# Not sure how to go about measuring this part

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#### echoone

I did not see an official introduction thread that I should have introduced myself prior to asking my 1st of many questions. If there is my apologies in advance. At the company that I work at, they have done a recent rev change to a part that we have made for sometime with little or no GD&T on the print.

I have attached a sketch of the part to this thread. My question is how do I go about measure the position of 6 radial holes that are on a 60° basic angle using only a vision system? I may be just over thinking this one today. In the past all that they wanted was the location from datum and how far off of center was the drilled hole.

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• position question.pdf
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#### Fredrik001

##### Registered
I think the best way to measure, using a vision system, is to fit measuring pins (gages) in the holes.
Since the pins (gages) are calibrated (known Ø), you can receive both the angle between the holes and the height from datum B.

#### dsanabria

##### Quite Involved in Discussions
I think the best way to measure, using a vision system, is to fit measuring pins (gages) in the holes.
Since the pins (gages) are calibrated (known Ø), you can receive both the angle between the holes and the height from datum B.

Totally agree - in addition, place the maximum size of plug gauges into holes (Dia.) and find the center of the plug gauge - but stay as close to the outside diameter of the part. The next step is to do the same but from the inside of the part. This could give you additional information about the position of the holes.

#### Michael_M

Trusted Information Resource
Not sure if this is also part of your question but to calculate the true position takes a bit of math. You will know the error of .216 easy enough however, to caculate the error of the 60 degree angle you will need the following information:

What is the actual angle at (we will say 59.9 degrees for our example)
What is the OD of the Part (we will say 2.000 for our example)

Now you have to calculate the error based on 59.9 degrees at 1.00 long (1/2 diameter) or Error=(1.000*sin60)-(1.000*sin59.9). Note, I have always used the 1.000 as the hypotenuse of the triangle.

the math with actual numbers:

error= (1.000*.86602)-(1.000*.86515) or error = .00087. Note as the diameter gets bigger, .1 degree makes the error higher (longer distances).

#### dsanabria

##### Quite Involved in Discussions
Not sure if this is also part of your question but to calculate the true position takes a bit of math. You will know the error of .216 easy enough however, to caculate the error of the 60 degree angle you will need the following information:

What is the actual angle at (we will say 59.9 degrees for our example)
What is the OD of the Part (we will say 2.000 for our example)

Now you have to calculate the error based on 59.9 degrees at 1.00 long (1/2 diameter) or Error=(1.000*sin60)-(1.000*sin59.9). Note, I have always used the 1.000 as the hypotenuse of the triangle.

the math with actual numbers:

error= (1.000*.86602)-(1.000*.86515) or error = .00087. Note as the diameter gets bigger, .1 degree makes the error higher (longer distances).

Great math lesson that newbies don't know or realized or .... because the older generation did not want to share.

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#### echoone

I always seem to leave a little bit out of the question or comment that I post. What I should have asked was how to calculate the true position. I will check out what Michael had to say. Thanks again for the help

#### howste

##### Thaumaturge
Trusted Information Resource
I did not see an official introduction thread that I should have introduced myself prior to asking my 1st of many questions. If there is my apologies in advance. At the company that I work at, they have done a recent rev change to a part that we have made for sometime with little or no GD&T on the print.

I have attached a sketch of the part to this thread. My question is how do I go about measure the position of 6 radial holes that are on a 60° basic angle using only a vision system? I may be just over thinking this one today. In the past all that they wanted was the location from datum and how far off of center was the drilled hole.

Welcome to the Cove Forums. I don't know that I can add anything more than what's been said above, but here's our introductions thread if you'd like to use it.

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#### echoone

Not sure if this is also part of your question but to calculate the true position takes a bit of math. You will know the error of .216 easy enough however, to caculate the error of the 60 degree angle you will need the following information:

What is the actual angle at (we will say 59.9 degrees for our example)
What is the OD of the Part (we will say 2.000 for our example)

Now you have to calculate the error based on 59.9 degrees at 1.00 long (1/2 diameter) or Error=(1.000*sin60)-(1.000*sin59.9). Note, I have always used the 1.000 as the hypotenuse of the triangle.

the math with actual numbers:

error= (1.000*.86602)-(1.000*.86515) or error = .00087. Note as the diameter gets bigger, .1 degree makes the error higher (longer distances).

Thanks for the help. Once I know the error for both the 60° basic as well as the .216 basic I just plug it into the formula for position POSITION=2*SQRT(X^2 + Y^2)