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klyons
member


Reged: 10/30/04

Grease for LX200 baffle?
      #5440452 - 09/25/12 07:05 PM

I would like to re-grease my LX200 baffle to reduce image shift. Does anyone know what grease will work and is safe to use in the Meade tube? Thanks.

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Whichwayisnorth
Pooh-Bah
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Reged: 07/04/11

Loc: Southern California
Re: Grease for LX200 baffle? new [Re: klyons]
      #5440649 - 09/25/12 09:21 PM

Here ya go. Click here

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klyons
member


Reged: 10/30/04

Re: Grease for LX200 baffle? new [Re: Whichwayisnorth]
      #5440680 - 09/25/12 09:39 PM

Thanks! Have you tried it?

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CORONA
member


Reged: 06/12/12

Re: Grease for LX200 baffle? new [Re: klyons]
      #5444596 - 09/28/12 01:54 AM

Don't mean to confuse you but the red grease that is available from Peterson Engineering is excellent. It looks like it is the same grease mead uses.

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imjeffp
Aluminum Falcon
*****

Reged: 09/30/03

Loc: Cedar Park, Texas
Re: Grease for LX200 baffle? new [Re: CORONA]
      #5447743 - 09/29/12 11:52 PM

For some reason, I think the hi-vac grease is OEM. True?

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klyons
member


Reged: 10/30/04

Re: Grease for LX200 baffle? new [Re: imjeffp]
      #5448097 - 09/30/12 09:08 AM

In fact I recently contacted Pete Peterson asking if I could use their red grease (I still have some), and he stated that it should not be used on the baffle - it is not stiff enough.

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CORONA
member


Reged: 06/12/12

Re: Grease for LX200 baffle? new [Re: klyons]
      #5451953 - 10/02/12 01:18 PM

I'm going with the Hi Vac grease then.

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klyons
member


Reged: 10/30/04

Re: Grease for LX200 baffle? new [Re: CORONA]
      #5459528 - 10/07/12 04:20 PM

Well I did go ahead and get the hi vacuum grease. I put it on the baffle tube and it did not change things much. I have always had a large amount of image shift (1/2 degree!), so it appeared that there was some other cause. I went back into the scope and removed the mirror assembly again. I observed that the metal assembly below the mirror (that is attached to the focus rod) was threaded on the shaft that slides onto the baffle tube. Above the mirror is a cork spacer, then more metal. The mirror seemed to be "loose" - the metal assembly below was not up tight against the mirror. I suspected that this gap caused the mirror to tilt. So I held onto the metal assembly below the mirror and rotated the shaft above the mirror to tighten everything down. The mirror no longer could shift, so I re-assembled everything back in the tube and checked it out. This turned out to be the problem - the image shift is very small, and the focuser knob turns very easily with no resistance. It had been harder to turn when the mirror was shifting in the loose assembly.
The mirror did rotate some when I tightened it, so I was concerned that the rotational alignment between the primary and secondary/corrector was lost. But the images I see have shown there is no degradation. If it did degrade I would just rotate the corrector to maximize image quality.

I have learned a lot from this exersize. Everything I have read about image shift referred to the grease issue - never have I seen comments about the mechanical assembly. If you are replacing the grease, you have the scope apart anyhow, and this is easy to check.


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CORONA
member


Reged: 06/12/12

Re: Grease for LX200 baffle? new [Re: klyons]
      #5614140 - 01/09/13 05:35 PM

About the Dow Corning High Vac Grease, is it good to use on all other parts of this scope instead of the red grease? or other lubes that are used in the gears etc.?
I got a tube of it and am thinking of removing all other greases and re-lubing with this stuff.
Any ideas?


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orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Grease for LX200 baffle? new [Re: klyons]
      #5614151 - 01/09/13 05:43 PM

Quote:

I would like to re-grease my LX200 baffle to reduce image shift. Does anyone know what grease will work and is safe to use in the Meade tube? Thanks.



I have used SuperLube Synthetic grease mixed with a little Mobile One Synthetic SAE 40engine oil. It works very well because it can be mixed a bit thinner for us up here in the Minnesota Iowa area where actual temps can reach 30F Below actual temp. I have also used White P.A.O. Synthetic grease
it neither thins or thickens but is expensive about $12.00 for 2 or 3 oz..


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Qwickdraw
Pooh-Bah
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Reged: 03/03/12

Loc: Ann Arbor, MI
Re: Grease for LX200 baffle? new [Re: orion61]
      #6016225 - 08/09/13 04:59 PM

I have huge image shift on a 12" LX200. I would guess it is as much as 3/4 of the FOV in just a 21mm EP. Does anybody have any photos or diagrams on how to disassemble the OTA to perform the greasing of the baffle and make the adjustments as outlined by klyons a few posts up? I don't want to go into this blind if I don't have to.

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rtanton
Vendor (Explorer Scientific)
*****

Reged: 02/06/07

Loc: Mission Viejo, CA
Re: Grease for LX200 baffle? new [Re: CORONA]
      #6017411 - 08/10/13 11:16 AM

Corona, the high vacuum grease is not your best choice as a lubricant. This grease is a vacuum stripped silicone polymer filled with fumed silica to increase its viscosity. It will work as a lube for non metal to metal contact. Its viscosity throughout a wide temperature range makes it well suited to damp between the baffle and primary in the SCT.

Pete is correct on his red grease. When I was at Meade, I had our guys try a high quality silicone lubricant. The SCT focused easily but would not hold position as the primary keep slipping.

Russ
former Meade and Dow Corning


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redlinedb16a
super member


Reged: 10/17/10

Re: Grease for LX200 baffle? new [Re: orion61]
      #6018120 - 08/10/13 07:16 PM

Quote:

Quote:

I would like to re-grease my LX200 baffle to reduce image shift. Does anyone know what grease will work and is safe to use in the Meade tube? Thanks.



I have used SuperLube Synthetic grease mixed with a little Mobile One Synthetic SAE 40engine oil. It works very well because it can be mixed a bit thinner for us up here in the Minnesota Iowa area where actual temps can reach 30F Below actual temp. I have also used White P.A.O. Synthetic grease
it neither thins or thickens but is expensive about $12.00 for 2 or 3 oz..



Oil and grease will separate over time

So at one point you may have oil leaking onto your mirror

Perform a test
Leave a blob of grease in a jar untouched for awhile
You will see liquid oil around the grease


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redlinedb16a
super member


Reged: 10/17/10

Re: Grease for LX200 baffle? new [Re: redlinedb16a]
      #6018122 - 08/10/13 07:17 PM

I will experiment with thin .005 thousands thick brass shim material to take up the slack

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P26
Vendor - Peterson Engineering


Reged: 05/02/12

Loc: RI, USA
Re: Grease for LX200 baffle? new [Re: klyons]
      #6019316 - 08/11/13 04:21 PM

For the record, that Corning product is a vacuum sealant and not intended as a lubricant.

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Qwickdraw
Pooh-Bah
*****

Reged: 03/03/12

Loc: Ann Arbor, MI
Re: Grease for LX200 baffle? new [Re: P26]
      #6020358 - 08/12/13 08:54 AM

Well, I got brave over the weekend and dismantled my entire 12" LX200 OTA. I was hoping to discover the cause of the large image shift. No such luck. After evaluating the construction I suspect the shift can be caused by at least two things...
1) the mirror actually tilting due force of the focusing arm tilting the outer tube as it travels up and down the inner tube.

2)I also believe that the inner baffle which is affixed to the back of the OTA could flex when the focus is used. The inner tube seems to be threaded into the back of the OTA by maybe 1/4" of thread connections. Either that threaded connection may have some flex and/or the whole back wall of the OTA may also be subject to a small amount of flex.

My image shift is very large. Roughly 2/3-3/4 of the FOV in a 21mm EP. It also seems to consistently travel in the direction parallel with where the angle of the focus arm is attached to the mirror so about at the 30 degree to 210 degree line.

I did not have any grease on hand yet but I wanted to get an understanding of the mechanics of the assembly.

The mirror locking mechanism is a large gear which when rotated opens or closes a collet which tightens around the inner tube preventing the mirror from wiggling.

I replaced the stock focuser with the Featherlight earlier. That offered no help on the image shift issue. I didn't think it would but I wanted the upgraded focuser anyways.

The whole image shift is as we know inherent to this design, specifically, not having uniform forces applied in radial directions while focusing.

Any grease applied can seemingly only temporarily cover up the symptoms.

Why is my image shift so much more than others? One can only assume manufacturing tolerances.

I am not satisfied in just accepting this issue and resorting to an electronic crayford as a work around. I have a Binotron 27 binoviewer which means adding the extra length/weight for a focuser is not really an option.


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nitegeezer
scholastic sledgehammer
*****

Reged: 11/27/07

Re: Grease for LX200 baffle? new [Re: Qwickdraw]
      #6020575 - 08/12/13 11:27 AM

I do not notice any shift in my 8", and a friend has a 12" and I don't remember any shift in it either. During alignment, when we center on a star, we defocus to make sure we are centered. I have never had my scope open so I can't comment there. With that much shift, how can you collimate? Is the secondary mirror off center?

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Qwickdraw
Pooh-Bah
*****

Reged: 03/03/12

Loc: Ann Arbor, MI
Re: Grease for LX200 baffle? new [Re: nitegeezer]
      #6020687 - 08/12/13 12:32 PM

Quote:

I do not notice any shift in my 8", and a friend has a 12" and I don't remember any shift in it either. During alignment, when we center on a star, we defocus to make sure we are centered. I have never had my scope open so I can't comment there. With that much shift, how can you collimate? Is the secondary mirror off center?




Not sure, I have only had the scope a week and it has been overcast every night but one. The one night it was clear, I didn't attempt to collimate it.


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Qwickdraw
Pooh-Bah
*****

Reged: 03/03/12

Loc: Ann Arbor, MI
Re: Grease for LX200 baffle? new [Re: Qwickdraw]
      #6039654 - 08/22/13 07:04 AM

Well, I have heard mixed reviews about reapplying grease but currently the scope is almost unusable.

I went ahead and ordered the grease as recommended above.

Grease

I hope this offers an improvement


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Qwickdraw
Pooh-Bah
*****

Reged: 03/03/12

Loc: Ann Arbor, MI
Re: Grease for LX200 baffle? new [Re: Qwickdraw]
      #6041743 - 08/23/13 11:48 AM

The grease arrived yesterday, I am not sure if I like the consistency. It is more of a sticky sealing paste than a lubricant. In any event, this weekend will be tear down time for this scope. I hope to report good news soon but I have my doubts.

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