View Full Version : Flatten a 3D object as a "cut list"

01-27-2008, 09:45 PM
I'm new at Inventor and am still learning the basics of the program. I have modeled a 3D box for electronics out of lexan and now I need to cut the lexan. I'd like to flatten the box and dimension it as a "cut list." Is this remotely possible?

Robert Thacker-
01-28-2008, 02:04 AM
I think you might want to bend the box up from a flat 2D pattern, if so, you want to make your drawing as a sheet metal part and play around with the buttons until you find out how to get what you want.

If you are drawing something in the middle of the object, you can simply select, or make, a plane in the middle of the firgure, press 2D sketch, then simply press F7 to get rid of the material on top of the sketch so you can see what you're doing.

If none of those are what you mean, then can you explain what you mean by "cut list?" (maybe I just have a lack of understanding)

01-28-2008, 02:09 AM
Do you mean like, the whole box is an extrusion in one part file and you want drawings for the separate sides? In that case you'd need to do it in separate .ipts...besides, depending on how the box is held together the dimensions of each side would be a little different (although I guess that's negligible)

Robert Thacker-
01-28-2008, 02:12 AM
That's true, you can do it either as one whole part, or two seperate parts in an assembly, depending on how you want to use it. You could do that in two extrusions the first way and at least one more the second way (depending on the shape of the lid).

01-28-2008, 08:52 AM
posted too soon, disreguard...

01-28-2008, 08:54 AM
Sorry, let me be a little more specific. I have a box with a top, back and a bottom section that has two sides. The sides will be bent upward, so it will effectively be three pieces. There is no front. I made the box in standard.ipt and started by making three rectangles, trimming out the lines to make one "u" shape and then extruded that out. I want to take the u and flatten it. The reason I want to do it this way is because when I go to bend the lexan, it won't be the same dimensions as if I had butt joints along the sides. Is there any way to copy this into a sheet metal file? I have 2008 pro.
http://www.chiefdelphi.com/forums/attachment.php?attachmentid=6160&stc=1&d=1201531969 I guess you can see I had some trouble with lighting, too...any suggestions?

Elgin Clock
01-28-2008, 09:17 AM
From what I understand you basically want to use a sheet metal feature of the software if one is available. (I'm not an Inventor user, so I'm not sure)

With Lexan it is a little different than sheet metal, because you won't know the material's K-Factor*, but the good thing is of you overshoot how much material you are going to use, then trimming or sanding some extra off is not a big deal.

If you think of your project box as a cube, all you would need to do is "unroll" it to get the needed shapes.
There are only a certain amount of logical ways you would need to make your pattern so that it makes your desired shape at the end.
You could do something like this (http://www.oreilly.com/catalog/hardwarehks/figs/I_4_tt109.png)where the solid lines define the edges of your part, and the dashed lines is where you would "fold" or bend the lexan to make a box shape.

If you wanted to, just send me the .sat file of your part you want to bend, and I could throw it in SolidWorks sheetmetal feature, and give a pattern from the defined end result you want.
Or, if someone else knows of a sheetmetal tool in Inventor, that may work better.
Just PM me if you want to send me the file.

We've actually done bending of lexan before (http://www.chiefdelphi.com/media/photos/13930), (bad picture, but the cover on top with all the stickers is the lexan part) and it's a little tricky, so I'm wondering what tool you have available to you to do the actual bending?


In Sheet metal engineering (http://en.wikipedia.org/wiki/Sheet_metal_engineering), the term k-factor has the following meaning:
During bending the inner surface of the bend is subjected to compression while the outer surface is subjected to tension. However there is a layer in between which is free from any forces and thus its length remains the same. This is called the neutral axis ( N.A ). The radius of this layer of metal is called the neutral bend arc radius ( NBAR )and is defined as the inside bend radius plus a percentage( K-factor ) of the metal thickness.
NBAR = BR + (T * K-factor)
The K-Factor ( K ) depends on the material, the type of bending operation (coining, air-bending), the ratio of the Bend Radius to the metal thickness ( R/T ) and is typically between 0.3 to 0.5. For most types of steels it is around 0.33 to 0.4

01-28-2008, 09:30 AM
think I'll just sketch the part on paper...much less complicated.
For bending, we plan on using plywood, clamps, and a heat gun. We have a shop teacher that has done it before. we also plan on welding the back on (somehow). I'll fill you in later with the results.

01-29-2008, 06:55 PM
It might be faster to start again, however you CAN convert a "regular" part to a "sheet metal" part which as discussed CAN be flattened. You would need to have modeled your box such that it could be flattened (so again, it might be easier to start again). You might want to look at making the box using the sheet metal features. Start with a flat "face" the size of your bottom and then add "flanges" for the sides (not sure how you were planning to do the top).

01-30-2008, 07:53 AM
Thanks Everyone for your help. As of now I have a finished and functional electronics box. I just sketched it. I'll use sheet metal next time I use Inventor.

As far as building it, we built a form and used a heat gun to warm up the bends. As they got hot enough, gravity and some clamps worked to form them. The box was done within five minutes of heating the lexan. Super glue and epoxy didn't work to bond it, but silicone will be our next try. At least the robot runs...