sample rate. Again, depends on what you want to spend on a system. I was fortunate in that I worked for a company with deep pockets. The link I gave you, running a single channel, will give a 2 KHz sample rate or 2,000 samples / second which gives you 200 samples in 0.1 second. I can tell you how to spend $200 to over$2,000 on a project like this depending on what you want as to uncertainty in your measurement plane.

Ron

Joined Jan 15, 2015
6,684
would i have to use an oscilloscope to capture readings this quick?
No, just a fast A/D and a means to record your data. Also, depending on your location there are a dozen vendors of what I suggested.

Ron

#### Hymie

Joined Mar 30, 2018
1,082
The easiest way to see the response of the device is to use a scope.

Joined Mar 10, 2018
4,057
You could certainly do a SAR or DelSig A/D approach, and simple LCD display to capture
the max pull exerted. Additional code could yield other statistics.

Even some filtering could be applied to reject

And UART or USB into a Python program to plot, plenty of libraries out here.

Something like this, attached. Note shows DelSig single ended, can be configed
for differential with gain. DelSig fast enough at 16 bits to oversample the pull
event I would posit (because your system has a measurable amount of inertia in it....?).

Regards. Dana.

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Joined Jan 15, 2015
6,684
need to instantaneously measure pull from 0 to 10 ounces and record the amount of pull on graph or have some way to see it.
pull will come and go in as quick as 0.1 second.
anybody seen anything like this or know how to build it?
thanks
Would this be a one time test or do you plan on measuring many times for something like product testing? Do you plan on building the fixture to hold whatever it is you are looking to test?
I also see a scope as a viable solution. Again, just a matter of what you want and measured to what uncertainty?

Ron

#### joewales44

Joined Oct 8, 2017
150
long term product testing.
i want a real time display like a scope has.
guess a cheap scope is the way to go?
guess i need a complete strain gauge that converts resistance to voltage?
i'm very electronically challenged so i will need a unit that comes with good instructions.
most of the cells i see are for push load. i must have pull load and any kind of mechanism to convert push to pull will slow reaction and could vary the force.
maybe i just haven't found a pull type?
thanks

Joined Jan 15, 2015
6,684
most of the cells i see are for push load. i must have pull load and any kind of mechanism to convert push to pull will slow reaction and could vary the force.
maybe i just haven't found a pull type?
While you can say push and pull you will do better using the terms I mentioned earlier like tension and compression and you want tension. Some do both but tension would be what you want. Also, you may see ounces, pounds, Kg or grams and either is easy enough to convert. I would also suggest as close to a turn key solution as possible since you mentioned being electronically challenged. Additionally either a scope or the A/D converters I mentioned will afford a real time display and store the data.

Ron

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#### joewales44

Joined Oct 8, 2017
150
While you can say push and pull you will do better using the terms I mentioned earlier like tension and compression and you want tension. Some do both but tension would be what you want. Also, you may see ounces, pounds, Kg or grams and either is easy enough to convert. I would also suggest as close to a turn key solution as possible since you mentioned being electronically challenged. Additionally either a scope or the A/D converters I mentioned will afford a real time display and store the data.

Ron
you sound like an expert with strain gauges.
i'm not lazy, just stupid in this area.
grams or ounces will be ok. pounds wouldn't show accurate enough since my range will probably stay below 3 ounces.
please, could you point to a device?
i could look for days and still not know if i'm getting the right one?
thanks

Joined Jan 15, 2015
6,684
need to instantaneously measure pull from 0 to 10 ounces and record the amount of pull on graph or have some way to see it.
That's why I focused on 1.0 Lb or 16 ounces or about 500 grams which is about 1.1 Lb.So OK if we drop down to:
grams or ounces will be ok. pounds wouldn't show accurate enough since my range will probably stay below 3 ounces.
please, could you point to a device?