discardedastro

So the answer is - Rowan make a tool, just buy it! For £15 and next-day shipping, really can't fault it. Snug and perfectly fitting in the nut, felt completely secure even when leaning on it all. https://www.rowanastronomy.com/productsa2.htm#neq6beltkit It does exactly what you'd expect and worked a treat. I'd naturally been soaking everything in lube so once they got moving - which took a fair bit of force - they came out good as gold and the threads look fine. Onwards!

https://en.wikipedia.org/wiki/Cheshire_eyepiece Wikipedia has it right! The Concenter is another useful tool to have in the toolbox. If you've got a Barlow lens (and laser) to hand, also have a search around for Barlowed laser collimation. Between those tools you can definitely achieve excellent collimation. Vic Menard's book is also well worth owning if you're a Newt owner!

Coma is very much to be expected and the MPCC is not a great corrector. I'd try some photos with and without it and try CCDinspector (there's a trial) on a really star-rich field (pick a nice spot in the milky way and not too long an exposure). I still had quite a bit of visible "coma" effects till I upgraded (to a Paracorr, but the GSO corrector is also apparently very decent, etc). I wouldn't be too quick to pin that on collimation. As others have said you will need a Cheshire at the least to get the secondary about right, laser or no.

Yep - sounds like I got very unlucky with assembly on this! There's always something. I'm soaking everything in good penetrating lubricant. I suspect the answer is it was overtightened on assembly and the thread was damaged - so am hoping that once I get them out 3-4mm they'll come out the rest of the way without issue. I'll do some measurements once I get it all apart. If the threads were damaged I'll go ahead and re-grind them. Worst case, given there isn't much load on any of this, if I can get the old part out - by hook or by crook, and my "last resort" will be carefully cutting out a 1-2mm section with a Dremel through the port or taking it to a local machine shop to remove the old nut - then I can use the existing threads, a metal washer, and a 3D printed nut to adjust tension. Dimensional tolerances on professional 3D printing are plenty good enough for the coarse thread, and will accommodate a bit of play with damaged threads, and a spot of adhesive will hold it in place well enough once it's set without ruling out adjustment in future. A good friend pointed out that Lucas used a similar slotted nut size for ignition switches for a while and so there are tools: https://www.holden.co.uk/p/lucas_switch_bezel_tools - exactly how similar we shall find out...

Yep, those are the ones, on the end of the worm gear carrier. On mine they appear incredibly tightly fitted, and it doesn't appear to be threadlock. I'm just drenching them in lubricant at the moment - we'll see how we go.

So the RA nut - that Facom tool is precisely what you need. Fits perfectly. What it won't do is the Dec axis top nut - which is recessed inside the saddle mount. I presume Skywatcher have a specific tool for that which is basically a big socket with some pins in it. However, you shouldn't need to get the Dec top nut off - though if you want to replace the top Dec bearing and can't get it to slide off readily, you may have no choice. What has got me completely stumped is the slotted nut. The amount of force I'm applying absolutely should shift it - I think whoever at Skywatcher did mine up was not doing so with a torque wrench and just cinched it down *hard*. I've managed to get it to move about 30 degrees and then damaged the tool as it skipped out, and the nut was in serious danger of being damaged at that point so I figured a safe option was to stop and regroup. I think the next step will be to carefully lubricate the threads with a penetrating lubricant - it'll all get degreased later anyway - and see if I can reduce the friction on the installed nut to ease it out. And then we're in to things like trying to freeze the nut with freezer spray and if that doesn't work I'm not sure what to do! Bit of a setback, but there was bound to be something!

This is what I've got coming for the RA nut, since I will need to do that up again and the oil filter wrench doesn't quite feel right: https://www.facom.eu/ProductSheets/ProductSheet_374_1.pdf That should do the trick nicely. The DSLR lens tool is one of these: https://www.ebay.co.uk/itm/264761144297 - looks cheap and nasty but so long as it holds for precisely two nuts, we're good!

I do have some 1.5mm mild steel lying around and that's definitely where I was heading next. Very much feels like there should be tools for this - I have a similar slotted nut arrangement on some of my modular synths but there's a tool for that. I've got a thing designed for opening DSLR lenses on the way which is the best tool I've been able to find. Be very careful with the optical encoder marks - best not to touch them at all (though if you have gotten dirt on them, then washing them is a good plan). The EQ6-R has no optical encoder so all we have to worry about is the end encoder for PPEC.

Just waiting for tools now - can't get the worm carriers out, though did get the worm drive gears off with some gentle encouragement from a screwdriver. So while I can't really clean the worm carriers yet I figured I might as well make a start on the rest, so cleaned the worm pinions. I settled on a first pass of Jizer to degrease followed by a rinse, gentle dry, and then final chemical clean with Ambersil spray cleanser which was left to evaporate. That's done quite a nice job of cleaning everything back to bare metal and removing all the grease from the pinions. The RA has some marking from the clutch plate on about 1/3 of the gear's circumference which I think is very likely some damage from early in this mount's life when I was learning how this astrophotography thing worked and was unaware of the potential perils of mount crashes. I think I'll carefully give this a light pass of wet-and-dry to restore the surface finish, but it's not too bad as-is. There was certainly a fair bit of nasty black gunk and debris left in the pot after cleaning up, especially off the RA gear. About the only other thing I can clean right now are the two shafts - which I will do, but need more drying space for first - and the RA half of the mount metalwork. I pulled all the alt-az bolts from the base and gave them the same cleaning treatment which removed an absolute tonne of nasty black gunk, corrosion deposits, etc. I similarly washed out the holes in the mount with the same two-pass Jizer/Amberclene approach. These clearly need a gentle deburr and in some cases could use a bit of fresh enamel paint. I need to dig out my old modelmaking supplies - I'm pretty sure I have a pot of paint for a Saturn V model which will do just fine for this... The screws cleaned up pretty good, though there's definitely some rusted bits left I might try and clean up further mechanically. The altitude bolt spring is well past saving but not the end of the world to lose. I'll give these all a coat with a corrosion inhibitor (ACF-50) before reassembling with Copaslip which should do well for keeping the threads happy long-term. Lastly I cleaned up the inside of the RA bore. This featured quite a bit of debris, including some loose metal bits which are now gone. Everything's fairly well degreased in here, at least on contact surfaces.

That's really useful to see, so thanks for the link! I hadn't found that in my Googling. He seems to have gotten rather luckier on tolerances on shafts etc. Latest fun in my rebuild - the slotted nuts for adjusting the worm gear bearing float end are stuck in hard. Narrow nosed pliers just skipping out, can't get enough force on them. Rather futilely trying to find a slotted nut driver of roughly the right size and failing - I may need to ask a friend with a mill to grind back a cheap ~18mm socket to leave two slot-sized protrusions so I can get some force on them. The slots are about 1.5mm across and the bore is about 21mm, so it's a tad larger than a screwdriver will manage. I did also find Facom's 117.B adjustable pin spanner which looks like it'd be just the job for refitting the RA nut (and removing it!) - so will see how that does. However, I did get the worm carrier off the RA now and cleaned it all - quite a bit nastier than the Dec axis with more blackened lube on the gears and visible swarf in quite a few spots around the assembly. The RA worm optical indexer is a trivial job to remove and as simple as you might imagine (circuit is just a pull-up resistor for the opto switch emitter, with the switch connecting pin 3 and ground on the connector. The RA worm carrier otherwise looks pretty well identical to the Dec and suffers from very similar issues with respect to edges not being properly deburred, etc. Edit: and just to add, while both the video linked above and this one below I also stumbled over from that video feature a teflon washer on the bottom of the RA shaft (i.e. between the lower pinion bearing and the mount head) this was not present on mine...

I am, and am now the proud owner of a big pile of good quality SKF bearings with which to do this. The part codes listed above so far seem to have produced credible-looking parts though I've not done the worm carriers yet. It's definitely a bit marginal as to if it's worth it or not, but I figure the cost is not huge (total set of bits with spares was sub-£200 delivered) and I am a fan of doing things once and comprehensively/completely as far as possible - I'd prefer not to have this open again once I'm done! There are a couple of bearings which may be a challenge to remove without tooling - mostly I'm thinking of the top bearing on the declination axis. This is pretty well recessed into the saddle "holder", and is going to be a pain to get a puller on, but I've not explored how that assembly might come apart yet. Every other bearing has either fallen out with a bit of gentle encouragement or come off with a very gentle tap or two with a plastic hammer. I've been out all day today but hopefully will finish tearing down RA and get the worm carriers apart/rebuilt tomorrow...

I have a big VX16 Dob I happily look through with my Mk. 1 eyeballs, dodgy as they are. I shove it around and the bearings on its mount are all a bit sticky and rubbish so it'll achieve probably a degree or two of pointing accuracy if I'm careful, maybe. This mount hosts a modest little 200mm Newt - a 200PDS, like you - and a camera imaging at 0.5"/px for very high resolution galaxy imaging. For what I do the difference between mount performance of 1-2 arcseconds and 3-4 arcseconds of error is the difference between a superb image and a dissatisfying result. Without all this faff I produced the below and a dozen other images I am very happy with. Is any of this necessary? Well, no, probably not. Will it extend the life of this expensive bit of equipment? Certainly. Will it reduce the amount of time I spend swearing at my mount at 1AM when the tracking isn't quite perfect? Possibly. Will it improve the performance of my mount? Probably. Will I enjoy doing this, regardless of any of that? Absolutely! For me, astrophotography is as much about the optomechanics, sensors, optics, and precision engineering as it is about the stars, galaxies, and nebulae that I get to image. I take great pleasure in knowing that mechanically, everything is sound, working well, and doing what I want, and that I am able to achieve such precision in my back garden. The skies above aren't the only thing we can marvel at - modern engineering and precision brings some of us joy, too. You may as well ask a classic car enthusiast if it's really necessary to rebuild their car's engine or replace some rusty panels!

The RA procedure started fairly similarly to the AB guide. The polar scope alignment indicator comes off with a gentle twist of the inside ring. The indicator itself just pulls off. The mounting ring for the polarscope cover comes off readily with a couple of grub screws. These also get replaced with stainless steel. I will shout out https://modelfixings.co.uk/ at this point - all the bolts/grub screws etc hardware I'm sourcing from them, they've been fantastic for years and do a great set of M2-M6 grub screws and good quality stainless bolts etc. So the answer to the RA smooth nut is one of these rubber oil filter changers, for sure. But you will need to pull out the altitude adjustment bolt to get a good clean pull on the thing. I also fully removed the grub screws around the shaft just in case and will replace these with stainless also. After a lot of attempts, off it came.... Rear bearing exposed as per the AB guide. The axis came out good as gold, nice and easy, and the bearing fell out. I noted some debris in the bearing as I removed it which appeared metallic, but it's 50/50 if this was metal or some particularly robust bits of the earwigs I found above this bearing... either way, happily I will be replacing this with a brand new SKF 32208 J2/Q. Extracting the shaft, the top bearing remained. This was removed pretty readily with a gentle bit of tapping from a rubber hammer - I'm replacing this so not precious about getting it off. The RA set ring comes off easily. We also have a teflon washer below this bearing, less damaged than the other but will be trying to replace in any case. Unfortunately I last tightened up the RA worm carrier bolts with a really hefty hex driver which I've since misplaced, so I'm now waiting on a bigger hex driver to make more progress. However, the big smooth nut was the last major challenge on the primary axis stripdown, so I am expecting that the rest should be fairly straightforward. The only possible snag I can foresee is removing the bearings from the ends of the axes; these are pretty snug in their positions and because the rods are pretty long I'm not sure my bearing pullers will actually reach that far or fit into the recess. I suspect that I might need to do some unspeakable bodges to get that last bearing off. I have also started looking at the worm carrier stripdown. Circlip pliers are a must for taking the end cap off and taking the slotted nut out. Once I have absolutely everything stripped down and some basic cleaning done I plan to slather degreaser all over everything for a first pass and then take everything to work where I have a big enough ultrasonic cleaner in the lab I can make use of for an afternoon to get everything completely clean. Then it's on to the super fine wet and dry paper for surfaces and I'll have a look over the gears.

Personally I find videos can be helpful in parts but nothing beats carefully taken photos and text. Having said that I'll try and film some bits of the reassembly and do a bit of a video about it all - I'm short a video camera but phones work pretty well and I might be able to borrow work's proper camera for a few days. Bearings arrive tomorrow along with some of the missing tools - I have some things to do at the weekend but will try and make some progress on Sunday. The main nut (smooth) on RA Is an absolute nightmare so far - a chain-style oil filter remover has done nothing but marr the surface (even with some amalgamating tape to protect/grip) so am hoping a rubber version of the same tool will do the trick. I suspect Skywatcher have a specific tool that engages with the recesses on the back like a giant pair of circlip pliers! I've got both EP and regular bearing-grade lithium grease on the way. I would say that generally the grease I've found so far is looking like decent lithium stuff. Not the notorious Synta Tar. Shims and replacement Teflon washers I'm just trying to find a good source of now - given the (theoretical) simplicity of the "hypertuning" of the worm gear alignment, i.e. make a few accurate measurements and shim accordingly, seems a no-brainer to do it while I've got it all open. I am giving a bit of thought to what I might need to do to properly tune the alignment later on. Current-based measurement of motor load seems a sensible easy "precision" method beyond sticking an ear on it while adjusting worm gear offsets, belt tension etc. I've got a fairly accurate bench power supply handy (Rohde & Schwarz NGE100B - marginal but can do 6A in parallel mode) as well as a R&S Scope Rider with precision ammeter clamp probes, both borrowed from work, so I think I'll give that a go! I've also been giving some thought to vibration measurement; back in my drone engineering days we used to do FFT analysis of accelerometer data which would pretty readily show peaks at resonant frequencies relating to e.g. improperly balanced props, or damage in bearings. I have a few precise MEMS accelerometers handy so I figure it wouldn't hurt to just try doing some measurements with that and see if anything interesting falls out.

Right - given I can't find one, here's a bit of an addendum to Astro-Baby's excellent EQ6 teardown guide, updated for the EQ6-R Pro. Mine is the original version but I don't think anything changed mechanically on the facelift version - YMMV. I'm tearing mine down to give it a proper clean and service throughout, and to proactively change the bearings to proper quality SKF bearings throughout. Mine lives outside year-round under a Telegizmos cover - but we're in a very humid spot (there is what the EA calls main river about 20m from the mount - in reality it's a drainage ditch but it is full of water most of the year). Consequently lots of the low-quality bolts, as well as the counterweight shaft, are corroded badly. It's been outside for about 3-4 years. All of this assumes you're reading primarily this thing: https://www.astro-baby.com/astrobaby/help/rebuilding-the-skywatcher-eq6orion-atlas-mount/ I do intend to follow the "supertuning" offsetting/shimming procedure if it looks like mine needs it. Before teardown this mount was running OK and managing reliably 1-2 arcseconds RMS guided, which is fairly standard for these out of the factory, but I do a lot of high-scale oversampled imaging so good mount performance is nice to have! Electronics and prep I dismounted the mount from the tripod and got all the snail excrement out of the az/el wedge. This turned out to be quite tricky and I let it dry completely before getting in with a narrow vacuum nozzle which did the trick. They haven't found a way into the mount, happily, but I am going to try copper tape on the tripod legs - works for slugs on pots... Getting the electronics board off isn't strictly needed for much stuff but on the -R it's pretty much mandatory to get the belts freed off when we get there, so best to get it out of the way early. Usual set of (outer) pozi screws to get the cover off, and then a small screwdriver and gentle wiggling to get the connectors out of the back. Put the PCB to the side and then tape up the connectors/cables. Very easy for these to fall outside the case and get trapped under the mount otherwise. At this stage it's easy enough to do a quick look for debris and see how it all looks. In my case, pretty decent, all-told. The R has a pretty similar mechanical setup to the NEQ6. Of note though is the RA indexing optical encoder which is used for periodic PEC (not an absolute encoder, just generates a pulse once per worm rotation based on a slotted disk on the end of the worm shaft). Dec axis The saddle comes off nice and easy. These are 5mm hex head bolts rather than the inset hex screws used on the NEQ6. Better, but note corrosion (the counterweight bar bolt is also shown for reference). Pushing the counterweight bar up through the middle of the axis worked, but only after I'd sanded the corrosion off the bar. Will probably look to polish that back and coat it with something to try and eke a bit more life out of it, but a decent stainless bar would be better. The clutch lever assembly came off easy - pozi screw and again corroded. The brass insert on the end of the screw came with the screw, which confused the hell out of me while I spent 5 minutes trying to find it. Also of note is that the clamp on the counterweight bar is done via a small, black plastic (delrin?) insert. This is not obvious and falls out readily. The screwing off of the main nut here was straightforward - no real resistance once the (M2, I think) grubs were slackened. Design a little different to NEQ6. Likewise the removal of the dec shaft at this point went as you'd hope. The revealed bearing (which is still a 30206, as on the NEQ6) is easily removed thereafter without any effort. The shaft came out easily. Generally looks fine - I don't know if the blackened portions are painted or treated in some other way, but they're not in great shape - I presume that this is largely done to avoid reflections for the polarscope. The bearings used along the shafts are JESA W2 series 6008 RZ bearings. I've opted for SKF 6008 2RS1 as a replacement. The grease used throughout looks to be reasonable quality lithium stuff rather than the dreaded black Synta grease. It is worth noting that I could not find any washers at this stage. Whereas the NEQ6 has a teflon washer on the top of the bearing surface. Moving on to the worm gear carrier, instructions are per the NEQ6 guide. However - there's a belt drive here! Hat-tip to Tom Boland on Twitter for pointing out that the motors themselves need to be released to free up the belt. Undo the tension screw, then the three (4mm, I think) hex bolts accessed behind the electronics panel associated with the motor. Just slacken off. Then use a narrow screwdriver to guide the belt off the large gear. The gear can't be removed yet - but note the flathead screw (how many screwheads! Pick one!) plug in the worm gear carrier to allow access to the set screws in the large gear for later... Undo the top and bottom set screws, the 5 M5 bolts, and with the belt released this just lifted off nicely. Set screws were again corroded so will be replaced. This yielded our worm carrier, shown below - you of course don't need access to the top of the assembly to get at the set screws for the gear here, which makes the decision to put another external penetration in the casing a bit weird! I wonder if there's some form of setup at the factory that requires this, or similar. The surface finish here is okay, but I'll give it a few rounds on a surface plate with some wet and dry to clean it up before it goes back together. Interestingly the grease distribution here is less than uniform and the right hand side of the worm is basically dry. Note quite a bit of visible burring around the edges of the casting and paint flecks that will want cleaning up. The end float adjustment plate is here and looks fine. The bearings used in here seem to be the same manufacturer, 608 Z family. I've ordered 608-2RSH SKF parts as a replacement. Back to the brass... This is as it was just after removing the worm. You can see the freed up belt and the contact surface for the clutch. I've not inspected this in tons of detail but will give it a full degrease and surface polish before it goes back in. There's some indication of wear on the gears but I've not had a really good look yet! This is the only washer I found in the entire Dec assembly - sat between the bottom of the brass gear and the top of the bearing supporting it. Teflon, some signs of cracking/damage - this is well on the way to become another cracked and broken washer, I think. Sadly my calipers have failed so I haven't measured this yet. The last bearing popped out with just a little wiggling. The brass blocks top and bottom are the points your set screws are pushing against when adjusting the worm positioning for backlash. Again lots of tool marks - this'll get cleaned up before it goes back together. And that's all for now! I've made a bit of a start on the RA but I'm waiting for some tooling to arrive, so in the meantime figured I'd write this up as the guide I wish I'd had when I started. I'll add to this as I do the RA, clean up, worm position tweaking, and rebuild/testing.

Looking abysmal here, sadly. I haven't yet set up the imaging rig because it keeps being awful here. Every clear night has been a full moon or started so late I'm not able to take advantage. Definitely need to sort the observatory out to take advantage of the inevitable 1am-4am imaging windows that I'm seeing so often.

That's a gorgeous scope and a wonderful looking chair. I'm a bit heavy for the Berlebach chairs and the Skywatcher one I got is definitely a bit rubbish, so I may have to steel myself and get some wood!

Powerline is very dependent on: How your wiring is done, topologically, and how "good" the wires are as antennas How much radio noise you have in the local area, and now many interferers you have injecting noise back onto your mains ring The relative alignment of planets and their moons How many animals you've sacrificed to the Old Ones in the last year It can work OK, but (and we've got data from thousands of deployments of powerline at $dayjob) it's very much luck of the draw and maybe 25% of people get a nice reliable experience. Getting the really good units helps a lot with your odds, since they've had some good R&D in them, but for point A to point B WiFi bridges will always perform better and more reliably (and then cables). Worth trying if you don't mind reselling the units if they don't work out.

Worth mentioning that if you're using the Pi for DSO imaging, where data transfer rates are less critical, and you've got Ethernet, you can run KStars on a desktop/laptop PC and just run indiserver/indiweb on the Pi. This is much lower burden so older Pis can work fine (though I'd definitely stick to a 4 with the faster Ethernet performance and USB3) and it means all the interaction with KStars is fast because it's local - delay is just in the download time of the images, which is pretty fast. You can also download the files "as you go" to the local device so at the end of the night the Pi has nothing on it. In general Ethernet via cable is always going to work dramatically better but if you're stuck using WiFi then there are dedicated bridge products (e.g. Ubiquiti, Mikrotik) which will seriously outperform the integrated WiFi on a Pi (or anything else, for that matter). Some of these support 12V so can be fed without a separate power supply, and just spit out Ethernet on a wired connector at each end. The highest-end form of this would be something like the Mikrotik Wireless Wire which is a 60GHz (unlicensed in the UK) product, e.g. https://linitx.com/product/mikrotik-wireless-wire-cube-kit-60-ghz-link-with-5ghz-failover-pre-configured-pair/16698 or https://linitx.com/product/mikrotik-wireless-wire-pre-configured-60ghz-link---rbwapg-60ad-kit/15214 - these take 12V in. Definitely a major upgrade over no cable, but no patch on a cable...

This is largely unrelated to the power of the device, and more about the limits of VNC and Linux RDP implementations, which aren't great. There is some great progress being made to unpick some of the older bits of the Linux display composition stack (X11) and replace it with something a bit more modern (Wayland) which should help fix this but it's likely to be a while before that lands in many distributions. If you've got a Linux box at the far end then X11 forwarding can be pretty performant - I've used this in the past without issue. But yes, for focusing with live video VNC is not fast enough today. No issue for DSO stuff where you're doing 1-2 second exposures for focus, mind - it's only a limiting factor for stuff with high frame rates. This used to be much more of an issue than it is today - the Pi4 ditched the USB-based Ethernet controller in favour of a chip with the Ethernet side of things directly integrated, so all the infamous overhead of USB interrupts etc that limited Pis to about 200-300Mbps throughput and caused fun with some real-time applications is now essentially dead and gone, happily!

You're realistically never going to get live video out of VNC, and 1-2 FPS is pretty "normal". RDP can do partial updates which will help a bit, but even that isn't very good for video (which is what you're talking here). RDP from Windows to Windows will work better because of the deeper integration of RDP with the Windows compositors etc (and it's a "better" though proprietary protocol in other ways), but it's still taking photos of window contents and sending them over the network. None of this stuff is terribly efficient for fast update rates of real video compared to e.g. video encoders! Pis can work great for AP - solar/planetary/lunar is probably their weakest side because of the higher volumes of data, and it's where a NUC or similar will be an easier thing to deal with. If you're just using VNC to monitor unattended capture it's OK, but if you want high update rates you're going to need a directly attached monitor or some form of external video/display encoder/long cable to move HDMI video from A to B.

And if you want to go deeper (much deeper - it's not for the faint-hearted) then Stages to Saturn is an excellent historical look at the engineering and development of the rockets. It is completely mad what they did back then!

On the F-1 engines, it's the cold gas from the turbopump, which gets routed through pipes going around the engine bell and then dumped at the "skirt" of the nozzle. This is used to cool the engine bells/nozzles and stop them melting. But the cold gas undergoes only partial combustion in the exhaust, and also cools the exhaust gases in the outer rim of the nozzle, so the darkening of the flame in those regions.

The Pi runs from an SD card but the SSD's there for more space. I've set up both the Pis to avoid writing temporary files so the SD cards should live more or less forever! Absolutely - and try other things! I'd add to this that it's all great learning opportunities if you have the time, so you can try out a few things and see what works for you. I started out on Windows with Sharpcap and then SGP before I made the plunge into the Linux ecosystem - it's taken me about three years to settle down with what I'm using. There's absolutely no right answer for all this stuff.

It is basically Debian, so in a way you've been able to do this for far longer than there's been a Raspberry Pi 😉 but nice to have the "usual" RPi desktop for some users I guess.