Establish a plain from highest points

[[K...]]

Can someone kindly help me with following question:

How can I establish a plain from five highest points which are chosen from 20 defined points?

Thank you

[[SH...]]

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Option one: setting evaluation as outertangential, in the evaluation window.

Option two: check the coordinate value of each points and select the maximum highest points for creating plane.

[[Is...]]

There should be many ways to do it,
Here you have one idea (Bubble Sort):

numberofpoints=20
for i=1 to numberofpoints 
Points[i]=getActual("Point"+i).z
Point[i]=i
next i

for i=1 to numberofpoints 
    for n = i + 1 to numberofpoints
      if Points[n] > Points[i] then
        Temp = Points[n]
        Points[n] = Points[i]
        Points[i] = Temp
	 Temp = Point[n]
        Point[n] = Point[i]
        Point[i] = Temp
     endif
next n
next i

for i=1 to numberofpoints 
display(formatL(Points[i],0,4) + "  " +  Point[i])
next i

20points.7z

[[SH...]]

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This is using PCM??

[[Is...]]

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Yes...

[[K...]]

Thank you Israel / Shabu:

I am not comfortable in PCM but I understand the basics

As I understand this code will simply order the list of 20 points in descending order, the last for loop is just to output the top five values of the list.

Where / how can I apply this code.


Thank you,

[[Is...]]

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In that example the PCM code is the presetting of the Text element:
(You can put it in the pre/post-settings of any characteristic or feature executed before the Plane and the Theoretical points.)

[[Mi...]]

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Nifty, but is this better than using an OTE evaluation like Shabu suggested?

[[Is...]]

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Who knows, I don't know anything about the inspection purpose. I just found it interesting..

[[Mi...]]

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Actually, I guess OTE would just use the 3 highest points. If he wants, say, LSQ of 5 point, he'd have to have some way to sort or filter them like you said.

[[K...]]

Hi guys:
I haven't tried but Israel understand my requirement. I appreciate Shabu's suggestion but it's not meeting my requirements.

Surface is uneven ( flatness is 0.500 mm) and within ”Ø120 to Ø135 zone.

Customer want parallelism from highest points.

I hits 20 places, don't know which points are at highest level.

I think we must have to use PCM option in order to pick five or more points from those 20 points for defined plain during execution.

[[SH...]]

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If you have pcm , then it would be the best way...

[[Da...]]

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How does this looks like on the drawing?
Or is it only verbally communicated to you?
Which standard is the drawing to?

[[K...]]

Please see attached picture:

Parallelism.PNG

[[Jo...]]

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Wouldn't that mean Outer Tangential ? It would simulate surface plate or maximum condition.

[[Me...]]

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Exactly. If you use more than 3 points you aren't fulfilling the requirement of the drawing. You would be doing some sort of fitting to average them out, not using the highest points. Outer tangential plane is the way to go.

[[Me...]]

If intent of the drawing requirement is for the tangent plane fall within the specified tolerance zones, then as other have stated, you would evaluate the plane as an outer tangential element. However, the plane cannot be directly entered into a position or parallelism characteristic. The reason for this is that each characteristic will automatically include the form error in the result. For evaluation, you will need to recall the measured outer tangential plane into a new feature via “Recall One Feature”. This will allow each characteristic to only evaluate the location / orientation of the associated feature.

[[Me...]]

Excellent information, Phillip!

[[Da...]]

Great answers people!

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Zack, as others suggested the drawing indicates the OT feature to be tolerated.
Since such situation is clearly indicated in ISO 1101:2017 you can suggest designer to change it to:
|TP|0.5(T)|B|
|Parall.|0.3(T)|B|

(T) is capital T in circle

I can't say for sure, but I assume there is such thing allowed in ASME too.

[[Da...]]

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Again, it looks like they want it for both parallelism and TP.

[[Da...]]

Zack, I assume your situation is similar to this:
I haven't fully tested, but be careful, it could get tricky. As Phillip pointed out, this would be an associated tangential feature and evaluation of TP will throw out number from one of the 4 corners.
Again, haven't tested but I assume Calypso will pull orientation for this tangential plane from Base Alignment. Some kind of "manual best-fit" (with PCM), would get handy.
I hope I make some sense and someone can confirm this.

[[SH...]]

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New knowledge...

[[Me...]]

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You are correct.
In your example, the four corners will be used in both evaluation types.

[[Jo...]]

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I don't understand this. If you right click evaluation within that characteristic, you can select OT method. Why the recall ?

[[Me...]]

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Because, in order to evaluate the orientation / location of just the tangential plane, you must remove the form error. To illustrate, open a parallelism characteristic that has measured data and change the fitting method. You’ll notice that the actual value will not change regardless of the fitting routine selected. The reason for this is that the default behavior of the characteristic is to evaluate the measured points instead of the associated feature.