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Let me get this right...Steppenwolf + Dobsonian ???


steppenwolf

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OK, I know it is a huge step into the 'light' from the 'dark side' but I have a lovely Sky-Watcher 10" SPX Newtonian Reflector just sitting in a wardrobe unused despite having been fully upgraded with flocking and a gorgeous Baader SteelTrack focuser!!

At SGL9, I faffed about with a Megrez 72 and a GoTo alt/az mount, looking for opportunities in the gaps in the cloud and was rewarded with two deep sky objects!!!! However, John (Global Moderator on here) was merrily swinging his 12" Dobsonian all over the place and observed 15 (YES, that's right, FIFTEEN objects in the same time)..... OK, John is a very experienced observer but the limiting factor for me was the silly GoTo system that had to be calibrated through 'holes' in the cloud cover before I could even use it and then, that 72mm aperture - great for imaging, less so for observing!

Lesson learnt, I got some great advice from Shane (Moonshane on here - thanks Shane) and set to building my own Dobsonian mount in readiness for the next star party. I am so loving learning some new skills!!

This is part one of my new adventure, showing the parts I have made so far:-

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I too was considering trying observing and getting a Dob.  Problem now is finances - one household income instead of two, so more (if not all) my pension income will be absorbed by household outgoings :(  I'll probably try the MN190 though - with a ladder :eek: unless I sort something else out.

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Looks excellent Steve, very nice handiwork :-)

I cheated and bought the OO base but similar to you I still have my dob L plates on!

Stu

Sent from my iPhone using Tapatalk

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excellent start Steve - in fact you are not far off already!

a couple of recommendations:

you may know this but for smoothest movement place your Teflon pads on the rocker sides at points around 70 degrees from the centre. like this

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you may need to adjust the top arc of the rocker box to accommodate this but maybe not.

cut away some of the rocker sides if you can - saves weight, provides a grab handle like your side bearing circles and also lets the wind blow through. like John's if you recall.

other than that it's looking great!

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I've just finished building my 150p f/5 Dob, literally finished today! All I can say Steve is your going to love the feeling when you finish it and stand back to admire your new scope! :) You've got off to a cracking start with some nice routing :)

Wishing you a smooth dob build :)

Chris 

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wow looking good steve..no hanging about,,,think you will be able to get it into your mitsy for next time your up my way..great bit for it up the campsite hills lol...see why the pipes are struggling now lol..davy

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Nice start to your new Dob base! Have you thought of adding a setting circle while you're building? Add a Wixey magnetic elevation meter (£20) you've got a fast action push-to which can be get you lined up quickly while you wait for the clouds to part! 

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Great idea Steve !  :smiley:

Those holes in the alt bearings will make great handles for carrying the tube around too. 

I'll look forward to an evening "dobbing" with you at the next star party  :smiley:

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good luck to you, looking good so far! looking forward to the follow up  'MAKING EVERY PHOTON COUNT', a Beginner's Guide to Deep Sky observing by Steve richards

Now don't tempt me ............

Does this mean you will be posting "which eyepiece" questions  :grin:

You can see it coming can't you?

you may know this but for smoothest movement place your Teflon pads on the rocker sides at points around 70 degrees from the centre

I shall follow that advice carefully!

Wishing you a smooth dob build :)

I've loved every bit of it so far! Learning new skills is something I never tire of. So far all has gone according to plan.

I cheated and bought the OO base but similar to you I still have my dob L plates on!

I looked at and then drooled over the OO base but once I'd added the cost of all the bits together and then ADDED VAT (!?) I decided that I could/should make my own. However, I realise that the OO version is very finely crafted.

Nice start to your new Dob base! Have you thought of adding a setting circle while you're building? Add a Wixey magnetic elevation meter (£20) you've got a fast action push-to which can be get you lined up quickly while you wait for the clouds to part!

My original design had a circular base and I had allowed for a calibratable azimuth setting circle viewed through a small 'porthole' in the rocker box base. However, the whole idea of this huge departure from my normal astronomy practices was to get back to basics and have a really simple mount. I have, however, made a small concession to this and have ordered a Wixey to use as an altitude 'scale' - for dim, more obscure objects, my plan is to choose a star near the object I wish to locate,(with a very similar altitude) and then sweep in azimuth to find it and keep the actual mount as simple as possible otherwise I can see me adding encoders, a motordrive, GoTo and a de-rotator thus completely defeating the reason for the project! :grin:

I'll look forward to an evening "dobbing" with you at the next star party  :smiley:

I'd be delighted to learn from the master! You won't approve of my Hyperions on a F4.7 telescope though, John!! 15 objects to my two - humppfffhhh...... :grin:

Thank you all for your encouraging comments!

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OK, I know it is a huge step into the 'light' from the 'dark side' but I have a lovely Sky-Watcher 10" SPX Newtonian Reflector just sitting in a wardrobe unused despite having been fully upgraded with flocking and a gorgeous Baader SteelTrack focuser!!

i want wardrobes like yours...

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My original design had a circular base and I had allowed for a calibratable azimuth setting circle viewed through a small 'porthole' in the rocker box base. However, the whole idea of this huge departure from my normal astronomy practices was to get back to basics and have a really simple mount. I have, however, made a small concession to this and have ordered a Wixey to use as an altitude 'scale' - for dim, more obscure objects, my plan is to choose a star near the object I wish to locate,(with a very similar altitude) and then sweep in azimuth to find it and keep the actual mount as simple as possible otherwise I can see me adding encoders, a motordrive, GoTo and a de-rotator thus completely defeating the reason for the project! :grin:

I sympathize entirely with your wish for simplicity and 'getting back to basics'. After a whole set of modifications to an SW supplied Dob base I have been seriously considering a Dob mount construction like yours from scratch in an attempt to get the alt axis 'feel' right. But having got used to the azimuth setting circle with porthole system, I wouldn't leave that out of the build.   

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i want wardrobes like yours...

.... but I'll guarantee that you don't want to dress like me :grin:

I have been seriously considering a Dob mount construction like yours from scratch in an attempt to get the alt axis 'feel' right.

From my research, the key seems to be a large bearing free from brake/tension devices - my bearing (wheel section) is 487mm* in diameter which should result in a reasonably large amount of travel for even small changes in pointing.

I have just spent a fruitless evening on the Internet trying to find the best bolt/bush sizes for the azimuth bearing. For some reason, I am thinking a 12mm bolt is about right for my size of mount/telescope. What I am hoping to achieve bolt head - washer - rocker box floor (18mm) with a metal sleeve to avoid wear - a thin (half) nut - washer - ground board (18mm) - washer - nyloc nut. This will leave the rocker box floor to revolve freely around the shank of the bolt and the bolt itself to be solidly attached to the ground board. I have found some 'Oilite' bronze bushes with an ID of 12mm BUT does that mean that a 12mm bolt will pass freely through it? Next problem is that from the suppliers I have found so far, I am unable to determine the thread length and I need this to be long enough to allow for the two washers + 18mm + nyloc nut + half nut!!

* Obviously keep this to yourself but it was supposed to be 485mm according to the circle cutting jig I made but real life added 1mm to the radius :eek:

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I use T nuts Steve for the azimuth bearing. use one on the ground board underside as is and the other on the topside of the rocker but with the threads drilled out. I then epoxy both in and put a Teflon pad with a hole in it glued over the rocker 'sleeve' to hide it.

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Excellent image Earl, I can only agree that it does look rather like a cannon - but will it blast holes in the cloud?

I use T nuts Steve for the azimuth bearing. use one on the ground board underside as is and the other on the topside of the rocker but with the threads drilled out. I then epoxy both in and put a Teflon pad with a hole in it glued over the rocker 'sleeve' to hide it.

OK, so your azimuth bolt isn't self supporting on the baseboard as there is only one threaded fixing (the T nut on the base of the baseboard)? I like the idea of drilling out a second T nut to use as a plain bearing - cool idea.

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