Sheet metal Flange oddity

[salariua]

Edited: swapped acute/optuse in original post. (long day)

I can’t get my head around this one. I’ve tested 2015 and 2016 same results and I don’t think it’s right so hopefully one of you will set me straight and back to where I belong… 😛

In sheet metal if you use flange with orthogonal height datum and the angle is more than 90 (obtuse) then the measurement in the Height Extents is to the highest point on the flange but if the angle is less than 90 (acute) then it’s measured on the lowest point !

I believe that it should always be on the highest point. Now get me sorted please.

[jeanchile]

I am in total agreement with you from a design standpoint Adrian but I'm not a sheet metal fabricator. I've only used that option once in my IV career and I wanted the height to the absolute tallest point. Maybe someone who has some actual machine-time-bending-experience can shine a light on why AD did it this way. Maybe there is a reason the guys doing the bending "think" about it the way AD did it?

[CCarreiras]

It's always from the outside... as the image claims... the rest is... thickness...

[blair]

The same face for measuring, don't cross your faces.

[-niels-]

I agree with Carlos and Blair.

Imagine drawing it as a contour flange:

It depends on which side the thickness goes.

[salariua]

Thank you guys,

Logical explanation on measuring same point / face / termination but I can’t think of a case where I would need the lower point measurement. I am hoping one of you has, and is willing to share it because otherwise we would need to develop a formula for the height and it’s no fun.

One possible explanation would be that the workshop guys would grind the top edge making the top face parallel with the bottom flat face but not in all the cases, especially on large parts.

On half and quarter of a mm thickness it doesn’t even matter, it’s not sticking up enough to be considered but think about larger plate thickness, 10, 15, 20 mm and even bigger.  There have been situations where I had the bending line of the plate flared out red to help bending it and furthermore, we used the bevel gap for welding.

So in all my life I’ve always wanted the total height and not what’s easier to measure but I am curios if this was intended or just easier to program from AD.

[-niels-]

Adrian, i'm not sure if the (2016) file i've attached is clear enough but i've added 2 flanges with their settings a little different to compensate for the issue you reported.

It might be a bit annoying to remember how this works everytime you encounter these types of angles, but it should be as easy as subtracting the thickness from the desired distance and selecting the "bend from inner faces" height datum...

(having the "aligned vs orthogonal" enabled is also important.)

Hope this is of some use...

---edit---

Added a 2015 version file.

[salariua]

Don’t have 2016 at hand, will check later but this is what I end up doing:

The problem is that you need to change from formula to static value when the angle is over 90.

I guess I could use iLogic:

If angle > 90 then ...

[-niels-]

I added a 2015 file to my previous post, does that help any?
My method, with the change in height datum, probably wouldn't be very suited for iLogic though...
(and it still requires the "- Thickness" for the length)

[salariua]

I get what you’re saying now. Haven’t realised you attached 2015 as well.

You’re saying that for angles of less than 90 we should use the inside face option with Total Height – Thickness while for angles more than 90 we should use outside face option with Total Height.

I have changed your part to suit me (height of 10 total); see the attached please. Is this it?

We would still need to change this manually when angle goes from obtuse to acute but it’s better than my solution.

 Edit:

It seems Inventor measures to the extent of the face instead to the highest point of the flange so choose your face option inside/outside properly.

[-niels- · Accepted solution]

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@salariua wrote:

You’re saying that for angles of less than 90 we should use the inside face option with Total Height – Thickness while for angles more than 90 we should use outside face option with Total Height.

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I didn't take the total height into account, but yes.

Your file switches the height datum around to get the total height, so you got the idea. 😉

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@salariua wrote:

We would still need to change this manually when angle goes from obtuse to acute but it’s better than my solution.

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And that's the remaining problem, which i don't think can be solved with iLogic.

But how often does an existing flange change its angle that radically...

[salariua]

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@-niels- wrote:

But how often does an existing flange change its angle that radically...

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radically? switching from 89 to 91 wold be enough to mess it up.

this will do for me.

Thank you all.

[blair]

In Sheet-Metal, you are always dealing with the same face/surface for measurements. I understand from your picture you are mating the S-M part to a face and then require the overall height with the thickness for the assembly.

I can't think of a single application the would use this within an assembly but in S-M, it's always calculated this way. You always work off the same face/surface.

[salariua]

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@Anonymous wrote:

 I understand from your picture you are mating the S-M part to a face and then require the overall height with the thickness for the assembly.

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I just need the overall height of the part and I was hopping I don't need a formula or special setup but I am out of luck.