Inventor General

## Inventor General

Valued Mentor
Posts: 475
Registered: ‎07-25-2012
Message 1 of 9 (1,594 Views)

# Sheet Metal Door - Inventor vs General Rule of Thumb Method

1594 Views, 8 Replies
09-14-2012 11:31 AM

A simple sheet metal door, 1/8 mild steel, 60"x32" with 1" on all 4 sides. I worked in a fab shop and we had customers literally walk up and ask for this door and other sheet metal components like gaurds etc etc., with no prints or drawings and we had no issues creating these parts within a tolerance of 1/16 or less. Rule of thumb was to subtract the material thickness from each break and break the flanges by subtracting the material thickness from length. So a blank for this door would be 61.5"x33.5" with 4 knotches in the corner 7/8"x7/8".walk over the break press and bend the lips up at the 7/8" and final output would be a door 60"x32" with a 1" lip all around, weld the corner seams together, buff up nice and voila.

Now I am using inventor professional 2012 to create this door, and my blanks are calculated to "crazy" value of 61.62x33.62 and my knotches have to be something like .90 inches. I understand that this has to do with the input of the bend radius and the kfactor, but for such a simple part that doesnt need to be that toleranced, how can I set up my bends to give me something in my 1st paragraph? I have been playing with the settings but can't seem to get a close enough result.

My work around so far has been using the override function while dimensioning in the drawing, but I know this is wrong and am going to pay for it soon.

I guess my question is how can I provide my fabricator with a drawing for him to cut out a "regular" size blank of 61.5"x31.5" and knotch corners 7/8" which I know will produce the door that I need within tolerance, instead of the inventor one 61.62"x31.62 and knotch corners .90 "?

Attached is part file of the door.

I have thick skin, so lay it on me! Haha

Sean Farr
Product Designer at TESInc.ca

Inventor Professional 2014-Update 2 - AutoCAD Electrical 2014
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Posts: 1,946
Registered: ‎05-18-2011
Message 2 of 9 (1,586 Views)

# Re: Sheet Metal Door - Inventor vs General Rule of Thumb Method

09-14-2012 11:50 AM in reply to: SeanFarr

1st off you need to set your styles so it will keep your bend dedutions for each sheet metal thickness.

but for the door you are making change the kfactor to .136 and this will give you the flat pattern you want.

James Letcher
2012 Factory Design Suite ( will not load 2013)
What happen to my Inventor :-(
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Registered: ‎05-18-2011
Message 3 of 9 (1,581 Views)

# Re: Sheet Metal Door - Inventor vs General Rule of Thumb Method

09-14-2012 11:55 AM in reply to: SeanFarr

James Letcher
2012 Factory Design Suite ( will not load 2013)
What happen to my Inventor :-(
Valued Mentor
Posts: 475
Registered: ‎07-25-2012
Message 4 of 9 (1,579 Views)

# Re: Sheet Metal Door - Inventor vs General Rule of Thumb Method

09-14-2012 11:57 AM in reply to: jletcher

Would it be too much to ask how you came up with that value??

The results are exact!!

Thanks

Sean Farr
Product Designer at TESInc.ca

Inventor Professional 2014-Update 2 - AutoCAD Electrical 2014
Win7-x64 | ASUS P8Z77-V | i7 3770 -3.4 GHz | 32GB RAM |
240GB SSD | nVidia GTX 670 4GB - 320.49
*Pro
Posts: 1,946
Registered: ‎05-18-2011
Message 5 of 9 (1,575 Views)

# Re: Sheet Metal Door - Inventor vs General Rule of Thumb Method

09-14-2012 12:06 PM in reply to: SeanFarr

When I go to a clients to set them up I get a list of materials and bend deductions. Then I make a part 2 x 4 long and I put a 2" bend I unfold look at the extents and change the kfactor till I hit the number they need.

I wish autodesk would put this back the way it was in Inventor 4 that was when it worked right no one that I have worked with for the last 20 years ever use the kfactor.

Kfactor was made for none hydraulic brake presses when the tooling had to be oversized to bend the sheet because there was no speed control but now to get precision +- .005 the tooling has to be as tight as it can but still bend and so kfactor is no longer the norm.

But Autodesk has no clue and never will because they are not smart enough to ask me

James Letcher
2012 Factory Design Suite ( will not load 2013)
What happen to my Inventor :-(
Valued Mentor
Posts: 475
Registered: ‎07-25-2012
Message 6 of 9 (1,564 Views)

# Re: Sheet Metal Door - Inventor vs General Rule of Thumb Method

09-14-2012 12:21 PM in reply to: jletcher

Well, I sure appreciate your help, and respect that you use your experience to help others on this forum.

Thanks again, have a good weekend,

Sean

Sean Farr
Product Designer at TESInc.ca

Inventor Professional 2014-Update 2 - AutoCAD Electrical 2014
Win7-x64 | ASUS P8Z77-V | i7 3770 -3.4 GHz | 32GB RAM |
240GB SSD | nVidia GTX 670 4GB - 320.49
*Pro
Posts: 1,946
Registered: ‎05-18-2011
Message 7 of 9 (1,562 Views)

# Re: Sheet Metal Door - Inventor vs General Rule of Thumb Method

09-14-2012 12:24 PM in reply to: SeanFarr

You have a great weekend too my friend..

James Letcher
2012 Factory Design Suite ( will not load 2013)
What happen to my Inventor :-(
Valued Mentor
Posts: 475
Registered: ‎07-25-2012
Message 8 of 9 (1,479 Views)

# Re: Sheet Metal Door - Inventor vs General Rule of Thumb Method

09-19-2012 11:39 AM in reply to: SeanFarr

I am fairly new to working with sheet metal in Inventor, attached is another simple part. I am curious, is this how someone experienced would produce this part? This was definitely the easiest way I found, but that doesnt necessarily mean it is most functional.

Thanks

Sean

Inventor Professional 2012

Sean Farr
Product Designer at TESInc.ca

Inventor Professional 2014-Update 2 - AutoCAD Electrical 2014
Win7-x64 | ASUS P8Z77-V | i7 3770 -3.4 GHz | 32GB RAM |
240GB SSD | nVidia GTX 670 4GB - 320.49
*Expert Elite*
Posts: 26,186
Registered: ‎04-20-2006
Message 9 of 9 (1,474 Views)

# Re: Sheet Metal Door - Inventor vs General Rule of Thumb Method

09-19-2012 11:56 AM in reply to: SeanFarr

You should have started a new thread for this problem?

First question - is it dimensionally and geometrically correct  in folded form (the reason I ask is because when I measure it out to max decimal places the dimensions don't make logical sense to me and are not manufacturable or inspectable).

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