Full Strip and Rebuild of an Intes Alter D-6 Mount

Adapter - 2010

OK. A great mount, big capacity, legendary Russian tank-like build and very little information to be had. A certain astronomer friend has one, the dec axis had a small and yet annoying movement contrary to the axis rather than with it. Opening up the drive end and doing the normal adjust the bearing compression had no effect on this issue and so a deeper expedition had to be considered.

It's pretty much impossible to get information on this mount - I have as yet found nobody prepared to tell me what's inside, how to dis-assemble it, what wears out, etc. so I was pretty much on my own. Here's a couple of pics - first the scope end and then the drive end that most of us are familiar with. It's at this point it all gets a bit worrying though because once the drive is out you are on your own!

And so, as mentioned above, the movement was not in the easy-to-reach bearing on the drive end but on the other end... this created a problem since there is no information on how this thing is made!

Let's get to it anyway - first up remove the drive electrics and the side plate.

Take out the motor (this is an AWR conversion - yours will be similar, the same or totally different!) To remove the drive plate you need to undo the screw in the centre revealed when you remove the motor, and

... the two screws underneath the housing also.

Motor and gear mount out and safe, note brass levelling adjuster may need to be loosened also to get the plate out - remember to make a record of roughly where this is first though before moving it.

Remove the locking nut from the end of the shaft - this is the only way of adjust drift in the bearings - *DO NOT DAMAGE IT OR THE THREAD*

That big (and as far as we are concerned here, OK) roller bearing will need to come off - it's a push fit on the aluminium shaft, should be a simple matter of lifting it off... Yes, I know I said it *should* be... but a bit of judicious wiggling of the shaft will see it loosen up.

With the bearing out the bearing sleeve must also be removed... four screws around the outside of the case  (one actually in the motor drive housing area) and then the bearing sleeve complete with it's housing can be coaxed out...

Once the bearing and housing is out, the Byers gear is revealed completely... six screws and this can be lifted out. Ours had a number (2 actually) stamped underneath - this number 2 had made an impression in the seating step so replacing the gear in the same place was easy. If yours does not have a similar mark then make sure you mark the orientation of the gear to the shaft.

At this point, the main shaft can be removed from the housing (actually the other way around - lift the housing off of the main shaft)

Almost right away you can begin to see what the problems might have been caused by... paint flakes, general machine swarf, all sorts of other crud has found it's way to the bearing. A bearing, note, that had only a light greasing and even that was hardening...

Now then, it was at this point that we came to a bit of a dilemma. This roller bearing is fitted from the scope end of the shaft, and yet there is no visible way of checking just how to get it off. No reall worry since all I wanted to do was clean the bearing, re-grease and re-assemble. However, the clutch on the head - when released - allowed the head to revolve and this was in a terrible state, grabbing, rumbling, jerking... just not smooth at all. How to get the thing apart though? After a lot of advice, hand-wringing, thought, legwork and general messing about it was decided that the central part of the shaft was nothing to do with this scope mounting/clutch and the owner of the mount, (around to see the progress so far), noticed that under the felt ring that sits on the axis scale was a locking ring. Ah Ha!

This was removed, the clutch lever unscrewed and the whole housing gently tapped off...

This revealed two more roller bearings sandwiching the clutch ring. Absolutely *NO* grease on the bearings, nor never had been...

With the axis now stripped as far as I needed, it was a case of tidy up and get the shaft degreased, hi-pressure cleaned and polished and then re-assemble the axis ready for the big night.

Re-Assembly

And so, with the shaft spotlessly clean, thread tidied, and everything else sorted, it was time to put things together. I have a plastic sealing machine which meant I could easily make up a piping bag to force the *HMP Lithium-based* grease into the bearings - so I was pretty much ready to go.

First up - regrease the two roller bearings inside the scope mount and gently, carefully, slowly, *squarely*, tap the cover/seat back into place making sure you align the clutch lever hole properly. Then pack more grease into the top roller bearing...

and re-fit the axis scale and felt ring (I had to cut a little from the ring as it seems to have grown!)

Finished at this end, so drop the outer housing into place on the shaft...

... and refit the Byers gear - remembering to locate it in the same orientation it was removed and to grease the shaft first. Below pic shows the gear with various unwanted members of the local flora and fauna removed... for this I use a solution of about 90% lighter fuel and 10% 3in1 oil, and a toothbrush.

Then refit the top roller bearing housing, the four screws that hold it in place...

... grease up the roller bearing itself and

... fit it snugly back into place.

Below you can see I have loosely fitted the locking nut (as this adjusts all the bearing pressures I will do final adjustment on the pier) and am ready to re-fit the motor/gearbox

It was only when I was taking the above picture that I noticed I had totally forgotten to grease the Byers gear... you won't will you?

Clean completely the drive and worm using the same solution mentioned above and copiously re-grease - note lots of grease on Byers gear!

Fit the drive plate into the housing with the three screws, remembering to set the brass adjuster somewhere close to it's original setting.

Finally, drop the motor back in, refit the electrics and go have a cup of tea!

Later...

Time came to re-install the mount in the observatory and see if all this work had been worthwhile (or not...) Put everything back on top of everything else and initially all seemed to be perfect - so the scope was fitted

... and final tightening and all that stuff was done...

A quick test showed - shock! - that there was still some movement to be had... buggerit! I left the installation with a promise to come back and re-adjust the bearings after they had had time to settle and see if that sorted things.

Later that day I got a call... some bloody idiot had not noticed that the movement we had was in fact *not* the movement we initially wanted to get rid of (which it turns out was now gone for ever) but was actually in the worm/Byers connection... a quick tighten of that brass bolt (remember that one I mentioned earlier and said not to forget? That's the one...) and all is now pretty much perfect.

Exit stage left one happy rabbit