Balance Procedure


spcrichey <drichey@...>
 

What's the procedure for rebalancing. If I have very good polar alignment and a good
pointing accuracy, but need to loosen the clutces and reblance the load due to adding
equipment, how do I maintain my pointing model.


Edd Weninger
 

My AP900 is very tolerant of imbalance, so I don't bother even when
changing from a 1 1/4" eyepiece to a binoviewer with 2 Radians on my
AP155.

Don't know what equipment you're changing, but try it without re-
balancing.

--- In ap-gto@yahoogroups.com, "spcrichey" <drichey@...> wrote:

What's the procedure for rebalancing. If I have very good polar
alignment and a good
pointing accuracy, but need to loosen the clutces and reblance the
load due to adding
equipment, how do I maintain my pointing model.


Dick Steinberg <steinberg@...>
 

I have successfully used the following:

1. Slew the mount to the park 1 position (with locked clutches).
2. Precisely note the positions of the setting circles.
3. For each axis, loosen the clutches and balance without disturbing
the positions of the setting circles.
4. After each axis is balanced, use its setting circle to return it
manually to its prior position and lock the clutches.
5. Voila!

Regards,
Dick Steinberg











--- In ap-gto@yahoogroups.com, "spcrichey" <drichey@...> wrote:

What's the procedure for rebalancing. If I have very good polar
alignment and a good
pointing accuracy, but need to loosen the clutces and reblance the
load due to adding
equipment, how do I maintain my pointing model.


Roland Christen
 

In a message dated 4/21/2007 8:52:34 AM Central Daylight Time,
drichey@sandia.net writes:


What's the procedure for rebalancing. If I have very good polar alignment
and a good
pointing accuracy, but need to loosen the clutces and reblance the load due
to adding
equipment, how do I maintain my pointing model.
Your pointing model is not affected if you loosen the clutches to rebalance.
On the other hand, why do you need to do this? I image all the time without
ever rebalancing. It is not really necessary. I have been as much as 8lb out of
balance on both 900/1200 mounts, and recently ran 6lb out of balance on my
little bitty Mach1 mount. The tracking/guiding was spot on perfect.

Roland Christen


**************************************
See what's free at
http://www.aol.com.


Roland Christen
 

In a message dated 4/25/2007 9:21:36 AM Central Daylight Time,
J.Zeglinski@rogers.com writes:


You use the phrase "8 lbs out of balance", do you mean 8 inch-lbs?
Being "out of balance" with an 8 lb camera overhand at 6 inches is different

from the same weight overhanging 2 feet away.
I have had an imbalance of 8 lb at the end of a 160F7.5 refractor. You will
know when the imbalance is too large because the motors will have a problem
slewing in one direction, but it will take more than 8 lb except maybe when it is
bitterly cold outside. Also, if the clutches won't hold, it is probably too
much imbalance. I doubt very much that you could ever damage the worm gear
teeth. These are quite large and rugged.

Rolando


**************************************
See what's free at
http://www.aol.com.


Joe Zeglinski
 

Hi Roland,

This is good news - I was becoming concerned about "meticulously"
rebalancing the counterweights, every time I crossed the meridian. Indeed, the
AP900 is a superb design, and even more so, from what you say about the
rebalance issue.

One question:
You use the phrase "8 lbs out of balance", do you mean 8 inch-lbs?
Being "out of balance" with an 8 lb camera overhand at 6 inches is different
from the same weight overhanging 2 feet away. Could you be more specific about
the "moment arm" on the OTA imbalance you are describing?

Actually, it would be interesting, if someone there could do a bit of
testing in this regard, on various "moment-arm measurements", before you would
consider the AP900 or AP1200 seriously out of balance, for the expected
performance. For that matter, before you would consider possible damage to the
worm gear. That might provide a good rule of thumb which could be applied to
any OTA overload situation, to specific AP mounts.

I suppose one might say that the imbalance on any mount has reached a
maximum, if the clutches won't hold, but some might torque down the clutches
too tightly, even with a wrench, in order to avoid having to shift the
weights.

Thanks for any further info,
Joe

----- Original Message -----
From: <chris1011@aol.com>
To: <ap-gto@yahoogroups.com>
Sent: Monday, April 23, 2007 1:04 PM
Subject: Re: [ap-gto] Balance Procedure


In a message dated 4/21/2007 8:52:34 AM Central Daylight Time,
drichey@sandia.net writes:


What's the procedure for rebalancing. If I have very good polar alignment
and a good
pointing accuracy, but need to loosen the clutces and reblance the load due
to adding
equipment, how do I maintain my pointing model.
Your pointing model is not affected if you loosen the clutches to rebalance.
On the other hand, why do you need to do this? I image all the time without
ever rebalancing. It is not really necessary. I have been as much as 8lb out
of
balance on both 900/1200 mounts, and recently ran 6lb out of balance on my
little bitty Mach1 mount. The tracking/guiding was spot on perfect.

Roland Christen


**************************************
See what's free at
http://www.aol.com.






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see http://groups.yahoo.com/group/ap-gto
Yahoo! Groups Links




Jeff Young <jey@...>
 

Joe --

I accidentally balanced my 600E GTO once without diagonal or eyepiece.
When a 2" diagonal, 2" Barlow and T4 Nagler was added, it produced
intermittent stalls when slewing (but not when tracking). I'd guess it
was about 40 in-lbs out of balance.

I never re-balance my 1200 GTO with equipment changes. I might go from
no eyepieces in either SCT or refractor to a heavy T5 Nagler in each
with a Barlow in one. These weights are much farther out on the moment
arm, so I'd guess we'd be looking at more than 100 in-lbs of inbalance.
I've never had this mount stall.

Lastly, when I load up my scopes on the 1200, I load the c-weights
first. This leaves the mount temporarily some 2,500 in-lbs out of
balance.

Cheers,
-- Jeff




________________________________

From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] On
Behalf Of Joseph Zeglinski
Sent: Wednesday, April 25, 2007 3:22 PM
To: ap-gto@yahoogroups.com
Subject: Re: [ap-gto] Balance Procedure



Hi Roland,

This is good news - I was becoming concerned about
"meticulously"
rebalancing the counterweights, every time I crossed the
meridian. Indeed, the
AP900 is a superb design, and even more so, from what you say
about the
rebalance issue.

One question:
You use the phrase "8 lbs out of balance", do you mean 8
inch-lbs?
Being "out of balance" with an 8 lb camera overhand at 6 inches
is different
from the same weight overhanging 2 feet away. Could you be more
specific about
the "moment arm" on the OTA imbalance you are describing?

Actually, it would be interesting, if someone there could do a
bit of
testing in this regard, on various "moment-arm measurements",
before you would
consider the AP900 or AP1200 seriously out of balance, for the
expected
performance. For that matter, before you would consider possible
damage to the
worm gear. That might provide a good rule of thumb which could
be applied to
any OTA overload situation, to specific AP mounts.

I suppose one might say that the imbalance on any mount has
reached a
maximum, if the clutches won't hold, but some might torque down
the clutches
too tightly, even with a wrench, in order to avoid having to
shift the
weights.

Thanks for any further info,
Joe

----- Original Message -----
From: <chris1011@aol.com <mailto:chris1011%40aol.com> >
To: <ap-gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com> >
Sent: Monday, April 23, 2007 1:04 PM
Subject: Re: [ap-gto] Balance Procedure

> In a message dated 4/21/2007 8:52:34 AM Central Daylight Time,
> drichey@sandia.net <mailto:drichey%40sandia.net> writes:
>
>
>> What's the procedure for rebalancing. If I have very good
polar alignment
>> and a good
>> pointing accuracy, but need to loosen the clutces and
reblance the load due
>> to adding
>> equipment, how do I maintain my pointing model.
>>
>
> Your pointing model is not affected if you loosen the clutches
to rebalance.
> On the other hand, why do you need to do this? I image all the
time without
> ever rebalancing. It is not really necessary. I have been as
much as 8lb out
> of
> balance on both 900/1200 mounts, and recently ran 6lb out of
balance on my
> little bitty Mach1 mount. The tracking/guiding was spot on
perfect.
>
> Roland Christen
>
>
> **************************************
> See what's free at
> http://www.aol.com. <http://www.aol.com.>
>
>
>
>
>
>
> To UNSUBSCRIBE, or for general information on the ap-gto list
> see http://groups.yahoo.com/group/ap-gto
<http://groups.yahoo.com/group/ap-gto>
> Yahoo! Groups Links
>
>
>
>


Joe Zeglinski
 

Hi Roland,

Not knowing the centre of gravity of your (160/F7.5) OTA, but assuming it
is at mid point (23.6 inches), that would be approximately a moment of 189
inch-lbs.
O.K. that is a useful working example to know, to judge our own OTA
conditions.

I am a bit surprised that AP uses "weight" instead of "moment (torque)"
when talking about imbalance. I found the same terminology used on page 23 of
the AP900 user manual: Troubleshooting - (additional explanation) - "It
typically takes about 4 lb. of unbalance to trip the overload circuit ...
etc."
This is a "weight", not a "moment arm" reference, which really depends on
which OTA you are using on the mount. A long OTA with 4 lbs is different from
a short SCT with the same 4 lbs. of unbalance.

As for not being concerned about "damaging the worm gear teeth", once
again, the user manual page 15 - RA & DEC Clutch Knobs: "3: How tight can they
be...etc." warns:
"You should not attempt to push your scope by hand against this locked up
resistance, or undue stress will be placed on the worm wheel/worm an
bearings".

My concern arose from reading that section in the mount set-up manual. In
using the mount for astrophotography, it is "recommended" to tighten the
clutches a bit more (1/8 turn by wrench). An overly "unbalanced OTA" may
introduce the same stress situation as "pushing the mount by hand", as
described in the manual. No "guideline" is given about how many "inch-lbs of
torque", potentially from OTA imbalance, are considered crossing the line on
too much stress on the worm gear.

Of course, the safest bet is to minimize any imbalance, as best as one
can.

Joe

----- Original Message -----
From: <chris1011@aol.com>
To: <ap-gto@yahoogroups.com>
Sent: Wednesday, April 25, 2007 10:47 AM
Subject: Re: [ap-gto] Balance Procedure


In a message dated 4/25/2007 9:21:36 AM Central Daylight Time,
J.Zeglinski@rogers.com writes:


You use the phrase "8 lbs out of balance", do you mean 8 inch-lbs?
Being "out of balance" with an 8 lb camera overhand at 6 inches is
different

from the same weight overhanging 2 feet away.
I have had an imbalance of 8 lb at the end of a 160F7.5 refractor. You will
know when the imbalance is too large because the motors will have a problem
slewing in one direction, but it will take more than 8 lb except maybe when
it is
bitterly cold outside. Also, if the clutches won't hold, it is probably too
much imbalance. I doubt very much that you could ever damage the worm gear
teeth. These are quite large and rugged.

Rolando


**************************************
See what's free at
http://www.aol.com.






To UNSUBSCRIBE, or for general information on the ap-gto list
see http://groups.yahoo.com/group/ap-gto
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Joe Zeglinski
 

Thanks Jeff,

I had forgotten about the large initial worm stress, with no OTA. I
suppose if it can (and must) survive that, then the normal imbalance is no
issue at all, in comparison. I had some concerns about operating the mount,
and not rebalancing on meridian changes, if something of the size of say a
large SBIG camera were hanging out there. Shifting weights so often, to
protect the worm drive, would be a hassle. I'm also relieved, that the servo
motors have a safety trip point protection circuit against this as well.

I see from your comparison of the 600GTO and 1200GTO mounts, that I made a
very good decision in purchasing the AP900, in this regard.

Thanks for the added reassurance. The AP900/1200 are one heck of a nearly
bullet-proof mount.
Joe

----- Original Message -----
From: "Jeff Young" <jey@adobe.com>
To: <ap-gto@yahoogroups.com>
Sent: Wednesday, April 25, 2007 11:10 AM
Subject: RE: [ap-gto] Balance Procedure


Joe --

I accidentally balanced my 600E GTO once without diagonal or eyepiece.
When a 2" diagonal, 2" Barlow and T4 Nagler was added, it produced
intermittent stalls when slewing (but not when tracking). I'd guess it
was about 40 in-lbs out of balance.

I never re-balance my 1200 GTO with equipment changes. I might go from
no eyepieces in either SCT or refractor to a heavy T5 Nagler in each
with a Barlow in one. These weights are much farther out on the moment
arm, so I'd guess we'd be looking at more than 100 in-lbs of inbalance.
I've never had this mount stall.

Lastly, when I load up my scopes on the 1200, I load the c-weights
first. This leaves the mount temporarily some 2,500 in-lbs out of
balance.

Cheers,
-- Jeff




________________________________

From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] On
Behalf Of Joseph Zeglinski
Sent: Wednesday, April 25, 2007 3:22 PM
To: ap-gto@yahoogroups.com
Subject: Re: [ap-gto] Balance Procedure



Hi Roland,

This is good news - I was becoming concerned about
"meticulously"
rebalancing the counterweights, every time I crossed the
meridian. Indeed, the
AP900 is a superb design, and even more so, from what you say
about the
rebalance issue.

One question:
You use the phrase "8 lbs out of balance", do you mean 8
inch-lbs?
Being "out of balance" with an 8 lb camera overhand at 6 inches
is different
from the same weight overhanging 2 feet away. Could you be more
specific about
the "moment arm" on the OTA imbalance you are describing?

Actually, it would be interesting, if someone there could do a
bit of
testing in this regard, on various "moment-arm measurements",
before you would
consider the AP900 or AP1200 seriously out of balance, for the
expected
performance. For that matter, before you would consider possible
damage to the
worm gear. That might provide a good rule of thumb which could
be applied to
any OTA overload situation, to specific AP mounts.

I suppose one might say that the imbalance on any mount has
reached a
maximum, if the clutches won't hold, but some might torque down
the clutches
too tightly, even with a wrench, in order to avoid having to
shift the
weights.

Thanks for any further info,
Joe

----- Original Message -----
From: <chris1011@aol.com <mailto:chris1011%40aol.com> >
To: <ap-gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com> >
Sent: Monday, April 23, 2007 1:04 PM
Subject: Re: [ap-gto] Balance Procedure

In a message dated 4/21/2007 8:52:34 AM Central Daylight Time,
drichey@sandia.net <mailto:drichey%40sandia.net> writes:


What's the procedure for rebalancing. If I have very good
polar alignment
and a good
pointing accuracy, but need to loosen the clutces and
reblance the load due
to adding
equipment, how do I maintain my pointing model.
Your pointing model is not affected if you loosen the clutches
to rebalance.
On the other hand, why do you need to do this? I image all the
time without
ever rebalancing. It is not really necessary. I have been as
much as 8lb out
of
balance on both 900/1200 mounts, and recently ran 6lb out of
balance on my
little bitty Mach1 mount. The tracking/guiding was spot on
perfect.

Roland Christen


**************************************
See what's free at
http://www.aol.com. <http://www.aol.com.>






To UNSUBSCRIBE, or for general information on the ap-gto list
see http://groups.yahoo.com/group/ap-gto
<http://groups.yahoo.com/group/ap-gto>
Yahoo! Groups Links













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Yahoo! Groups Links




drgert1
 

Hi Joe,

It's best to have a slight imbalance so that any (small) gear backlash
is always pushed out. I prefer the mount always to 'pull' a bit.

Clear Skies,

Gert

--- In ap-gto@yahoogroups.com, "Joseph Zeglinski" <J.Zeglinski@...> wrote:
...

Of course, the safest bet is to minimize any imbalance, as best
as one
can.

Joe