Step 1. We start with a blank barrel as cast. As you can see, we have a very large header and the gating to remove.
We wheel into the machine shop a cleaned blank that has been sand blasted to remove residual plaster and mold material to cut off the header and gating.
Step 2. Next we add computer geeks and their state-of-the-art computers to some very big machines. . . and we cut the bore with deep bore milling machines.
At this stage we test and verify the purity of the metal throughout the barrel. (Look for how we test and X-ray in an upcoming article.) If ANY porosity or imperfections are found, the barrel is scraped. At Cannons Online, the safety of our customers always comes first.
Step 3. Cutting the exterior with Computer-Numeric-Controlled (CNC) lathes. We have the capability of lathing 27,000 pound barrels when necessary.
The barrel is put into the lathe and enclosed in the “cutting chamber” where it is turned up to the “belly-band." This is but one of the many ways we employ state-of-the-art technology to ensure a quality product. The barrel is now placed in the CNC milling machine where we perform the second stage of cutting; the removal of material from the trunions and belly-band by indexing and profiling.
As seen in the computer graphic – a tooling bar cuts back and forth over the trunions and barrel leaving the tell tale pattern as seen in the far left photograph.
It is now ready for hand polishing. Some of our guns do not require machining, just as the original counterparts did not.
In the photos on the right you can see the surface quality of our castings right out of the mold.
From time to time a customer wants a particular barrel to have a cast-in liner (more about cast-in liners and testing in a future article), and it is at this time we take a sample of the liner for our lab to test elongation and tensile strength.
Step 4. Venting is next and it's one of the most critical stages in gun making. Here precision tooling is a must. If a vent has any gaps, out of roundness, or even if the threads extend into the barrel chamber - a chance of catastrophe exists. We make the finest vents from copper, as were the originals, or with steel liners that extend unbroken from the surface to the bore. Then we inspect the blending and mating to the interior so no extension exists and a perfectly smooth clean bore is left.
Step 5. Last is our quality control inspection (Q.C.I.).
Of all the stages in the making of a gun (i.e. planning, pattern making, casting, machining, and polishing), Q.C.I. is the most important. Our Q.C. Inspector, as with government inspectors, verifies that all measurements and tolerances are satisfied, including many modern military standards.
It’s how we at Cannons Online know when you receive your cannon or mortar the highest industry and safety standards have been met.