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@... [mailto:ap-gto@...] On
Behalf Of Joseph Zeglinski
Sent: Wednesday, April 25, 2007 3:22 PM
To: ap-gto@...
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@... <mailto:chris1011%40aol.com> >
To: <ap-gto@... <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@... <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


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