Giro Type Mounts - AZ Stiction

[steveex2003]

19 hours ago, AdeKing said:

 

Thanks Dave, I do need to strip down the GR2 version as the tension adjustment screws don't seem to work very well so I'll take a look.

I would be interested to know what you find here. I have said head, and think it such a wonderful little thing other than similarly not having complete confidence in the tension adjustment screws.

[Solar B]

I think this is a SUPERB 👍 thread as we are perhaps really getting to the crux of what 

is important to the individual with regard to Alt Az mounts , I am sure your Ercole is a 

great mount  Ade and one that you will enjoy and it's like everything you won't really 

know unless you try , I for one am leaning toward a certain mount (yes that one) but 

I currently do not require that capacity however probably will next solar season.

Brian 

[John]

Getting at the azimuth bearing of a Giro mount is not easy !

There is a trick to it - I'll try and find a link to the method.

 

[RT65CB-SWL]

I can't say I have ever noticed any stiction on my Tele-Optic Giro GR-DX II when loaded with one or two 'scopes attached. Though unloaded I have noticed it is there, but not a lot... and none with the AOK-AYO II loaded or unloaded.

[steveex2003]

1 hour ago, Philip R said:

I can't say I have ever noticed any stiction on my Tele-Optic Giro GR-DX II when loaded with one or two 'scopes attached. Though unloaded I have noticed it is there, but not a lot... and none with the AOK-AYO II loaded or unloaded.

I cant say I ever noticed anything on my (balanced) Ercole either, at least nothing that drew attention to itself.  Of course the knowing may well now be the curse.

[Stu]

4 hours ago, John said:

Slow motions are very useful I agree. I can cope OK without if the mount motion is smooth on both axis.

I'm delighted with my T-Rex which suits my 130mm F/9.2 perfectly. The Ercole and the Skytee II carried it OK but the T-Rex showed me what a top end alt-az mount can do. Unfortunately the T-Rex is out of production and getting on for AZ100 in terms of pricing if you can find one:

 

Having used this very mount, I know just how good it is John. The slow motion cables are the best I’ve ever seen!

I would buy one like a shot (if available) if it weren’t for my love of dual scope setups. The AZ100 just has a great combination of load capacity, slo motion controls, encoders and dual mount capability which is hard to match.

[John]

10 minutes ago, Stu said:

Having used this very mount, I know just how good it is John. The slow motion cables are the best I’ve ever seen!

I would buy one like a shot (if available) if it weren’t for my love of dual scope setups. The AZ100 just has a great combination of load capacity, slo motion controls, encoders and dual mount capability which is hard to match.

Good point about dual scope setups Stu - when I want to do that my Skytee II copes with it quite well or even the Ercole. I don't use two scopes that often though.

When I was beta testing the AZ100's I found that I needed two of their 3.7kg counterweights on the other side of the mount to get smooth slow motions with my 130mm F/9.2 triplet. This would have led to a rather heavy set up had I decided to go for the Rowan mount. The T-Rex, as I'm sure you know, needs no counterweights at all.

 

 

 

[Stu]

7 minutes ago, John said:

Good point about dual scope setups Stu - when I want to do that my Skytee II copes with it quite well or even the Ercole. I don't use two scopes that often though.

When I was beta testing the AZ100's I found that I needed two of their 3.7kg counterweights on the other side of the mount to get smooth slow motions with my 130mm F/9.2 triplet. This would have led to a rather heavy set up had I decided to go for the Rowan mount. The T-Rex, as I'm sure you know, needs no counterweights at all.

 

 

 

Yep, it’s definitely a very capable mount, and for heavy single scope use is hard to beat I’m sure.

My mount is pretty much permanently setup so weight is not an issue. I do often use it for Ha and white light solar and using the slow motion controls to pan around the surface at high power is very enjoyable.

I used to use the Vixen GP for solar more often (obviously single scope at a time) with dual axis motors but actually this ends up being slower than using the control rods as at the slow slew rates I use, the time taken to take up the backlash using the handset is quite long.

[HollyHound]

On 08/08/2020 at 23:02, John said:

I remember having both my ED120 and an ED150 on the mount when I was testing the latter and the mount seemed very smooth on both axis then.

Maybe these things do better when heavily loaded ?

I’ve definitely found that both my SkyTee and Castor work much better when loaded with two scopes. I’ve setup a lightweight grab and go dual scope setup using the Castor mounted on an AZ3 tripod. With just the C5 on one side, it needs the counterweight bar, but even then it’s not super smooth in AZ, but with an ST80 on the other side, it’s remarkably smooth 👍

[iPeace]

22 minutes ago, HollyHound said:

Castor work much better when loaded with two scopes

 

22 minutes ago, HollyHound said:

it’s remarkably smooth

Indeed, it was the Castor gave me the 'wow' moment with two scopes - but it was very particular re. which two scopes I deployed.

[John]

I think the lesson is clear with these "T" type mounts - balance is the key to getting the best from them and that needs some experimentation to get "just right". Even more so than I originally thought.

 

 

[iPeace]

7 hours ago, Solar B said:

we are perhaps really getting to the crux of what is important to the individual with regard to Alt Az mounts

Very well...

Dear Alt Az Mount, thou shalt:

• not move on either axis without my express physical intervention
• not move on either axis while I change eyepieces
• immediately begin moving on the desired axis when prompted by me
• smoothly continue moving on the desired axis while so prompted by me
• immediately cease all movement when I cease to prompt
• not fall apart at an awkward moment
• not cost more than an average bicycle

...but I'm willing to negotiate.

[Alan White]

11 hours ago, Philip R said:

I can't say I have ever noticed any stiction on my Tele-Optic Giro GR-DX II when loaded with one or two 'scopes attached. Though unloaded I have noticed it is there, but not a lot... and none with the AOK-AYO II loaded or unloaded.

But the two have decent bearings in both axes if I remember correctly, the AYO certainly does, this may be the bigger issue on some other mounts.

A decent bearing, suitably lubricated always beats a bushing arrangement under load in my opinion as a dedicated Alt Az user.  But on a Dobson, clearly that does not apply, but we are talking another mount type totally.

Ade, I think it’s a bit like getting used to most kit and a learning curve, once you find the knack, all should go well.

Slo-mo or nudge, nudge are personal choices, not a defined way things need to be done......it’s a Marmite thing.

 

[AdeKing]

15 hours ago, John said:

Slow motions are very useful I agree. I can cope OK without if the mount motion is smooth on both axis.

I'm delighted with my T-Rex which suits my 130mm F/9.2 perfectly. The Ercole and the Skytee II carried it OK but the T-Rex showed me what a top end alt-az mount can do. Unfortunately the T-Rex is out of production and getting on for AZ100 in terms of pricing if you can find one:

Thanks for this John, the T-Rex is probably what I would opt for if it was still in production I think as I'm not an avid user of a dual scope setup.  However, after my dual scope solar session yesterday, this may well change.

It looks like a fantastic mount and its such a shame that it is no longer in production.

15 hours ago, Macavity said:

When I had a nice (Red!) Giro III mount, I used to measure the distance from
the center of the scope (and centre of that the counterweight) from the axis.

The distances are not always equal in Giro mounts. It is not as easy to judge
balance across the Azimuth axis (as it is in Altitude). So I would WEIGH the
scope (including the rings, disgoneal, finder, eyepiece etc.) and then do a
(back of envelope!) "See Saw calculation" (Weight x distance etc.) and then
CALCULATE the *required* counterweight to balance the system exactly.

A bit excessive? lol. But it worked for me. (Sorry if this has been noted!!!)
I could even play "silly beggars" and SPIN the axes around and around! 🥳
But then such *precise* balance can become an issue in it's own right...

I do find that my SkyTee II has a slight wobble on the Azimuth axis. So I
tend to use a slight *imbalace* so that it does not suddenly "slop" over!
As is the case with these mounts it is a tad non-obvious how one might
even tighten up the Azimuth axis. 🙄

Thanks so much for this, this post has actually been the lightbulb moment for me and the GCSE physics refresher has proved invaluable.

After reading this post yesterday, I decided to approach things a little more logically and follow your methodology and its revealed that I am absolutely useless at estimating weight. 

I had no idea that my double stacked LS60 and Baader zoom weighed 4.5kg, I'd estimated it at 3.0kg.  What was more of an eye opener was that the little ZD66 solar setup was 3.1kg and my ED120 was 8.1kg, no wonder I'd been struggling.

So basically I was using much lighter counterweights than were needed. A bit more googling around the see-saw calculation to refresh the "little grey cells" yielded this:

So when I realised that I could work out the distance of the second weight from the pivot point by using L1 = L x W / W1 I was good to go.

And what a result, with the ED120 loaded on and balanced in Alt and by using a combination of counterweights closer to the actual (and not my badly estimated) fully loaded OTA weight I calculated the distance required and BINGO a balanced mount with very little initial stiction indeed.

Basically with the counterweights I'd been using, to balance the ED120, the centre of the weights would have needed to have been placed about 200mm beyond the end of the counterweight bar, D'Oh!!!!!!!!!!!

I'd been blinded by the fact that I'd considered an Alt Az to be foolproof, but obviously not resistant as as bigger fool as me.

Anyway, result is that I had a nice session on Jupiter and Saturn with the ED120 and Ercole last night.  A little stiction is there, but barely noticeable compared to what it was.

So thanks again for providing the light bulb moment.

14 hours ago, steveex2003 said:

I would be interested to know what you find here. I have said head, and think it such a wonderful little thing other than similarly not having complete confidence in the tension adjustment screws.

I'll keep you posted, but having had a quick look at these mounts at the moment I have no idea where to start dismantling them.

14 hours ago, Solar B said:

I think this is a SUPERB 👍 thread as we are perhaps really getting to the crux of what 

is important to the individual with regard to Alt Az mounts , I am sure your Ercole is a 

great mount  Ade and one that you will enjoy and it's like everything you won't really 

know unless you try , I for one am leaning toward a certain mount (yes that one) but 

I currently do not require that capacity however probably will next solar season.

Brian 

Thanks Brian, see above for the lightbulb moment.

14 hours ago, John said:

Getting at the azimuth bearing of a Giro mount is not easy !

There is a trick to it - I'll try and find a link to the method.

 

Thanks John, that would be very much appreciated.

7 hours ago, HollyHound said:

I’ve definitely found that both my SkyTee and Castor work much better when loaded with two scopes. I’ve setup a lightweight grab and go dual scope setup using the Castor mounted on an AZ3 tripod. With just the C5 on one side, it needs the counterweight bar, but even then it’s not super smooth in AZ, but with an ST80 on the other side, it’s remarkably smooth 👍

Thanks, I'm beginning to get the picture that these mounts really come into their own when used for a dual scope setup.

6 hours ago, John said:

I think the lesson is clear with these "T" type mounts - balance is the key to getting the best from them and that needs some experimentation to get "just right". Even more so than I originally thought.

This has been a real learning experience and I think that never a truer word has been spoken John.

It has been a real eye opener for me.

[iPeace]

9 minutes ago, AdeKing said:

BINGO

That's what I wanted to read.

[Macavity]

13 minutes ago, AdeKing said:

So basically I was using much lighter counterweights than were needed. A bit more googling around the see-saw calculation to refresh the "little grey cells" yielded this:

Glad you found that! I DID find a 40 min Youtube Video that weighed things
in Newtons! I still shudder inwardly when I see "Applied Maths" diagrams! 🤣

[Solar B]

A happy ending me thinks 🙂

Brian 

[John]

I'm going to be experimenting with my Giro Ercole this evening. Fortunately I have quite a lot of scopes and counterweights to play with !

Forums are really helpful with these sorts of issues - a number of folks kicking ideas around can be really productive 

[omo]

Really informative thread thank you everyone.  I just wish i hadn't done the arithmetic, it appears that to do the AZ100 and C9.25 justice, i need a third counterweight 😡

Think i will have to get a skywatcher 5Kg drilled out and never mind the aesthetics