It’s been raining a lot here recently. During the heavier rains my back yard turns into a lake with most of it being under 3 to 4″ of water. It was 7″ deep in one spot during the last rain. I’ve decided I want to fix this by installing some kind of drain. I can tell from the way the yard dries out that my yard isn’t flat and there a several high and low spots. There are drainage ditches around my house that I might be able to run the water into. To see what was possible I decided I should survey my yard to see what could be done. The first step in doing this was to acquire a surveyor’s transit. I could have bought a level but I liked the idea of being able to rotate the scope vertically. To that end, after a little research, I decided that I’d like to get a David White 8300 transit. It seemed like a good one and after watching Ebay for a bit I found one on Craigslist with a tripod for less than I’d seen on Ebay. Of course this one wasn’t in the best shape but I can fix that without much trouble. Or at least that’s what I thought.
I’ll jump to right now…this project bit me both figuratively and literally. Figuratively, I quickly learned that when aluminum and brass corrode they stick together really really well. Most of this transit is aluminum and all the the screws and knobs are brass. I tried penetrant, heat, tapping with a hammer, anything I could think of and the pieces have stayed stuck together or the brass broke. There’s a large nut that holds the transit to the tripod. I have tried everything I know of and it will not budge. I finally, threw in the towel and decided they’ll be together permanently. Literally, I got hurt working on this project. I was drilling out a broke bolt in the bottom of the tripod in the drill press. This part of the tripod head was still attached to the heavy bottom of the transit. It was going smoothly until it didn’t. The bit aught, torqued the piece around, and then tossed it at my chest. The chunk bounced off me harmlessly but along the way, one of the wings of the tripod head, slashed my palm in two places. After bleeding for a short time, I took a trip to the ER where I got to watch the doc skillfully sew four stitches into my palm. In a week or two I’ll be fine but I should have had the piece clamped down. So, do what we all know to do and clamp down the piece you’re drilling.
I’ve watched a few more transits go by on Ebay in much better condition than this one and for cheaper than I paid for mine. I like to think it’s the universe laughing at me. In retrospect I should have passed on this corroded transit but hind sight is 20/20 and if I had you wouldn’t be about to learn how to disassemble a David White 8300 transit. I hope this info will be useful to someone else out there cause there’s not much out there on these things from what I found.
Here’s the sad subject. Not much would move on this thing. It would rotate up and down and the leveling studs moved but everything else was frozen. I checked the optics out and they looked clear but the crosshairs were gone.
I’m sure there is a correct order to taking this thing apart but this is the way I did it. First, I removed what I’ll call the eyepiece. It’s more of a microscope that focuses on the cross hair. After light prying the assembly popped out. It was frozen and wouldn’t adjust so I needed to free that up first. The retaining ring at the end can be removed to get access to a circlip.
With the circlip removed I could slide the pieces apart and get to the corrosion. Once it was removed a bit of oil smoothed out the operation and I was able to put it back together.
Next, I wanted to remove the insert that held the eyepiece in place. I removed the two small screws at the end of the scope which actually hold it in place. It was, unsurprisingly, stuck. The four screws before the raised potion of the scope body hold in a brass ring that I assume is some kind of field stop. Further up the body, on the other side of the raised portion, are four screws that have been crossdrilled. These hold a thick ring which holds the cross hair. They can be worked in unison to position the cross hair. I used a small drill bit to remove all four.
On the bottom of the scope tube is a level. It’s held in place by four circular nuts with holes in it. Removing two allows the level to be removed. The level can be removed at any time. I randomly decided to do it here.
At this point I had clear access to the other end of the brass piece that held the eyepiece. I rammed it out with a wooden dowel. The little winged piece sit into a hole and helps keep the whole thing centered I think.
I started removing more knobs at this point. The one prominently shown locks the scope to the alitude tangent arm to allow for fine movement via the blurry knob in the back of this picture.
The altitude tangent knob was well stuck and I tried everything to get it out. Below I’ve wrapped an old bike inner tube around the knob. I am also using older channellocks with worn teeth covered in electrical tape to minimize damage to the soft brass. It didn’t work well. More on this in a bit.
At this point I decided to separate the transit into what I’ll call the upper part (scope and vertical movement) from the lower part (horizontal movement and leveling). Four screws hold these parts together. Here I am removing one.
With the top half off we get access to the azimuth vernier. The wide rimmed casting has the azimuth scale on it even though it can’t be seen in this picture. There is a central assembly here that is held in place by a wide flat brass ring that is threaded at the bottom with two opposing slots cut into it. It can be unscrewed allowing removal of the assembly.
With the assembly out of the way the large azimuth indicator piece and azimuth lock ring can be removed. They were very tight and require a lot of delicate work to remove. The azimuth indicator piece is pretty solid. The lock ring is very fragile though and I broke part of it trying to get one of the brass knobs out. It was later JB Welded back together.
Back on the upper half… The two lock tabs can be removed by taking off the split nut and then the top screw. The pieces that the tabs fit into can also be removed at this time by unscrewing the screws that hold it on. They’re better shown in the seventh and eighth pictures.
There is a flat brass piece that acts a spring for the fine altitude adjustment that is held on by two screws. The brass cap on the end with two holes can be removed to allow removal of the altitude tangent arm.
As best I can tell there are two mechanisms centered over the altitude axis. They can be adjusted to change the altitude movement resistance. On mine they were completely and utterly frozen solid. Attempting to remove the brass nut on one sheared off the post that it attached to and reveled a spring. My best guess is the nut puts pressure on the spring which puts pressure on a brass plug that increases the friction in the movement. They put pressure on two brass cylinders that support the scope. One of the brass cylinders has the altitude scale piece on it. The scale piece is held onto the brass cylinder by a clamp that can be loosened by removing the screw in it. On the bottom of the scope centered over each brass cylinder is a set screw that keep the brass pieces in. After removal of the adjustment mechanism and set screws I imagine it’d come apart easily. Not on mine though. I drove one of the brass pieces out with wedges and then used a punch through that side to drive the other brass piece out. Now the scope can be separated from its supports.