What am I doing wrong?

[jeff g 0]

OK, I cut the pipe patterns from the vinyl and I decided to do something intelligent for a change.  Instead of just applying the vinyl to the metal and cutting my pattern, I decided to roll the cones in the vinyl to see how they actually came out.  The dimensions aren't quite right...close, but I need exact.  I cut from the roll and I did pull the roll loose.  I noticed that the vinyl bunched up and tried to wrinkle somewhat while it was cutting, so I'm sure that is why the dimensions aren't right.  Other than cutting the vinyl into small pieces what am I doing wrong, if anything.  The 36" Pcut has 3 pinch rollers.

I made a couple of club stickers for the guy who is helping me test fit and dyno test the pipes using scraps of vinyl and the small pieces fed and cut perfectly.  So, I recut the patterns tonight using pieces cut off the roll and the bunching didn't happen.  The cone patterns were dimensionally correct, so I applied them to sheet metal and cut my patterns.  I've got 2 of the cones for 1 of the 2 needed pipes rolled and welded up so far. 

Here are pics of the patterns.  Sorry for the bad quality...they are from my cell phone.  I'll take some pics of the final product when I get it done this weekend.

Rough cut (I'm working with 2X4 foot sheets of metal)

Finished pattern