Stripping down the RA and DEC (right ascension and declination) bearings

After much hand wringing, anxiety and head scratching  I though I’d give stripping down the bearings a shot. The Declination Axis seemed the easiest to begin with, being attached to the face plate of the head. A few hidden and painted over Allen key grub screws located and loosed and it a disassembled without too much fanfare.

The brass on brass bearing surfaces seem to all be in good condition. The old solidified, waxy grease was removed with methylated spirits and a new synthetic low viscosity grease was applied. I dropped the bottle of meths all over my wooden  surfaces and unfortunately my workshop now smells like a solvent factory. Tasty.

So it’s all reassembled and turning with only a fraction of the force needed before so it should rotate nice and smoothly with 30KG of OTA attached to it. There is corrosion on the steel shaft that was exposed between the counterweights and the bearing housing but it’s well greased so shouldn’t need turned down in a lathe.

Two simple clamp rings fix the DEC axis to the equatorial head so it’s a 5min job to remove and refit.

A notable point is brass on brass bearing is technically self lubricating and requires no grease but since there’s the steel shaft mating with the brass I applied it to all surfaces. It will no no harm unless dirt ingress becomes a problem at which point the brass can become scored or damaged. As the sealing is very good I’ve got no such concerns.

 

The RA bearings were a little more problemsome. I was barely able to spin the RA gear as it was so badly seized up. The various collars were exceptionally hard to remove having been in place many decades. However with a little bit of gentle persuasion and some tricks I learned from Uri Geller I eventually got it all apart. The shaft took a fair old smack with a piece of wood and a lump hammer to free it from the bearings.

Again the old grease and waxy deposit was removed, the entire assembly greased and rebuilt and it all spins more smoothly than a politicians tongue. For an 80 year old scope the mechanics are surely in very good condition. Job well done.

At 40KG all in it is a beast to handle. The mechanics dealt with I will have to have a careful thing how I treat and protect the outer surfaces. Areas where he paint has flaked off  the brass may well need stripped completely and repainted or lacquered which may necessitate another complete strip down, but this is now a job that will take minutes as all stubborn parts are freed.