goto dob level base

[StephenV]

I have a skywatcher goto dob which I am having trouble with. After alignment it is not very accurate, only pointing in the general direction of the selected object. How perfectly level does the base have to be for it to work properly?

[mental4astro]

Hi Stephen,

On what surface are you setting up the scope on, lush turf or hard compacted stuff/concrete?

Alex.

[Ukastronomer]

Surely all scopes need to be level ?


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[Startrek]

Stephen
I have a Skywatcher 12” GoTo Dob and from experience you need solid ground under it and the base has to be really level on all four sides to achieve good Goto accuracy
My dob sits on a concrete driveway, I use 4 adjustable furniture feet from bunnings ( 10mm threaded stud ) with thick rubber washers to sit under the base.I use a 17mm open ended spanner to adjust and good Stanley 300mm builders bubble level
My Goto is very good at each observing session after a 2 Star alignment using alignment stars at 50 to 60deg in Alt and 60 to 70 deg apart in Az

Cheers

[Malcolm]

You only need three adjustable feet, replacing the original rubber studs. I fitted three 19mm hardwood blocks, screwed and glued to the base to take the Bunnings adjustable feet. They have a nylon base and are adjusted by hand. I have two small spirit bubbles fitted each side of the mount base and one circular bubble fitted in front of the az motor. The bubbles were from eBay around a dollar each. If I'm on soft ground, such as a public park, I use three timber pads, each one has been drilled with a spade bit the same size of the feet halfway through the timber to prevent the mount sliding on the timber. I also have a small spirit level and a digital inclinometer for accuracy.

[Startrek]

Malcolm
I use 4 adjustable feet as my driveway has a splaid slope , 3 adjustable feet don’t quite achieve perfect level
I also set my OTA in the home position pointing true north along its centre axis I have 2 small 5mm alignment holes in the driveway 3 metres apart which designate true north ( solar noon meridian line using shadow method and Stellarium solar noon time ) This is not a critical requirement but I do it anyway
You spend time and do all the prep work right and your Goto is really accurate with these Skywatcher Synscan Goto dobs. Once you manually slew and nail your first alignment star spot on ( I use an Orion 20mm 70deg illuminated retinal eyepiece ) and then select your second star , the scope ends up really close with just a minor tweak. After that your off and running all night with excellent goto and tracking
Cheers

[knightrider]

I built a copy of the Orion Dob Dolly/Base. Came up pretty schmicko after i did the black iron on edging.

https://www.telescope.com/Dob-Dolly-for-Orion-45-10-Dobsonian-Telescopes/p/102784.uts

Works a treat for my scope.

[knightrider]

Pics as per below.

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[StephenV]

thanks for all the replies, very helpful.

[Sconesbie]

Hi Dale. What is the round thing toward the edge of the base and how did you do that ruler scale on the edge? I have a 10" dob and this looks like a great idea.

[knightrider]

Hi Scott, the setting circle I got it off Cloudy Nights. https://www.cloudynights.com/topic/514545-free-printable-setting-circles/

I had to use the circle done by "natdiamond" as he did a reversed version to go onto the top base plate rather then the bottom base plate. I wasn't interested in cutting a viewing notch or hole into the scope so opted to put it on the top base plate.

It's for a 12inch base plate, so I had to scale it down on my printer. Printed onto A4 in sections, laminated, cut them out and taped them together.

This also means I don't need to align the scope to North, as I have a movable indicator, I can just find my object, get its coordinates and plonk the indicator on that azimuth degree. I clip the indicator to the bottom base plate. I can get a pic if you want.

The little circular thing is just a bulls eye bubble level.

Cheers,
Dale.

[Sconesbie]

Thank you Dale. A picture would be awesome if you could. I currently have a round disc between the base and the actual mount. I have a section cut out so I can read the increments. Only issue I have had with this is that it moves sometimes when I spin the mount and I lose my alignment.

The bubble level is a good idea. I have a small spirit level in my kit but this would work well too. Probably better.

[knightrider]

It sounds like you just need to find a way to brace your movable setting circle/disc once it's set. Blue Tack maybe?

The indicator/needle I just rigged up out of a couple of angle brackets I had at home. It serves it's purpose.

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[MPS]

Hi
I had a very similar issue with my 10' skywatcher goto dob. After having a perfectly level cement block placed in the paddock I was still getting the scope in the general direction. After factory resets, trying on different level sights, and using both the synscan handset as well as the Wi-Fi module nothing changed. After a few calls to the dealer I bought it through advised to set my altitude to 0m..........even though I'm at 200. This for me worked perfectly! And after my 2 star alignment the dob falls smack bang in the middle of the eyepiece! Every time! An odd fix but worked for me

[Startrek]

I might try setting the elevation to “0” even though mines really accurate at the moment when set at 25m
Thanks for the tip