counterweight shaft extension and PVC half pier

[orly_andico]

hi all

I got a Vixen Polaris last weekend thru vpost. It has one of those old threaded counterweight shafts.

I would like to have a longer C/W shaft because I'm gonna put a rather heavy OTA on it and it's already marginal so I don't want to add more weights.

Anyone have any idea on where to have one fabricated for example?

Also does anyone have plans for the PVC half pier? As usual my C/W shaft is hitting the tripod leg.

[rlow]

If you lengthen your c/w shaft, wouldn't it require taller half-pier?

Since it is only marginal, one easy way is to add a small dumbbell weight, it doesn't look great but it had worked for me. A small weight is easier to get and cost less, no?

I built a half pier from stainless steel pipe, easier to weld. Would the vixen half-pier work for you?

[timatworksg]

I have a Vixen GP with a vixen half-pier and with heavier scopes the cw needs to be all the way at the end of the shaft with no extension. I do the same and add small dumbbell weights above the Vixen weight with a jubilee clip topping it off. I don't use an extension but add the weights for my C8 instead.
Adding an extension will allow the use of no additional weights, but on a half pier, it will hit the tripod leg as its lower down on the extn.shaft.
A taller pier or custom one will work...but the cheaper option would be the dumbbel weights. The holes may be a little wide for the shaft but various clips are available.

[10,000rpm]

For my CG-4 mount, I turned the "North" marked tripod leg to the south and made a shortish PVC pier extension just high enough to prevent the counterweights from hitting the front 2 legs.

[10,000rpm]

Repeat post deleted.

[orly_andico]

hi rlow,

i meant the Polaris is marginal for the OTA i intend to put on it.

(this is a Polaris, not a Super- or Great Polaris, but i got it for only $250 SGD + Vpost shipping, so can't complain)

if I add barbells to it, the weight will be increased tremendously, and the OTA i'm planning to use is already overweight for the Polaris. hence i'd like to use a C/W extension shaft so i don't need to add more counterweights (and overload it even more....)

[rlow]

Ok. So how long will you need to extend to achieve the same effective counterweight? Then you need a taller PVC pier. Will all these affect the performance, stability and durability of your mount?

[timatworksg]

I see your predicament. You could try what 1000rpm suggested?
A DIY PVC pier needs to be rigid....no idea of plans but you could look at the High pressure type Plastic pipes which are thicker and dark grey in color. They are much stronger than the normal white general plumbing ones and are used for pool and high flow piping needs.

[orly_andico]

i really have no idea how durability will be affected... nobody really knows how much a Polaris can carry (some say 10lb, others claim 15lb). i understand that's exclusive of the C/W right? so i can go over that so long as i cut down on the counterweight. i'm thinking about a 12" extension..

http://www.cloudynights.com/ubbthreads/ ... in/3417378

this guy seems to be happy with a C8 + guide scope

[kingkong]

i've played with building a pvc half-pier before. it's not rigid enough as a serious solution. if you'll take my word for it. skip that idea. if you are in singapore, you should be able to have an SS or alu one done without too much challenges...