Cero external merge fails when merged file made with different units

[BK_9693158]

When unsung Merge/Inheritance to merge a part file (raw material file) into another file (machined part file) I am getting failures with the scaling of the parts. This only happens when the files are made using different units of measurement i.e. the part file being merged is mm and the part file that is being worked on is inches. 

What seems to be happening is a part made in metric being merged into an inch file has a scale that is 25.4 times the intended size because Creo isn't making the unit conversion and instead bring in the mm units unscaled into the inch file and vice-versa. 

This issue can somewhat go away when toggling between Merge/Inheritance but that will bring in the design tree which isn't ideal. 

We cant make them the same units of measure since the prints need to be in there respective units for documentation/customer reasons. 

Edit: using Creo 9

Edit 2: When changing the units in either model to match the part end up working fine, so there is something not connecting when scaling the units from a part file to a merge file.

[tbraxton]

I suspect this is an accuracy issue and not a unit issue. When using data sharing features the absolute accuracy of source and target models should be matched. Do you have the absolute accuracy set for both parts and if so, what are the values?

What version of Creo are you using?

Are you using start parts for either part?

[BK_9693158]

I am using is Creo 9. When I changed the accuracy from relative to Absolute on both models the issue did not go away.  When setting the absolute accuracy equal to each other that did not change anything, 

Edit: This issue was also present on Creo 7 and we are using start parts when making these.

[tbraxton]

"When setting the absolute accuracy equal to each other that did not change anything, "

This may seem an odd question, but it is important here.

Absolute accuracy has units of length so .001 mm is not equivalent to .001 inches. Can you verify the actual values of each model are equal?

[BK_9693158]

Yes, I did do the conversion from .001 inches on the inch model to .0254 mm on the mertic model. to clarify, the model imports and the merge itself isn't failing when the model has the correct absolute accuracy (it will fail when the metric and inch absolute values are not converted). It will however merge in a feature that is suppose to be 10mm in length as 10 inches in length rather than .3937 inches. 

[tbraxton]

I just did a quick test in Creo 7.0.9 and it is working as expected.

My source model is in units of mm with 0.001 mm accuracy. The target model is in inches with 0.0000393701 inch accuracy. The target model regenerates and the measured bounds of the model match that of the source model in size (both are the same scale).

It appears to behave exactly the same as doing this with the source and target models both in units of mm.

[BK_9693158]

I just retested. I ordinally put a value that apparently just didn't work at all rather just not matching. However, after experimenting with this a little i did find that when I recreated the Raw material file in a new part file (this raw material file was made in an much older version of Creo circa 2013) that this issue is not happening. so it is something in the model properties or start part properties that is not connecting. 

Any help in what the issue could be with the older file is still appreciated.

[tbraxton]

Can you post the older start part here?

[BK_9693158]

I think I may have figured it out (or at least fixed it on these parts). There were some features that created sharp points that when creo was trying to convert from metric to inch it was lower than the accuracy thus creating some problems.

this was fixed by redoing revolves that snapped to a corner then changing it to go through that point if that makes since. and rounds/fillets had to be redone to eliminate sharp points at any point in its construction.