Helios scope, continued.
The task with this scope is to economically fix the problems with the OTA and the minor quibbles with the mount. After all, the whole idea is to get an economical 8" scope. Unfortunately, upon opening the OTA more problems were found. Aside from the main mirror being spherical, the secondary is a simple handmirror of questionable suitability for astronomy use. Also, the secondary mount vanes are of a thickness causing light loss.
These issues could be addressed one at a time. A set of vanes is about $75, a new mirror is $120 and a new secondary is $35 or so. However, the most economical path given our time was to instead junk that tube and order a complete 8" 1000mm f/4.9 OTA of known optical quality from Orion. The total cost was $269. While the tube was in transit, we addressed the defects in the mount.
The mounting holes on the dec gear mount. The material needed to be removed is marked with a Sharpie. Basically, the holes have to be elongated so that the gears can mesh.
Using a drill with a 3/16" bit, pressure is applied sideways to elongate the holes. Note that this is bad safety, but the metal is soft and the process does not take long. Not much material has to be removed to get the gears to mesh. If you get hurt doing this, blame the factory for sending them out needing this.
The holes, partially elongated.
When the gear is reattached, pressure to hold the gears together must be applied when the bolts are tightened.
The 8" Orion OTA has a greater outer tube diameter than the Helios. Therefore, the ring bolts had to be replaced with longer ones. These are 3 1/2" long 1/4" bolts from the toolbox. 3" would be better (note the spacers) but did not have. The tube is also 18" longer and about 8 lbs heavier, but the mount is up to the task.
The Parks 8x50 illuminated guidescope is attached to one of the auxiliary mounts on the Helios rings.
The finished scope. This will be referred to as the Helios-Orion in upcoming usage. The total cost is $260 + $270 = $530 which is only a little short of the Orion 8" with motorized mount. However we now have a serviceable scope. The Orion OTA will be reviewed at a later date. However, the preliminary judgment is the images it produces are very good to excellent, with Cassini and the planetary shadow visible on the rings of Saturn (using 6.3mm Helios eyepiece) after only a quick collimation (as viewed Jan 18 2003).