Hello,

I am designing a box to be laser cut with 1/4" acrylic.  I use a box joint, which requires a very precise offset from the original dimensions of the box to account for laser kerf (width of the laser beam).  I am using SW 2015.

To accommodate for laser kerf I follow these steps:

1. create a new subconfiguration of the original-dimensioned part

2. click a face of the part>sketch>convert entities to get an outline of the part.

3. offset entities, set thickness to global variable "laser_kerf_quarter_inch_acrylic", which is 0.0025"

After I click the little green arrow, I get the message: "identical contours in the same sketch are not allowed for this operation".  It seems like unpredictable behavior, as this happens with some parts and not others.  Sometimes I can restart solidworks, restart steps 1-3, and I won't get the error.  Sometimes I set the offset to 0.005", exit the sketch, rebuild, re-edit the sketch and change the dimention to 0.0025", and SW will crash.

Through trial and error, I found the minimum distance that this error will not happen at is 0.005".  I ran a test with this offset distance, and there is too much wiggle room in the acrylic to make for a strong bond using acrylic cement (which needs the material to be touching, i.e. no wiggle room).

Any ideas on a permanent solution to this?

Here are some pictures describing what I am talking about: