My 12" Orion Optics Dob with Equatorial Platform

[John]

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

[michael.h.f.wilkinson]

Nice looking piece of kit

[swamp thing]

It all looks very nice indeed. I'll look forward to your report on it's performance John.

[todd8137]

Nice keep saying am gonna sell my image tackle and but another big dob

pat

[Moonshane]

looks great John - nice and solid.

[scarp15]

Looks great, would be interesting to learn in your feedback regarding the additional height gained. I expect that you primarily intend to use it on planetary observing, so perhaps this elevation will be OK.

[Earl]

Tidy, If i was a larger Dob owner I would consider one of these.

[Damo636]

A very useful piece of kit John, looking forward to hearing how it performs in the field.

[John]

I first lighted this platform this evening. It really works !!!

I aligned the base N-S using a small compass attached to it. Put the top board on and stood the scope on it (as per the above pics). I started the motor and found Saturn. It stayed fairly still in the eye piece but there was some "creep" towards the East indicating that the motor was running a little fast. I adjusted the speed control a couple of times until the planet remained in the centre of the field of view. This was at 265x. The seeing is not great tonight but to test the platform I tried 318x and then 398x. At each step up in power Saturn remained almost motionless in the FoV. I could study it at leisure, change eyepieces, play with the focus and even pop in for a coffee and still come back to Saturn and it's moons sitting steadily there for me to view.

Over several minutes there is a very slight drift in a South direction so I'll find out what adjustment I need to make to counter that but it's very minor and takes many minutes to be obvious.

The platform has raised the eyepiece by around 5 inches which will make a shallow step needed if I'm viewing objects in the region of the zenith with it.

Overall a great success so far - it's been a few years since I had a tracking mount and while I'd got well used to nudging at high powers I can see that really scrutinising an object in a relaxed manner is much easier when the target stays still !

[foundaplanet]

I had seen these and never really taken much notice of them nor how they work, now I see what a clever invention they are. Certainly going to be helpful when using the ortho's and make planetary viewing a more relaxing experience. Made in the UK to, how good is that..

[Mr Flibble]

When aligning mine N-S I also place a bubble level on it and shim a few bits of thin plywood under the feet to get it level. I don't know if you've tried it John but it might improve the tracking accuracy a bit more?

[John]

When aligning mine N-S I also place a bubble level on it and shim a few bits of thin plywood under the feet to get it level. I don't know if you've tried it John but it might improve the tracking accuracy a bit more?

Thanks David - I'll have a play with that.

I can adjust the position of the 3 feet on mine although not with the scope on board so I'll try some shims to find out what has the desired effect before adjusting the feet.

I'm also going to try offsetting from magnetic north a little so that the axis of the mount is closer to Polaris.

I was pleasantly surprised at how well the platform did even with the basic setup I did last night though. I might even try some lunar and planetary imaging with the scope !

[Laurie61]

Hi John, I also have a 12” OO newt and have been thinking about some type of tracking platform. I always assumed the platform would need to be tilted, to point at the pole, for these to work and was a bit worried about balance issues but you appear to be able to use this with the platform level which would make things a lot easer. Nice set up

[Moonshane]

the platform turns on the basis of a large conical section which points at Polaris. imagine you are looking at polaris with a traffic cone. only a small section of the bottom of the outside of the cone is tracked giving about 10-15 degrees of tracking (about an hour) depending on design.

this shows what I mean better

[John]

I think the pic that Shane has posted illustrates it perfectly. The platform that the scope is standing on never gets more than a few degrees away from level so the scope remains stable. This does restrict a tracking run to around 50-60 mins but the reset routine is no more than lifting the corner of the top platform to disengage the drive roller and then moving it back to it's starting position. It just takes a few seconds really.

[Laurie61]

Ahh, that's clever. 50/60 min is plenty for doing this. Thanks

[Nevy]

Very nice john, I'm not sure but it you adjust the feet it may alter the latitude adjustment presuming it is set for your exact lat in the first place , I should get mine tomorrow and I'll check the instructions to see if this is the case.

[Mr Flibble]

Just a bit of info I've discovered this evening concerning the motor drives on these platforms (I've got the TS platform but I think the Watch House uses the same motor unit?).

Its possible (at least on mine) to screw the housing of the motor unit back on with the two black knurled knobs so that its just slightly out of position. This can cause the housing to interfere with the full movement of the N and S and On and Off switches so that they don't make properly because they fail to reach the end of their travel. Took me a while to work out why the motor wasn't working in the one direction. Just something to keep in mind when having it off to change the battery, etc.

[John]

Thanks for that feedback David, I'll watch out for that.

@ Nevy: I suspect the southwards drift is due to the base not being on an entirely level surface. It's so slight I'm not bothered by it as an object at high power still remains pretty static in the FoV for many minutes which is a major boost to studying it.

I can play around with the feet on the base as they are all adjustable and also try aligning to Polaris rather than magnetic north.

[Nevy]

Just a bit of info I've discovered this evening concerning the motor drives on these platforms (I've got the TS platform but I think the Watch House uses the same motor unit?).

Its possible (at least on mine) to screw the housing of the motor unit back on with the two black knurled knobs so that its just slightly out of position. This can cause the housing to interfere with the full movement of the N and S and On and Off switches so that they don't make properly because they fail to reach the end of their travel. Took me a while to work out why the motor wasn't working in the one direction. Just something to keep in mind when having it off to change the battery, etc.

I was tempted to get the ts one but it didn't like the look of the motor sticking out( judging by the pictures on their website) , it looked like it could easily be stood on and get broken or bending of the shaft , I went for the watch house in the end as the motor is tucked away underneath , also the platform looks more substantial & of better quality although a bit more expensive. Here's the watch house motor

 

[Nevy]

Thanks for that feedback David, I'll watch out for that.

@ Nevy: I suspect the southwards drift is due to the base not being on an entirely level surface. It's so slight I'm not bothered by it as an object at high power still remains pretty static in the FoV for many minutes which is a major boost to studying it.

I can play around with the feet on the base as they are all adjustable and also try aligning to Polaris rather than magnetic north.

Yes that sounds a good idea john let's us know how it works out , did you get instructions with yours?

 

[John]

Mine is the same as yours Nevy but they could be the same units as David's has with slightly different graphics. Mine has to be in the southern hemisphere position to work with the equatorial platform. It's a clever design that allows such a small motor drive a 50 lb's + scope around the RA axis

[bingevader]

Only just caught up with this!

I'm glad it's working so well.

Tried any astrophotography yet?

Cheers

[John]

Only just caught up with this!

I'm glad it's working so well.

Tried any astrophotography yet?

Cheers

No - I don't do imaging so I've no suitable gear.

I might get a cheapo webcam and give it a try on the moon and planets one day for fun though.

[Moonshane]

No - I don't do imaging so I've no suitable gear.

I might get a cheapo webcam and give it a try on the moon and planets one day for fun though.

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