A poor quality photo, I know, but I was grabbing a few seconds when I should have been doing something else so had to make the best of it. Jupiter is at the top, separated from Venus by what appears to be an aeroplane that I didn’t notice at the time. Much fainter down close to the horizon (and easier to see in the full-size image, linked) is Mercury.
There were patches of blue sky this evening, but plenty of thin cloud too, Jupiter and Venus were visible before sunset though, so I decided to get the Mak outside cooling and hope we’d have enough clear sky to do a star test.
After dark I connected up the motor drives and moved the scope around to pick up Procyon. Defocusing the view in a 20mm eyepiece I saw what appeared to be a nice set of round, concentric diffraction rings. By eye, and without an artificial star, I think I’m unlikely to do any better.
I’ll see if I can get an image of the diffraction rings with a camera later.
[Update]
Here’s an image taken with my SPC880 webcam. I think it shows that a little more tweaking vertically could be done, but otherwise I think it’s not bad.
I was bracing myself for low numbers this month as December, January and February are apparently only expected to account for about 7.5% of our total yearly output, but was pleasantly surprised when I read the generation meter to discover that we actually produced 178kWh last month, almost as much as November and December put together. It may have helped that I have rather drastically pruned a tree that was partially shading some of the panels when the sun was low in the sky.
From installation at the start of September to the end of February we’ve generated 1007kWh, worth around £450 in FITs income plus up to £150 worth of electricity that we haven’t used.
On the assumption that the models I have are reasonably accurate we’d expect to generate fractionally under 23% of our total annual output over the last six months, suggesting our total annual output would be around 4,400kWh which puts something of a strain on my credulity, I have to admit.
With a new DEC motor drive in place, I decided I’d take apart my old DEC drive gearbox to see if it could be improved at all. Once split from the motor I used two pairs of pliers to hold one of the gearbox sideplates close to each of the three brass pillars joining them and levering the pliers against each other eased the plates apart. They actually came apart quite easily, and I was able to separate them and remove all the gears (and a small spacer):
To remove the remains of the nasty black goop I soaked everything for twenty-four hours in isopropanol and then scrubbed the parts with a small brush. It wasn’t a perfect result, but not too bad:
Then it was just a case of attempting reassembly, lubricating everything as I went. There are four shafts excluding the output shaft. If we count them in order from the one on the right in my picture, the fourth shaft is larger in diameter and will only accept one of the brass gears, leaving two others plus the nylon one. The first gear to go back is one of the brass gears with the smaller bore and larger teeth on the bigger of the two gears. It goes with the smaller gear up on shaft three:
That’s followed by the only gear that fits on shaft four, also smaller gear up:
Next up is the nylon gear that’s driven by the motor, on shaft one. Smaller gear up again:
And then the last brass gear, on shaft two and this time smaller gear down:
The spacer goes back next, above the gear on shaft three:
And finally the output shaft is put back into place:
With everything in place I then slid the upper sideplate down over the output shaft and with just pressure from my fingers it snapped neatly back into place on the three brass pillars:
The most surprising thing about the entire process was not that everything went back together so nicely, but that once done, the gearbox turned very easily as I turned the output shaft in my fingers. When I started it was possible to turn the gearbox, but it was very stiff. Sadly it still has more backlash than my new one, so I won’t be putting it back on the mount.
Another point to note is that the sideplates are not identical as the bushings for the output shaft are different on each, but they do have five unused holes each that are aligned with each other. Two appear to be the same size as the ones for the existing brass pillars whilst the others look the same size as some of the gear shafts. I’d hazard a guess that Synta use the same sideplates for several different gearboxes and just have different sets of gears to fit in them.
Having done a fair bit of work trying to improve the motor drive for my EQ3-2 mount I wanted to look particularly at the DEC motor to see if I could improve its performance at all. It’s had a tough life and been repaired at least a couple of times, so a bit of TLC probably wouldn’t go amiss.
First step was to remove the cover and bracket and split the motor from the gearbox. The motor drive housing just slides off (image 2 below) which makes it easier to get to the screws holding on the mounting bracket.
Removal of the bracket (image 3) reveals three screw heads on the output shaft face that can be unscrewed to split the unit into motor, gearbox and mounting flange (image 4). It’s useful to note at this point the orientation of the gearbox and mounting flange as the entire drive won’t go back together if they’re wrong.
The gearbox was full of sticky black goop (image 5) that I removed with a brush and isopropanol, but even that was tough work. Not all of the grease would come off, but it wasn’t too bad in the end (image 6).
Testing the gearbox suggested there was quite a large amount of slop in the mounting of the first driven gear (the nylon one) which could rotate noticeably on its axle when then second gear was held still. I couldn’t see anything I could do about this problem without the risk of destroying the gearbox completely, so in the end I left it alone and just lightly re-greased the gears before reassmbling the unit.
Testing the motor afterwards it became clear that not only was there a significant amount of backlash, but also the DEC motor skipped on occasion, failing to turn smoothly. After much deliberation I decided to replace the motors rather than trying to fix something already running poorly. The first thing I did when I received the new motor set was to strip down the new DEC motor the same way and compare the two. You can see the much better condition of the new (uncleaned) gearbox here:
The slop in the first gear wheel was also about half that of my original one. I’d still like to reduce that if possible, so I may now attempt to dismantle the original gearbox as a test run to see if I can improve it. If I can then I’ll probably do them all.
Last week, two and a half months after I submitted the readings, I finally received my first FIT payment for the electricity generated by our solar PV installation during September, October and November last year. Very pleasant at last to see money coming back in to pay off what we spent six month ago.
The total payment was very close to 2.4% of the cost of installation. I don’t think the next three months, mostly covering December, January and February will be anything like as much. Looking at my data, about 15.5% of the annual total is supposed to be generated between September and November compared with 7.5% between December and February. Things should start to look a good deal better from now on though as production ramps up through the Spring and Summer and the annual FIT rate increase (4.85% this year) takes effect in April.
I’ve been doing a fair bit of fiddling around with my 127 Mak recently. The initial reason for this was that the mirror had become loose on the carrier mechanism, meaning lots of trouble getting reliable focus.
To fix this it was necessary to remove the corrector lens from the front of the OTA, remove the focuser knob and slide the entire mirror assembly off the baffle tube whilst fiddling the focuser spindle through the backplate and trying not to get grease everywhere. The mirror carrier itself is an externally threaded tube with a flange against which the front of the mirror rests. Behind the mirror is an o-ring. The focuser plate screws onto the thread behind that to hold the mirror in place and behind the focuser plate is a locknut which, in theory at least, should keep the whole lot fixed in place.
Having taken the scope apart it was going to be necessary to collimate it once reassembled. I don’t have a proper collimation cap, so I made one up out of the nasty 2x barlow shipped with some Skywatcher scopes (from which I have already removed the lens so I can use it as an extension tube). I then found a plastic bottle top that would fit over the end neatly and drilled a 3mm hole through the middle. This went into the back of the baffle tube and I started to follow the instructions here:
(Should this link break and the file isn’t available elsewhere, I have a copy of it.)
It’s actually somewhat more tricky than might be suggested given that effectively all six screws (three “pull” and three “push”) need to be adjusted at the same time to move the backplate, thus moving the baffle and the mirror. I found it helped to move to the front of the scope and stand at the focal distance. By lining up the reflections it was then much easier to tell if I was out and by how much. The rings formed by all the reflections are fairly obviously skewed if it is out of collimation.
Over half an hour or so of tweaking the adjustments I got it as close as I felt was possible without a star test (and I don’t at the moment have an artificial star). A final check through the colli cap to make sure that looked ok and, oh, now that’s not good. The mirror appeared to be collimated properly, but the baffle tube was clearly not central and I could see more on one side of the secondary mirror than the other.
It’s worth noting at this juncture that I didn’t buy the Mak new, and when I did it came with an SCT adapter and two inch diagonal attached. I wasn’t too enamoured of the quality of the diagonal and am not entirely sure that it makes sense to have one on this scope, so I decided to remove it. Easier said than done as it turned out. The SCT converter was jammed onto the baffle retaining nut and wouldn’t unscrew from it. I ended up having to remove them both together and separate them in the workshop where I could get at things with proper tools. Because the converter was jammed, I surmise that either when it was put on or when I removed it, the baffle became skewed in the tube.
Not much to do other than take it all apart again now though, so that’s what I did, removing the backplate, separating the baffle tube from it and cleaning all the mating surfaces before reassembling it. Here are all the bits before reassembly.
I’ve now put everything back together (and I didn’t even have any bits left over!) and redone the collimation, checking it by eye from the front at both ends of the mirror travel. The baffle tube looks much more central through the collimation cap and I now await a clear night to do a star test. I really should sort out an artificial star. Tweaking the collimation in the dark is far from simple.
I’m sitting here this morning eating rhubarb crumble for my breakfast. It makes an interesting change from the usual toast or cereals and I’m very much enjoying it. The thought also strikes me that as it was home-made from rhubarb grown in our own garden it’s also quite probably far healthier than most usual breakfast fare that leaves a factory in a cardboard box (and by and large tastes like sugar-coated cardboard too). It wasn’t cooked specifically for breakfast, I should point out. It’s left over from Sunday’s dinner.
Given the huge variety in breakfast meals around the world (and, in fact, in what we have eaten for breakfast in our own nation over the years), I think it might be time to experiment a little more with the options. Why on earth would you really want to allow massive multinationals to dictate what you should eat for what some people describe as “the most important meal of the day”?
Well, kind of. I’ve already got broad beans under cloches in one of the veggie beds and a sowing of peas in the polytunnel, but they were all planted last year…
Anyhow, my daughter has been getting at me to go and sow some seeds with her so this weekend we went out and made a start. We’ve planted tomato varieties Gardener’s Delight, San Marzano, Costoluto Fiorentino and Cour di Bue. Some of the seeds were left over from last year, but we’ll see how they get on. Last year we had tomato plants everywhere, but we use them for making pasta and pizza sauces as well as in salads and can never have too many.
Next up were Zimbabwe Bird Pepper and Jalapeno chiles. Something else we can never have too many of. The instructions say they need a temperature of 28C to germinate. Not sure we’re going to get that much heat anywhere. I bet even our airing cupboard doesn’t get that warm. Still, they’re in the propagator and we’ll see how they do.
I was hoping to get some sweet peppers and Cayenne peppers in, too, but we ran out of time. I’ll catch up with those later in the week. I really must put together a planting plan over the next few days or I’ll not get anywhere.
This morning at stupid o’clock I took our two Large Black pigs off to slaughter. Large by name and large by nature, too. I’d estimate they’re somewhere up around the 120kg to 130kg mark, live weight.
We’ve had them eight months, so they’re about ten months old, and it was really time for them to go before they ate their way out of their run. They’ve been living in a fenced off area of grass of around a quarter of an acre which they’ve they’ve turned into something that looks like part of a film set for the Somme, as well as chewing through the bases of some of the fence posts. I did put things in the run for them to play with, but that just seems to have encouraged them to eat everything in sight. They even chewed through some of their pig ark and completely trashed it. Whenever I fixed it they’d just break it again within a few days. It was time for them to go. Besides, I have a walnut tree that I want to plant in the run and it wouldn’t survive with them there.
Coaxing them into the trailer took a bit of time (you really can’t make a 120kg pig do much that it doesn’t want to). In the end I managed to lead them in with a bucket full of feed, running around the back and closing the trailer up behind them before they could change their minds. Then we set off for the local abattoir, about ten miles away.
Abattoirs are fairly surreal places on the best of days. On my first visit to one I was unloading the pigs with the assistance of the vet when one of the slaughtermen came out of the door into the pen, heavily spattered from head to foot in blood as if it were the most normal thing in the world. Which it might have been, for him, but it was pretty weird from where I was standing. Then there was the time when someone brought in a wild boar immediately before or after mine. A squealing ball of fire and fury that beat its way through the gates before anyone could stop it, smashed through a wooden fence and disappeared into the maze of buildings. Someone who could use a rifle was sought and after a short hunt the boar was returned in a wheelbarrow, dead.
Today I arrived, did the paperwork in the office and was asked to put the pigs in a small holding pen, which I’ve not had to do before. I drove the trailer round and discovered the entire place to be devoid of human life, which wasn’t helpful as given the design of the gates I couldn’t see how I could possibly get two large pigs out of the trailer and into the holding pen without the risk of them escaping. Whilst I was still trying to work this out, a slaughterman appeared and told me I could drop them off in the main pen as they were just about to move the current batch of pigs in.
And that’s one of the other disturbing things about taking pigs to slaughter. Sheep, in my experience, go fairly quietly, but once one pig starts squealing because it things something’s up the whole lot get set off. Standing amongst three or four dozen madly squealing pigs is not one of life’s most pleasurable experiences.
By this stage I’d been abandoned to myself again and had to get on with reversing the trailer up to the pen gates and persuading the pigs to leave the trailer without pushing the gates open and escaping into the yard all by myself. My biggest worry was that once I pulled forward to close the gates they’d be off, but by that stage they’d gone to introduce themselves to the other pigs and I got everything closed up before they realised. I clearly need to practice reversing with a trailer more. Perhaps it’s fortunate there was no-one there to see my efforts.
So, now we wait to see what turns up at the local butchers on Thursday. Depending on what the vet thinks of the livers and kidneys we may or may not get those back and then next week we’ll decide how to have the carcass cut up. Time to order some sausage skins and get the bacon curing mix ready.
