Grub screws hidden on Atlas mount !

[Ali Alhawas]

Hello,

 

I did a good Belt modification to my mount Orion Atlas eq-g as I have a reasonable mechanic background . 

Every thing is perfect now.. except a little stiffness in Dec. axis.

I tried every thing like the down tapped bearing tightness, top ring bolt which is under the Dec. head.. still some stiffness ,,

Then I decide to adjust the hidden grub screws under the slotted head screw.

But I cant find the concept behind them or a regular rule to deal with them

 

One thing I noticed, that they affect the Dec. axis stiffness.. But in what way I can adjust I don't know 

I tried to tighten the in sequence by a tiny turns ( Clockwise and Anticlockwise ).. same result.

 

Any Ideas ?

 

Thanks

Ali

[Ali Alhawas]

So,,

I think these hidden grub screws will remain a secret for ever ..☠️

[discardedastro]

Assuming this is similar to the EQ6-R...

The grub screw under that cover shouldn't need to be anything more than nipped up - if memory serves it's pressing against the top Dec bearing to make sure that it's under tension/load.

If you undo the top three bolts holding the saddle on you'll be able to see the other side relative to the top Teflon washer and bearing.

If you've got friction in Dec, then I would start at the other end of the axis. It could be the end nut is too tightly tightened or the bearing lubrication isn't in good condition. If it's the end nut, that's a really easy fix and very simple to adjust by releasing the grub screws and backing it off a smidge, then nipping up and securing the grub screws.

[Ali Alhawas]

On 27/01/2022 at 15:24, discardedastro said:

Assuming this is similar to the EQ6-R...

The grub screw under that cover shouldn't need to be anything more than nipped up - if memory serves it's pressing against the top Dec bearing to make sure that it's under tension/load.

If you undo the top three bolts holding the saddle on you'll be able to see the other side relative to the top Teflon washer and bearing.

If you've got friction in Dec, then I would start at the other end of the axis. It could be the end nut is too tightly tightened or the bearing lubrication isn't in good condition. If it's the end nut, that's a really easy fix and very simple to adjust by releasing the grub screws and backing it off a smidge, then nipping up and securing the grub screws.

Thank you for your nice hints..

Last update :

I followed your recommendation about those 3 grub screws and I only finger tight all in regular basis , then I removed the Dec. tapered bearing and test it by hand , feel a little friction ( small clicks ) despite the lubricant is excellent as I greased it 3 months ago, but I think its damaged by unknown cause , maybe aging (7 years).

Wonder why I didn't test the bearings when I rebuild the mount

Also I removed the  Ra. tapered bearing and feel a little friction but less than the Dec. bearing. All other bearings are good.

So , I ordered a new set of bearings for all bearings in the mount, total 12.

Hope this well end the stiffness issue.

BR,,

[Ali Alhawas]

Hi,

Finally .. I could get the idea of these 3 grub screws (as I tested)

They affected the Dec. rotation to go smoother when the clutch is disengaged ..

At least this is what I found after many trials ..

You start with untighten the 3 screws and move the Dec. head while the clutch is disengaged:

1-If you feel its smooth and you happy with it.. just tight the 3 screws a little .. not too much ( tow fingers tight is enough )

2- If you feel stiffness .. stop the rotation in a position that you feel the highest stiffness is occurred and try to tight ONE screw only and check. If its smoother just tighten the others two.

If stiffness still untightens the screw and try other one till you find the affected one.

Now this is what works with my mount and may not works with others. I am just sharing in case someone struggled to solve this bad stiffness.

BR,

Ali