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Useful Information: Reproducing the Ellsworth Gun Reproducing the Ellsworth Gun Robert C. Hubbard Jr., 7th Wisconsin.It started with a leisurely read of a book called "Field Artillery Weapons of the Civil War." I came to a chapter called the "The Rare Ones." One of the accompanying photographs showed a detail of the breech parts, another showed the entire barrel laying on two pieces of wood on the floor. The breech parts looked easy enough to make. It had a 1.5 inch bore with a square hole going through the breech across the barrel. It only has a 48" barrel. Look...two of the extant barrels are in my home state. I thought, "Hmmm?" At the next artillery event I asked Don Lutz of Loomis' Battery, someone whom is consider an expert in Civil War artillery, if he might know who had one of the Ellsworth's in our state. He asked "why?" I told him I would like to look at one and maybe take some measurements because I was thinking of trying to build one. He told me "he did" and I could come measure and look, if I wanted. Two weeks later and a nearly a two-hour drive put the little barrel before me. It took about 10 seconds and I knew if I was ever going to have an artillery piece, this was going to be it. We moved the barrel out into the sunlight and I spent the next two and a half hours measuring everything and making sketches. The following weekend there was a skirmish and I decided to take my drawings along. I showed them to one of the serious artillerymen. He said that he would be interested in the project also. I asked a couple of machinist their opinion and one of them was interested also. It was decided, we would make one for each of us. After all, you know, everyone likes artillery! Barrels Once we decided to get to work, it became clear that boring a hole through a four foot piece of steel was beyond the capacity of the machines we had available. The square hole going across the breech also presented a problem. The cost of the broach to cut this square hole was staggering, especially for one piece of tooling! Luckily, I found a shop that would supply the material for two barrels, cut the bore, and Electrical After getting the barrels from the shop that did the boring and EDM work, the first thing we did was cut the external taper onto the barrel. This required a removal of 2.5 inches of steel over the distance of three feet. A flat with a shoulder was machined into the barrel for the trunnion ring to set on. The radius at the breech and the molding on the muzzle swell were also put on at this time. Shown above, Brian Haack machines the overall taper onto the exterior of the barrel, using his WWII vintage lathe.  Next the trunnion ring was made. The trunnions on the original gun were attached to a ring, which is a separate piece than the main barrel. A piece of steel was bored to .010 under size of the flat on the barrel. The trunnions were inletted into the ring and welded in place. Weld was used as fill to complete the radius from the ring to the trunnion rim base and then ground to shape. The trunnion ring is shown at right, after grinding the radius as described above after the trunnions were attached. This view shows the holes in the trunnions through which bolts were run to hold the trunnions on while welding. The next step was to attach the trunnion ring to the barrel. To do this, we needed to heat the trunnion to expland it so it would fit over the flat on the barrel. The trunnion was put into a kiln and heated to a bright orange/yellow and slid onto the barrel flat. Once in the proper location it was allowed to shrink in place. This would put a tremendous holding force on the barrel. Exactly how much force, we would discover later. Shallow holes were drilled into the barrel through holes left in the trunnions, and set screws were tapped into the barrel for additional sheer holding strength.
Once the trunnion rings were attached, the things really started to look like cannon, but the originals were rifled guns, and ours so far were smooth bored. We had to solve this issue, and so I built a rifling machine to cut some grooves into the bore. I based my machine on several drawings of old rifling machines used in Appalachia to hand rifle rifle barrels. Our machine, however, is driven by a drill motor. We tried the first rifling out on a piece of PVC tubing, in an effort to prevent damaging the barrels on an untested machine. 
After a few tool adjustments the barrel was clamped into place. The rifling machine is a relatively simple affair. There is a gear on a shaft which holds an indexing arrangement with a set of indexes that determines the number of grooves to be cut into the bore. The shaft is held in place by a pair of bearings. A rack (gear teeth on a flat bar) runs under the gear on a shaft and is connected to a sine bar. A sine bar is a bar set on an angle to the centerline of the bore, and the angle of the sine bar determines the twist rate of the rifled grooves. These parts all were mounted on a block containing linear bearings. The image below on the left shows the mains gearing and indexing head of the rifling machine. There are twelve indexes, allowing for 12 lands and grooves in the rifled barrel. The hand in the image is removing the hex head bolts that keep the indexes in place. The image to the right is ove the cutter as it enters the bore. The rifling machine is off image, to the left.  
The whole assembly is moved back and forth by an acme screw with a motor, which moves a small cutter in the bore. The cutter is a bore size piece of steel that has a single cutter tooth mounted in it. The cutter is adjusted for the depth of cut by a jack screw and held from movement by a set screw. When we started rifling the first barrel, the tool got hung up about half way through the barrel. After we pull in through, we gave the cutter more chip clearance a finer cut and started again. It stopped in the same place again. This time the cutter had left a burr where it was hung up. We set a reamer to a size which would only take off the top of the burr, and had to turn this reamer through by hand. As we pushed the cutter body back through to the breech end by hand, (we pulled our cutter toward the muzzle) we felt some resistance in the same area. This is when we discovered that the trunnion ring had collapsed the bore slightly when it cooled in place after being heated. The material at this point was 5.5 inches in diameter with a 1.5 inch hole through it. Who would have thought that .010 shrink would be enough pressure to do that? We reamed the bore back to proper size (again by hand) and started again. The rifling went pretty easy from here. We started around .0005 per pull and later increased as the groove got deeper. It still took an entire long day to rifle the twelve land and grove barrel to .015 deep. Every groove was pulled several times and the cutter was only re-adjusted up after all grooves had been cut. The cutter was kept well oiled. The twist rate that we used is about the same as a musket, about 1 turn in 66 inches, which is very fast for artillery. Almost all of the rifled artillery of the Civil War had a rate over 1 turn in 120 inches or 1 turn in 10 feet. Some of the heavy guns had even slower rates. After the rifling job was complete, we had to make a return trip to see how the original gun was chambered as additional research had shown that it was chambered for a cartridge. We made a casting of the interior of the breech of the original and it showed that it was indeed chambered for a cartridge. The casting also showed a couple of interior angles that we were not sure about. After re-checking the breech in the original, it was time to cut the reproduction breech. A 1 15/16 drill was used to open the size of the breech to accommodate the breech block. The lead on the drill was the then re-ground to the same angle as the gas checks. The depth here was critical as the gas checks must be forced against this angle to create the seal so that the gasses do not leak out of the breech of the gun. Another reamer had to be procured and ground to put the throat (ramp like area) in front of the cartridge that was determined by the castings we had made. After this was done the barrel was nearly complete. The gas checks and breech block were machined from two inch 1018 steel. The inside angle of the gas checks were machined first. Then a fixture was made to hold them so that the outside angle could be cut to match the inside of the barrel. Then slits were cut into the gas checks with a thin abrasive wheel. The checks work much like the rings on a piston, the rings being forced open by the cone and against the barrel making the seal. 
The breech block was turned to size, stepped down and turned to the smaller diameter. A 1.5 inch slot was then milled into the block to correspond with the square hole in the breech of the gun, paying special attention to the forward location. The inside of the slot was then clean cut .015 on both sides. A hole was drilled for a cam handle on the back of the breech block. A slot was cut in the rear of the breech block for the handle to fit in. This handle pivots down and forces against the breech of the barrel to withdraw the breech block and break the seal of the gas checks. Next, the cross bolt was machined. It consists of two opposing angle blocks with a handle that move the angles against each other causing them to expand in height, which then locks the breech block into the barrel’s breech for firing. After the cross bolt was finished came the final hand fitting of breech block and cross bolt to the barrel. This is carefully done so that the cross bolt forces against the front face of the breechblock and causes the gas checks, which work like piston rings, to open and seal. The rear sight mount; which had been machined from solid brass, was mounted to the side of the breech. The front sight mount, a half circle, was mounted in its location on the trunnion ring. We made the rear sight post and mounting from information we received through Ken Bauman of one of the privately owned barrels in Pennsylvania. It was a semi circle on a post, which allowed for windage adjustment as well as elevation. This lead us to believe that the sight must have been either a telescope or a tube sight. I found an advertisement in an 1856 magazine for telescopes "for rifles and cannons". 1856 was the same year as the first manufacturing of these guns. The rear sight mounting was made along with a tube sight. Measurements were carefully made for the distance from the back of the breech to the face of the breechblock assembly. The outside of the barrel was marked for that location and lifted back onto the milling machine. Did I mention that every time you do something to the barrel you have to wrestle 320 lbs. in and out the machines? This is particularly rough on days of short operations on multiple barrels. The hole for the vent was then drilled. The barrel was now near complete, except for paint. Carriages The carriage for the original gun is somewhat of a mystery. One of the original barrels, located in Greenville S.C., had been cemented in place with what appeared to its original trunnion straps. They are interesting in that they do not match any period artillery carriage known, they are exceptionally long. It is likely that the carriages for these guns were unique to them. With this being the only information we had, we decided to put our reproduction barrel on a First Model Prairie Carriage. In the time since we decided on our carriage, the city of Greenville tried to move the monument and it broke revealing a near complete set of irons and hardware in the concrete indicating that the gun was intact at one time.
One process that was interesting in constructing the carriages was the construction of the wheels. Making the wheels was also an early portion of the project. First the hubs were turned to shape and then they were mortised for the spokes. Next the fellies (the wood on the outside of end of the spoke, that will later hold the iron tire.) are cut out and mortised for the outer end of the spoke. The parts were then assembled and clamped in place, as shown at left. Tires for the wheels are made of iron, and protect the wood fellies from being damaged by the road.
The tires were bent on a three point roller and then welded to the proper size, which is smaller than our wheel diameter. The tires were then heated on a small but hot fire until they became a dull red. The hot tire was removed from the fire and carried to the waiting assembled wheel. Heating the tire this way makes it expand around 1/2 inches, enough so that it will now go over the wheel.
The tire is the taped into place all the way around and cooled. During the cooling process it is important to wet the wheel down well to prevent the wood from bursting into flames. The image shows both smoke and steam. As the tire cools, it contracts and puts pressure on all the parts holding them together. You can hear the wood creak and groan as it is forced into final position. It really is an impressive amount of smoke, steam, and noise! Projectiles and Cartridges Once the barrels were mounted on a carriage, we needed ammunition! One interesting feature of the original Ellsworth guns is that they were chambered for a metallic cartridge. Our cartridges. Our cartridges were made from copper tube which has a steel freeze plug silver soldered into one end. A small hole was drilled in the side of the cartridge for ignition thru the vent. As with the original, our cartridge will hold up to 3oz. of F grade black powder. Primers were not yet in use in cartridges for ignition when these guns were designed in 1856. This cartridge is just a method of carrying powder much like the bags of the other civil war artillery pieces. The most known breech-loading rifled guns of the civil war, the Whitworth also used a cartridge. A bullet mold was made of aluminum and based roughly on a Read shell with the exception that ours has a hollow base rather than the flat base of the originals. There are two different types of projectiles that have been loosely identified as Ellsworth projectiles, and our projectile is similar in design to one of them. The image shows the first set of projectiles we constructed for the cannon, including the projectile, cast from lead alloy, and the copper case. First Firing As with all projects of this kind, the closer you get to being done the more eager you are try it out. But we had a problem. The carriage was not nearly complete. What to do? After searching high and low we were unable to locate a place which offered cannon carriage rentals. A deal was struck with Battery C, 1st Michigan Light Artillery to use their scale carriage until our carriage is complete. The night that we got the carriage reassembled after it had been taken apart for transportation, we found the barrel would nearly drop in place. We tightened the last nut and looked at each other. “Well?” A round was quickly prepared and the gun moved to where it could be test fired. A primer in place; a long string to the lock; a gentle tug on the string and the first round was done! We would go to the range the nest day, Sunday, for more rigorous testing. All those present who help in construction of the gun fired it that day including our wives. 
Since that first firing we have changed the mold three times in search of the "right" projectile. We greatly reduced the powder charge as a result of the rounds firing at such a high velocity, and it tightened up the group considerably. Whether or not this little gun can be competitive with its bigger brothers remains to be seen, but it is looking promising. The one real advantage the little gun does have is that it can fire a ten shot match for about the same price as one shot from a 12 pounder. Conclusion This short article was written to show some of the work involved in this kind of project. I found the research for this unique project interesting. It lead me through many reports which often clued me to others. The historic research for this project is really an ongoing process, even after finishing the reproduction guns. Most of the work in recreating them is basic metalworking and wood working skills. Though we sometimes found engineering the tooling or method of completing a particular task with the tools at hand challenging, it was rewarding. Before we were done, I found myself wondering what I would work on next. It wouldn’t take long to find out. If your interest is in artillery, and the full size field pieces are cost prohibitive; think small. There were well over 200 small size artillery pieces used in the American Civil War. For more information about the historical facts about the Ellsworth, and some other smaller guns, please read my other article at http://www.nwtskirmisher.com/useful-extra5.shtml . If you have any questions, or more information to add about these small guns, please contact me Robert C. Hubbard Jr., 7th Wisconsin.  
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Discharge Machine (EDM) the square hole across the bore for less that the cost of the broach. So, we purchased four pieces of 4140 steel and to work we went.
