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Now it’s time to return to the DEC axis. The process is pretty much the same as for the RA axis, starting with the removal of the clutch lever (having remembered to release the clutch first).

The worm housing should then just lift off (note the plastic shims here, too).

At this point, replacing the gear driving the worm is exactly the same as for the RA axis, so here we are again with that all done.

Reassembly is pretty much identical too, at which point the DEC axis can be put back on the mount. This was a touch awkward. I had to try three or four times before everything dropped into place correctly. I think it must be very sensitive to alignment and once I got it right everything just dropped into place easily.

That’s most of the hard disassembly/reassembly work done. All that remains is to modify the motors and refit them.

With the worm housing in a vice (protected from damage by the vice) I used circlip pliers to remove the worm end caps. I do actually have the additional tool from Rowan Astronomy for doing this, but circlip pliers were easier.

Then the retaining grub screws for the gear driving the worm need to be released. I’ve seen people fighting with these in videos, but in my case they came out without too much pain. Certainly they were tight and my allen key did flex a little until they first released, but they really weren’t that bad.

Then the retaining collar for the worm needs removing. I did use the Rowan Astronomy tool for this. It’s just a lot easier in this case to have something that fits perfectly.

The tool itself is on the left here:

After that the worm dropped out (together with the bearing at that end) after the lightest possible tap with a drift. Again you need one hand for the drift, one for the hammer and one to catch the worm so it doesn’t drop on the floor. If you have a fourth hand to catch the gear as well, even better. Or try to do the entire removal process with the housing laid down (my workbench has a handy lip on one end, fortunately).

I then used a larger drift to remove the remaining worm bearing as I’d decided to replace the worm bearings at the same time as doing the belt mod.

The new bearing for the gear end went into place very easily and after that it really was just a simple case of following the instructions to reassemble everything. When fitting the new belt pulley I very lightly tightened the grub screw that bears against the flat on the end of the worm, stopping as soon as I felt any resistance. Then I wiggled the pulley about a bit to get it pretty much central on the flat, lightly tightened it again and repeated the process until it wouldn’t wiggle any more, finally tightening both grub screws fully.

The second grub screw protrudes a fair way out of the pulley collar even when fully tight. It only just clears the inside of the motor housing. I reckon there’s no more than 0.5mm in it:

Then it’s back down to the observatory to refit the worm housing.

In fact I decided this was more easily done by propping up the RA casting, dropping the RA gear into place and then feeding the worm housing over the top:

(I also cleaned off all of the unnecessary grease and re-greased the DEC gear ring.)

The little brass block in the above photo is actually part of the adjustment mechanism for the worm engagement. The grub screw in the worm housing pushes against it.

With the worm housing back in place I put the four retaining screws back in, but only tightened them just enough to stop the housing being able to move. They get fully tightened after the worm adjustment is done.

Here you can see the belt drive where it comes through into the main motor housing.

With that all done, the entire housing can be replaced on the mount.

So, RA axis next, starting with the polar scope. This just unscrews. I was almost tempted not to put it back at the end. Now I have an observatory I only used it for a rough polar alignment before doing the rest with Ekos.

After that the collar with the pointer for the polar scope scale has to come off. Just three screws this time.

And then the retaining collar for the bottom end of the RA axis. This was a bit more awkward. I’ve seen people use oil filter removal tools for this, but I wrapped some thick card around the collar and used a large adjustable wrench. It wasn’t actually that hard to turn once I’d got a grip on it so I didn’t have to get out the Stillsons, and in fact once loosened by quarter of a turn I could turn it off using my fingers.

The RA clutch mechanism needs to be released at this point so it’s free to turn easily and then the lever can be removed by undoing the screw holding it on.

The clutch mechanism can then be unscrewed by hand. I wound it out a fair way so there was no chance of it getting caught on anything as the RA axis was disassembled, but there’s a small brass disc on the end that might drop somewhere awkward if it’s undone all the way, so it’s probably best left in place.

After that the entire RA axis lifts out and you’ll once again need to use your third hand to catch the tapered roller bearing at the bottom end in case it falls out.

A quick peer down the end of the remainder of the mount shows grease in places I’m sure it wasn’t meant to be and some fairly dodgy casting at the bottom end.

Removing these four retaining screws from the worm housing allows it to be removed just by lifting it off:

Above the remaining bearing on the RA shaft you can just see a white plastic shim which needs to stay there, but I’m not going to touch that. When I lifted the top bearing off the worm housing I found a couple more.

So I made a note that they need to go back between the two. There’s also an awful lot of grease here that doesn’t seem to be serving any purpose whatsoever.

After undoing the screws that hold the DEC collar with the hour markings on, the worm housing just lifts off and it’s time to visit the workshop.

Next the entire DEC axis has to be removed, starting by unscrewing the collar for the counterweight bar, which comes off very easily.

There’s a tapered roller bearing at this end of the axis which could potentially fall out when this is removed, though mine didn’t and I’d generally expect it to stay in place. It is likely to fall out when the entire DEC end is now lifted out of the mount though, so you need to have one hand ready to catch the bearing whilst using the other two to lift the DEC axis out of the mount. Some videos show the removal being quite awkward and I was prepared for a bit of a fight, but mine lifted out very easily and I fitted the bearing that I dropped caught back on the end of the axis for the time being.

The instructions suggest leaving this to come back to later, so that’s what I did, though if you’re just congenitally unable to follow instructions exactly there’s no reason the rest of the conversion work couldn’t be done on this axis now.

The first job was to remove the control panel by undoing the four outer screws (the inner ones hold the circuit board in place). What’s inside is actually pretty uncomplicated:

That actually looks less threatening than the inside of the EQ3-2/EQ5 after-market motor handset 🙂

The cables that have to be unplugged are all that the end near the top of the photo, neatly labelled, though actually all the plugs are different and keyed so it wouldn’t be possible to put them back the wrong way. The RA connection is a bit odd in that it runs down the inside of the mounting posts for the circuit board.

It was a bit fiddly to get back on at the end, but nothing major.

With the circuit board removed access to the motors is pretty straightforward:

The RA motor came out very easily by undoing the two large screws.

There was a small disaster when I tried to do the DEC motor though.

Fortunately I was able to fish all the broken bits of screwdriver tip out of the inside of the mount without them disappearing anywhere awkward. And then I found a better quality screwdriver to complete the job 🙂

Just before the bank holiday this arrived in the post courtesy of First Light Optics:

Such was my enthusiasm for getting started that I’m not sure I have a photo of the contents, so until I find it (assuming it exists) I’ll just have to say that in includes the separate kits for the RA and DEC axes (pulleys, belts, motor mounting plates and idler wheel plates), some allen keys, a pair of tweezers and six pages of detailed instructions. Somewhat more daunting than the HEQ5 conversion I did very recently. I’d watched a few videos of the NEQ6 belt conversion being done and it looked like a significantly bigger job.

On the positive side, the recommendation was again to leave the mount on the tripod (or pier in my case) whilst doing the work, which means I shouldn’t need to redo the polar alignment afterwards.

No excuses not to get on with this now. A little delayed (it was ordered at the same time as the HEQ5 Pro kit), but it has now arrived…