Okay, so let's get started! But first, it must be considered that Cave changed the design of their scopes throughout the years and there are significant and subtle differences to be found. I'll address what I know about these differences as we go along.

The procedure goes to first dismantle the OTA and then the Mount.

Now, we're going to need some tools. Nothing fancy, but definitely needed to get the job done. Since we're starting with the OTA first, I'm going to recommend just the tools for this part of the job...



Not much! A set of Allen Wrenches, a couple flat head screwdrivers, wrenches, sockets, a marker and the Rubber Mallet and Wooden Drift.

But if you have a really old Cave, you may also need a drill and drill bits.

Remember to wear eye protection as needed - and of course, this is only a guide and you are ultimately responsible for your work and outcome. Be safe, patient and careful and the end result will be just awesome!

 

Step 1 - Remove the Optics!

It's important to remove the Optics and put them in a safe place to prevent any accidents, such as a tool falling loose during disassembly and damaging the mirrors. The Primary Mirror will be removed first.

The Aluminum End Rings may need to be removed first to easily remove the Primary Mirror and Cell. If the Aluminum End Rings have a lip that overhangs the end of the Tube, then it may be difficult to remove the Mirror and Cell. I think that during assembly, these Aluminum End Rings were the last finishing touches to be done on the OTA after everything else was attached. Earlier Caves have an Aluminum Band that is riveted on and presents no obstacle for sliding the Mirror and Cell out the tube. Rather than find out if the Mirror Cell will clear the End Ring's lip, I prefer to remove the End Ring first...

The Aluminum End Rings that are not riveted on are pushed on. Use the Wooden Drift, in this case, a sawed off section of broom handle and the Rubber Mallet (or a plain old hammer) to work off the bottom (Primary Mirror) end ring by firmly but gently holding the Drift against the edge of the End Ring and tapping it lightly with a hammer. Work around the End Ring to evenly slide it off the tube. In some cases, the End Ring will be on tight, other times, it's just barely held on. If it doesn't seem to be moving, don't force it! Soak the Tube and the End Ring in some warm water for an hour or so and try again.

For the early Caves with the riveted on end rings, you probably do not need to remove them now to remove the Primary Mirror and Cell since they do not have a lip that obstructs the Mirror Cell.

Up to this point, we are getting ready to remove the Primary Mirror and Cell. But have you thought of Gravity?

 

Yes a torch is also handy for removing those stubborn parts We'll cover more of that when it comes to removing rusty things off the Declination Shaft!

 

Now about Gravity... When the Primary Mirror and Cell is removed from the OTA, the OTA will become unbalanced. In order to prevent the OTA from swinging around and knocking something over or causing damage while you are holding the Mirror and Cell in your hands and cannot prevent the disaster from happening, it's best to either point the OTA so that the Eyepiece end is down or remove the OTA from the mount and sit it on a suitable work surface. Since my work surface (shop bench) is always cluttered with junk, I prefer to disassemble the entire scope on the mount.

Here is another Cave (8" f/4.5 RFT) with the Eyepiece end pointed down - the Declination Circle reads 90-degrees):

 

I wont post a picture of my workbench, I'll leave that to the imagination

There are usually 3 machine bolts that hold the Mirror Cell to the Tube. The Big Caves have 6. Before removing the Mirror and Cell, mark on the Cell and the inside of the Tube to indicated which leg of the Mirror Cell matches the mount hole on the Tube. It seems that every Cave Telescope ever made was put together by eyeball without any precision measurements. The Mirror Cell is no exception and its bolt holes will only match up one way to the Tube. Sometimes, Cave would mark the Mirror Cell Leg with a punch mark into the metal for the leg that should be aligned with the Eyepiece or Tube Seam. I've never seen one; it's easier to just make my own marks. Later, we will consider a permanent mark on the OTA and Mirror Cell.

 

Remove the Mirror and Cell. Now is a good time to inspect the Mirror surface and decide if it needs to be recoated with the idea that while we are overhauling our scope, the Mirror (and secondary) can be sent off and hopefully finished and returned before we're ready to put the scope back together again.

In the case of this scope, the mirror was recoated about 3 or 4 years ago and doesn't need to be recoated again. The Mirror Cell, however, although functional, has some things done to it that I want to un-do. But we'll also get to that later



Do you see my permanent mark for the Mirror Cell legs? There is an "EP" written with a permanent marker on the edge of the leg in the forefront. That helps me to know exactly which leg matches which hole in the OTA when installing the Mirror and Cell. The leg with the mark of "EP" lines up with the longitudinal position that is closest to the Eyepiece.