LondonNeil

Hi @FrankRyanJr ! I started typing my last response last night, and finished it tonight after your response. Good to see I'm not talking to myself! Your mount looks good. Half hour centred you say, and presumably a little longer if you're fov is wide and you accept a bit of my drift. Yes I've seen a few comments on vns designs they suggest that sort of range while CS designs seem to be getting twice that, I guess th lots of people are making their bearings a bit short. Either they print Reiner's segments and these aren't more than about 8 degrees, or the rollers are short and the bearings are traversing their length over about 8 degrees? Anyway whatever, CS designs seem to get about 15 degrees/1 hour

I fear I may be talking to myself but typing is like saying it out loud isn't it? It helps me think it through anyway. Still trying to settle on a design. I've worked out I want. A. durable build. i don't want motors to burn out, rollers or bearings to wear out and so on B. reliable, i don't want slipping drive wheels or temprementality C. i want accurate tracking...just because! I'm a competent diyer with a decent skills and tools but not professional, nd not equipped with more than hand tools, this combines with A and B to mean we need a reasonably simple design but can do some stuff needing neat and accurate. C....well thats the perfectionist and engineer in me. i'm looking at all the designs on the web and seeing assumptions and lazy shortcuts. many may make sod all difference....i'm to lazy to do the maths! haha! but i am intrigued to see if i can solve the puzzle with a simple design that is perfect mathematically, eas to build and works reliably. so on to things i don't like. VNS designs. i don't like that the north bearings have to be basically carefully filed to shape, its not accurate. i don't like that they don't say vertical as the table tracks and since they aren't a knife edge, you get more inaccuracy. I don't like that the bearing contact point moves on the roller, even with the angled bearings, again it leads to tracking inaccuracy in rotation speed. this last one can be overcome by curving and twisting the bearings...but you'll need good maths and a 3d printer so...no. https://chrismadsen.org/2020/09/3d-printed-equatorial-platform/ the answer here is a CS design, easy to cut very accurately. ...if its own inherent drawbacks can be overcome. for example, this high quality looking design is a CS https://www.teleskop-express.de/shop/product_info.php/language/en/info/p2700_Geoptik-Equatorial-Platform-for-Dobsonian-Telescopes---variable-Polar-height.html friction drives, inherently unreliable and subject to wear, particularly tricky with a CS design for a higher latitude and heavy dob. screwdrive should be more reliable than friction, but the rotational rate will not be uniform, the screwdrive drives the pin and a uniform rate but as its only tangential to the bearing at one point, and its angle to the driven point on the bearing varies, the rotational rate will vary https://www.kirchdorferweb.com/astronomy/eqplatform.html My next idea was to consider a gear drive, but such a large difference in size from small drive gear to driven gear would be far from ideal, basically just one tooth meshing at anytime, noisy and vibration and even if I could make the teeth on the bearing edge (3D printing possibly) in reality that's not going to happen. Then I considered using a piece of chain wrapped round the platform CS bearing and acting as the large gear, meshing with a sprocket, that is simple to make but the vibration would be worse, with the sprocket only meshing on one tooth. Sprockets are designed to have the chain wrapped around them....Ah ha! so wrap the chain! I think I have a workable idea,...so bicycle chain wrapped along the CS bearing edge and attached at the end of the segment, set a drive sprocket over to one side and have the chain come unwrapped from the bearing (which it will do tangentially) over to the drive sprocket, around half of it, across the mount to an idler sprocket at the other side of the mount, wrap half way around that and then back to the CS bearing where it wraps around that and is attached at the far end of the segment. Cracked it....I think. this would give a totally linear pull on the chain as the sprocket is driven,and that would pull the CS bearing at a uniform , smooth and constant rotational rate. I just need to decide....is this overkill ...probably, but is it actually that much harder than a friction drive? probably not so....there may be a detailed build coming. can't start until the Dob is in my hands and i can take measurements. Oh yes, the Dob, a 12" Skywatcher f/5 classic tube. not sure on the weight but must be about 40kg at a guess, hence why i don't want a simple friction drive! comments welcome (polite ones haha!)

reviving an old thread with some questions If any of the platform users could give some comments based on longer use? I'm particularly interested in how well the drive works, any problems with slip? I'm researching a build for a 12" dob so am thinking about the extra weight. I'm also interested to know if the hand filed segments lead to any noticeable error/wobble? I've worked out a design in my head that would tackle both possible issues but makes it a more complex build...and KISS has a certain neatness! Also long term experiences with the EQ1 motor would be interesting. I think i may go with a PWM digital speed control and high torque low speed 12V motor, maybe with a worm gear reducing gearbox but again, KISS is tempting!

Or if anybody that occasionally travels between Ayrshire and London with space in their car would consider doing a member a favour then I would be keen to re-home the scope in light polluted SE19!

What about. Cassegrain scopes? Optically better but more complex and expensive so I'd ruled them out but if a used deal can be had is the smaller form much advantage? How heavy are they?

Cheers! I admit eBay seems tempting as there must be many lockdown whim purchases, used once and now gathering dust I am now more inclined to use the classifieds here though. Thank you

I'm in a similar situation and thinking stage to the OP, and this scope looks to have many pluses. I'm slightly nervous of the apparent reliance on the app though. How many years will it be before phone or operating system changes, or skywatcher laziness, mean that it starts to new a pain and not work on whatever tech your have?

Thanks, useful to get a counter view. I can see it taking a while for the kids to learn not to touch the scope, and partly assumed that would be similar with many set ups. I've learnt never to expect anything with kids! It's about giving them many experiences and occasionally you're get lucky! I'm SE19, crystal palace. Nearest club is Croydon.

Super images Peter! Love the spiral galaxy

Yes I'm going round in circles again, I'd come down from 10" to favour 8" because of weight, but forgotten that. Although I've just come across the Explorer scientific ultra light 10". Is it just me, or are truss designs very sexy? Just me? ok that's the engineer in me! It's top end of (bit over) budget and doesn't come with EPs so really it's £100 over budget but packs small and is well made, aluminium not MDF/chip board. It is also very light. Low CG so could probably build an equatorial platform with a few degrees more travel and it would still be very stable. AHH.... Stop it Neil... It's over budget so stop with the man logic attempts to justify it ... It IS sexy though!

I know a car in a garage is rare these days, but mine does get garaged every night. I can't see a problem though, it doesn't sit there running and is well ventilated. It does get damp on occasion but I've not noticed damage to the old kitchen units I've got in there.... But then I've not studied them either. There are feet on the base aren't there? So the board isn't in direct contact with dewy grass etc and you can level the scope? Still, something to mind or for though, ta.

How prone to damage from damp are dobs? I had assumed they could live in an unheated, occasionally moist shed/garage/observatory. Or would be easy if I can put it in the garage and throw a blanket over it rather than try and make space in the house..... 3 kids and a London semi, space is a premium!

Boxes are the BEST! See now I thought I'd settled on an 8-10" dob second hand as affordable and wouldn't lose much if it got sold after gathering dust for a while. Now I'm back to looking at new and the 6" reflector with synscan/goto seems very attractive, both price and ease of use. Would that track well enough to attempt a bit of imaging photography? If I could get an 8" with goto for under £600 I'd look hard at that.

Thanks, if I but new then I'd thought about https://www.ebay.co.uk/itm/Skywatcher-Skyliner-250PX-Flextube-Dobsonian-Telescope-SKY10157-/233897156869?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=710-127635-2958-0 I've not seen a new 8" for much less. Is there much that can go wrong with a scope that isn't immediately obvious to a newbie? Ie, is used kit a bit of a minefield, or just the usual 'beware of the unscrupulous' that always applies to any second hand purchase?

Clanger hunting must be part of it surely!

Peter, you and I are thinking similarly. I've done garden camping several times this year with the 6 and 4 yo, and was thinking that the telescope outside the tent would be fun for them. Decent sleeping bags, warm PJ's and a wooly hat and they managed the first time in the tent back in march. We woke to frost on the tent and heavy condensation on the inner, but still warm and happy. I recommend some effort to insulate from the ground, some old cardboard boxes flattened out do quite well but I also have a few left over off cuts of 50mm kingspan and we sleep on those.

The one at £650? Probably a fair price with the extra bits but hard for me to tell, or tell which of those extras I'd use. The 200p I missed on eBay yesterday went at £170, and I can see bend new skywatcher 250 flextube dobs for £720, all I know it's that's probably an upper and lower end to aim inside!

Thanks Peter, that's great ideas 👍

Oh yes, thanks for the reminder, short spells and don't get disheartened by the '5 mins or less of focus'!! Yes frustrating the light pollution, if only the milky way and gorgeous galaxys and nebulae could be seen more clearly, oh well. Still, an 8 or even 10" dob would fit in the car (kids on the roof 🤣) so visits to relatives in slightly more remote places might become mini star parties.

Bearing in mind their age, while I may be reading. Tl@o, they will be watching cbeebies 'maddie, space and you'. Actually I'll watch with them.... Any dad's of young kids will know why 😉

Kids still pretty young so I might be too early... Or rather must not get disheartened if there is no 'wow!' initially.... Try again in another 6 months! Eldest is 6, then a 4 year old. Youngest at 15 months....too young for now! Mr thinking is there is no rush but would be great to have the kit and enough practice to be able to enjoy a future 'event' ....a comet or a lunar eclipse or such. Maybe a planetary transit, but then my first book just got delivered, I opened a random page and... Mercury doesn't transit again for nearly 100 years, Oh well! Cool. Yes I've been hunting on eBay and was outbid in the last minute on a 200p skywatcher yesterday and missed out on a 250 skywatcher (on manual equatorial mount) too, that was over twice as much but I'd probably stretch to a 250 Dobson if one comes up.

Hi there, I'm thinking of launching out on an exploration across the cosmos.... By telescope, not rocket, obviously! I've been studying a few bits on YouTube and have ordered some books including turn left at Orion but I'd appreciate a bit of a check on my logic so far. I have been looking mainly at reflectors and probably Dobson because the main reason for trying this is to show my young kids some space stuff and hopefully amaze and inspire them. Saturn's rings, spiral galaxies and vast nebulae will be great, but it will be the look on their faces that I hope to enjoy most. If they enjoy it then it's something we can do and learn together. So my primary objective is to show them stuff that makes them go 'wow!' Predicting that is impossible but I reckon looking at a computer screen of a processed image won't do it, looking at a bright dot and then the same target through a scope and seeing stuff in more detail could. So Saturn, Jupiter, the moon, some stars that become visible doubles. Targets that hopefully are a nice bright image and with some detail/something that is very different to the naked eye. I'm thinking a dob, as it's affordable, and should give a nice bright image. Personally I am inspired by the incredible images of DSOs so if we enjoy observing, then I might build a equatorial platform (I'm ok with DIY/woodwork so pretty sure I could manage one), and buy a cheap camera, learn a bit about photography trying to image the planets and then think about what next. How does my logic sound? Thanks Neil

@AMcD. AHH it was just the way you phrased your post, 'i get lots of help from...'. 😀

@AMcD. Are you astrobiscuit? , If so I'd like to say I've thoroughly enjoyed several of your videos, excellent and inspiring. I hope you are able to do more. I have an idea for a video, how about a help a newbie/ newbie with astrobiscuit mentor Vs a pro? I know a newbie in need of help🤣 Yes I get all the variables so to say a newbie could be as good, or Rory is in the top X is silly, it was just a style of question to get an idea. I suspect I'd fall into the archetypal stargazer but who knows, if one of my kids gets inspired it would be fun to do together. I've ordered TL@O, and a couple of other cheap beginner books to read through. Missed out on the 8" dobsonian. Skyliner with 5 EPs across London and I was the only bidder at £155 until the last minute, outbid by one person. The search goes on. I've been considering a 10" skywatcher on a manual eq mount in Chiswick, and the guy a few questions and he seems very genuine and helpful. 2.5 times the price though so I'm unsure, might, but might wait for another bargain dobie.

No just observing. I'd like to take some photos as you can get so much more detail and I love the DSOs but the extra cost, and the extra time needed (with 3 young kids time is singing I don't have in abundance!) So observing really, and see if I can excite the kids.