Rolled vs. Milled Tube Rings

[thehand]

It seems that lower end OTAs come with rolled tube rings vs. the higher end which have machined Rings.  Has anyone had experience with both on the same OTA?  Is there a noticeable difference?  Thanks.

[Bukko]

Hello,

I have a small 80mm frac and both rolled and machined rings for it.

In use, even imaging, I have mot seen any difference in stability, etc, so at this size and fl (500mm) there is no real difference.

But the machined does allow me to piggyback another something on top, which the rolled tubes do not.

Which ones do I generally use? The machined ones, of course

I also have a bigger Newtonian; 12" f4 which uses rolled rings and have found them to perform adequately.

However, I cannot say if some of the OAG errors I see are due to any movement from the rings or not... They are tight and in comparison to the play inmy NEQ6, do not seem to be a problem, so I would say they are fine.

HTH and good luck.

Gordon.

[thehand]

Thanks!

[laser_jock99]

Machined tube rings are always a 'nice to have' feature. They give a feeling of solidity and have better fixing hole on top. However for large tubes they can be prohibitively expensive.

The cheap and simple way to add mechanical stability to a large scope (or any scope for that matter) is to add a Top Bar. This has the effect of tying in the 'loose ends' of the tube rings and reducing flex. It also pays to may the the dovetail bar and top bar as long as possible on bigger scopes. Where possible upggrade to a Losmandy style bar too.

In this picture you can see how I attached a length of aluminium profile to make the 'top bar' on this 6" Newtonian scope. The main dovetail and top bar are also much longer than the supplied 6" bar that came with scope.

My added top bar also supports a heavy, 80mm guidescope (with it's fancy CNC tube rings!). Beefed up like this I'd say the typical cast 'monkey metal' tube rings are perfectly adequate! There is no flex on this imaging rig.

[thehand]

Thanks for the pic! How close are you to the weight limit of your mount? Did you have to extend the counterweight bar when you piggybacked the scopes?

[laser_jock99]

Thanks for the pic! How close are you to the weight limit of your mount? Did you have to extend the counterweight bar when you piggybacked the scopes?

The mount in the picture is a Skywatcher EQ6 and is easily capable of supporting these two small scopes. I think there are only two 5kg counterweights on this rig.

My main observatory imaging rig has 35kg of counterweights (also on an EQ6)- not recommended but it still works