Very weird - Dimensions in sheet metal component cuts different when flat vs folded...

[whf]

I'm not sure what's going on with this part, but it is very disturbing.

The circular cuts are different dimensions when the part is folded as opposed to when the part is flat. When the part is flat, the dimensions are correct. When it's folded, they are off by 1/4" and 1/8" respectively....not even the same amount so it makes no sense. These cuts should not be affected by stretching/compression due to the bends.

Note that the cuts are tapered and are made by sculpting out a cone while the part is folded. So there are 4 total diameters. ...or actually 8 different diameters, 4 for the flat pattern and 4 others for the folded.

Any assistance is very appreciated. This is very troubling to me as I would expect to be able to trust the 3d model but it appears to be wrong.

Best Regards, Bill

[brendan.henderson]

Hi Bill.

I'm thinking you are getting confused by each hole having 2 radii, an inner and an outer because of the taper. I put your part into an IDW in both folded and flat views and dimensioned both the inner and outer half circles and they all appear correct. See attached PDF.

Hope this helps.

BrendanH

[whf]

Hi Brendan,

Thanks very much for your reply and for spending time with my part.

Unfortunately no, I wasn't confused on the multiple diameters due to the tapers.....which is why I added "Note that the cuts are tapered and are made by sculpting out a cone while the part is folded. So there are 4 total diameters.." Though I should have said that there SHOULD be 4 diameters, however there are 8.

It is the measure tool that is giving different measurements for flat vs folded part. Using the measure tool within the part model itself (the inventor analog to dist in acad, on the actual part, in 'model space' if you will) it does in fact give a different value for each of those 4 measurements in flat vs folded.

Dimensioning is a whole different animal and when sheeted the model is referenced in a different way. Yes, the sheet you made shows a total of 4 different values for the given radii both as a flat and folded part when it is sheeted out. But if you use the measure tool on the folded part itself then you'll get a new set of 4 different values for those 4 radii.

So I still have this huge problem.....which is a make-or-break issue for me regarding continued use of Inventor...

Best Regards, Bill

[brendan.henderson]

Bill, I'm not seeing (measuring) what you are seeing.

With the model and in both folded and flat pattern I measure all of the radii the same. 4 hole sets are the same R1.1081" outside/R1.1143" inside & R1.2845" inside/R1.2907" outside and the 5th hole (not a hole in folded but is in flat?) is R1.1816" outside/R1.1878" inside & R1.3574" inside/R1.3636" outside. I turned dual units on and set the measure tool precision at the whole range of options and I'm not seeing any change at all and certainly not in the order of 1/8 to 1/4"!

Don't think I can help any more but am willing if you can identify anything else.

[whf]

Hi Brendan,

Ah, you did in fact figure it out for me! Thank you very much. It appears I was regularly measuring the one bad hole while in model and one of the others in flat. Although it's only served to highlight another problem..

I don't know why that 5th hole is different as all were created the same way. So I ripped the assembly apart and recreated it, reconstraining everything. Same thing...only now there are different holes that are like this....the entities doing the sculpting are all copies of one another so I'm at a loss.

I'll play with it more when I have a chance and post what I find in case anyone else comes across this issue. Thanks again!

Best Regards, Bill

PS, thanks for making mine your first posting!