Reviving a U.S. Navy Mark V Collimator

 While Cory Suddarth was a Naval reservist, he would perform routine maintenance on a 20 x 120 Kollmorgen style Big Eye binocular during his yearly two-week tour. For eight years he worked with the Mark V collimator, however, after leaving the Navy he went over a decade without laying eyes on this instrument. In 1990, Bill Cook took Cory in and reacquainted him with what a Mark V collimator does and although the basics had been forgotten, with Bill's help, he was back to using one professionally. Much like riding a bike, previously lost knowledge came rushing back.

In 2015, Cory was contacted by former Navy Instrumentman, IM Chief Michael O'Hearn. He had in his possession some original Navy Mark V optical components. Wanting to build a complete collimator to present to his wife, a former Navy Opticalman, he picked Cory's brain about the details of this undertaking. What O'Hearn did not know is that he would also need an auxiliary scope equipped with a rhomboid prism to make this bird fly. Cory offered O'Hearn a completed 6 inch variant of the Mark V collimator that he had made along with an original Navy auxiliary scope and an X-Y axis platform in exchange for the Mark V optics. Done deal! With these optical components in hand, Cory was looking to move to the next phase of making a new Navy Mark V.

Cory is a seasoned machinist capable of making parts as needed, however, the size of the components he desired to make was too large for his Grizzly 0602 lathe in the shop. He was looking to have a set of large rings made to house and support the 10-inch optics, holding the alignment perpendicular and parallel as needed on a 2 x 4 inch aluminum rail. Knowing the limits of his lathe, he contacted Eric Schleppegrell, who took the sketches of these rings and turned them into usable prints.

In 2018, Cory and his daughter, Cat, with their orange C-8 collimator, went to the Okie-Tex star party located in Boise City, OK. which is near the farthest edge of the OK panhandle, offering some of the darkest nights in the southwest. The conditions were so poor that year that the event was later dubbed "Soakie-Tex" due to the continuous rain that lasted throughout the week. This was not necessarily bad for Cory and Cat as the vendor hall remained packed during the event. On one of the rain-soaked days, Vencil McCurdy wandered by their table and said, "I see you dabble in binoculars!" and after an hour or so of chatting and looking over the prints that Eric Schleppegrell had made, he offered to make these rings at his shop near Oklahoma City. He used an 11-inch diameter heavy wall 6061 aluminum ring to construct the finished product and did a beautiful job.

With the rings completed, Cory was able to get busy on finishing this project. Reviving a U.S. Navy Mark V collimator.

Cory designed the rings to have a small yet sufficient gap between the cell wall and the original Mark V optics that he bartered off of O'Hearn. A strip of cork was used to line the inner surface of the rings to provide cushioning with the edge of the outward-facing lens riding on an O-ring. Three Delrin spacers were used to separate the twin PCX objective lenses, which are free-floating so that the spring tension applied to the rear lens is then transferred to the forward lens.

The rear cell houses two separate optics, one with a forward-facing reticle that was marked in degrees and minutes of arc, 10 MOA per Div. The rear-facing element which would be seated near a light source is a diffuser plate that was made in shop using a sacrificed glass and 100 grit aluminum oxide.

With all of these components in place, a monochromatic light source was needed. A green hue somewhere near the middle of the visible light spectrum would be the desired outcome, however, using some form of green filter with a standard light bulb typically causes a ghosting effect that many technicians would find annoying. To rectify this issue, Cory used a green 3-watt Duracell LED A-19, which negated the need to hunt for the correct color glass or filter while bypassing the ghosting effect.

The next to final step in this endeavor is to calibrate for parallel light rays, which tends to be a straight forward affair. The objective lens set is fixed with the reticle having fore and aft adjustability. A binocular is then set to focus on a target that is over 2000 nautical yards while an auxiliary scope is used for critical focus. Remembering not to make any additional adjustments to the binoculars, a second person then makes adjustments to the reticle until a clear focus is achieved. The setting is marked and bolt place to maintain this position.

Once that was completed, the finished covering was placed along the housing rings: A tube lined with a graphite composite texture and the inscription "U.S. Navy Mark 5, SuddarthOptical.com". The long road to building the U.S. Navy Mark V comes to an end.

With their newly assembled collimator, S.O.R.'s Cory and Cat headed to the 2019 Okie-Tex star party. Smiles were brought back to many sleepy-eyed astronomers as they serviced 44 items, free of charge, most of them being the Skyview 15 x 70, an apparent popular glass used by astronomers. In total, S.O.R. collimated 36 binoculars with the new Mark V in just a few days.

Cory would like to give special thanks to Bill Cook, IM Chief Michael O'Hearn, Eric Schleppegrell and Vencil McCurdy for their involvement in making this Mark V come to life.