Hello All,

Need some advice here.
My 1200 mount axes have been attached for about ten years, no oil or grease used (didn't read the manual thoroughly!).
Any suggestions on how to separate them without doing harm?
Also, what type of lubricant and how much should be used for reassembly?

Thanks for any help,
Mike C.

On Jul 30, 2022, at 19:07, Mike Cadwell <mikecadwell@...> wrote:

Hello All,

Need some advice here.
My 1200 mount axes have been attached for about ten years, no oil or grease used (didn't read the manual thoroughly!).
Any suggestions on how to separate them without doing harm?
Also, what type of lubricant and how much should be used for reassembly?

1. Call AP and order a grease kit. It's cheap and has both types you'll need. You may also want to replace the delrin clutch plugs if your axis is rather stiff when unclutched. A baggie of those doesn't cost much, either. Depending on the age of your mount, there may be other things you want to consider. Older motors that might need the ESD protection board, A new/spare Y cable to have on hand, a fresh battery for your keypad, placing the RA axis clutch knobs with hex key set screws, etc. Call AP and George can help you figure out what you might want to do. Might as well do all you can while the patient's on the table.

2. Put the mount in Park 3, remove the OTA and stow any cables out of the way. Remove the motor Y cable and counterweights. Before you remove the CWs, stick a ring of painter's tape around the shaft to denote the upper and lower extent of the stack of CWs so you don't have to rediscover that later. You can choose to remove the CW shaft as well or leave it on, depending on how much you don't mind lifting later when you remove the dec axis.

3. Loosen the two large silver dovetail knobs on either side of the CW shaft. You can grab the saddle with one hand and the CW shaft with the other and pull up on the shaft. If the dovetail pins inside still catch, lower it back in place and unscrew the knobs some more. When the dovetail pins are sufficiently retracted, you can grab the CW shaft/bottom if the dec axes and pivot the entire dec axis up while also holding it securely by the saddle. Pivot it up from the bottom then lift it up and off the RA axis.

Remember to remove the OTA first, then the CWs. When you put things back together, CWs go on first followed by the OTA. You don't want to take the CWs off and have a loose clutch cause your OTA to violently rotate down into the pier or side of the mount.

/dale

On 7/31/2022 3:30 AM, Dale Ghent wrote:

2. Put the mount in Park 3....
3. Loosen the two large silver dovetail knobs on either side of the CW shaft. You can grab the saddle with one hand and the CW shaft with the other and pull up on the shaft. If the dovetail pins inside still catch, lower it back in place and unscrew the knobs some more. When the dovetail pins are sufficiently retracted, you can grab the CW shaft/bottom if the dec axes and pivot the entire dec axis up while also holding it securely by the saddle. Pivot it up from the bottom then lift it up and off the RA axis.

Dale's detailed instructions are spot-on.

As I built my observatory, I shot many photos. The third photo on this page: <http://house.mdodd.com/proj_obs_scope.html> shows the dovetail fitting on the RA unit, and the fourth photo shows one of the silver knobs that lock the RA unit in place.

My comments on that page say the RA unit weighs 31 pounds, and the CW shaft weighs 14 pounds, so if you leave the shaft attached, you're moving 45 pounds.

I recommend unscrewing the CW shaft. I was assembling my 1200 from cartons used to move it, so the CW shaft was not attached. I was thankful I had to lift only 31 pounds to the RA unit.

Hope the photos help.

--- Mike

On 7/31/2022 8:48 AM, Mike Dodd wrote:

...and the fourth photo shows one of the silver knobs that lock the RA unit in place.

Sorry, I meant to write "Dec" unit.

--- Mike

--

--
Roland Christen
Astro-Physics

The R.A. unit "polar fork axis" weighs around 50 lbs

It's an aluminum to aluminum interface. I imagine that the mount would have to be in a visibly poor shape and pretty much extremely abused for the dec and RA axis to be bonded via corrosion in such a way. There is no lubrication there to begin with and there is no need for any.

On 7/31/2022 1:38 PM, Dale Ghent wrote:

It's an aluminum to aluminum interface. I imagine that the mount would have to be in a visibly poor shape and pretty much extremely abused for the dec and RA axis to be bonded via corrosion in such a way. There is no lubrication there to begin with and there is no need for any.

That's my opinion as well. I used my 1200 in an observatory for 3+ years before packing it for a move. The mating surfaces were pristine. Seven years later, they were still pristine when I unpacked the cartons and installed the mount in my new observatory.

I never even thought of applying lubricant to the machined aluminum surfaces.

--- Mike