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matt_baker

CGE Wrong Pier Placement

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I've been given a key to go to my local observatory whenever I like, since it never gets used in the 2 years it's been built.

It houses a C14 and an original CGE which are mounted on a pier and a big long piece of steel.

My issue is that I can't turn the azimuth bolt far enough to the right for polar alignment, since it reaches it's limit, and since it's a pier there's probably no way I could rotate one of the plates so it moves?

It's a hard thing to explain fully but I've attached a few pictures

Hopefully someone could help me

 

Matt

1.jpg

IMG_20191013_221757970.jpg

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Matt,

I think I understand the issue.....

The text in the images obscures the bottom connection to the pier plates...

Is there any option of re-setting/ adjusting the mount at this interface??

(or at the base of the pier??)

Ken

 

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2 minutes ago, Merlin66 said:

Matt,

I think I understand the issue.....

The text in the images obscures the bottom connection to the pier plates...

Is there any option of re-setting/ adjusting the mount at this interface??

(or at the base of the pier??)

Ken

 

Sorry about that, here's the original and to be honest, I'm really not sure

IMG_20191013_221757970.jpg

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Matt,

What's the small orange piece and spring at the bottom - just odd bits?

When you look through the "gap" at the base of the mount - anything visible???

Ken

 

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8 hours ago, Merlin66 said:

Matt,

What's the small orange piece and spring at the bottom - just odd bits?

When you look through the "gap" at the base of the mount - anything visible???

Ken

 

Yes, that's just an odd bit unfortunately. The gap at the base of the mount are just for the levelling screws

Edited by matt_baker
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Ok,

but could the top plate be removed and redrilled/ modified to give more Az adjustment......

 

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Is the issue that the bolt going vertically down (with the knob on it and ringed in your 2nd picture) hits the edge of a semi circular slot in the mount base ?

Or am I misunderstanding?

And do you know how far you are out?

Steve

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It looks like there are 3 screws on the bottom of the electronics pilllar, eg there is one right under the "off" label.  If you undo all those screws you should be able to rotate the mount 120 degrees.  That might be more then you need, although you could use the azimuth adjusters on the mount to go back a bit.

 

EDIT:  I see that only further degree or 2 is needed, so this suggestion is no good.

Edited by Oldfort
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If the mount and/or pier is bolted down you could enlarge the holes to give some rotation.

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1 hour ago, teoria_del_big_bang said:

Is the issue that the bolt going vertically down (with the knob on it and ringed in your 2nd picture) hits the edge of a semi circular slot in the mount base ?

Or am I misunderstanding?

And do you know how far you are out?

Steve

Yes, you're correct. I know I'm about 1 1/2 degrees out from doing a polar alignment with sharpcap

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1 hour ago, Mr Spock said:

If the mount and/or pier is bolted down you could enlarge the holes to give some rotation.

That's kind of the problem, I'm trying to see if there's a way without having to take apart the entire rig and redrilling holes

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It is not ideal but you could get somebody with a lathe to "neck" the bolt.

Similar to below. This would give you a little bit extra movement.

image.png.1de48c0cef0095cbc5653b8c6f4ba491.png

So the thread is the same size but the top section that is slightly longer than the thickness of the plate with the slot in it is narrower which might give another 1/2 degree of movement (maybe ??). Otherwise you need the slot in the plate  making longer in one direction.

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Is that clear plastic angular piece in the foreground of the electronics pillar a reference marker?

That would suggest the entire pillar can be rotated if something is loosened. Perhaps the large screws?

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Beware of loosening screws near the base of the pier to avoid toppling the whole lot over!

I've just noticed a small thumbscrew to the north east of the pier top by the nearest large screw. What does that do?

Edited by Rusted
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I must admit I never contemplated doing this with the scope and CB weights attached but unless I am missing something one of the two top plates need to rotate more than it is doing right now.

So if I have understood then one of two things have to occur to get the polar alignment.

image.png.6058b5c416bd6fbb7d6c97097e696f94.png

The black one cannot rotate far enough because the bolt ringed by the OP is hard up against the semi circular slot in the black plate. So to rotate any further the slot needs to be longer (not possible easily) or there needs to be another threaded hole for the thread on the bolt to go into.

For the orange shiney plate to rotate any more there needs to be other threaded holes in the pier for the 3 or 4 dome headed bolts to screw into.

But yes do not try that without at least removing the scope and the CB weights, if not the mount as well.

The other thing that would get a very small amount of extra movement is to relieve the threads on the part of the bolt (ringed by the OP) that are in contact with the black plate to allow it to rotate that tad further.

 

Edited by teoria_del_big_bang

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59 minutes ago, teoria_del_big_bang said:

image.png.9fab370ccc05aa50264b53283156cefd.png

Steve

Really not sure and I think I agree with rusted, I don't really want to find out incase the whole thing topples

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This is getting more and more confusing. There are no obvious slots for the big screws to move along.
Unless the mounting was wrongly installed at first set up it should be easily rotatable in azimuth.

What happens if you unscrew the big plastic knob completely?
Is there a fresh hole in which it can be re-inserted, further around, if the whole mounting is rotated in azimuth?

What I thought to be a plastic angle piece now looks much more like a galvanized nut.
With another on the opposite side hidden under the same thick ring [or flange.]
Are there slots in the surface where these nuts screw down?

Some clear pictures taken in daylight without the obscuring text would help.

 

Edited by Rusted
typo

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The 14" and the mounting will each be very hefty lumps for a single person to manage alone.
Don't even try unless you are comfortable with such heavy lifts!
Besides, it shouldn't be necessary just to turn the mounting in azimuth.
There has to be a trick to it. Where's Peter when you need him? :biggrin:

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How is the pier bolted down ?

Dave

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8 minutes ago, Rusted said:

This is getting more and more confusing. There are no obvious slots for the big screws to move along.
 

Again, unless I have misunderstood we are talking about a semi-circular slot here under the big bolt with the knob. So when loosened slightly the black plate can rotate to align.

image.png.343d3cf8a92ec4e35a351a79abbe0197.png

So again like you I wondered if there was another hole further round for the big bolt to screw into.

Edited by teoria_del_big_bang

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2 minutes ago, teoria_del_big_bang said:

Again, unless I have misunderstood we are talking about a semi-circular slot here under the big bolt with the knob. So when loosened slightly the black plate can rotate to align.

I gather they're already rotated as far as possible and need more.

Dave

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