Scope balancing

[souls33k3r]

Hi All,

Let me start by saying this, i worry too much and some times because of that worry i do stumble across a few pointers which then leads me another rabbit hole.

The usual rule of thumb is when balancing the scope (SCT and Refractors), you do the following:

1) Loosen the RA clutch and tighten the Dec clutch. Move the mount in horizontal position and then check if your OTA side is heavy or the counter weight side is

2) Move the mount back to home position where the counter weights are now pointing downwards. Tighten the RA cluck and put the OTA in horizontal position. Check whether the OTA is front or back heavy.

Now here's a question of the day.

Do you then keep the mount in the same position as 1 or 2 and point the scope vertically and see if that's balanced too? How critical is that for a better guiding?

I do and some times i go super crazy about it. Not only when the scope is pointed straight up but also when it's pointed at say 45/60 degree angle and see if the scope dips to one side. 

Thanks in advance

[vlaiv]

I check balance in "dynamic" way - don't just leave it in one position and see if it starts moving on its own. I put it in certain position and actually start the spin in one way and observe how long does it take to come to rest and is that action "smooth". I do this multiple times in each direction to get the feel if things seem balanced and smooth - as you would expect if there is no disbalance of any kind.

[RayD]

I always balance my dec axis (OTA front to back) with the RA axis horizontal.

[souls33k3r]

55 minutes ago, vlaiv said:

I check balance in "dynamic" way - don't just leave it in one position and see if it starts moving on its own. I put it in certain position and actually start the spin in one way and observe how long does it take to come to rest and is that action "smooth". I do this multiple times in each direction to get the feel if things seem balanced and smooth - as you would expect if there is no disbalance of any kind.

Wow that's a bit clever. Is this time consuming process for you? 

40 minutes ago, RayD said:

I always balance my dec axis (OTA front to back) with the RA axis horizontal.

So no 3rd axis balance then mate? Is that on your MESU or with you AZ-Eq6? 

I only ask this because I once got in to a situation where my stars were all over the shop when my scope was pointing at the zenith. Because of this, I've started doing the 3rd axis balance where the scope is pointing vertical to the ground. Never had the same issue again but doing this meant that more time checking the balance and also issue with framing objects now in the camera sensor because to counter the scope dip, I have to move my FW in the anti-dip side if this makes sense. 

[RayD]

20 minutes ago, souls33k3r said:

Wow that's a bit clever. Is this time consuming process for you? 

So no 3rd axis balance then mate? Is that on your MESU or with you AZ-Eq6? 

I only ask this because I once got in to a situation where my stars were all over the shop when my scope was pointing at the zenith. Because of this, I've started doing the 3rd axis balance where the scope is pointing vertical to the ground. Never had the same issue again but doing this meant that more time checking the balance and also issue with framing objects now in the camera sensor because to counter the scope dip, I have to move my FW in the anti-dip side if this makes sense. 

No I don't balance the third axis with one OTA mate, only on a side-by-side.  I think if a single, short focal length OTA is causing major issues at the zenith when balanced in 2 axes, I'd probably be looking at the mount rather than the balance.

[vlaiv]

1 hour ago, souls33k3r said:

Wow that's a bit clever. Is this time consuming process for you? 

No, not really, I get it all done in matter of minutes, just a standard part of my setup routine.

Put OTA on mount, give dec few spins (balancing by moving weight on dovetail bar rather than moving scope in saddle - both my scopes need to be quite a bit forward and balanced with additional weight), lower weights on counterweight shaft and do few spins in RA. When both seem balanced I undo both clutches and just have spin about in both axis. There is always a point of disbalance in my setup because OAG and guide camera are at 90 degrees to both RA and DEC, but it is very small weight so it can just barely be felt.

[souls33k3r]

1 hour ago, RayD said:

No I don't balance the third axis with one OTA mate, only on a side-by-side.  I think if a single, short focal length OTA is causing major issues at the zenith when balanced in 2 axes, I'd probably be looking at the mount rather than the balance.

I think you're quite right about the possibility of something wrong with the mount mate. I do feel my Dec is slightly loose ... however i don't know what the dec should be like apart from what i've always known from using my mount. Will be seeing a few friends over the weekend so will have a look at their setups too. One of them is a EQ6-R mount but principle remains the same.

1 hour ago, vlaiv said:

No, not really, I get it all done in matter of minutes, just a standard part of my setup routine.

Put OTA on mount, give dec few spins (balancing by moving weight on dovetail bar rather than moving scope in saddle - both my scopes need to be quite a bit forward and balanced with additional weight), lower weights on counterweight shaft and do few spins in RA. When both seem balanced I undo both clutches and just have spin about in both axis. There is always a point of disbalance in my setup because OAG and guide camera are at 90 degrees to both RA and DEC, but it is very small weight so it can just barely be felt.

Ok now i get it. With me the thing is that even a slight bit of imbalance when the scope is vertical in dec, i try to eliminate that. Maybe i'm getting a bit too over cautious.

[Seanelly]

11 hours ago, vlaiv said:

I check balance in "dynamic" way - don't just leave it in one position and see if it starts moving on its own. I put it in certain position and actually start the spin in one way and observe how long does it take to come to rest and is that action "smooth". I do this multiple times in each direction to get the feel if things seem balanced and smooth - as you would expect if there is no disbalance of any kind.

Yes, I have not had my kit for long but this right off seemed the best way to find the most accurate balance.

[ollypenrice]

On 14/11/2018 at 19:47, souls33k3r said:

 

I only ask this because I once got in to a situation where my stars were all over the shop when my scope was pointing at the zenith. Because of this, I've started doing the 3rd axis balance where the scope is pointing vertical to the ground. Never had the same issue again but doing this meant that more time checking the balance and also issue with framing objects now in the camera sensor because to counter the scope dip, I have to move my FW in the anti-dip side if this makes sense. 

When the mount is pointing at the zenith, what's different? Well, any fore-and-aft imbalance in Dec has reduced to zero because that axis is vertical. So we must conclude that, in other positions, the fore-and-aft imbalance was working constructively to kill Dec backlash by keeping the payload on one side of mesh. When the payload is vertical you now need an imbalance at right angles to the vertical to re-introduce the constructive imbalance.

Why do I like backlash-free mounts??? (Mesu, Avalon, anything but worm and wheel...)

Olly

[DaveS]

On the DDM I balance around RA, and the Dec in both axes. The Autoslew software has a balance routine that measures the current needed to move the scope each way. The scope is balanced when the current is equal and as low as possible. No PE or backlash with a DDM mount.