Cap and hat screen printing can be tricky without the right equipment. There are numerous methods available for screen printing caps, hats and visors. Some are better than others.
One of the best solutions that we've seen (and have used) is The Hat Champ offered by Livingston Systems. Livingston's Hat Champ is an attachment that will fit on your existing screen printing press. Special screens are not required–you can use your regular screens. These two features are very worthwhile. If you have ever used "cap screens" you know that they can be a real pain to work with. Being able to use your existing screen printing press is ideal and cost effective.