My 12" Orion Optics Dob with Equatorial Platform

[John]

noooooooooooooooooo....................................noooooooooooooooooooo.

Don't worry Shane - I'm not going over to "the dark side"

[Moonshane]

ha ha I know, only joking - you'd have every right to do so if you wanted to though. my prediction is that like with myself, you'd get worked up feeling like the camera was hogging the scope and stop before you even got going.

[nightfisher]

This platform seems a superb idea, having seen Shanes working very nicely, could be some aperture fever coming my way

[John]

I've been using it again tonight. Basically it just works, simple as that. I've been staring at Saturn at 318x for 20 mins or so with just a couple of touches during that time to re-centre the planet. It does help ones concentration and relaxation

The seeing is rather touch and go but in the short bursts where it's "go" the detail on Saturn tonight is impressive. I can see the Cassini Division clearly bisecting the narrowest part of the ring system, where it crosses in front of the planets disk. I'm also seeing a slight contrast variation in the A ring around 2/3rds of the way from the Cassini Division to the outer edge of the A ring. I've not been aware of that before as I recall.

[Nevy]

I just tried mine out tonight and the seeing was pretty good for a change , I was also looking at Saturn at about 200 x and it was AWSOME , I was seeing 3 bands , a super sharp Cassini division , the rings on the outer edge after the Cassini division were a bit darker and I also got quite a few glimpses of detail in the polar region , I then took it to 300 times and it was nice the super sharp views were there but not for as long durations but still very nice , the platform performed flawlessly and it's a pleasure to just sit there without all the nudging every few seconds. It's a very nice way to observe and I highly rate them , I just wish I could get one that's capable of taking the weight of the 16" lightbridge ( about 70 kg with accessories & counter weights).



 

[Moonshane]

really nice base. I presume you made this using a skywatcher base as a router template?

[John]

Welcome to the eq platform club Nevy - that's a nice setup you have

Interesting you mention Saturns polar region. In the moments of good seeing I could see a darker circular polar "cap" around the N pole of Saturn last night. It was not that large and there was a lighter zone separating it from a thinnish belt, then a thin pale zone and then the wide main eq belt around the planet.

I'm glad you are enjoying the still views

I notice you have your platform on grass. So far I've stuck to the patio but I'll try the lawn this evening perhaps. It's not as level as the patio but it will be interesting to see how the platform reacts to that.

[Nevy]

Yes moonshane , that's exactly what I did and I also put an ebony star ring & virgin Teflon pads on and it's smooth as silk to move , I also ebony stared the alt bearing and made some Teflon trunions to replace the nylon ones , but I then remade them with Teflon with 30% glass fibre as the pure Teflon ones were to good (slick).
@ john , ah yes the darker polar cap , that was what I was trying to say but couldn't think of a word to describe it , ( I put detail in the polar region cause I didn't know if it was called a cap because its all gas lol).
I did set it up the night after I got it , my grass is far from level so I put it on a 2 inch thick paving slab and I got a bit of a drift in tracking because I only used a cheap plastic two way bubble level and have confirmed now that it's not accurate , I also didn't like the extra 2 inch height it added.
I spent Sunday cutting a load of 5 inch discs from 2 mm thick steal so I could level the base in 2 mm increments and also to spread the weight so the feet wouldn't sink in the grass and upset the level ( I'm not sure if you can see them by blowing the pictures up) I undead up using one on the back foot ( south foot) and five each on the front ( north feet ) i also made a few out of 3/4 inch plywood just in case but didn't need them , I'll post some pictures later.

 

[Nevy]

Here's the discs , I'm gonna make some more using 1/2 "ply & 1/4 " ply so I can have more control with levelling



One thing I should mention is that I used to get nice sharp images with nice Cassini division but a bland whitish planet with hints of bands , but I made and installed a sealed baffle system with a nice vibration free fan , and now I get multiple bands with subtle colour and all the extra detail , it was well worth the effort.




 

[John]

Some great mods there Nevy

I'm going to have to think about improving the fan on my OO dob I think. It has a tiny fan on the back of the primary cell but the baffle approach looks interesting. When I was reading about this on another forum they talked about having a further single baffle inside the scope tube just above the primary mirror, to deflect the airflow and remove the boundary layer that sits directly above the primary more quickly. Have you done that as well ?

My OO dob has curved secondary supports which I do think helps with planetary and lunar contrast.

[Nevy]

No john I didn't put a baffle ring inside the scope , I just use a 120 mm noise blocker fan on the back , I have means to slow the fan down by altering the voltage but I don't really need to slow it as its got zero vibrations , I just leave it running at full speed.
 

[John]

Thanks Nevy.

I got another session in tonight but the seeing is was not quite so good. I could see the same details that I did last night but more intermittently. I put the EQ platform on the lawn this time but did no special leveling. It still tracked well though. The standard plastic feet on mine are not great on grass (they dig in a bit) so I will make some nice flat feet for it.

[vlebo]

I thought I'd just post a few pics of my Orion Optics SPX 12" F/5.3 dobsonian in it's latest form. The dob base for the scope was made by one of our members - Moonshane. I've added a lightweight AE light shield to stop stray light finding it's way into the focuser / secondary area. I've also added a lower tube counterweight which comprises a magnetic knife strip and a couple of iron kitchen scale weights, as required.

My equatorial platform arrived today and thats what the scope is standing on. It's a used model made by Equatorial Platforms UK, their Watch House Equatorial Platform.

The platform forms a really solid, but tracking, platform for the scope and I should get around 60 mins tracking between resets, which take a few seconds to perform and the scope stays on the platform for these. The drive runs off a single battery and is a simple RA motor. The bearings, of which there are 4 plus the drive shaft, are really hefty. When the platform is aligned and tracking you move the scope as usual from object to object with the difference being that they should stay in the field of view, even at high power, without the need to nudge !

I'll post a report on how this device works in practice once I've used it for a few sessions

Heres one for Moonshane. Would it be possible to make a dob base that would be fixed permanently onto the equatorial platform therefore you would only need to place the ota onto the whole platform thereby making it easier to set up abd balance ? Go on Moonshane , you know you want to !!

[Nevy]

I was thinking of doing it for mine , all I would need to do is drill a 14 mm hole in the middle of the platforms top board & add 3 Teflon pads. It would lower the eyepiece height by nearly 2 inches which would make it just about perfect, but you can't store the scope like this as the instructions say that you shouldn't store it with a scope on or even with the top of the platform board on because it may cause a flat spot on the rubber on the shaft , but it wouldn't be a big deal to set it up for each session.

 

[John]

Heres one for Moonshane. Would it be possible to make a dob base that would be fixed permanently onto the equatorial platform therefore you would only need to place the ota onto the whole platform thereby making it easier to set up abd balance ? Go on Moonshane , you know you want to !!

I thought about this but it's so quick to set the platform up that it's really no extra bother. The additional bulk / weight on the base would cause storage / mobility problems for me as well. Currently I can pick up the whole dob and move it around the garden but with an EQ platform attached I don't think this would be the case.

Nice idea though

[Moonshane]

it's a good idea to use the eqp as a ground board and a lot of larger scope users do just that. I have often considered it and if I did, I think I'd make a ground board too and then it could be used with an without. I'd certainly make the rocker removable though and a handwheel to fit it. then it could be quickly and easily removed.

but as John says it's actually not that bad to remove it. with my 6" f11, the scope's cog is so high and the scope so spindly that I bolt the scope to the eqp for added security just in case.

here it is and you can see why I think!