This Information is part of an effort to provide information showing how the original Cricket Air Hammer was designed (Circa April, 2017).  There are thirteen videos on YouTube that introduce the Cricket and show how the original Cricket was built.  There will be even more videos later demonstrating its use.
There are links within this website to those videos.
Hopefully, this information will be useful to a wide range of audiences….  From those that are just curious about air hammers to those that want to build one from scratch.  For readers that just want a component list for the Air Circuit and a short description about how it works, just study the first diagram, read the Components Short Story and make a list from the Components Section. 
The "Air Circuit Interview"  would be a great first read for many of you if your primary interest is learning about how the Air Circuit on a Utility Air Hammer works... or you have run a Utility Air Hammer, but have no understanding of Air Circuits.  
If you want to really understand how this stuff works, study the whole document.
My goal is to distribute information that provides a simple approach to building an air hammer with a very small footprint that can be built by virtually anyone that can weld, has access to basic metal working tools and has reasonable fabrication skills.  
I do not claim to be an expert in the field of fabrication, fluid dynamics or the myriad of air flow control products available today.  I am a great scrounger (of materials), a reasonably good welder (yes, I grind) and have educated myself (with the help of others, documentation and online information) to understand how this particular Air Circuit and its components work.  
Once I fully understood the Air Circuit and decided on the basic hammer design (and gathered materials), I had a running hammer in just a few days.  To get to the the final design took several weeks (mostly because of a design issue with a pneumatic valve I was using).  Later, I built a second hammer of the same design (about half the weight) in just 4 days (after I gathered materials).
I thank several friends that reviewed this document as I was writing it.  They offered numerous perspectives and ideas that helped me make it better.  I acknowledge the contributions of many others (Professional and Hobbyist Blacksmiths, Engineers and Manufacturers) that provided valuable information and discussions about Air Circuit Components, design and performance issues on blacksmith forums I either participated in (since 2004) or researched using archives dated back to 1996.  If I recall correctly, discussions about Utility Air Hammers picked up in pace on online forums around 2001.
I especially thank John Larson (Iron Kiss Hammers) for sharing his approach to Single-Hit and Clamp features on several forums. 
Finally, I want to thank those early Utility Air Hammer pioneers that were the primary innovators for Utility Air Hammers that have come into the reach of most hobby blacksmiths.  
The Cricket is based upon (and has extensions to) the accomplishments of many that have preceded me.   
My expectation is that this hammer will be built and used mostly by hobbyists. 
Dave Hammer