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Dennis & Hogly, Congrats on joining the 12" Dobbie Club!!!!
How do you move it around on your own?
I take the OTA off the base and place it to the side. Then I carry the base outside. Then take the OTA out and put it back on the base. The OTA is not too heavy, just awkward due to size.
I fiddled with the two screws under the focuser but dont quite understand them. (crayford)
The bottom screw locks the focuser in place when you acheive best Focus. It stops the focuser moving when using heavy EP's or your eye pushing the focus tube in.
The top screw is like a clutch. Screwed in it will grip tight and you can carerully focus heavy EP's (I do this when using 2" Barlow & 2" EP together). Screw it out and it lightens the focus (I use this most times). The more you use it screwed in the more it will gradually waer tracks into the focus tube. Only use it 'screwed in' if necessary.
Alt pans smoothly but Az is tight, can you use some silicon spray or something on the nylon pads?
Best results have been achieved by placing a washer system in the centre. There is a thread in here somewhere about using Plastic Milk bottles to make the washers. The weight of the whole dob box and OTA are pressing down on those 3 teflon pads, so the centre has to be supported, that's what the washer system does.
Collimation, it was WAY out when I got it, I have centred the mirror by setting all 3 scews to same depth, but was then forced to adjust the three in the secondary to get the centre dot to come close to the middle of the eyepiece,
Don't worry about getting the 3 screws in the big mirror the same. It isn't accurate that way.
Firstly: look down the focuser without an EP, and look AT the small 2ndry mirror. You should adjust the 3 screws on the 2ndry until the Big Primary mirror is pefectly centred in it. Then go to the Primary mirror and gently adjust the 3 screws in it until your centre spot it centred.
This will not collimate the scope to it's best but at this point that is as close as you can get. Next step is to do a star test to collimate it perfectly. I use a collimating tool called a Cheshire Eyepiece, then Star test.
What mistakes did you make?
Lots! I was collimating in the wrong order, I tried to change the Azimuth without Teflon pads (mine came with horrible roller bearings), I didn't set my 2ndry mirror in the right place (in the centre of the focuser and with a slight offset), I didn't understand what the 2 screws on the focuser were for and fiddled with them too much and slightly scored the focuser tube, I did not use the 3 Primary mirror screws the correct way, etc, etc.
It was with help from all the great guys and gals in here that I finally started to get things right.
I still have a lot to learn but I can pass on what I have already learnt. I have owned scopes for 20 years but this GS 12" was a new monster to me and I'm sure I will learn even more about it yet.
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