Stiction issues with Altair Astro Sabre V2

[DeepSkyMan]

Hi there, wondering if someone can help me with stiction problems I'm currently experiencing with my new Sabre mount.  First light for the mount on Friday night proved most frustrating, almost impossible to accurately frame an object in the field of view.  I believe that I've got the setup as balanced as it is ever going to be until I can improve the fluidity of the motions.  Pic of setup attached.  All up weight for the SCT with dew shield,  Nagler 22mm, Baader Steeltrack Focuser, Baader click stop diagonal, laser pointer and finder is about 9.5kg.  The counter weight is 3.7kg.

[knobby]

I'd say it's very unbalanced ...The 3kg weight looks about the same distance from pivot as the 9kg scope, I'd guess you need 9kg weight or 3 times the length... Which axis is sticky ?

[DeepSkyMan]

Knobby, its mainly in Alt, though azimuth I think could be better.  Taking on board what your saying, on reflection it seems logical that I need more counterweight.  I do have an additional 1.9kg unit, but adding this didn't seem to make much difference.  Time to search for 5kg counterweight methinks.  Thanks for your feedback.

[spaceboy]

I agree. You need a heavier counter weight or longer CW bar. Both axis will bear an uneven load.

[Dave1]

Old thread revival. 

I've recently taken delivery of my Altair Sabre 2 mount. When I start to move the mount from standstill, in the azimuth axis, there is a sound and also vibrations, but when it gets moving it is buttery smooth. My telescopes weight 7.8kg and 3.5kg. This is really not going to be helpful when trying to do fine adjustments.

Is this stiction? Or is there something else wrong? Like the bearing might need lubricating? 

Dave 

[John]

Sounds like a dry brearing. I'd consult Altair Astro if you can - they will know how to sort it out better than anyone else.

The Sabre that I had for a while was pretty smooth in it's motions but it did need a counterweight on the opposite arm to the scope to get the smoothest motions.

[Dave1]

Cheers John, I thought it might be a dry bearing. Just wanted confirmation. Sent an email to Altair Astro last night. Tried to phone them today, they are away at Kelling Heath. Hopefully they will offer to sort it, or can advise me how to do it. 

Great build quality on it though. Very happy.

[parallaxerr]

I'd put all of the above issues down to balance. Both the Alt and Az axes will be unevenly loaded if the balance isn't even across the alt bar.

I had to load the C8 on the short end and ST120 on the long end to get close, but even then there was a tiny bit of stiction because the ST120 was lighter. If I rested my hand on the ST120 very gently to even the load, the whole mount went floaty light on both axes.

@Dave1, that's a strange effect you mention, sorry to hear it. But, by the weight of your scopes, again, I'd say your well out of balance. When I was reading up on manual Alt/Az mounts, there was a recurring statement made that "balance is critical". I very much doubt the bearings are dry, I believe you can separate the mount to inspect the Az bearing by removing Az friction knob and pulling the two halves apart.

[Dave1]

The Alt balance is spot on for both telescopes. The lighter telescope of 3.5kg is on the longer end. The only thing left is even the weight difference on the az difference is too much, or the bearing is dry.

Yes I've also read about the balance being critical. I have a 5" refractor I can try as well, to rule out the weight difference.

Dave

[parallaxerr]

9 minutes ago, Dave1 said:

The only thing left is even the weight difference on the az difference is too much

Yeah that's what I meant.

[Dave1]

Hello everyone, just an update, I've tried my 120mm refractor tonight with my Skymax 180 pro, and all is well. There is now no sign of stiction at all or any vibrations. Infact both the altitude and azimuth have been improved. Both are now silky smooth and like butter, I'm very impressed. 

Dave