Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

EdgeHD 8" TEMP-est Install -- GREASE!

  • Please log in to reply
14 replies to this topic

#1 Dave Bush

Dave Bush

    Vanguard

  • *****
  • topic starter
  • Posts: 2049
  • Joined: 28 Jul 2004

Posted 21 February 2019 - 11:02 PM

OK, so I have my edge HD OTA mounted on the Evolution mount and so that means that the two vents are at 12 and 6 o'clock respectively.  When I removed the bottom one to install the TEMP-est fans a glob of black grease fell out.   The factory vent/screen was coated with it.   I did the clean up before I though to take any photos but I did snap one of the fan's cable as it emerged from the bottom.

 

So now I'm thinking that the fan that I just installed is going to have this gunky black grease dropping on it and almost certainly fouling it.

 

Has anyone else noticed this?  Suggestions??

 

IMG_7645.jpg



#2 gnowellsct

gnowellsct

    Voyager 1

  • *****
  • Posts: 14110
  • Joined: 24 Jun 2009

Posted 21 February 2019 - 11:29 PM

My suggestion is that you remove the grease.  This may require that you dismount the corrector plate and pull the primary to get in there.  

 

With an edge the main thing is that there are four centering screws holding in the corrector in addition to what you see in this tutorial.  Just loosen ONE screw so that the others are properly positioned when you reinstall.

 

Notice in the 3rd picture down at this link the secondary is housed in a cup.  You can put a sandwich baggie over that cup and secure it with a rubber band.  That will keep it from getting dust while you are doing the project.

 

After you pull the primary put a plastic bag over the baffle tube opening and put a rubber band over it to keep it clean too.  There are optics in the baffle tube you dont want grease getting in there.

 

Then remove the excess grease.  An alternative plan is to return it to Celestron for clean up on aisle 4 (so to speak).  Greg N



#3 Dave Bush

Dave Bush

    Vanguard

  • *****
  • topic starter
  • Posts: 2049
  • Joined: 28 Jul 2004

Posted 21 February 2019 - 11:43 PM

My suggestion is that you remove the grease.  This may require that you dismount the corrector plate and pull the primary to get in there.  

 

With an edge the main thing is that there are four centering screws holding in the corrector in addition to what you see in this tutorial.  Just loosen ONE screw so that the others are properly positioned when you reinstall.

 

Notice in the 3rd picture down at this link the secondary is housed in a cup.  You can put a sandwich baggie over that cup and secure it with a rubber band.  That will keep it from getting dust while you are doing the project.

 

After you pull the primary put a plastic bag over the baffle tube opening and put a rubber band over it to keep it clean too.  There are optics in the baffle tube you dont want grease getting in there.

 

Then remove the excess grease.  An alternative plan is to return it to Celestron for clean up on aisle 4 (so to speak).  Greg N

Well, I'm definitely not going to disassemble the OTA.  I'm not going to take a chance on screwing something up.  I trust the precision with which it was assembled and am confident that I can't match it.

 

As for returning it to Celestron, actually as I looked inside it again, I'm thinking that the grease that is there, that is on the baffle tube and focuser rod is needed for smooth operation.  I don't really thing that I should remove any of it nor that any other OTA would be any less greased. 

 

I suppose it's just a byproduct of the fact that one of the vents is on the bottom.  Gravity can not be defied.

 

What I'm thinking I my just have to do is store the scope in a vertical position and periodically remove that lower fan/vent and clean off any grease that may have dropped on it.



#4 HenryB

HenryB

    Vostok 1

  • *****
  • Posts: 159
  • Joined: 11 Jan 2013

Posted 22 February 2019 - 09:58 AM

Well, I'm definitely not going to disassemble the OTA.  I'm not going to take a chance on screwing something up.  I trust the precision with which it was assembled and am confident that I can't match it.

 

As for returning it to Celestron, actually as I looked inside it again, I'm thinking that the grease that is there, that is on the baffle tube and focuser rod is needed for smooth operation.  I don't really thing that I should remove any of it nor that any other OTA would be any less greased. 

 

I suppose it's just a byproduct of the fact that one of the vents is on the bottom.  Gravity can not be defied.

 

What I'm thinking I my just have to do is store the scope in a vertical position and periodically remove that lower fan/vent and clean off any grease that may have dropped on it.

That is a good "Do no harm" approach. The problem is a symptom of too much grease applied at the factory. There are other ramifications of too much grease, such as outgassing on the optics, getting grease on darkened surfaces making them shiny and others. This is a factory problem and should be fixed at the factory.

 

Because I have a lifetime of takening my SCTs apart, I would disassemble it carefully to determine the amount of over greasing and then fix the problems. This would be especially true of an SCT that I believed had better than average optics. There is a risk of shipping damage.

 

There is a risk involved with taking an SCT apart. Sure there are plenty of instructions online, but unless your are confident in your abilities, send it back to the factory. It is not as simple as it may seem from the instructions.



#5 Xeroid

Xeroid

    Apollo

  • *****
  • Posts: 1230
  • Joined: 21 Sep 2013
  • Loc: USA

Posted 22 February 2019 - 10:00 AM

Why not contact Celestron Support and ask for a recommendation?



#6 Bill Barlow

Bill Barlow

    Skylab

  • *****
  • Posts: 4201
  • Joined: 03 Dec 2007
  • Loc: Overland Park KS

Posted 22 February 2019 - 10:27 AM

Do what Xeriod said.  Include a picture of the vent with the grease on it.  Maybe they will send you a new scope if it is still under warranty.

 

Bill


  • Xeroid likes this

#7 gnowellsct

gnowellsct

    Voyager 1

  • *****
  • Posts: 14110
  • Joined: 24 Jun 2009

Posted 22 February 2019 - 11:01 AM

Excess grease has been to drip on the corrector plate and or mirror. I love scts but "precision assembly" is not a phrase that comes to mind to describe them. In a sense they were, like the kalachnikov rifle, designed to work well without needing tremendous precision.

Excess grease is a known production issue on these scopes. The amount needed to lube an entire baffle is about what you have in the picture. When I lube mine, which is very rare, I distribute grease around the baffle, put the mirror on, move it up and down a few times, then wipe away the excess that accumulates at the bottom of the baffle and the rear of the mirror.

The slick 50 bearing grease I use sees more use on a car's trip to the supermarket than it will get in several lifetimes on a scope. This is not something that needs doing often.

My idea of a precision assembly is an apo lens cell. These are hard to do. And at lower price levels often done poorly.

#8 AxelB

AxelB

    Apollo

  • -----
  • Posts: 1177
  • Joined: 22 Mar 2015

Posted 22 February 2019 - 05:33 PM

That’s the crapy grease they use on the focusser (the crappy goo used on the baffle have a reddish tint). One or both of those have a tendency to outgaz and leave a deposit on the mirrors and inside of the corrector plate. Depending on the temperature variations, sooner or later you may notice a bluish halow on your optic. The good news is it can be cleaned. The bad news is to fix that, you need to completely dismantle the ota, replace the greases by something better, clean everything, reassemble and realign the whole thing. Or you can just ignore it. If you plan to ignore it, just never use a flashlight to look inside...

Now you can hate me.

Edited by AxelB, 22 February 2019 - 05:34 PM.


#9 Dave Bush

Dave Bush

    Vanguard

  • *****
  • topic starter
  • Posts: 2049
  • Joined: 28 Jul 2004

Posted 22 February 2019 - 05:42 PM

That’s the crapy grease they use on the focusser (the crappy goo used on the baffle have a reddish tint). One or both of those have a tendency to outgaz and leave a deposit on the mirrors and inside of the corrector plate. Depending on the temperature variations, sooner or later you may notice a bluish halow on your optic. The good news is it can be cleaned. The bad news is to fix that, you need to completely dismantle the ota, replace the greases by something better, clean everything, reassemble and realign the whole thing. Or you can just ignore it. If you plan to ignore it, just never use a flashlight to look inside...

Now you can hate me.

Hmm.... Is this all a new issue (as in within the last few years)?  I've owned several SCTs over the years and never have I seen any effects of outgassing.  And I'm rather OCD on clarity of my optics.

 

When I did peer into the hole I did see that the baffle had the reddish grease.  The focuser was black.  Checking again the grease is around the inside of the rear housing (as far as I can stick my finger) but it's not so much that I now think it'll be a problem.

 

My scopes are kept in my always-cool basement and when I go out in the summer they're not brought out during the heat of the day so temperature swings are kept to a minimum.  I wouldn't expect too much outgassing.  



#10 AxelB

AxelB

    Apollo

  • -----
  • Posts: 1177
  • Joined: 22 Mar 2015

Posted 22 February 2019 - 06:32 PM

Mine was bought in 2015. I sometimes use it for white light solar during summer and also at polar temperatures in winter.

Edited by AxelB, 22 February 2019 - 09:08 PM.


#11 NMBob

NMBob

    Apollo

  • *****
  • Posts: 1455
  • Joined: 21 Nov 2015
  • Loc: New Mexico

Posted 23 February 2019 - 11:42 AM

I removed the big globs that I could find with a flashlight with something like a long popsicle stick. There was way too much of it in the Edge8, but not a gross amount in the Edge11. That stuff stains everything.



#12 gnowellsct

gnowellsct

    Voyager 1

  • *****
  • Posts: 14110
  • Joined: 24 Jun 2009

Posted 23 February 2019 - 11:51 AM

The thing about China is U.S. seller can spec a grease but find unauthorized substitutions have been made on delivered product. The grease may have characteristics unknown to Celestron. So outgasing, grease glue can make there way into products. Often times these substitutions are in the you-gotta-be-crazy-to-do-this category.

#13 Rovert9988

Rovert9988

    Vostok 1

  • *****
  • Posts: 132
  • Joined: 22 Jan 2017
  • Loc: WA State

Posted 23 February 2019 - 12:17 PM

I'm surprised at how much grease there is! I would opt for cleaning it as well as I can without removing the corrector plate personally. I would likely also take the fans out now and then for a while just to double check that it isn't becoming an issue again.

Does anyone have an idea of how much the tempest fans help? I would love it if I could cut cool down time in half with my edge, but heard that in the 8" the tempest fans don't help a ton.

#14 gnowellsct

gnowellsct

    Voyager 1

  • *****
  • Posts: 14110
  • Joined: 24 Jun 2009

Posted 23 February 2019 - 12:32 PM

Does anyone have an idea of how much the tempest fans help? I would love it if I could cut cool down time in half with my edge, but heard that in the 8" the tempest fans don't help a ton.


Are you observing on grass or asphalt cement gravel.

If it's possible to try the rig over grass you might be surprised at the difference.

If you are observing on your own driveway, or patio, hose it down in late afternoon. Maybe more than once.

Your scope cools fine. But it gets heated by radiative and convective heat transfer from the ground.

#15 AxelB

AxelB

    Apollo

  • -----
  • Posts: 1177
  • Joined: 22 Mar 2015

Posted 23 February 2019 - 03:37 PM

I'm surprised at how much grease there is! I would opt for cleaning it as well as I can without removing the corrector plate personally. I would likely also take the fans out now and then for a while just to double check that it isn't becoming an issue again.

Does anyone have an idea of how much the tempest fans help? I would love it if I could cut cool down time in half with my edge, but heard that in the 8" the tempest fans don't help a ton.


It’s night and day, not only for initial cool down but to breakdown tube currents while observing.


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics