20 January 2021 at 11:08 pm #574869Grant PrivettParticipant
Last spring – soon after COVID Lockdown#1 started – anticipating lots of spare time, I decided it was time to upgrade my circa 2008 NEQ6 using a Rowan Astronomy belt drive kit (it was that or buy another mount and I’m mean). As it happened, I continued working from home throughout, but I’ve now finally got around to doing the upgrade. Anyway, it was mentioned when I first pondered buying the upgrade kit, that others might appreciate some sort of idea how hard it is to do and whether its worth paying someone else to do it or better to just upgrade to an AZ-EQ6. Here are my thoughts.
The EQ6 has been a pretty reliable mount for me with a quite good periodic error – for the price – but in recent years it has become prone to sharp spikes in the autoguiding trace. As the spikes knacker long exposures, I’ve tended to limit myself to 60, 120 or – rarely – 240s, so the idea of replacing the gear attached to the worm shaft was attractive.
I started work about a week ago, taking over the kitchen table entirely – I’m sure the gouges in the wood will sand out and merely add character. The instructions provided by Rowan Astronomy are pretty good and, as I was taking the thing to pieces for the first time, I thought I should check the state of the lubrication – a common complaint with older EQ6s. For that I found the Astrobaby notes and after reading them once went at it armed with a set of hex keys and small Philips head screw driver plus – most importantly – the optional bearing removal tool sold by Rowan. It wasn’t cheap for what it is, but I strongly recommend buying it.
The strip down isn’t intrinsically hard, but you do need time and space and to think about what you are doing. I quickly confirmed that it was worth doing as I discovered that while thick brown grease had been ladled on to the motor gears and Dec axis, there was none at all on the RA axis and some of the surfaces were slightly corroded – only a nylon shim eased the rotation. So, I’m glad I did the full strip down as things move freely now. For lubricants I used heavy molybdenum grease on the taper bearings and other steel-on-steel surfaces, with lithium grease on the other surfaces – though I have heard that superlube and lubriplate are pretty good too with the latter recommended for Paramounts. Previously, the mount was quite stiff and sticky in RA at times, but is now finger smooth
Probably, the toughest bit of the upgrade – which led to the use of variety of colourful anglo-saxon expressions at 3am this morning – was the reinstallation of the motors. At that point you are pushing the motor gear into the loop of the drive belt. However, as you get closer, the body of the motor obscures the loop and you cannot see exactly where it lies. That was no fun. It is immensely fiddly and there is a knack to it. I took about a dozen attempts in total for one axis, but then had to take it off again when a bolt fell behind the motor and refused to move. Oh, how I laughed.
By contrast, the most difficult bit of the strip down was taking off the large bolt that secures the RA axis taper bearing. Its smooth, its circular and had been Loctited. Following failed attempts with WD40, a hot water bottle, rubber gloves and mole grips I bought a metal belted oil filter wrench and, after applying a significant part of my body weight, it came off. So, 2 days lost there.
At one point I got really concerned that I had lost one of the slotted insert nuts that holds the bearing worm bearing in place but, luckily, someone on Astro Buy/Sell had a spare they gave me – thanks Graham! Having searched the entire ground floor of the house and the kitchen rubbish bin, I rather think it was never in there and I just didn’t notice during disassembly. Fortuitously, the bearing that the nut adjusted was still held in place by a rough edge on the casting.
Overall, the job has taken about a week with pauses during which Amazon delivered the oil filter removal tool, plus the supply of two new bearings for the worm shaft – the ones I found in the EQ6 seemed a bit loose. But, realistically, if you spent your formative years with Meccano and don’t rush, then you will have no real problems with this. But patience is required and leaning over it for 3 hours at a stretch can be quite painful – as my back is informing me.
So, if you are careful, don’t rush and willing to read and reread the instructions, plus watch the occasional video, then the upgrade and strip down is manageable by people with minimal practical skills like me. But set aside a whole weekend for the job. I’ve yet to run it on the sky, but its much quieter and feels smooth which is a good sign.
How has everyone else who has done this got on?
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