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P26
Vendor - Peterson Engineering


Reged: 05/02/12

Loc: RI, USA
Re: Grease for LX200 baffle? new [Re: Qwickdraw]
      #6041812 - 08/23/13 12:35 PM

As noted on my posting of 8/ll, the Dow product you have is a sealant and not a lubricant. I've still got a tube of it purchased for an evaluation 10 years ago when the old MAPUG forum mentioned it while searching for the best baffle tube grease. But I sure didn't and wouldn't use it on my scope.

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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: P26]
      #6042205 - 08/23/13 04:47 PM

Thanks Pete, Can you advise a product that is good for the job?

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P26
Vendor - Peterson Engineering


Reged: 05/02/12

Loc: RI, USA
Re: Grease for LX200 baffle? new [Re: Qwickdraw]
      #6046818 - 08/26/13 11:32 AM

My 10" Classic image shift wasn't all that bad so I never did follow up by regreasing its baffle tube. My lubricant study was primarially a search for the grease still used on our focuser, gears and clutch upgrades. The image shift problem never was fully investigated so regretfully I can offer you no suggestions regarding baffle tube grease.

After a talk with Russ Tanton about grease last week it occurred to me that the stiffer the grease the greater the "striction" and the greater the force required to push the mirror sled up and down the tube. And the greater the force on the offset mirror sled pin the greater the tendency of the mirror to shift.

So, while a stiffer grease might better inhibit mirror flop (the tendency for gravity to pull the mirror down against its natural stops) it may not help with mirror shift. We do know that having adequate grease reduces mirror shift. But there's a possibility that a light grease will work as well as a higher viscosity grease. Consider the hypothesis that while a stiff grease better resists forces that cause mirror shift a higher force is required to push the mirror into focus when using a "stiff" grease. The greater force may push the mirror held by the "stiff" grease the same amount as a lesser force will when using a lower viscosity grease. So the benefit of the higher viscosity grease is canceled out by the higher force required.

This is all just my speculation.

The root cause of mirror shift and mirror flop is the gap between the baffle tube and the mirror sled tube. While Meade's optics are wonderfully precise their machining is less so. And some scopes have more of a gap than others.

If I were to look to solving mirror shift problems on an individual bad-behaving scope I'd look into gluing shim stock into the internal circumference of both ends of the mirror sled tube so as to reduce the internal diameter by just .001 or .002 inches. Don't know just how tight/loose the fit normally is but a little trial and error would be called for even if one measures first.

Clear skies,


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Whichwayisnorth
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Reged: 07/04/11

Loc: Southern California
Re: Grease for LX200 baffle? new [Re: P26]
      #6055461 - 08/31/13 02:27 AM

I had a 10" ACF that had such bad mirror shift that I ended up engineering my own solution which was to add roller bearings in four locations 90 degrees apart along the back of the mirror that I could adjust. Then I used the hi-vac stuff I linked in second post for everything to ride on. For anything like gears or focusers etc, use Superlube synthetic.

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Qwickdraw
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Reged: 03/03/12

Loc: Ann Arbor, MI
Re: Grease for LX200 baffle? [Re: Qwickdraw]
      #6057284 - 09/01/13 09:12 AM

Today is the day, After ordering the high vac grease and then determining it was more for sealing than lub I read that Tri-Flow Red Grease is a suitable grease for this purpose. Having once already taken the OTA apart 100% to try to determine the cause of large image shift, I feel confident it is a fairly easy task. I will post results as soon as I have some clear skies to test. I did read where one person attached a laser to the outer baffle tube and focused in and out to determine the extent of image shift so maybe I will try that as a before and after test.

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wd8sbb
super member
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Reged: 08/26/12

Loc: Southwest Ohio
Re: Grease for LX200 baffle? new [Re: Qwickdraw]
      #6137771 - 10/14/13 08:11 PM

FWIW, I used graphite powered and lubriplate grease some 15 years ago on our 8" LX200. The oil has never separated, and the image ship was improved. I forget, but seems to me I had a large percentage of graphite powder vs grease.

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Cliff Hipsher
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Reged: 12/31/08

Loc: North Chesterfield, VA
Re: Grease for LX200 baffle? new [Re: klyons]
      #6138040 - 10/14/13 11:05 PM

Dow Corning High Vacuum Grease .

Unlike petroleum or synthetic grease, this product will not out gas.

A little bit goes a LONG way....


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AnhTuan
member
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Reged: 03/31/11

Re: Grease for LX200 baffle? new [Re: Cliff Hipsher]
      #6157559 - 10/25/13 02:25 PM

I just bought a tube on eBay for $18. It's a heavy duty grease for sure. I will be regreasing my 14" LX200 OTA this summer.

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MrJones
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Reged: 09/15/10

Loc: Indiana
Re: Grease for LX200 baffle? new [Re: AnhTuan]
      #6159638 - 10/26/13 06:38 PM Attachment (8 downloads)

Don't use vacuum grease. This grease is designed for high vacuum glassware that chemists and such use - not for lubrication of moving parts. Otherwise SCT baffle lubrication is an incredibly undemanding application. Meade has seriously screwed up by using their sticky gunk and Celestron has remarkably gone one step further in using grease that can out-gass and even drip. I use Mobil 1. It's probably the most tested grease in history and is a good Group III grease. The boutique greases like Superlube are ok but not any better. So really, buy a tub of the pink stuff Celestron recommended and be done.

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Qwickdraw
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Reged: 03/03/12

Loc: Ann Arbor, MI
Re: Grease for LX200 baffle? new [Re: MrJones]
      #6170086 - 11/01/13 11:49 AM

I would second the recommendation not to use the vacuum grease. I bought a tube and when I saw the consistency said no way. It is a sealer, not a lube.

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