EQ3-2 Mount Tune-Up (Part Two)

Posted on January 31, 2012 by james

Whilst I had the mount on the bench I thought I’d have another look at what seems to be a perennial problem with the Skywatcher mounts at UK latitudes: the mounts are at the limits of their design spec. for the alt adjustment which regularly results in problems with the south side bolt bending or running off the adjustment cam, or both (as in my case).

I’d already had the south bolt out to straighten it and not been at all happy with the way the bolt worked since. I know that some people have fixed an extra piece of stainless sheet over the cam with epoxy resin effectively making it harder and longer, but having gone to the trouble of cutting some suitable sheet up I decided that it that doesn’t seem like entirely the right solution. It struck me that what’s required is some sort of “tappet” that rides on the cam and is free to rock as it changes angle relative to the bolt, preventing the bolt being loaded sideways. In a box of plumbing bits I found a 10mm brass end cap and an 8mm olive that would fit inside it nicely. (You can see them in the bottom left of the photo.) The bolt fitted inside the olive with some room for the end cap to rock, though not much. I made obeisance to the Greek Goddess of Adhesives, Araldite, and used a little to fix the olive inside the end cap. I then fiddled the entire thing onto the end of south side bolt so it rests on the alt cam.

Whilst it’s an improvement, it’s not a big improvement and I’m not entirely happy with it. I’m now thinking that what’s probably required is a block with a dished centre to be fixed to the back of the came so the bolt always bears in roughly the same place and can’t slide down the cam as it moves further away. It’s more tricky to do, too. Of course what’s really required is for Skywatcher to redesign the mount for more northerly latitudes, but I can’t see that happening before Betelgeuse goes supernova.

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EQ3-2 Mount Tune-Up (Part One)

Posted on January 31, 2012 by james

Having read a posting on Stargazer’s Lounge about converting the EQ3-2 to direct(-ish) drive on the DEC axis, I thought I’d have a go myself. My EQ3-2 mount is one of the older models with a “Sky Scan 2001” logo and finished in something resembling Hammerite black.

The manufacturer of these mounts has a reputation for using something more akin to glue than grease for lubricating the gears and one of the first recommendations for improving any of them is to split the mount, clean the grease off and regrease with something that more closely resembles a lubricant. A little apprehensive as I’d never seen one taken apart before, I took the mount over to the workshop and made a start.

First job is to remove bar for the balance weights from the bottom of the mount and the cover for the top end of the polar scope. Through the hole you should just be able to see the bottom of a 17mm nyloc nut at the bottom end of the DEC spindle. That needs to be undone by turning the nut in the centre of the mount saddle (16mm, oddly).

With the nut undone you need to fiddle it, the plastic washer and metal washer out of the inside of the mount. Having small fingers really helps here. Sadly I don’t. Then the entire saddle and DEC drive lifts off. Remember that for re-assembly the metal washer goes on first and the plastic washer goes between it and the nut. More on that later.

Next to come apart was the worm drive housing. This is held on by four allen bolts, two long ones that fit into the saddle from what is usually the bottom, and two short ones that fit horizontally (and have a grub screw between them for adjusting the tension between the DEC gear and the worm. With those out, the DEC housing just lifts off. You can see the full extent of the horrible black gunk used instead of a lubricant now.

The worm drive will come out for cleaning properly. It’s held in at one end by a bush with an external thread. The bush screws into the worm gear housing and keeps the brass worm drive firmly located in the bush at the other end. The bush is locked in position with a lock nut that has to be undone first.

Once the lock nut is off it’s possible to remove the threaded bush. There are probably several ways to do this. The bush has a couple of slots cut into the top edge and I found a screwdriver that would fit one and turned it using that until it was loose enough to undo with my fingers. If you happened to have another nut that fits you could lock the two together at the end of the bush and use them to unscrew the bush. In theory it should then be possible to withdraw the brass worm gear, but I found I had to clean a lot of the black goop off before it would actually feed through the hole.

On the worm drive are a number of o-rings, washers and bushes that also need to be removed and cleaned. I thought the washers were black when I first took them off, but they’re actually clear plastic. Looking at this photo I’m sure there’s another bush that I’ve left in the housing at the right hand end. I’d not be surprised to find another o-ring behind it, either. I shan’t worry too much that I’ve missed those.

The final item to remove was the DEC bearing. This just lifts off. I found two red washers on the top (as it appears here, but the bottom in its normal orientation) and one at the other end. I then collected up all the icky black bits and took them off to clean them properly. I’m told that isopropyl alcohol or brake cleaner work well for this. Not much else seems to with the exception of towels, curtains, door handles and anything else you never wanted to get the stuff anywhere near.

Once cleaned up, reassembly is simply the reverse of disassembly, as it says in all the best workshop manuals, putting some decent grease onto the gears as you go. There really aren’t too many tricky bits though. The first is to get the worm drive retaining bush screwed in far enough so there is no lateral movement in the worm. It’s easier to get it roughly right and then get the housing mounted onto the saddle at which point it can be wiggled around to see if there’s any play. If you overdo it, the worm becomes hard to turn. The intention is to get everything to run as freely as possible whilst removing as much play as possible.

Next is getting the tension between the worm drive and the DEC axis gear correct. Once the housing is held in place with the long allen bolts, the short ones can be fitted. Try to get them so the housing first as square as possible. The game is to undo the grub screw and take up the slack squarely with the allen bolts without making the worm bind against the DEC gearing. Very small changes can make a big difference here. I found that an eighth of a turn on the allen bolts could make the difference between turning freely and binding.

Finally, putting the washers and nyloc nut back on the end of the DEC axis through the polar scope cut-out. If you have small fingers it might be easy. I found it simpler to turn the mount upside down meaning that the washers could be dropped over the threads and the nut held in place with pliers until the threads were engaged, avoiding dropping them all down inside the polar scope “tunnel”.

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Observation Report, 27 Jan 2012

Posted on January 30, 2012 by james

Something of a shock, being about to get out with a telescope three nights out of five, but given a decent forecast my intention was to go out and find M32 and M110, the two galaxies close to the Andromeda Galaxy. I’ve never been able to find them before despite them looking very obvious in Stellarium.

As luck would have it, that part of the Andromeda constellation was quite close to the zenith and I ended up standing the ST120 tripod on a table to allow the scope to tilt almost vertically whilst allowing me to get close enough to get to the eyepiece. I spent some time looking at the main galaxy itself, trying to spot M32 in its outer reaches before it dawned on me that in such a small scope I might only actually be able to see the main galaxy core and that both M32 and M110 would therefore be much further out than I was looking. Sure enough M32 was then easy to pick out as a small fuzzy blob and star-hopping got me to M110 which was difficult to distinguish from a single star even at fairly high magnification.

Whilst in the area I thought I’d look for the Triangulum Galaxy, about the same distance the other side of the main “spine” of Andromeda; another on my “yet to see” list. Finding it by position alone proved beyond me, so I star-hopped from the bottom star of the Triangulum constellation, Mothallah. There’s a set of stars leading down to a single brighter star labelled in Stellarium as HIP7906 which is just over half way to M33 from Mothallah. On this night at least, this galaxy appeared very small and faint and was barely visible with direct vision.

Moving to the north I found Merak in Ursa Major and then star-hopped down a chain of stars to M108 which was only just discernable as an elongated blur and beyond that M97, the Owl Nebula which was very difficult to make out, but clearly forms one corner of a box with a set of three stars between about 6.5 and 8.5 in magnitude. Averted vision was possibly the easiest way to actually see that anything was present at all.

Final target of the evening was M109. Dropping down to Phad at the bottom of the Plough I star-hopped down to a triangle of 8.5 to 9 magnitude stars surrounding the galaxy, but it was just as hard as M97. Eventually I finally saw it, but only with averted vision.

These six have left me with very few Messier objects left to find in the winter sky (M61, M74, M77, M79 and M104) so I might start returning to some of those I found first now I’m finding it easier to recognise what I’m seeing.

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Observation Report, 26 Jan 2012

Posted on January 27, 2012 by james

It’s been some time since I’ve been out with the ST120 so with a forecast for clear skies last night I decided to have a change and moved it outside to cool down. Unfortunately the weather didn’t live up to its billing and whilst there were regular patches of clear sky there were also regular drifts of cloud. I was keen not to write the evening off entirely however. Top of my list of targets — mainly Messier objects I’d not managed to find last winter — was M50. That seemed like the best choice to try as I planned to find it by a short star-hop up from Sirius.

I used the RDF to locate Sirius and then with a 32mm eyepiece hopped north to find a small triangle of stars including 11 CMa. A little further north and east took me to Theta CMa whose intense red colour was obvious compared to the stars around it. North of Theta CMa is another triangle of stars of about 6.5 magnitude. That triangle points north, just to the west of M50 which came into view as I moved the scope in that direction.

I have to admit that in 32mm and 25mm eyepieces M50 didn’t look exactly overwhelming and even at 60x magnification with a 10mm eyepiece it was indistinct and the stars wouldn’t resolve clearly as a result of the cloud. There was a definite “fuzz” around the brighter stars where others would had been visible had the sky been more clear. Now I’ve found it I think this will be one to revisit when the seeing is better.

Virgo was near fully-risen at this point and my next target was M61, but even Mars (currently in Virgo) wasn’t visible because of the cloud so happy with finding my 70th Messier object I decided to call it a night there. Clear skies are still forecast for the small hours of the morning of the 28th so I’ll see if I can do better then.

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Observation Report, 23 Jan 2012

Posted on January 25, 2012 by james

Clear skies were forecast today, so I got the Mak 127 out early in the afternoon so it would be cool as soon as I wanted to use it. Then the clouds rolled in and it started to rain. I was certain another night’s viewing would be written off because of poor seeing in the moist air.

Sometimes it’s pleasant to be wrong. By 10pm the clouds had cleared nicely and whilst there was a certain amount of haziness around the horizon, the sky generally was clear, bright and steady. Just as well, as I wanted to try out my new illuminated reticle eyepiece as well as counting the stars in Orion for the CPRE Star Count.

To centre a planet in the webcam image my usual method thus far has been to start with a 32mm or 25mm eyepiece and centre the image then keep stepping down the focal lengths to around 6mm, then add a barlow, and finally swap to the webcam, swapping back and forth with an eyepiece if it didn’t immediately show up on-screen. Plunging straight in, I lined up Mars with the RDF, centred it in the new eyepiece, added the barlow and re-centered and then switched to the webcam. The image of Mars was immediately visible in the capture program and needed nothing more than a little refocusing. I was most happy with this improvement and set about capturing some images.

That done I spent a bit of time just re-familiarising myself with the winter skies. There have been precious few opportunities to get out under good skies in the last six months, so I’m a bit rusty. Six stars were easily visible in the Pleiades, perhaps seven at a push, and the Beehive Cluster was quite clear for direct viewing with the naked eye, so I broke out the binoculars and took a closer look.

As soon as I put the eyecups up to my eyes a large fuzzy blob leapt out of the sky, causing me a few moments confusion. It didn’t look like I remembered M44 at all. It took a few moments to dawn on me that it was M67 I was looking at and a quick slide northwards revealed the Beehive in all its glory. Swinging back to Orion I had to have a look at the nebula. Not a huge amount of detail visible with the binoculars, but the extent of the gas cloud was vibrantly clear and impressive.

Three of the first few Messier objects I saw through a telescope were M36, M37 and M38 in Auriga. I clearly remember spending a couple of nights working out how to find them, probably with the ST80. Auriga was right in front of me now, so I scooted across to the southern end and hopped up to the first one following a “bent tuning fork” asterism. Within five seconds I’d located all three with ease. Having collected almost half “the set” now, it’s surprising how much easier it is to recognise a grey fuzzy blob when you see one…

Remembering that I also wanted to count the stars in Orion I ran through the constellation a few times picking them out. The “rules” are to count as many stars as possible visible with the naked eye within the rectangle formed by Betelgeuse, Bellatrix, Rigel and Saiph. The “belt” stars count, but the four corners don’t. After a couple of recounts I decided that twenty-five was a fair result. I could possibly pick out a couple more with averted vision, but I couldn’t be sure.

By this time it was gone 1am and the sky was starting to become quite hazy so I happily decided to call it a night. More clear skies are forecast for the tail end of the week. Hopefully I can get some footage of Venus and Jupiter, and perhaps go hunting a few binary stars.

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A (Relatively) Cheap Illuminated Reticle Eyepiece

Posted on January 23, 2012 by james

When imaging with the 127 Mak and SPC900, getting the target somewhere the webcam will pick it up is one of the most awkward things to do. It’s made more tricky by the fact that if the scope is sufficiently far from focus then there won’t be a discernable image on the webcam to start with.

My previous solution to this problem has been to start with a 32mm eyepiece, centre the target and then run up through a range of eyepieces (25mm, 15mm, 9mm, 6mm) checking that the object is still in the centre and realigning as necessary before dropping the webcam in. At that point I turn the gain and brightness full up in the capture program and hopefully I can see something resembling a fuzzy blob on the screen that allows me to adjust the focus.

For some time I’ve been thinking about getting an eyepiece with an illuminated reticle to allow me to short-cut this process, but I’ve been put off by the prices. I discovered last week however that Sky’s the Limit who I’ve used for kit in the past had just such an eyepiece with a 12.5mm focal length going for less than £40 so I thought it would be worth a try. Here it is:

The LED is powered by two GP189 batteries (included). The knurled knob at the end of the LED unit turns it on and controls the brightness. There’s also a knurled adjuster on the top of the eyepiece. This is used to get the reticle lines in focus, but it does also change the point of focus of the telescope at the same time.

I’ve had a very quick test this evening looking at Mars and am happy that it does what it says on the tin. Unfortunately cloud prevented me from trying it out a bit more. What was quite surprising was how fast the image of Mars crosses the field of view at 120x magnification. I’m used to it happening, but somehow it seems far more obvious when you have some sort of visual reference.

I look forward to trying it out properly in my next imaging session. The only down-side is that I’ve run out of room in my eyepiece case…

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New Apiary Progress

Posted on January 22, 2012 by james

I found time this weekend to get out into the new apiary area and clear up the mess from felling the trees last time, including cutting one of them up into shorter lengths to dry out this year. That allowed me to get the digger in to form the second “terrace” level which turned out to be somewhat trickier than planned. Whilst the soil was quite deep under the top level, further down the slope I discovered that there was little more than 50mm of soil on top of solid rock. I had to change my plans slightly, but I think I’ve done an acceptable job in the end.

Once this area was clear I realised there were two possible bullace trees. Both had a fair amount of dead wood and one was very tangled with branches growing in all directions. I’ve pruned them fiercely, leaving five to six feet of trunk standing. Either they’ll come back this spring or they won’t. If they do, they should be able to grow in a far nicer environment where they have plenty of access to light and little competition.

Behind those I cut down some standing dead trees and started cutting the hazel down to size but eventually ran out of light. I also have one sycamore trunk I’d like to remove as it will overhang the apiary. Anything else can be taken out at a later time as it will fall in a more convenient direction.

So, here’s how it looked when I stopped work this afternoon:

Whilst working on the hazel I discovered a pile of seven or eight bottles lying underneath it. I have no idea how long they’ve been there, but they look very much to me like the old-style (1970’s) milk bottles I remember from my childhood. Each one has “CONTENTS 1 PT” moulded into the glass on the outside, so I guess it’s possible. I’m going to clean some up and have a better look as they’re rather green at the moment:

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Cleaning a Celestron Ultima Barlow

Posted on January 22, 2012 by james

I had a close look at my Celestron Ultima 2x barlow the other day having spent a few nights out imaging Jupiter and Mars and discovered that it was disgustingly filthy. No idea how it should have got so dirty given that when it’s not in use it’s stored in an eyepiece case with end-caps on, but there you go. This was more than just a couple of specks of dust that would probably get lost in the overall image, so I had to do something about it. Fortunately some time back I purchased some Baader Optical Wonder cloth and cleaning fluid for just such an occasion.

Dismantling the barlow was pretty straightforward, though I had no idea what to expect. I first unscrewed the two halves to leave just the lower metal barrel section containing the optics. From the bottom I then unscrewed the lens retaining ring by putting my thumbnail into one of the notches in the ring and turning it anti-clockwise. With that removed all the elements could be pushed out from the other end of the barrel. First item out is what appears to be a thick lens, but is actually two lenses cemented together, with the thinner one at what would normally be the open end of the barrel. Next was a thin spacer, and finally another lens that is convex side uppermost in the barrel. In this photo the parts are in the order they came out, left to right.

I following the instructions for using the cleaning fluid and it was immediately obvious that the lenses were much improved afterwards. It’s not particularly easy to get them all back into the barrel one at a time however, so I first stacked all the pieces up on the table, and then slid the barrel down over them before screwing in the retaining ring:

I mainly use this barlow for imaging and I’ve not had much time for that in the last few days, but I look forward to improved images next time I can get out.

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My First Full Double Rainbow

Posted on January 22, 2012 by james

From our position here, pretty much on the top of a hill we have a good view in all directions and that means we often see lovely rainbows. Even so it’s not particularly common to see one complete from ground to ground and so when I saw this one I thought I’d take a photo and rushed in to get my camera.

As I came back out of the back door I was confronted with something even better: the first complete double rainbow I have ever seen. I’d love to have found a better vantage point for taking the photos, but I didn’t dare move in case the rain stopped or the sun went in and we lost it altogether. The second rainbow is not wonderfully clear I’m afraid, but it’s the best I could do with my Ixus 40 and it’s definitely visible in at least some of the pictures.

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This Year’s Veg Plot Plans

Posted on January 22, 2012 by james

This week I finally got around to ordering most of the seeds for our vegetable plot. Somewhat later than I usually do it (I plan to get everything sorted in November if I can, but events have overtaken me somewhat this winter).

So, what have I got? Well, in no particular order, two different carrots, various lettuces, mizuna, red and green peppers, salad and maincrop potatoes (and International Kidney, aka Jersey Royal, for new potatoes), Jerusalem artichokes, mangetout, early and late peas, sugar snap peas, sprouts, melons, aubergines, parsnips, spinach, cabbages, three tomato varieties, sweet corn, cauliflowers, brown and red onion sets, pumpkins, courgettes, cucumbers, kale, purple sprouting broccoli, french beans, broad beans, garlic, calabrese, celeriac, leeks, celery and three different chiles. I also have a few other seeds left over from last year. It’s going to be a busy year in the veg plot 🙂

As soon as the tomatoes and chiles turn up I think it will be time to make a first sowing of those in the propagator. Before then I’d best get the greenhouse cleared out and make sure there’s room in the polytunnel. Garlic really needs to go in as soon as possible too. I already have broad beans in the ground under cloches and some early peas and lettuces in the polytunnel. I’ll do some early potatoes and mangetout in the polytunnel early on as well.

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