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SeanFarr
Posts: 475
Registered: ‎07-25-2012
Message 1 of 19 (1,150 Views)

Sheet Metal Guru's - Is Flat Pattern Needed on a drawing?

1150 Views, 18 Replies
10-16-2012 09:51 AM

Hello All,

 

I have a simple sheet metal part that does not require explicit bend radii. We leave it up to the shop to fab this part up as long as it's final outcome is within tolerance. We don't normally include a flat pattern, simply because it could cause confusion when cutting a blank. I use the default bend allowance and bend radius, which gives the exact blank size and bend locations. But our local fab shop probably doesn't/won't use the correct tooling to provide the exact bend radius, so this will throw off the final outcome if the blank was cut using the flat pattern dimensions.

 

Not sure what should be done so that I can apply the flat pattern to my drawings, because there is some sheet metal components we have that require the flat pattern to show cut profile features.

 

Thanks

 

Sean


Inventor Pro 2012

 

 

Sean Farr
Product Designer at TESInc.ca

Inventor Professional 2014-Update 2 - AutoCAD Electrical 2014
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Message 2 of 19 (1,144 Views)

Re: Sheet Metal Guru's - Is Flat Pattern Needed on a drawing?

10-16-2012 09:59 AM in reply to: SeanFarr

The last sentence doesn't really make sense.

If you want the flat pattern for only some uses - you could put it on second sheet in the drawing.

 

Also - your first sketch isn't constrained and you are doing too much work.

 

Sketch1.png

 

I recommend using construction lines for clarity (I should have add a horizontal line at the bottom as well).

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Valued Mentor
SeanFarr
Posts: 475
Registered: ‎07-25-2012
Message 3 of 19 (1,140 Views)

Re: Sheet Metal Guru's - Is Flat Pattern Needed on a drawing?

10-16-2012 10:12 AM in reply to: JDMather

I understand the sketch is bad format (bad habits, I am getting better though)... but going back to the flat pattern, we have been supplying our fab shop with drawings that don't have flat patterns, well before I started here.The guys would sketch on piece of paper what they wanted and fax it it the fab shop and they would build it. Now I get the sketches, I model it,draw it and then email to the shop.

 

I want to start applying flat patterns to my drawings to show cuts, holes, other features etc. etc. but I don't know if I start applying them if it is going to start confusion because of how exact Inventor is.

 

Or should I not include a flat pattern, and annotate all features off the folded state view in the drawing??

 

I have been through the Sheet Metal section of Mastering Inventor 2012, and was hoping it would help me decide what to do. But after going thought the chapter, I am still unsure if flat patterns are needed or not?

Sean Farr
Product Designer at TESInc.ca

Inventor Professional 2014-Update 2 - AutoCAD Electrical 2014
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Posts: 292
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Message 4 of 19 (1,121 Views)

Re: Sheet Metal Guru's - Is Flat Pattern Needed on a drawing?

10-16-2012 10:55 AM in reply to: SeanFarr

Without the shop's input to "fine tune" your bend table and/or tolerances, you'll never "get them what they need" (if you're not already).

 

Give them the flat pattern and insist that they use it.  The shop MUST evalate your Work Orders (the fabricated, bent, finished product) vs. what was ACTUALLY produced from the instructions given.  Having the shop being the only ones who know exactly how to complete your sheet metal part is a very dangerous thing.

 

Finally, what will happen when you need to have your sheet metal part produced out-of-house?  Will they be able to use the "bent", Work Order or will they insist on a flat-pattern?  If they require a flat pattern, will your employees have helped you to insure that your flat-patterns are real-world usable?  Not if they don't use a flat-pattern!

 

"Be not afraid of moving ahead slowly.  Be only afraid of standing still."  Chinese proverb quoted on PBS.

:mantongue:

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Message 5 of 19 (1,119 Views)

Re: Sheet Metal Guru's - Is Flat Pattern Needed on a drawing?

10-16-2012 10:57 AM in reply to: SeanFarr

I think most people sending to outside would only send the dimensions of the finished folded part.  The vendor should know how to get the correct part from the finished dimensions.

 

For internal use - or if you have a very very close working relationship with external vendors, you could try to work together to reduce costs by supplying flat patterns, but you have to have information about there manufacturing processes (to get the correct bend allowance) and this works best if you can walk out onto the shop floor and get sample bends directly from the person who will run the job.  On small run jobs there might not be a payoff for the effort.

 

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Message 6 of 19 (1,118 Views)

Re: Sheet Metal Guru's - Is Flat Pattern Needed on a drawing?

10-16-2012 11:00 AM in reply to: jdavis417

jdavis417 wrote:

Without the shop's input to "fine tune" your bend table and/or tolerances, you'll never "get them what they need" (if you're not already).

 

Give them the flat pattern and insist that they use it.  


 

 

These two sentences seem to contradict each other.

The finished part dimensions are what the customer pays for.  The finished part is what performs the function.

 

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Curtis_Waguespack
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Registered: ‎03-08-2006
Message 7 of 19 (1,106 Views)

Re: Sheet Metal Guru's - Is Flat Pattern Needed on a drawing?

10-16-2012 11:50 AM in reply to: SeanFarr

Hi SeanFarr,

 

I've seen it done many different ways, and it all depends on the capabilities of all involved. But currently, I send out drawings with dimensions of the finished folded part only (no flat pattern), as JDMather mentioned. But I do provide a DXF, STEP and IGES file of the finished folded part along with it. Some of the shops we work with use other software to bring in the 3D files and apply their bend information to it to get the correct flat pattern.

 

On occasion, I have added a "thumbnail" flat pattern to the drawing, with a note that states that the size is approximate, in order to communicate a complex part.

 

I hope this helps.
Best of luck to you in all of your Inventor pursuits,
Curtis
http://inventortrenches.blogspot.com

 



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Valued Mentor
SeanFarr
Posts: 475
Registered: ‎07-25-2012
Message 8 of 19 (1,096 Views)

Re: Sheet Metal Guru's - Is Flat Pattern Needed on a drawing?

10-16-2012 12:00 PM in reply to: SeanFarr

Thanks Everyone for the input, for now, I have decided to not use flat patterns, unless there is something that would require me to do so. Not exactly sure yet what that would be, haha,  At least I can continue without any issues.

 

Ciao for now!

 

Sean

Sean Farr
Product Designer at TESInc.ca

Inventor Professional 2014-Update 2 - AutoCAD Electrical 2014
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JimSteinmeyer
Posts: 326
Registered: ‎05-16-2011
Message 9 of 19 (1,061 Views)

Re: Sheet Metal Guru's - Is Flat Pattern Needed on a drawing?

10-16-2012 03:32 PM in reply to: SeanFarr

On the other hand, since our holes and contured edges are done on the laser table the exported DXF file of the flat pattern is important.

 

Jim

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Valued Mentor
SeanFarr
Posts: 475
Registered: ‎07-25-2012
Message 10 of 19 (1,055 Views)

Re: Sheet Metal Guru's - Is Flat Pattern Needed on a drawing?

10-16-2012 04:03 PM in reply to: JimSteinmeyer

I did read that flat pattern files can be exported and used for that purpose, but wasn't sure if all or most automated cutting machines could accept files such as DXF. Do most automated cutting machine set-ups require there own specific file formats and inputs or does the majority accept exported files such as DXF (from Inventor)?

 

If I send a drawing of a sheet metal product without a flat pattern to a shop that utilizes a laser cutting machine, are they capable of using the information on the drawing to input whatever info they require into the program/software to cut? or is a flat pattern required?

 

I don't have any experience with automated cutting tools and there software, what can be used as inputs or how to input data to produce and accurate cut.

 

I imagine there is a certain percentage offset to allow for precise cutting, example; cutting a square, the laser cutter would not line up directly on the line of the drawing, the cut has a certain thickness, is this taken into account by the machine or does it have to be calculated by the operator and applied?

 

Thanks for bringing this up JimSteinmeyer!! Any help or direction is appreciated.

 

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

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