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EQ platform problem

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#1 Astrocava

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Posted 14 September 2017 - 03:32 AM

Hi all!

 

Despite my lack of woodworking abilities, I managed to finish a (VNS + south circular sector) eq platform for my Explore Scientific 305 mm. I got good tracking with the celestron motor I've attached but I have some problems...

When the scope is pointing 45º east or west of N-S meridian and with less than 50º (more or less) in Alt, when trying to move the scope in Dec pushing the end of the OTA, the force I'm applying instead of being used to move in Dec is used to rise one of the VNS above the motor bearing, moving the whole top table (with the scope) along the friction less bearing. bawling.gif

I'm thinking that perhaps the telescope has more than necessary friction in the dec wheels but I don't know how to fix it. If I could manage to reduce the initial friction that seems to be high, the problem will be less important. If I move the scope by pushing the mirror box, obviously the unwanted tilt doesn't happen but its a nightmare to centre the objects without seeing through eyepiece...

Perhaps another solution is putting more weigh in the rocker box... I'm thinking about attaching the battery to the scope instead of lying in the bottom table...

 

What do you think? Any ideas are welcome,

 

Sergio



#2 DLuders

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Posted 14 September 2017 - 03:48 AM

Do you have any pictures that you can post?  It's hard to visualize your custom-made item....


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#3 happylimpet

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Posted 14 September 2017 - 04:54 AM

That's annoying. You cant increase the friction on the EQ platform bearings?


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#4 Jon Isaacs

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Posted 14 September 2017 - 10:20 AM

I'm thinking that perhaps the telescope has more than necessary friction in the dec wheels but I don't know how to fix it.

 

 

Try putting bar soap on the bearing surfaces.. Just use regular bar soap, wet the surface and rub it over the large bearing surfaces so you've been over them 3 or 4 times. Let it dry for a few minutes.  I do it with the scope in place.

 

Jon


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#5 Astrocava

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Posted 14 September 2017 - 03:37 PM

 

I'm thinking that perhaps the telescope has more than necessary friction in the dec wheels but I don't know how to fix it.

 

 

Try putting bar soap on the bearing surfaces.. Just use regular bar soap, wet the surface and rub it over the large bearing surfaces so you've been over them 3 or 4 times. Let it dry for a few minutes.  I do it with the scope in place.

 

Jon

 

As simple as soap bar.... Thank you very much Jon. I've just tested again the scope with the soap and works wonderful. I needed to put some weight to balance the eyepieces but that's a minor issue compared with my former problems.


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#6 Jon Isaacs

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Posted 15 September 2017 - 08:58 AM

As simple as soap bar.... Thank you very much Jon. I've just tested again the scope with the soap and works wonderful. I needed to put some weight to balance the eyepieces but that's a minor issue compared with my former problems.

 

Sergio:

 

I'm glad it worked for you.

 

Using soap on Dob bearings was a fortuitous discovery, as they say, " necessity is the mother of invention"

 

A couple of years ago, my wife and I were camped in our motor home in the desert, about 100 miles from the nearest town.  My 16 inch Dob had been outside in winds of 40 mph plus for almost 2 days and when the wind died, the Dob was hard to move and very jerky. I cleaned the bearing but it was still barely usable.

 

I was looking through the motor home trying to find some wax or something to lube the bearings and my wife suggested I should try some soap.  It was really a miracle how well it worked.  It was as if I had build a new scope.

 

I do find that I need to re-soap the bearings every 3 months or so.

 

Jon


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#7 Pinbout

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Posted 15 September 2017 - 10:03 AM

 

and my wife suggested I should try some soap.

see,  wives know best...


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