Frame Generator parts have incorrect diameter

[wrw0007]

I am currently working on an assembly using frame generator with about 200 pipes made with frame generator and the OD of the pipes is showing the incorrect size.

In my specific case, I am using 2 1/2" Schedule 160 pipe. The actual chart value of the OD of such pipe is 2.875" (2 7/8"), but frame generator models it using 2.88".... Clearly a case of rounding to 2 decimals. In most cases this would be negligible, but in my case I have a model that needs to have these pipes extremely close. Practically touching in my model, and actually touching in real world application due to tolerances. In my case I need a center to center distance of 2.879, which would normally leave a very small clearance, but being that FG models it at 2.88, it actually creates a .001" interference. This causes my drawing views to need "interference edges" visable, but I cannot dimension those.

Is there a way to change all of my frame generated pipes to have an exact 2.875" Outside diameter so that I can properly dimension them?

Not sure why Autodesk would allow rounding to only 2 decimals in their created parts as it has a possibility to create such errors and does also affect mass and other properties. Probably just overlooked.

Any help is appreciated.

[cbenner]

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@wrw0007 wrote:

I am currently working on an assembly using frame generator with about 200 pipes made with frame generator and the OD of the pipes is showing the incorrect size.

In my specific case, I am using 2 1/2" Schedule 160 pipe. The actual chart value of the OD of such pipe is 2.875" (2 7/8"), but frame generator models it using 2.88".... Clearly a case of rounding to 2 decimals. In most cases this would be negligible, but in my case I have a model that needs to have these pipes extremely close. Practically touching in my model, and actually touching in real world application due to tolerances. In my case I need a center to center distance of 2.879, which would normally leave a very small clearance, but being that FG models it at 2.88, it actually creates a .001" interference. This causes my drawing views to need "interference edges" visable, but I cannot dimension those.

Is there a way to change all of my frame generated pipes to have an exact 2.875" Outside diameter so that I can properly dimension them?

Not sure why Autodesk would allow rounding to only 2 decimals in their created parts as it has a possibility to create such errors and does also affect mass and other properties. Probably just overlooked.

Any help is appreciated.

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@wrw0007  How are you obtaining the 2.88 diameter?

[wrw0007]

After creating a centerline skeleton, generating a frame on it using ANSI ASTM - Pipe, 2 1/2 x 0.276 (which is actually schedule 80 my mistake in original post), I then use the measure tool to check the diameter and it is 2.8800000000000000

[cbenner]

@wrw0007  Wow...I was kind of hoping you would say you only checked it to 2 decimals. 

This sounds like a real issue.  And if the CC table is set to the right dimension, there's nothing you can do there.  Must be a pre-set accuracy built into FG?  Let's ask some experts:  @johnsonshiue @ChrisMitchell01??

[Mark.Lancaster]

@wrw0007

Family table data shows it as 2 plc decimals.   Since all of your frame generator parts are custom you can open and change them individually.  Just make sure to change the browser view from Frame Generator to Model.  If you want to change the actual CC stuff you'll will need to create your own custom read/write CC library and copy the existing stuff over to it.

I don't know your design but if you are working that close together with pipe distance, I would think you would have more issues with the real world pipe being true at 2.875 along the entire length and not be concerned about a round pipe diameter in Inventor.  

[swalton]

I could not find any Diameter or straightness tolerances for pipe on the web.

How much inspection and material rejection will be required to find 200 lengths of pipe that fit these design constraints?

Ryerson lists 3" OD x 11/32 wall tube which could be turned/ground with a 2.879 od shoulder at each end and 2.875 od body. That should give a similar ID to 2 1/2" schd 80 pipe.

[wrw0007]

"I don't know your design but if you are working that close together with pipe distance, I would think you would have more issues with the real world pipe being true at 2.875 along the entire length and not be concerned about a round pipe diameter in Inventor"
That is absolutely true and I am aware of this. That is one of the benefits to having our fabrication shop attached to our office. I have used a micrometer to check many actual pipe diameters and have not yet found one to be a true 2.875. In most cases they are at the high end. Typically we allow for about a 1mm gap between pipes which works out well, however this is a special case and is not the first. This is merely the first that I've tried to do it with frame generator. In these special cases the pipes are cleaned of any paint, rust, etc and ground to a usable width. It is a royal pain, but there are times in which it is necessary like this one.

"Family table data shows it as 2 plc decimals.   Since all of your frame generator parts are custom you can open and change them individually.  Just make sure to change the browser view from Frame Generator to Model.  If you want to change the actual CC stuff you'll will need to create your own custom read/write CC library and copy the existing stuff over to it."

Such a shame that they would not use real nominal values and would only use 2 decimals. As mentioned I have around 200 pipes generated. Changing diameters one by one is not going to happen. Unfortunately, my 200 pipes means i have about 400 constraints already placed and authoring a custom pipe will result in all of those constraints breaking, unless I can author it and then use the "change with frame generator" option to replace all of the pipes.

I will go that route and post my results.

[wrw0007]

i do not currently have the tolerance in front of me, but they can be found. I know we have multiple reference materials here that show it. Looking under Ansi A106 gr B (extruded seamless steel pipe) would probably ease your search.

We will not be demanding perfect Ø2.87500000" pipe. We are a custom fab shop and can work with standard pipe and tolerance in the real world. 

The point of the thread is to show that frame generator uses inaccurate values and to ask if there was a way to modify it to the correct nominal value.

[johnsonshiue]

Hi! I am sorry I am a bit lost with the issue. If the geometry is set to 2.5", it should be 2.5". The body geometry is accurate up to 0.00001mm. I am not aware of a workflow leading to deviation from the accuracy. Display precision is a different matter though. It would obey the unit settings in Document Settings or the display option in Measure tool. I need to see an example of what you are talking about.

Many thanks!

[Mark.Lancaster]

@johnsonshiue

The information within the structural content center appears to be in 2 place decimals.  So a 2 1/2 in pipe has a OD of 2.875.  In the actual piping CC information, the OD is listed as 2.875 but round/hollow pipe or tubing in the structural section, the OD is listed as 2.88.

[salariua]

@wrw0007

I can't replicate this.

I had to hunt down and find the family first but I am assuming you are referring to "ASTM A 53/A 53M Pipe".

My content center shows it as 2.875 and generated members have 2.875 both by measurement as in parameters.

Could it be that you have 2 digits precision in you measure tool?

Have you actually opened a member and checked the sketch dimension and parameters?

[salariua]

Please ignore my previous message....

So it seems I was looking at the wrong family. Your "Schedule 160 pipe" sent me on the wrong path.

You are correct, structural shapes have 2 digits precision but you can overcome this by copying the family over to your custom library. I did a test and it generates correct diameters.

You can copy the correct sizes from "ASTM A 53/A 53M Pipe" if you don't have time to manually change every size.

On a separate note, you can update all your already generate members by creating a parameters export xml and importing it to all the members and you can do this really quick with iLogic for all the components in the assembly.

Since I am a metric guy I don't know if your generated files have imperial or metric units but you can use the attached xml to import just "Diam" or "G_H" (confirm your family exactly for us) parameter to all your files.

Come to think about it, you can change the parameters directly without needing to import any xml....

Run this code from the assembly, it should process all parts no matter how deep down the browser tree:

(this uses "Diam", change it to "G_H" if that's your case)

' Set a reference to the assembly component definintion
Dim oAsmCompDef As AssemblyComponentDefinition
oAsmCompDef = ThisApplication.ActiveDocument.ComponentDefinition


' Get the occurrences that represent this document.
Dim oOccs As ComponentOccurrencesEnumerator
oOccs = oAsmCompDef.Occurrences.AllLeafOccurrences

' Iterate through all occurrences
Dim oOcc As ComponentOccurrence
For Each oOcc In oOccs'oAsmCompDef.Occurrences
	Try
		Parameter(oOcc.Name,"Diam") = 73.025
	Catch
		'MsgBox(oOcc.Name & vbLf & ": Parameter 'Dia' not found.")
	End Try
Next

I have attached the xml anyway...