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Date: 20 Sep 2006 09:05:59
From: Mika Yrjola
Subject: Stuck T-bolt on mount and CRC?
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Hi,
I noticed lately that one of the two altitude adjustment t-bolts on my
Skywatcher EQ3-2 mount has became stuck; while the other bolt can be
loosened and tightened, this one can't be turned much on either
direction. I'm afraid of using much more force, because the grooves
might get damaged (hopefully they already aren't...).
So, what I'm wondering is whether applying a bit of CRC is a good idea
to get it unstuck, or if there's something inside the mount that might
not like it. Any opinions / experiences / other ideas? While the
adjustment is not _that_ far from correct, it's still more than enough
to prevent the motor drive to tracking anything properly.
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Date: 20 Sep 2006 18:04:54
From: William Hamblen
Subject: Re: Stuck T-bolt on mount and CRC?
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On 20 Sep 2006 09:05:59 +0300, Mika Yrjola <myrjola@kapsi.fi > wrote:
>I noticed lately that one of the two altitude adjustment t-bolts on my
>Skywatcher EQ3-2 mount has became stuck; while the other bolt can be
>loosened and tightened, this one can't be turned much on either
>direction. I'm afraid of using much more force, because the grooves
>might get damaged (hopefully they already aren't...).
The altitude adjustment bolts on these mounts have been known to bend.
You don't say which bolt is stuck. I am going to guess it is the
bottom one. Back out the top bolt. Take the pressure off the bottom
by raising the equatorial head. Back out the bottom bolt. Replace
the bent bottom bolt with a new metric size bolt. Get a hex head
replacement bolt and just turn it with a wrench. Unfortunately I
don't know offhand what the diameter and pitch are on the bolt. When
adjusting the mount for altitude, back out the top bolt slightly
before turning the bottom bolt. When you have the altitude adjusted
properly, turn the top bolt just finger-tip tight to lock the
adjustment. Gravity holds the equatorial head against the bottom
bolt. You don't need to apply any force to the top bolt.
Bud
--
The night is just the shadow of the Earth.
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Date: 20 Sep 2006 14:22:12
From: trope
Subject: Re: Stuck T-bolt on mount and CRC?
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Mika Yrjola wrote:
> Hi,
>
> I noticed lately that one of the two altitude adjustment t-bolts on my
> Skywatcher EQ3-2 mount has became stuck; while the other bolt can be
> loosened and tightened, this one can't be turned much on either
> direction. I'm afraid of using much more force, because the grooves
> might get damaged (hopefully they already aren't...).
>
> So, what I'm wondering is whether applying a bit of CRC is a good idea
> to get it unstuck, or if there's something inside the mount that might
> not like it. Any opinions / experiences / other ideas? While the
> adjustment is not _that_ far from correct, it's still more than enough
> to prevent the motor drive to tracking anything properly.
Take all the weight off the mount. Use a small amount of WD-40
lubricating oil. With small wrench turn back and forth to loosen. Take
bolt and chase threads with the appropriate die. Watch out for thread
pitch ie metric or standard. Clean with IPA and relubricate. You may
have to use the matching tap to clean out the holes. Takes time and
patience. No problem you are an astronomer. Good luck trope
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Date: 20 Sep 2006 22:27:26
From: Pieter Litchfield
Subject: Re: Stuck T-bolt on mount and CRC?
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"trope" <bobray584@gmail.com > wrote in message
news:1158787331.093741.133910@d34g2000cwd.googlegroups.com...
>
> Mika Yrjola wrote:
>> Hi,
>>
>> I noticed lately that one of the two altitude adjustment t-bolts on my
>> Skywatcher EQ3-2 mount has became stuck; while the other bolt can be
>> loosened and tightened, this one can't be turned much on either
>> direction. I'm afraid of using much more force, because the grooves
>> might get damaged (hopefully they already aren't...).
>>
>> So, what I'm wondering is whether applying a bit of CRC is a good idea
>> to get it unstuck, or if there's something inside the mount that might
>> not like it. Any opinions / experiences / other ideas? While the
>> adjustment is not _that_ far from correct, it's still more than enough
>> to prevent the motor drive to tracking anything properly.
>
> Take all the weight off the mount. Use a small amount of WD-40
> lubricating oil. With small wrench turn back and forth to loosen. Take
> bolt and chase threads with the appropriate die. Watch out for thread
> pitch ie metric or standard. Clean with IPA and relubricate. You may
> have to use the matching tap to clean out the holes. Takes time and
> patience. No problem you are an astronomer. Good luck trope
Let's be clear - WD-40 is not a lubricant, it's a water displacer (hence the
name). It's better used for keeping gun barrels from rusting. It does not
lubricate well.
I think the rest of the suggestion is very sound advice, but I'd suggest a
good penetrating oil like Liquid Wrench for example. After the bolt is
removed and the threads repaired, clean the threads with a solvent and use a
tiny bit of a graphite based grease like Never-Seize to prevent any seizing
of dissimilar metals. I often use Tri-Flow light oil which contains teflon
and is very slippery with good results.
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