Inventor General

## Inventor General

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Message 1 of 27 (1,227 Views)

# Limits of an Inventor part or assembly?

1227 Views, 26 Replies
03-03-2010 05:25 AM
Hello, all -

Visiting from the AutoCAD side of things, I wondered if there was a limit to the size of an Inventor part or to the dimensional extents of an Inventor file?

Thanks,

-Bill
*Dennis Jeffrey
Message 2 of 27 (1,227 Views)

# Re: Limits of an Inventor part or assembly?

03-03-2010 07:35 AM in reply to: bill
AutoCAD is the only unitless CAD system in popular use. Because it is
unitless, there is no maximum distance.

3D Modelers are unit based, and mathematically there is a limit on
individual part sizes. The Inventor 2010 part I have attached is a 5
foot diameter cylinder with a length of 6400 feet. It fails to extrude
somewhere between 6400 and 6500 foot in length. This is a single part file.

Assembly files in Inventor do not have a distance limitation since
individual parts and subassemblies are merely linked, not calculated
within the assembly file.

Do you have a need to create single parts over 6400 feet? BTW, the Mass
of this part in mild steel is: 61661137.021 lbmass (Relative Error =
0.000000%).
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Message 3 of 27 (1,227 Views)

# Re: Limits of an Inventor part or assembly?

03-03-2010 07:42 AM in reply to: bill
>Because it is unitless, there is no maximum distance.

Actually the size limit or extreme distance from origin is well known problem in AutoCAD.

Here is info from Rhino - I have seen similar information for virtually all CAD programs I have used.

Rhino, like most CAD products, represents position in double-precision floating-point numbers. That means the x, y, or z coordinate of any point can have a value ranging from as large as ±10E308 to as small as ±10E-308. Most CAD software, including Rhino, uses double-precision floating-point arithmetic.
Because of the limitation of current computer technology, we expect calculations to be accurate to 15 digits of precision in a range from ±10E20 to ±10E-20. This limitation is found in all modern CAD products.

Older CAD products often have additional limitations because they were developed originally to run on computers with less precision. For example, many CAD modelers are designed for performing calculations on geometry that is restricted to be in a box of size 1000x1000x1000 meters centered at the origin. (Geek alert: Another of the popular off-the-shelf modeling kernels requires parameterizations that are within a factor of 10 of being arc-length parameterizations.) Rhino has none of the limitations found in these older products.

Jeff Howard covered this topic here a while back, but now I can't find the thread.
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Active Contributor
Posts: 35
Registered: ‎04-04-2007
Message 4 of 27 (1,227 Views)

# Re: Limits of an Inventor part or assembly?

03-03-2010 08:58 AM in reply to: bill
This is what I was wondering about -- just curious. No 1.2 mile long single parts in my immediate future! Thanks to all.
*Igor Mironenko
Message 5 of 27 (1,227 Views)

# Re: Limits of an Inventor part or assembly?

03-03-2010 10:21 PM in reply to: bill
Here is an AutoCAD file which shows our Solar system in 1:1 scale. If you
zoom close onto the Moon you will see the lunar module over there plus a
memorial plate left by the astronauts.
The file was created years ago to demonstrate AutoCAD zooming capabilities.
BTW, using AutCAD since R12 it is the first time I hear that there is a
"well known problem in AutoCAD" with parts size or extreme distances.
Regards,
Igor.
Web: www.meqc.com.au
www.boatworks.meqc.com.au

----- Original Message -----
From:
Newsgroups: autodesk.inventor
Sent: Thursday, March 04, 2010 12:04 AM
Subject: Re: Limits of an Inventor part or assembly?

>Because it is unitless, there is no maximum distance.

Actually the size limit or extreme distance from origin is well known
*Dennis Jeffrey
Message 6 of 27 (1,227 Views)

# Re: Limits of an Inventor part or assembly?

03-04-2010 05:48 AM in reply to: bill
I agree.

Actually, AutoCAD is the only CAD system that can handle angstroms to
parsecs in measurement.
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Message 7 of 27 (1,227 Views)

# Re: Limits of an Inventor part or assembly?

03-04-2010 06:10 AM in reply to: bill
>the first time I hear that there is a "well known problem in AutoCAD" with parts size or extreme distances.

Guess I'll do some research for you and post links to numerous sources and proofs when I get a chance - check back for the urls in a couple of days.
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Message 8 of 27 (1,227 Views)

# Re: Limits of an Inventor part or assembly?

03-04-2010 10:42 AM in reply to: bill
The maximum size of an Inventor part model (only part) is bounded by a cube of 10000cm X10000cm X 10000cm. When a solid body exceeds the boundary, the modeling commands will behave unpredictably.
For assembly, there is no internal size limit on how big an assembly can be. However, it is restricted by hardware (memory, CPU) and OS (maximum floating number allowed).
Thanks!

johnson.shiue@autodesk.com

Johnson Shiue (johnson.shiue@autodesk.com)
Principal SQA Engineer, Inventor
Mechanical Design
Autodesk, Inc.

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Message 9 of 27 (1,227 Views)

# Re: Limits of an Inventor part or assembly?

03-04-2010 04:26 PM in reply to: bill
>Here is an AutoCAD file which shows our Solar system in 1:1 scale.

I believe there are a few known tricks to get around the problem. Scaling, inserting....

Here is an interesting read. I'll post more examples as I have time to find.

>" Of course by simply moving this object temporarily closer to the origin of 0,0 the offset works perfectly because less digits are used in this calculation and no rounding issues. "

The other examples I will reveal deal with 3D solids editing problems - can't add fillet or can't shell, that sort of thing.
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*Igor Mironenko
Message 10 of 27 (1,227 Views)

# Re: Limits of an Inventor part or assembly?

03-04-2010 04:37 PM in reply to: bill
It is funny that you jump into such topic head on but when I asked a real
Inventor question you were nowhere near to see.
Regards,
Igor.

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www.boatworks.meqc.com.au
wrote in message news:6348571@discussion.autodesk.com...
>the first time I hear that there is a "well known problem in AutoCAD" with
>parts size or extreme distances.

Guess I'll do some research for you and post links to numerous sources and
proofs when I get a chance - check back for the urls in a couple of days.

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