Coordinate based model challenge

[AnthonyC]

Hello all,

i am having a hard time trying to model a part based off the measurement report that we have gotten and i am wondering what i am doing wrong or how to more accurately model the part. 

when i try to use a sweep function, i find that one or more corners (depending on if it has 3 or 4 faces) tend to be slightly off. is there a different function i can use to force creo to make a body that fits within the coordinate boundaries? the surfaces should be flat .

CREO Parametric 6.0.6.0

[MartinHanak]

Hi,

I think that coordinates included in Excel file are wrong.

See ITEM1 (for example)

S5-S8 points have Z=0 ... this means they lie in a plane (let's call her PLANE 1)

S5 -3,6244 16,3355 0
S6 8,5455 45,5814 0
S7 58,309 0 0
S8 0 0 0

S1-S4 points do not have the same Z value ... this means they do no lay in a plane parallel with PLANE 1

S1 -3,6151 16,3385 -50,0018
S2 8,5564 45,5903 -50,0067
S3 58,322 0,007 -50,017
S4 0,0088 0,007 -50,0018

Also:

S1-4(X) <> S5-8(X)

S1-4(Y) <> S5-8(Y)

This probably means that points does not belong to planar faces.

[kdirth]

I agree with @MartinHanak that the points in your spreadsheet do not create planer surfaces.  This may be due to rounding errors in creating the point values.  If I create a datum plane from 3 points on a side, the 4th point is not on that plane except for the surfaces with all Z locations 0.

[kdirth]

To create the shapes that match all of the points you need to create curves between the points and use boundary blends to create the sides.

[MartinHanak]

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@kdirth wrote:

To create the shapes that match all of the points you need to create curves between the points and use boundary blends to create the sides.

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... just it is necessary to take into account that in most cases the surfaces will not be planar ...

[AnthonyC]

yes, so the part was laid flat on surface S5-S8 and the opposite face was measured against it.

this would mean that only face S5-S8 is planar and flat as all other faces will have a high/ low point against the measurement report.

i am aiming to make the part as close to reality as possible. ill have a think about what would be the most appropriate approach.

thanks very much for the inputs

[MartinHanak]

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@AnthonyC wrote:

yes, so the part was laid flat on surface S5-S8 and the opposite face was measured against it.

this would mean that only face S5-S8 is planar and flat as all other faces will have a high/ low point against the measurement report.

i am aiming to make the part as close to reality as possible. ill have a think about what would be the most appropriate approach.

thanks very much for the inputs

---

Hi,

in case of ITEM1, you can create Creo model in two steps:

1. create datum points using S5-S8 coordinates
2. create Extrude feature
   • when creating section of this feature, you can use datum points as references

[tbraxton]

Assuming that you want to model these with planar faces, I would suggest that you specify a datum reference frame based on how the parts were inspected. Once you have this you can use an algorithm to get the best fit equation of a plane to define the faces of the parts using the measured points relative to the datum reference frame. You will need to decide what algorithm to use for fitting the planes to the coordinates.

[anursingh]

Hi @AnthonyC,

I wanted to see if you got the help you needed.

If so, please mark the appropriate reply as the Accepted Solution. It will help other members who may have the same question.
Of course, if you have more to share on your issue, please pursue the conversation. 

Thanks,
Anurag