Introduction

				CG-5 INFORMATION
				Introduction
				Preparation
				Getting Started
				Declination Axis
				Right Ascension Axis
				Tripod Tips
				ASTRONOMY INFORMATION
				Barn Door Camera Mount
				Equatorial Mount Animation
				Comet Hale-Bopp Photos
				Constellation Portraits
				Home Page

These web pages describe and illustrate how I improved my CG-5 German Equatorial Mount. I did this by disassembling its equatorial head; removing the existing grease; cleaning, smoothing, and polishing internal bearing surfaces; regreasing with a good-quality synthetic grease; and carefully adjusting the worm and other components.

These instructions are also available in PDF format. Click here [719KB].

The project required about nine hours to complete, and the final results are well worth the effort. I can now turn the RA and Dec worm shafts with my thumb and index finger without using the knob. I hope the pictures and descriptions presented here will prove useful to other CG-5 owners.

What Is a CG-5?
The CG-5 is a popular medium-duty equatorial telescope mount available from several manufacturers. Actually, "CG-5" is Celestron International's name for its version of this mount, but other manufacturers sell what appears to be the same mount, and some of them have "borrowed" the CG-5 name. The same mount is sometimes sold as the "EQ-4."

Once you've fixed your CG-5, announce it proudly to the world with Astronomy Boy's official "I Fixed My CG-5" t-shirt! Click here.

The CG-5 is a copy of the well-known Vixen Great Polaris (GP) mount. The Vixen GP apparently proved so popular that other manufacturers decided to clone the GP and sell it under the CG-5 name. The two mounts are nearly indentical in appearance.

Owners of both the Vixen GP and the larger Vixen GP-DX mount have informed me that the descriptions which follow were useful to them in dismantling and improving their mounts. It should noted that, compared to the CG-5, the Vixen mounts usually perform well without extensive refurbishing.

Room for Improvement
By all accounts, one area in which the CG-5 suffers in comparison to the Vixen GP is the smoothness and ease of movement of the Right Ascension (RA) and Declination (Dec) axes. This is attributed to the thick grease used in the CG-5 and the rough finish of its internal mechanical parts. Some users report that motor drives do not work well with the CG-5, due to the stiffness of the moving parts.

CG-5 owners report a marked improvement in the performance of the mount can be realized by disassembling the equatorial head, cleaning out the old grease, cleaning and polishing all internal bearing surfaces, and regreasing. Both of my CG-5s were very stiff, resulting in jerky movements when slewing the telescope by hand. Since I wanted to add motor drives to the mounts, refurbishing the equatorial heads seemed like a good idea.

I searched the web for instructions on how to disassemble the equatorial head but found nothing. Postings in the sci.astro.amateur newsgroup provided some very helpful information, as did private correspondence with other CG-5 owners. In the end, I plunged ahead and dismantled my first CG-5, documenting the experience with a digital camera. These web pages are the result.

The "New" CG-5
In mid-1999, a new and improved version of the CG-5 mount began to appear. The CG-5 was improved with the addition of two ball bearings in the RA axis. Celestron apparently initiated the improved design, so that the mount could better carry the company's 9.25" SCT.

Comparison photos: Old and New CG-5 Mounts
Photo of New CG-5 RA Components