In this post we will start with the making of a miniature Gardner Gun. The very first step that Joe did was to find someone with a Gardner Gun that would allow him to study and measure it. That was no easy task but one that he prevailed at. Joe spent a number of months just taking measurements of a full size Pratt and Whitney model Gardner Guns and converting them into a solid model in solid works. After gathering the information on a full size weapon he started the process of converting it to 22lr. His first attempt upon completion of the drawings was to make up a wooden mock up to get the basic concept to work from.
With this he had a starting point. Now it was time to convert all the data he had collected into semi working plastic model. This allowed for the checking of dimensions and operation of the weapon. It was also hoped that this would also provide the pattern for the castings. That would not be the case.
It was now time to self-educate himself on wooden pattern making and metal shrinkage. After a number, it took three attempts, of patterns he finally came up with a design that would cast properly. A number of problems that you will generally not find in books occurred. A few of the examples are getting the metal to flow properly, is the casting area to thin. How do you hold the cast part to machine it. Is there enough metal to machine away the rough surface. Is there to much metal causing extra machine time. Is the metal going to sringe to much causing an out of spec casting.
This is the wood pattern for the outside shape of the Gardner gun.
This pattern is for making the core mold. It took a number of attempts for this core mould as well
After casting the raw bronze casting with the sprues cut off would look like this.
In our next post we will go into the work necessary to machine it.
Actually, the wooden mockup was my very first attempt to understand the scale of the gun that I wanted to build. It was intended to be for the English model Gardner as that was what I really wanted to build. Unfortunately, I could not find any good information or photos and so the model was helpful yo give a starting point for the dimensions that I would try to derive from patent drawings.
The patterns shown are all later generation and all could really have stood further revision, especially as they relate to the cores.
As I poked at the project, I was blessed to begin finding people that owned gardner guns and were willing to help me…it happened that they were all Pratt & Whitney guns and so my project went in that direction instead of the English model. The more I learned about that gun, the moee I loved it. For all the perceived simplicity, it really is an engineering marvel!
Some things that I found interesting about the castings are that the main casing’s barrel shroud is machined along the entire bore, that the original tripod had a fire dispersion device incorporated and that the cores for the upper elevation mount are tapered!
Regards,
Joe
you used a 3D printer for the plastic mock-up ?
Nice work! I have been doing my own patterns and core boxes for a few years now (and still learning). I will be following this project with interest. Will the raw castings be for sale, or only finished guns?
S.N.A.L.-Yes, that was one of my first costly mistakes. I was attempting to get from drawing to pattern and had no pattern making experience. A local pattern maker wanted $14K for my patterns and speaking with a local prototyping company, I got sold on the idea that their SLA model would work for a pattern…Those models cost me my NFA Uzi and MG08 Maxim. In the end, they helped me home in on the rest of the design but were useless as patterns! Like any good obsession, I kept going.
Joe