Tension knobs are not holding 8 inch dobsonian in place

[Stargazer2007]

Hi, I recently got myself the GSO 8 inch professional dobsonian (a.k.a GSO Deluxe) and the tension knobs are not providing enough tension to hold the ota in one place. Like, if I am observing something near the zenith, the ota starts to swing upward till the end of the ota hits the front plate (the one with the handle) of the base. I have asked my friend who also owns the same telescope about this, but he says that his tension knobs are working just fine. Is there any way to fix this? I do know about adding counterweights but is there any way to fix the tension knobs themselves? Thanks in advance.

[Peter Drew]

You could try cutting washers from a plastic milk bottle or similar and fit them between the knobs and the mount.  This would increase the pressure and maybe improve the holding effort.     🙂

[Roog]

Initially I applied more pressure through the tension knobs but I felt that it made more sense to improve the balance of the tube rather than use more tension, especially as it makes the smooth movement of the scope tube harder. I use tool 'rack' magnets with lead bonded to the back, these 'cling to the tube' and can be moved about to re-balance the scope depending on the angle of altitude.  

The counter argument (pun intended) is that it isn't great adding lots of weight to the scope pivots either.

I noticed that things start to get a bit much when adding a new finder scope and a traditional DSLR to the nose of the tube.

[Ricochet]

That dob is the one where you have some adjustment on the balance point. What happens if you move the tube slightly "down" from the bearing (so the primary is further from the pivot)? What about at low elevations? Does the nose dive when you put an eyepiece in? 

[Spile]

The ota should be balanced so if you can’t change the fulcrum, add a counterweight to the opposite end of the one that dips down.

[Stargazer2007]

But if I change the fulcrum the tube is no balanced on all the angles

[Spile]

8 hours ago, Stargazer2007 said:

But if I change the fulcrum the tube is no balanced on all the angles

Why not? The balance point doesn’t change with angle. I appreciate adding a heavy eyepiece or phone will make a difference though. I have a magnet that I use as a counterweight.