dob prob

[dawntyrant]

can anyone help ? i have a 10 " revelation dob and i only have to look at it and it moves in the mount and changing eyepieces is a nightmare , has anybody got any ideas how i can reduce the sensitivity of the mount?

[Helen]

A couple of things to try... tightening the alt knob on the side should help, and/or add some counterweight to the bottom of the scope (magnets are good, but ankle weights and velcro also work!)Helen

[mdstuart]

Or Buy a HEQ6 mount for £399

[FLO]

... tightening the alt knob on the side should help

You are thinking of Skywatcher Dobsonians Helen, the Revelation Dobs are made by GSO and rely on a spring for altitude tension.

Dawntyrant, I am guessing you have just bought one secondhand? Is the spring fitted?

[scotastro]

Which way is the scope moving - around the base (Az) or up/down (Alt).

If the former you can tighten the bolt at the bottom is the latter you will need counter balance at the back particularly if using 2" eyepieces.

Mike

[dawntyrant]

the springs are fitted and its the altitude thats the problem but not through weight at the front its the back as it constantly tips up to nearly verticle

[Helen]

You are thinking of Skywatcher Dobsonians Helen, the Revelation Dobs are made by GSO and rely on a spring for altitude tension.

Dawntyrant, I am guessing you have just bought one secondhand? Is the spring fitted?

Oops sorry

Helen

[John]

The Revelation dobs have circular needle bearings (like a sort of "Lazy Susan") on the azimuth (rotational) bearing which can make the movement too free for some. Many owners replace this with teflon pads (like the ones that you get to put under the legs of appliances / furniture) which allow smooth movement but with a little more friction. Tightening the azimuth bolt can help as well.

The altitude (up and down) bearings are 2 thin teflon pads on each side, on which sit the circular black plastic bearings that are attached to the tube. The tension on these comes from a spring which attaches to a screw in the centre of the plastic bearing at one end and a screw on the mount upright at the other. I've seen Revelations where these are either missing (there should be one on each side of the scope) or have become stretched - they can be replaced by similar springs. Counterweights on the bottom of the tube will also help control altitude balance as Helen suggests.

John

[dawntyrant]

wouldnt counter weights at the bottom of the scope add to the problem as tipping up right is the problem im having , also both springs are present and the tension on them is good

[John]

I guess you need to add some more weight to the top of the tube then. I used to have the 8 inch version and found the balance OK but I swapped the 9x50 optical finder for a lightweight red dot type which did upset the balance a bit.

John

[scotastro]

It would not cause any problems to the light path if you permenantly attached a metal plate on the underside at the top of the tube with sufficient weight to balance the scope.

Mike

[The Warthog]

Does anyone have a copy of the manual, and does it give any suggestions?

[dawntyrant]

thanks for the help everybody , ive found the perfect solution , hanging my torch on the handle on the top of the tube works a treat