Date   

Re: Balance Procedure

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
>
>
>
>


Re: Balance Procedure

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


**************************************
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Re: AP900 Dec backlash - more help required

Jeff Young <jey@...>
 

John --

It's quite unlikely to be the motor shaft -- that gear is glued on as
well as being set-screwed.

The gears in the middle are just transfer gears, so they rotate freely
on the shoulder-bolts which hold them to the motor housing. The gear on
the worm shaft (that closest to the mount) is the most likely culprit.
You might try your pencil line trick with it and see if that shows
anything up. You should also be able to get to the setscrew in that one
more easily.

-- Jeff.


________________________________

From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] On
Behalf Of John Winfield
Sent: Wednesday, April 25, 2007 4:07 AM
To: ap-gto@yahoogroups.com
Subject: [ap-gto] Re: AP900 Dec backlash - more help required



Hi all,

Thanks to the guidance here, I've removed the motor box cover
and
inspected the gear train underneath.

I've discovered that when driving the Dec motor at 1x sidereal
speed,
it 'jumps', once or twice per revolution.
This seems to predominantly happen after changing direction - if
I
keep running in the same direction the jumps seem to stop after
a few
revolutions.
I'm guessing this is indeed due to a loose locking screw on one
of the
gears.

I put a pencil mark on the end of the motor shaft and after a
few
jumps it still seemed to be in the same orientation wrt to the
locking
grub screw, so I'm assuming it's not that one.

I can't get to the locking screw on the motor shaft through this
side
cover to check it's tightness and can't even see the locking
screws on
the other gear shafts.

Am I on the right lines - and are there any guidelines on how
best to
adjust the locking screws on these other hard-to-reach gear
shafts?

I'm not a mechanical whizz, but I'm reasonably competent.

Regards,

John

--- In ap-gto@yahoogroups.com <mailto:ap-gto%40yahoogroups.com>
, chris1011@... wrote:
>
> In a message dated 4/23/2007 2:08:04 PM Central Daylight Time,

> winfij@... writes:
>
>
> > Thanks for clarifying that - this is a circa 2003 mount,
purchased
> > used as you say.
>
> In a lot of cases, when a mount has been purchased used, the
person
who ships
> it will not package it correctly, and the result is that
stress is
put on the
> motor box/worm gear. This then results in poor worm mesh, so
the
first thing
> a new user must do when he/she recaives a used mount is to do
a
re-mesh on
> both axes. Probably the biggest mistake is to take such a
mount out
of the box,
> set it up outside and expect it to work perfectly. It probably
will
not work
> quite right until the gear mesh has been checked. Also, many
times a
mount can
> have other minor things out of adjustment which the previous
owner
never
> realized, but which the new owner will see right away.
Therefore do
not hesitate to
> check all things in the daylight before trying it out in the
dark.
>
> >
> > Are there any instructions/pictures as to how to remove the
motor box
> > cover, just to make sure I get the correct screws?
> >
>
> The motor box cover is located on the opposite end of the worm
shaft
cover.
> Remove the 6 small Allen head screws and the cover will slip
off.
You will then
> see the spur reduction gears. Once you see them, you will
understand
how it
> all works.
>
> Rolando
>
>
> **************************************
> See what's free at
> http://www.aol.com. <http://www.aol.com.>
>
>
>
>


Re: Balance Procedure

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


**************************************
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Re: AP900 Dec backlash - more help required

Roland Christen
 

In a message dated 4/24/2007 10:10:02 PM Central Daylight Time,
winfij@gmail.com writes:


I can't get to the locking screw on the motor shaft through this side
cover to check it's tightness and can't even see the locking screws on
the other gear shafts.
There is only one locking screw, and that is on the last spur gear on the
worm itself. The other gears all run free on their pinions. You can remove the
largest gear in the train (use a normal srew driver to unscrew the shoulder
screw). Once you remove this gear, you can see the underlying pinion gear which is
attached to the worm. This gear has a small set screw on the side, and this
set screw must be tightened - it also must be centered on the flat, otherwise
it will probably loosen on you. If you cannot follow this, please call AP and
talk to Wally. He will guide you step by step in this procedure.

By the way, I do not know what you mean by "jumping", but it could be that
you have dialed in some backlash compensation on your keypad. Go into the setup
procedure and put 0 for backlash in both RA and Dec axes. This will eliminate
any motions that you may not be familiar with, and will aid in your
visualization of what needs to happen when reversing the RA and Dec axis.

Rolando


**************************************
See what's free at
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Re: Help with orthogonality

observe_m13
 

If your telescope is orthogonal to the mount and the mount is even
moderately well polar aligned, when you point the telescope right at
the pole, Polaris will NOT be centered. It will be noticeably offset
even in a low power eyepiece field. Polaris can be used as a quick
alignment star for visual use of a moderately wide field telescope
with goto in most cases.

To rough polar align I use the PASILL with great success. In fact,
with a bit of care, I manage to achieve very good to excellent polar
alignment. One can drift after that to fine tune it further if
shooting close to the poles where field rotation really makes a mess
of things if you are not well polar aligned.

Rick.

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

So, one person says "Uh, no you should not be able to center
Polaris, Polaris is not at the
pole, it is beside it." , and another says "the mount can certainly
go to Polaris." I am very
confused. Is not being able to center Polaris an orthogonal error,
or not? I have a "normal"
refractor and "normally well" machined rings, so either I am not
well enough polar aligned,
or my equipment isn't "normal." --- In ap-gto@yahoogroups.com,
chris1011@ wrote:

In a message dated 4/24/2007 4:35:40 PM Central Daylight Time,
drichey@ writes:


I beleive it is .8º for CNP. So how does one do the alignment
routine in the AP manual using Polaris and another star?
The mount can certainly go to Polaris. No problem. When properly
polar
aligned, any mount can go to Polaris. If you have orthogonal error
larger than 0.8
degrees in your telescope, then no equatorial mount will be able
to access
Polaris. The mount will point to Polaris for sure, but the scope
will point
elsewhere. I assume that every amateur knows that the direction
that a telescope
points to is not necessarily the direction that the mount points
to. It is up to
you, the user, to align the two. Every basic book on astronomical
instruments
will point this out.

Rolando


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


[Non-text portions of this message have been removed]


Pulsed LED on Polar Scope

Joe Zeglinski
 

Hi,

I was wondering if there has ever been a consideration of adding "pulsed
power" control for the PASILL3/4 polar scope. This could be either an argument
to the keypad command to change not only the brightness, but also the on/off
rate for the GTOCP3 reticle socket, or an attached box with a small circuit in
the scope illuminator cable, with which you could adjust the pulse rate and
brightness. This is similar to the way the "Pulse Guide" product operates for
illuminated crosshair eyepieces.

The reason I bring this up, is that I took my PASILL4 outdoors for a dry
run test, in the light polluted skies of suburbia of a large metropolitan
city. It was somewhat difficult to spot Polaris, and did not expect any
success in aligning the second, let alone the third, star onto the reticle.
However, I was amazed to actually see the faint "glimmer" of the second star,
if I quickly rotated the scope eyepiece back and forth. Of course, this was
just a test of the scope itself, not yet mounted in my new AP900. It makes no
sense to oscillate the eyepiece, as in my test, when you are attempting to
precisely align the reference stars on the hash marks - that defeats the
purpose. But I realized that if the red LED illuminator were to be "pulsed",
instead of being steady, it would be easier to align two, or maybe even all
three stars on the reticle.

Since the battery powered setup has neither a dimmer nor a pulse width
adjust, the reticle is far too bright, making it difficult to align on
Polaris. An attached control module, and/or a similar control in the keypad
miscellaneous command set for the reticle port on the GTOCP3 control box,
would be useful. The latter, of course, would be used for not only the polar
alignment with the PASILL4, but also perhaps with an illuminated eyepiece on
the main OTA.

Thanks,
Joe


Re: AP900 Dec backlash - more help required

John Winfield
 

Hi all,

Thanks to the guidance here, I've removed the motor box cover and
inspected the gear train underneath.

I've discovered that when driving the Dec motor at 1x sidereal speed,
it 'jumps', once or twice per revolution.
This seems to predominantly happen after changing direction - if I
keep running in the same direction the jumps seem to stop after a few
revolutions.
I'm guessing this is indeed due to a loose locking screw on one of the
gears.

I put a pencil mark on the end of the motor shaft and after a few
jumps it still seemed to be in the same orientation wrt to the locking
grub screw, so I'm assuming it's not that one.

I can't get to the locking screw on the motor shaft through this side
cover to check it's tightness and can't even see the locking screws on
the other gear shafts.

Am I on the right lines - and are there any guidelines on how best to
adjust the locking screws on these other hard-to-reach gear shafts?

I'm not a mechanical whizz, but I'm reasonably competent.

Regards,

John


--- In ap-gto@yahoogroups.com, chris1011@... wrote:

In a message dated 4/23/2007 2:08:04 PM Central Daylight Time,
winfij@... writes:


Thanks for clarifying that - this is a circa 2003 mount, purchased
used as you say.
In a lot of cases, when a mount has been purchased used, the person
who ships
it will not package it correctly, and the result is that stress is
put on the
motor box/worm gear. This then results in poor worm mesh, so the
first thing
a new user must do when he/she recaives a used mount is to do a
re-mesh on
both axes. Probably the biggest mistake is to take such a mount out
of the box,
set it up outside and expect it to work perfectly. It probably will
not work
quite right until the gear mesh has been checked. Also, many times a
mount can
have other minor things out of adjustment which the previous owner
never
realized, but which the new owner will see right away. Therefore do
not hesitate to
check all things in the daylight before trying it out in the dark.


Are there any instructions/pictures as to how to remove the motor box
cover, just to make sure I get the correct screws?
The motor box cover is located on the opposite end of the worm shaft
cover.
Remove the 6 small Allen head screws and the cover will slip off.
You will then
see the spur reduction gears. Once you see them, you will understand
how it
all works.

Rolando


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




Re: Help with orthogonality

spcrichey <drichey@...>
 

So, one person says "Uh, no you should not be able to center Polaris, Polaris is not at the
pole, it is beside it." , and another says "the mount can certainly go to Polaris." I am very
confused. Is not being able to center Polaris an orthogonal error, or not? I have a "normal"
refractor and "normally well" machined rings, so either I am not well enough polar aligned,
or my equipment isn't "normal." --- In ap-gto@yahoogroups.com, chris1011@... wrote:


In a message dated 4/24/2007 4:35:40 PM Central Daylight Time,
drichey@... writes:


I beleive it is .8º for CNP. So how does one do the alignment
routine in the AP manual using Polaris and another star?
The mount can certainly go to Polaris. No problem. When properly polar
aligned, any mount can go to Polaris. If you have orthogonal error larger than 0.8
degrees in your telescope, then no equatorial mount will be able to access
Polaris. The mount will point to Polaris for sure, but the scope will point
elsewhere. I assume that every amateur knows that the direction that a telescope
points to is not necessarily the direction that the mount points to. It is up to
you, the user, to align the two. Every basic book on astronomical instruments
will point this out.

Rolando


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


[Non-text portions of this message have been removed]


Re: Help with orthogonality

Woodwind
 

Rolando,

You have put your finger on a phenomenon which so often seems to afflict us all at one time or another. Flawed leaps of logic - which can leave one totally bewildered by our inability to achieve an aim - and no apparent solution until someone points out the obvious.

Taking your point one stage further, there is a potentially flawed assumption that anything bolted to a mount is pointing in the right direction and indeed that any series of things bolted to a mount are pointing in the same direction.

Equipment-alignment and polar-alignment are two very different things which are both important.

Just a thought.

Murray







chris1011@aol.com wrote: In a message dated 4/24/2007 4:35:40 PM Central Daylight Time,
drichey@sandia.net writes:

> I beleive it is .8º for CNP. So how does one do the alignment
> routine in the AP manual using Polaris and another star?

The mount can certainly go to Polaris. No problem. When properly polar
aligned, any mount can go to Polaris. If you have orthogonal error larger than 0.8
degrees in your telescope, then no equatorial mount will be able to access
Polaris. The mount will point to Polaris for sure, but the scope will point
elsewhere. I assume that every amateur knows that the direction that a telescope
points to is not necessarily the direction that the mount points to. It is up to
you, the user, to align the two. Every basic book on astronomical instruments
will point this out.

Rolando

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

[Non-text portions of this message have been removed]






---------------------------------
Ahhh...imagining that irresistible "new car" smell?
Check outnew cars at Yahoo! Autos.

[Non-text portions of this message have been removed]


Re: Help with orthogonality

spcrichey <drichey@...>
 

That's what I thought. I beleive it is .8º for CNP. So how does one do the alignment
routine in the AP manual using Polaris and another star?--- In ap-gto@yahoogroups.com,
"Rick K" <JunkMailGoesHere@...> wrote:


Uh, no you should not be able to center Polaris. Polaris is not at the
pole, it is beside it.

Rick.

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

I have exactly the same problem, only an AP900. I use a 6" TV
refractor with a Robin
Casady saddle and Parallax rings (rings and saddle new). Spent
significant time on star
drift alignment, got it perfect for 5 minutes both S and E. My
finds are still off. I guess I
also have an orthogonality issue. Am waiting for weather to try the
AP Ortho check
routine.
Should one be able to center Polaris in a guiding EP at 60 power.
After the alignment (drift
method) I cannot.
Regards,
Dan Richey
--- In ap-gto@yahoogroups.com, "Louis Marchesi" <lmarchesi@> wrote:

I had some significant time with my new mount (AP 1200) and the new
camera this past weekend (finally!). One thing that is more
challenging than I expected is polar alignment. I did the 'daytime
polar alignment' routine using a carpenter's level and the Moon. The
mount/pier were reasonably level as well. Then, when I do the 2-star
calibration I seem to be 'oscillating' back and forth in azimuth.

What surprised me most is that the 'cone of error' seems very large,
as in half a finder scope's field of view. I am not sure how much of
that is how far I am from the pole versus non-orthogonality, but it
does make pointing the scope and camera at a specific target somewhat
challenging.

I have a 6-inch refractor with (IIRC) CNC-machined rings on a Losmandy
17-inch dovetail with 'riser' blocks, then attached to a Casady saddle
on the 1200.

In the manual for the mount, it says to 'simply shim' the rings until
I am orthogonal. I apologize for being dense, but does the shimming
happen to the contact point where the rings mate to the dovetail
plate, or where the dovetail mates to the saddle, or both? What is a
good shimming material ... soda can, 'aluminum' foil? One other thing
I should mention is that I don't yet have a permanent setup, so I'd
like a solution that is repeatable each time I set up.

I recognize that there is software out there to model pointing, but
I'm the kind of person that will be 'bothered' by this. I'd rather get
the scope as orthogonal as possible before I consider T-Point or its
equivalent.

Regards,
Louis Marchesi
New London Twp, PA


Re: Help with orthogonality

observe_m13
 

Uh, no you should not be able to center Polaris. Polaris is not at the
pole, it is beside it.

Rick.

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

I have exactly the same problem, only an AP900. I use a 6" TV
refractor with a Robin
Casady saddle and Parallax rings (rings and saddle new). Spent
significant time on star
drift alignment, got it perfect for 5 minutes both S and E. My
finds are still off. I guess I
also have an orthogonality issue. Am waiting for weather to try the
AP Ortho check
routine.
Should one be able to center Polaris in a guiding EP at 60 power.
After the alignment (drift
method) I cannot.
Regards,
Dan Richey
--- In ap-gto@yahoogroups.com, "Louis Marchesi" <lmarchesi@> wrote:

I had some significant time with my new mount (AP 1200) and the new
camera this past weekend (finally!). One thing that is more
challenging than I expected is polar alignment. I did the 'daytime
polar alignment' routine using a carpenter's level and the Moon. The
mount/pier were reasonably level as well. Then, when I do the 2-star
calibration I seem to be 'oscillating' back and forth in azimuth.

What surprised me most is that the 'cone of error' seems very large,
as in half a finder scope's field of view. I am not sure how much of
that is how far I am from the pole versus non-orthogonality, but it
does make pointing the scope and camera at a specific target somewhat
challenging.

I have a 6-inch refractor with (IIRC) CNC-machined rings on a Losmandy
17-inch dovetail with 'riser' blocks, then attached to a Casady saddle
on the 1200.

In the manual for the mount, it says to 'simply shim' the rings until
I am orthogonal. I apologize for being dense, but does the shimming
happen to the contact point where the rings mate to the dovetail
plate, or where the dovetail mates to the saddle, or both? What is a
good shimming material ... soda can, 'aluminum' foil? One other thing
I should mention is that I don't yet have a permanent setup, so I'd
like a solution that is repeatable each time I set up.

I recognize that there is software out there to model pointing, but
I'm the kind of person that will be 'bothered' by this. I'd rather get
the scope as orthogonal as possible before I consider T-Point or its
equivalent.

Regards,
Louis Marchesi
New London Twp, PA


Re: Help with orthogonality

Roland Christen
 

In a message dated 4/24/2007 7:48:26 PM Central Daylight Time,
mphammick@yahoo.com writes:


Taking your point one stage further, there is a potentially flawed
assumption that anything bolted to a mount is pointing in the right direction and
indeed that any series of things bolted to a mount are pointing in the same
direction.

Equipment-alignment and polar-alignment are two very different things which
are both important.
You are correct.

Rolando


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


Re: Keypad problem ?

Joe Zeglinski
 

Thanks Roland,

Glad that keypad corrosion is no longer a concern - and that the reference
to it in the Trouble shooting section of the keypad user manual, will be
removed in the next revision. After all, as far as trouble shooting is
concerned, I don't think you want the user checking the circuit board, in the
first three years. Non electronics specialists shouldn't be encouraged to
check inside anyway.

Joe

----- Original Message -----
From: <chris1011@aol.com>
To: <ap-gto@yahoogroups.com>
Sent: Tuesday, April 24, 2007 12:38 PM
Subject: Re: [ap-gto] Re: Keypad problem ?


In a message dated 4/23/2007 11:22:56 PM Central Daylight Time,
J.Zeglinski@rogers.com writes:


Your electronic friend was absolutely right about the "potential" keyboard
corrosion problem!
I think you are going overboard on this. This is the first time in 10 years
that a keypad has had this problem. Why make a mountain out of an Angstrom?

Rolando


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Re: Help with orthogonality

spcrichey <drichey@...>
 

I have exactly the same problem, only an AP900. I use a 6" TV refractor with a Robin
Casady saddle and Parallax rings (rings and saddle new). Spent significant time on star
drift alignment, got it perfect for 5 minutes both S and E. My finds are still off. I guess I
also have an orthogonality issue. Am waiting for weather to try the AP Ortho check
routine.
Should one be able to center Polaris in a guiding EP at 60 power. After the alignment (drift
method) I cannot.
Regards,
Dan Richey

--- In ap-gto@yahoogroups.com, "Louis Marchesi" <lmarchesi@...> wrote:

I had some significant time with my new mount (AP 1200) and the new
camera this past weekend (finally!). One thing that is more
challenging than I expected is polar alignment. I did the 'daytime
polar alignment' routine using a carpenter's level and the Moon. The
mount/pier were reasonably level as well. Then, when I do the 2-star
calibration I seem to be 'oscillating' back and forth in azimuth.

What surprised me most is that the 'cone of error' seems very large,
as in half a finder scope's field of view. I am not sure how much of
that is how far I am from the pole versus non-orthogonality, but it
does make pointing the scope and camera at a specific target somewhat
challenging.

I have a 6-inch refractor with (IIRC) CNC-machined rings on a Losmandy
17-inch dovetail with 'riser' blocks, then attached to a Casady saddle
on the 1200.

In the manual for the mount, it says to 'simply shim' the rings until
I am orthogonal. I apologize for being dense, but does the shimming
happen to the contact point where the rings mate to the dovetail
plate, or where the dovetail mates to the saddle, or both? What is a
good shimming material ... soda can, 'aluminum' foil? One other thing
I should mention is that I don't yet have a permanent setup, so I'd
like a solution that is repeatable each time I set up.

I recognize that there is software out there to model pointing, but
I'm the kind of person that will be 'bothered' by this. I'd rather get
the scope as orthogonal as possible before I consider T-Point or its
equivalent.

Regards,
Louis Marchesi
New London Twp, PA


Help with orthogonality

primeclash
 

I had some significant time with my new mount (AP 1200) and the new
camera this past weekend (finally!). One thing that is more
challenging than I expected is polar alignment. I did the 'daytime
polar alignment' routine using a carpenter's level and the Moon. The
mount/pier were reasonably level as well. Then, when I do the 2-star
calibration I seem to be 'oscillating' back and forth in azimuth.

What surprised me most is that the 'cone of error' seems very large,
as in half a finder scope's field of view. I am not sure how much of
that is how far I am from the pole versus non-orthogonality, but it
does make pointing the scope and camera at a specific target somewhat
challenging.

I have a 6-inch refractor with (IIRC) CNC-machined rings on a Losmandy
17-inch dovetail with 'riser' blocks, then attached to a Casady saddle
on the 1200.

In the manual for the mount, it says to 'simply shim' the rings until
I am orthogonal. I apologize for being dense, but does the shimming
happen to the contact point where the rings mate to the dovetail
plate, or where the dovetail mates to the saddle, or both? What is a
good shimming material ... soda can, 'aluminum' foil? One other thing
I should mention is that I don't yet have a permanent setup, so I'd
like a solution that is repeatable each time I set up.

I recognize that there is software out there to model pointing, but
I'm the kind of person that will be 'bothered' by this. I'd rather get
the scope as orthogonal as possible before I consider T-Point or its
equivalent.

Regards,
Louis Marchesi
New London Twp, PA


Re: Help with orthogonality

Roland Christen
 

In a message dated 4/24/2007 4:35:40 PM Central Daylight Time,
drichey@sandia.net writes:


I beleive it is .8º for CNP. So how does one do the alignment
routine in the AP manual using Polaris and another star?
The mount can certainly go to Polaris. No problem. When properly polar
aligned, any mount can go to Polaris. If you have orthogonal error larger than 0.8
degrees in your telescope, then no equatorial mount will be able to access
Polaris. The mount will point to Polaris for sure, but the scope will point
elsewhere. I assume that every amateur knows that the direction that a telescope
points to is not necessarily the direction that the mount points to. It is up to
you, the user, to align the two. Every basic book on astronomical instruments
will point this out.

Rolando


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[Non-text portions of this message have been removed]


Re: Help with orthogonality

Roland Christen
 

In a message dated 4/24/2007 1:01:09 PM Central Daylight Time,
lmarchesi@yahoo.com writes:


I had some significant time with my new mount (AP 1200) and the new
camera this past weekend (finally!). One thing that is more
challenging than I expected is polar alignment. I did the 'daytime
polar alignment' routine using a carpenter's level and the Moon. The
mount/pier were reasonably level as well. Then, when I do the 2-star
calibration I seem to be 'oscillating' back and forth in azimuth.
There is always some confusion as to what this 2 Star thing is supposed to
do. It is not a calibration routine. It does not calibrate anything in the
mount. It is simply one more of dozens of polar alignment routine options. This one
in particular can be hard to converge, especially if you happen to choose the
wrong two stars. As such, this polar alignment option is probably the weakest
of all. You should never conclude from this alignment routine that something
is amiss with your orthogonality. In fact, I am tempted to eliminate this
routine because of the confusion it seems to cause everyone who first uses this
mount after using other commercial Alt-Az mountings.

The best way to judge the orthogonality of your setup is to GoTo the same
star on both sides of the meridian. Choose a star near the zenith, then center it
on your crosshairs. Note the RA direction. Then choose the meridian delay
feature (1 hour delay either E or W) of the keypad to GoTo this same exact star
again on the other side of the mount. Note where the star ends up versus the RA
crosshair. Now you can see your orthogonality error - the error is exactly
1/2 of the distance from the crosshair and where your star ended up. Now you can
also see how much to shim the mounting ring, either front or back) to bring
the star 1/2 way to the crosshair. Once you have shimmed it, you can go back
and forth to the same star on either side of the meridian to do a final tweaking
if desired.

The other thing I want to point out is that with a normal refractor and
normally well machined rings, you will never have any orthogonal errors that are
too large. You should have very close GoTo accuracy if you are properly polar
aligned. If you do not wat to do accurate polar alignment, you can still do
precision GoTo by first picking a bright star in the area that you want to
observe, center it, press Rcal and then enter the faint object you wish to observe
and press GoTo. This way you can always find any object in your telescope field,
even if not polar aligned.

Rolando


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Re: Keypad problem ?

Roland Christen
 

In a message dated 4/23/2007 11:22:56 PM Central Daylight Time,
J.Zeglinski@rogers.com writes:


Your electronic friend was absolutely right about the "potential" keyboard
corrosion problem!
I think you are going overboard on this. This is the first time in 10 years
that a keypad has had this problem. Why make a mountain out of an Angstrom?

Rolando


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


DC power for 1200

Joe Morris <joemorris@...>
 

I'll be putting my 1200 GTO mount in a remote observatory that I plan
to power with 6 V golf cart batteries. This will give me the option
of applying either 12 V or 18 V to the mount. Recommendations?