I have a 20" o.d., 3/16" wall sheetmetal duct intersecting a 24" o.d., 3/16" wall sheetmetal duct. I need to develop flat patterns for both parts.

My problem is when I create a normal cut through the rolled sheetmetal part a gap opens up. I understand why this happens but I need to figure out how to work around this.

It happens because the cut is made at the neutral plane of the sheetmetal. So the thicker the sheetmetal the larger the gap. I can work around this by creating a seperate model with sheetmetal thickness set to 0.001 to create the flat-pattern but this creates extra steps in the process. Does anybody out there have a better solution? The older sheetmetal workers in our shop can lay these out by hand and I have an add-on for Autocad that works great but I am trying to accomplish this all in Solidworks. I have attached the part file as well.

Thanks

Ben