Hmm working with hats has always been an issue.
I hope this can help as I replied in another forum.
Doing embroidery on caps is not simple, but it can be well done if you know how to do it.
Make sure that you run the embroidery right from the bottom middle of the front side of the caps where the joint is. Starting point is very important here. From that bottom middle start point, then you can go on to the left/right or the top side of the embroidery.
You also have to pay attention to the garment type that you use. If it is thin, you should use 0.6-0.5 mm density, if it is medium use 0.5-0.4 mm density, and if it is thick use 0.4-0.3 mm density. So make sure you do the digitizing right.
If you want to create deluxe caps with thick garment and thread, I use 0.2mm density in my digitized design and foam to help creating the 3D effects. I'm pretty sure the caps will look really really good!!! I've done this all the time and customers are happy with the result..
I post some pictures to assist you in this matter, click here:
http://centdigitizer.com/3Deffect.JPG
http://centdigitizer.com/foam.jpg
http://centdigitizer.com/caps.jpg