Dob Dob Dob

[AlexB67]

Now, that's an interesting idea. Not that I'd be in a hurry to do so, but it does raise the point that problems with a Revelation mirror, should they occur, needn't be the end of the scope...

while true, it is a significant cost ( new optics )  of the whole scope. A recoating is also an option. John posted me some links for this, If I recall for a 10 inch it is < 100 pounds, for a 12 inch just over ( of top of my head ), but you'd have to remove it, send it and all that, a bit of a hassle, but no undoable.

[starwonder]

Yes, I'm starting to think on these lines too, maybe building a dob base may be an option.

The OOUK dob base is made of metal so no chance of rot but it is surprisingly light so maybe it's aluminium and not steel, not sure on that, either way it is strong and lovely machined.  To build an equivalent kind of structure in wood may make it heavier but regardless it would need some kind of protection like varnish or the like to stop water ingress over time.

I'll have a search on the web to see what I can find, thanks.

[starwonder]

Not having used the SW base in practice does anyone know how it compares with an OOUK dob base?  I only have experience of using the OO but I have seen a SW, just not used one.

[Moonshane]

if well adjusted (and you can mod them to make them work more smoothly) they are perfectly usable and many people have had them for years with no issues. the problems (some only potentially at least) are weight, bulk, warping if allowed to get too damp (you can seal the seams with silicone to mitigate this). balance can be an issue if you use heavy eyepieces and finders but again you can use a mod to mitigate this. there's always a way around anything.

OOUK mounts are very good (the best really) but not the only option and you may well find that you are totally happy with the one on the 200p dob as it comes.

[starwonder]

Thanks for that Moonshame.  

The base will be on grass for most of its use due to the rear of my house facing north so water ingress may well be a problem.  I'll certainly look at sealing the seams.

What exactly may need modding/adjusting to get the SW to move smoother, is it a simple job?

[Moonshane]

it is pretty simple - I'd add sheet laminate on the bottom of the rocker, ensure the teflon pads don't have nails poking out of them on the ground board, add an additional teflon pad at the central hub. personally I'd also redo the side bearings but if you start doing that, you may as well make a full base!

honestly, we have a 200p at school for the astro club and it's really quite good.

re sitting on grass, this is not an issue as you could just set it down on wooden blocks.

[starwonder]

Thanks for the tips, am sure I can find something like that to sit it on - it's funny but although I'm a pretty practical guy and don't mind a bit of DIY maybe it's because we're dealing with sensitive components here I guess I think they should be wrapped in cotton wool or something! 

[starwonder]

But as far as the laminate and teflon goes not sure about that, I guess I'll just have to try it out and see whether it's up to the job or not.

[RikM]

I agree completely with Shane's comments on the SW Dob bases. The OOUK ones are much nicer but at a price. On my SW 250PX I added a stack of washers cut from milk bottle plastic around the central bolt and made sure the teflon blocks were all attached correctly (mine were okay, but it might not always be the case) I actually find that the alt bearings are okay, nice and smooth and steady/stable movement, but I don't use super heavy 2" eyepieces. Up to the 250, the base size is manageable (I'm a 6ft, 14 stone, ex-rugby player) but the larger sizes are really a handful.

[starwonder]

Sorry but I'm at a bit of a loss here, knowing nothing about the physical design of the SW base where are these teflon blocks actually located?  And I take it the washers you added to the central bolt refer to the bolt that goes through the centre of the dob base holding it all together?  And the alt bearings, where are they?  Are they the ones that control the up and down movement of where the scope attaches to the uprights? 

[AlexB67]

Hre is the one for mine, I think the rocker box is the same on the 10 inch solid tube, at leats the design will not differ if any compared to the solid tube I think.

http://www.skywatcher.com/downloads/191110V1_Collapsible.pdf

you can see from the pictures there how it hangs together.

[starwonder]

Thanks for the PDF link AlexB67 which is really useful stuff.  I must admit I am very surprised that there's only one teflon pad on the 8" mount, surely to run smoothly it'd need a pad either side?  Hence I guess your comment Shane to introduce another.  But why would there be any nails protruding through it?

[RikM]

Thanks for the PDF link AlexB67 which is really useful stuff.  I must admit I am very surprised that there's only one teflon pad on the 8" mount, surely to run smoothly it'd need a pad either side?  Hence I guess your comment Shane to introduce another.  But why would there be any nails protruding through it?

The solid tube 8" and 10" bases are exactly the same as this.

The 'teflon pad' referred to is a chunky teflon washer that goes in the centre. If you look at the base part labelled 'D' you can see three little squares? These are teflon blocks nailed/stappled to the base board. Part 'C' rests on these blocks and the central 'teflon pad' and that gives you your 360° azimuth bearing. The staples holding the square teflon blocks to the base sometimes stick out a bit and would rub on the 'C' base board unless you tap them flat with a hammer and a (tool that I don't know the name of but it looks like a little blunt chisel).

[starwonder]

Ah, I see, thank you RickM for the explanation.  I was wondering how the two plates C and D maintained separation with just the bolt running through the middle.  With your information I'll be sure to check the surfaces of the Teflon blocks when I put it together.

Whilst I'll be building it from new I guess it might be wise to make the mods then rather than disassemble it later?  So adding another Teflon washer as Shane advises to the main bolt, but what about his comment about redoing the side bearings, if they're new will they need redoing or does he mean replacing with different ones that are slicker?

[Moonshane]

I meant remaking them in a larger diameter with new partial sides. as I said, it's easier in a way to make a new base. BUT they do work reasonably well. I honestly think you are over thinking it.

[John]

I agree with Shane. I've owned 2 Skywatcher dobs (8" and 10"), a Revelation 8" and a Meade Lightbridge 12" and their mounts have all worked pretty well without the need for anything much in the way of modifications. I did do the "milk carton washer" mod on my Skywatcher which comprises of cutting some large washers from an empty plastic milk carton and inserting a few between the ground board and the rockerbox to ease the motion of the azimuth axis a bit but that is about as far from "rocket science" as it gets !

The chinese dobs work well and are great value for money  

[starwonder]

Cheers guys, all your help, as always, very much appreciated.

Hope to pick one up this weekend from Opticstar (nearest scope shop to me) if they have them in stock, so should be built and ready for launch (!) for the weekend if skies are clear.

[jetstream]

I must admit my first scope was going to be a 10" OOUK but I'm hesitating for some reason that I don't know why, maybe it's because of the significant price difference?  Not sure but either way the OOUK is surely built far better than some other dob's out there?

For one thing you can specify a high grade PV on the primary mirror, what focuser to use, the simple but easy-gliding Dob mount with a much smaller footprint and slicker than any other Dob I've seen - what finder, EP's, etc. etc.  It seems a fully customisable setup from new, so you get exactly what you want from the off.  I guess that is attractive to some people, like me.  But do I need all that in my first scope?  Will I be satisfied with another make that isn't up to the high expectations that I'm under the impression I'd get from an OO, will I be kicking myself that I should have just got what I wanted in the first place and relished the "happy" feeling?  And knowing that I've bought a fully British made product with the care OO take to hand finished all there mirrors.

It is a quandary and as you and other's have said bingevader there is nothing to touch the 8" SW at that price but I guess it's whether I will regret not going for the OO in the first place and actually save myself £300 instead of buying first the SW and then the OO later on.

It sounds like you want an OOUK Dob,but are not sure given the price difference.Do you have the time and the inclination to do mods to the SW that you want?I here they work pretty well as is, and at a great price.Myself I decided that I wanted to buy a telescope that I have no reason to modify.I love observing more than tinkering with a telescope-but to each his own.

My OOUK Dob mount is fantastic-powder coated aluminum and is very easy to carry.I don't need to worry about moisture,if it gets damp so what.Very smooth,nice friction brake,reasonable size dia side bearings.The OOUK rings are also a dream,you can just slide the telescope fore & aft to balance & use the brake when changing eyepieces-no shenanigans.

The 10" OTA 1/8 wave @ 1200 mm works great and is my limit for portability.The telescope has held its collimation very well through numerous trips,the rear cell is great and I leave the included fan on when observing.Even after cooled the fan makes a nice difference on the planets-probably a mirror boundary layer thing.The focuser is good,no slipping,very smooth, with little focus shift when locked.As you can tell I am happy with my purchase.I have bought a lot of things only to want "bigger,better" etc.I find these days I just wait a bit longer so that I can purchase what I really want-i.e. my eyepieces,scopes etc.This telescope will be with me for a long time as will my Stellarvue refractor-I love it too.There is a price to pay however and this can be a major consideration.Good luck with your decision.

[starwonder]

Oh dear Gerry why do you have to remind me how good the OOUK 10" is, that is the exact model I would be getting now if it wasn't for my concern of the massive depreciation costs the OO will incure compared to a SW.  The OO is my dream scope!  The first time I saw the 8" I thought now that's a base, one that is practical but beautifully made with a small footprint and so more portable.  I think I would have pushed it to the 1/10 PV but nevertheless the 1/8 PV for our skies is perfectly acceptable I'm sure.

I take on board all the credit about the OOUK, it is a fab scope, I was impressed myself when I used the 8", so smooth to use but what are you comparing it to?  Have you had a SW or similar in the past?  

I don't mind a bit of DIY in the home but to be honest I don't really want to be tinkering with the mechanics of a scope and it's a good point you make and maybe I've not taken this into account.  I want to use it, in fact I can't wait to use it, I certainly don't want to be wasting any more time messing about with bearings and anything else.  

I guess the other half of the problem is I'm a perfectionist, I greatly admire good engineering and I support British manufacturing, one of the best in the world IMO. I work for a manufacture myself and very proud to be involved in what we make in this country, hence my keeness to support OOUK rather than imported products.

Maybe I should just stick with my gut feeling and buy what I wanted in the first place and never mind the depreciation issue. 

I've already checked stock at my nearest dealer of the SW 200P and I could pick it up today!  Or I could go to OOUK Head office, about and hours drive away, and maybe have a look at the range...

[jetstream]

Starwonder,this is my first Dob so I have nothing to compare it to.My Dob works,is very portable for a 10" and the base carries very well.....it is actually balanced when I use the one support as a handle.I carried everything about 100 meters last night-in a couple of trips-and it was alright.If extreme portability is an issue I would get the 8".After lugging it around I checked collimation at the end of the night & it was vey close.I followed the same train of thought as you....OOUK base,Chinese OTA,etc.Then I realized that personally I just wanted the OOUK and bought one.You should have seen what I saw last night.... Thing is a SW may have provided the same views.In the end it is your decision.I try to maximize my dollar,but sometimes,on some things I don't really care about depreciation and I plan on keeping my telescope.I have lost more money on vehicles than anything else,but I keep buying them .I do try to avoid impulse buying and wait & see what I really want at a price that I can afford.

PS-I'm still waiting for the Ethos to go on sale again.....it may be a long wait...

[starwonder]

 Nice one Gerry!!

Yes, after about a year deciding I too just want a OOUK really not anything else and I guess if I'd have bought anything else, even a new SW, I would always have a nagging feeling of what if...

Well today I visited the OOUK factory and bought my first ever scope, a VX10.    However, after much deliberation I decided to opt for a motorised EQ5 mount and not a dob despite being sold on that really neat design.  The EQ5 will give me much needed height in my back garden to improve views towards the South and with the motors will stay engaged on the item I'm viewing.   To be honest an equatorial mount puts the fear of dread in me,   it looks very complicated but then I thought collimation was too until I proved to myself I could do that, so maybe it won't be so bad once I get my head round it.

Now I just have to wait a few weeks when it'll be ready.

[jetstream]

Congratulations!You will figure out your mount fast I think,I may pick one up myself here sometime too.Good choice, as not  being able to see over obstacles is very frustrating.I too thought collimation was going to be very hard for me,but thanks to the help/advice here I am doing a reasonable job right off the hop.My star tests are good as far I can tell,no doubt there is a lot to learn here.Myself I am trying to get a handle on the Equatorial sky mapping-I hope to understand it soon-not a requirement to use a mount,but the knowledge will probably help.

My great grandfather was a pattern maker/machinist from Liverpool,where he apprenticed starting @ 12 years old.He made his own oak tool boxes,perfect dovetails and all-and his chisels,tools etc were made in Sheffield,so I know the quality that Uk can achieve.I have all his things oiled up and stored here-most in excellent condition.I feel my telescope reflects this quality and the views it has given me support this fact.Awesome choice.

[starwonder]

All change!  After discussing the match on here between EQ5 and 10" OTA it appears it might not be well suited and so I've gone back to my original plan and will order a dob mount instead.

[Moonshane]

good move I think.

[dweller25]

I think good move