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Safely installing a heavy OTA onto an AP900

Joe Zeglinski
 

Hi,

I recently received my AP900 and had a look at the DOVEM2 dovetail plate
for my existing Losmandy DSUB adapter on a 25 lb. Questar-7 OTA.

The AP dovetail doesn't quite mate the same way. The Losmandy has two
closely fitted V-grooves, into which the OTA's DSUB just slides down, and is
locked in place with one knob. The AP900 DOVEM2 has only one V-groove, and a
much wider, by about 3/16" channel, with a straight, non-grooved wall on the
other side - the two lock knobs act as both the other "channel" and the locks,
for the DSUB plate.

My "queasiness" is handling the heavy MAK OTA to get it locked safely into
the groove. I guess I would have felt safer if the plate was initially mated
"in both notched channels" as on the Losmandy mount. However, the DOVEM2 is
very well designed for a variety of OTA plates, and even balance point
offsets.

So, how do you owners of C9 and similar OTA's used with Losmandy mounts,
do the attachment now on your AP mounts?

Assuming, of course, the mount is positioned and locked in the CWD (counter
weights down) position:

1.. Do you preset the DOVEM2 knobs so they are very close to the width of
the DSUB, and similarly slide the OTA down the channel vertically (as on a
G11, for example), before lock in? Or ...

2.. Do you set the DOVEM2 knobs wide open, and "clip in" the OTA with DSUB
sideways, then tighten the knobs?

Which approach is safer, while precariously standing on snow?

The latter approach seems a bit more hazardous than doing the longitudinal
vertical OTA slide. It's just that using the two DOVEM2 bolt tips as a
substitute V-groove slide, seems prone to jamming the DSUB plate on the way
down.

It sure would be nice if at least, some of the AP documentation showed
"hefty OTA's" actually being installed, on portable mounts, instead of the
lighter refractors, or the large OTA's already pictured in observatories.
But I suppose those are AP refractors. Perhaps AP could show some shots of how
to "handle" their AP MAK in this situation - that would be instructive for us
who already have an investment in good SCT's and MAK's, and just want to
safely use our AP mounts, while perhaps avoiding wrenching our backs in the
exercise.

Opinions please.
Joe
Mal Speer <mal@...>
 

AP and Cassidy both make newer upgraded saddles with a much better
locking system using two large knobs. The reason for only a dovetail
on one side is that that is a tip in saddle. You don't have to slide
a heavy scope in from the end, just tip the scope into the dovetail
drop it down and lock it in.
Mal


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

Hi,

I recently received my AP900 and had a look at the DOVEM2
dovetail plate
for my existing Losmandy DSUB adapter on a 25 lb. Questar-7 OTA.

The AP dovetail doesn't quite mate the same way. The Losmandy
has two
closely fitted V-grooves, into which the OTA's DSUB just slides
down, and is
locked in place with one knob. The AP900 DOVEM2 has only one V-
groove, and a
much wider, by about 3/16" channel, with a straight, non-grooved
wall on the
other side - the two lock knobs act as both the other "channel" and
the locks,
for the DSUB plate.

My "queasiness" is handling the heavy MAK OTA to get it locked
safely into
the groove. I guess I would have felt safer if the plate was
initially mated
"in both notched channels" as on the Losmandy mount. However, the
DOVEM2 is
very well designed for a variety of OTA plates, and even balance
point
offsets.

So, how do you owners of C9 and similar OTA's used with
Losmandy mounts,
do the attachment now on your AP mounts?

Assuming, of course, the mount is positioned and locked in the CWD
(counter
weights down) position:

1.. Do you preset the DOVEM2 knobs so they are very close to the
width of
the DSUB, and similarly slide the OTA down the channel vertically
(as on a
G11, for example), before lock in? Or ...

2.. Do you set the DOVEM2 knobs wide open, and "clip in" the OTA
with DSUB
sideways, then tighten the knobs?

Which approach is safer, while precariously standing on snow?

The latter approach seems a bit more hazardous than doing the
longitudinal
vertical OTA slide. It's just that using the two DOVEM2 bolt tips
as a
substitute V-groove slide, seems prone to jamming the DSUB plate on
the way
down.

It sure would be nice if at least, some of the AP documentation
showed
"hefty OTA's" actually being installed, on portable mounts, instead
of the
lighter refractors, or the large OTA's already pictured in
observatories.
But I suppose those are AP refractors. Perhaps AP could show some
shots of how
to "handle" their AP MAK in this situation - that would be
instructive for us
who already have an investment in good SCT's and MAK's, and just
want to
safely use our AP mounts, while perhaps avoiding wrenching our
backs in the
exercise.

Opinions please.
Joe


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

Hi Mal,

Thanks for the info,

I went through the AP accessory list, and came across Roland's
justification, as you describe. The DOVEM2 is a nice design because as you
say - simply set the dovetail horizontal and flip the matching plate into it's
bottom edge, lock the knobs. However, I think there is also a "design flaw"
in the manufacture.

O.K. - please forgive this bravado, from a total newbie, however, I have
just attached the DOVEM2 dovetail and noticed what seems a bit of a problem -
not a deal breaker, but certainly an inconvenience.

I attached the DOVEM2 with the "offset hole pattern", such that it sits
higher up on the face of the DEC end face, so that the approx. one inch of
excess moment will be "towards the front of the MAK/SCT OTA (which is mirror
end heavy). If I were to flip the DOVEM2 around 180 degrees, the off centre
hole patter, would be towards the back of an SCT,, making the mirror end
moment even worse, and thus decreasing the adjustment range of the mating
plate, before it slips out of the bottom end, lock knob. I know, it could be
moved to a centre hole, but that would make the DOVEM2 effectively half
length, and the OTA "rocky".

I hope I am being clear, so far. Surely, those with SCT's must be aware of
this situation.
Please bear with me.

The bad news, if the DOVEM2 is bolted in, high up, as I started to
describe, and you then set it horizontal in preparation to receive your SCT
and plate, the lock knobs are now along the bottom edge. Also, the bottom
V-groove where you will drop the plate into for first contact is actually a
shallow, milled down channel (not a full notch, like the other side). So
basically, the SCT's mating plate edge is initially resting on just two
points - the two brass locking pins. As you then tip the horizontal SCT up, to
be fully inside the DOVEM2 channels, you must now screw the two locking knobs
"upward" against the entire weight of the SCT.
Note: I am intentionally not talking about a "refractor", here. This is an
awkward way of installing a mirror end heavy SCT or a MAK like a Questar-7,
correct?

The only other way to make this still viable, is to rotate the DOVEM2
"counter clockwise" instead, so that the knobs will be along the top, and you
will dip the SCT plate into the other, FULL V-groove, which now is along the
bottom edge. This is almost perfect, since after you tip the SCT into the
DOVEM2 surface, the lock knobs are loose, and can easily be screwed downward,
into a full lock, while the SCT's dovetail plate fully occupies the full
V-groove.

Perfect ... right?

Not quite. The problem in making this compromise - rotating the high
bolted DOVEM2 counter clockwise, is that you first have to remove your very
heavy SCT (C9) or a MAK (like my Q7), from the transport case, and flip it
around "hand over hand" (end to end), so it is facing now LEFT.

Problem is - my Q7 sits in it's case "facing right", and I suspect that
all telescopes, are placed in their travel cases with the objective or
corrector lens facing to the RIGHT. The alternative, to avoid hand over hand
flipping of a heavy scope, is to bend over from behind and over, the case lid,
and lift it out that way, backwards - back killer!

The solution:
Roland should have drilled a third "4-hole pattern", in the opposite
direction, relative to DOVEM2 centre. That way, everything I have meticulously
described above, will work correctly, with the lock knobs at the top, and the
SCT lifted from it's case, facing to the right, as you install it, and the
DOVEM2 dovetail will no longer be back end heavy, giving you more room to
shift the SCT balance in the saddle. We can't sacrifice any loss of adjustment
position for SCT's, because there will also be heavy eyepieces, and possibly
cameras, making things even worse for loss of adjustment range.

Looks like I am going to need a machine shop to drill 4 more holes in the
standard DOVEM2, for use with SCT's and MAK's.

I think that Roland may have chosen the "current direction" for the offset
hole pattern, is because he was thinking of AP "refractors", which are lens
end, forward heavy, and the DOVEM2 being eyepiece end heavy, provided more
latitude for adjusting a refractor's balance point.

As I said - I may be WAY OFF on this, since I haven't had my AP900 fully
configured, but at this point, the DOVEM2 seems not to be particularly made
very well for it. Certainly, it makes mounting an SCT inconvenient.

Fortunately, this can be easily remedied on future DOVEM2 production, by
simply drilling one more 4-hole mount pattern, on the opposite side of centre.

Perhaps, you or someone else in the group can explain if I am totally
mistaken. Your experience with the DOVEM2 will be much better than mine.
Certainly, after an evening of playing with the DOVEM2, to see how it will
seat itself on the end of the DEC axis, and how I would lift up my heavy MAK
OTA, I can see no easy procedure.

Please comment, and save me a trip to a machine shop. I hope I have explained
myself fairly clearly, above. Sorry for such a long post.

Thanks,
Joe

----- Original Message -----
From: "Mal Speer" <mal@malcoprecision.com>
To: <ap-gto@yahoogroups.com>
Sent: Friday, April 13, 2007 10:02 PM
Subject: [ap-gto] Re: Safely installing a heavy OTA onto an AP900


AP and Cassidy both make newer upgraded saddles with a much better
locking system using two large knobs. The reason for only a dovetail
on one side is that that is a tip in saddle. You don't have to slide
a heavy scope in from the end, just tip the scope into the dovetail
drop it down and lock it in.
Mal
blandp11
 

I have an AP 900GTO mount on the 54" pier and use it (mostly) with my
TEC APO180FL refractor. The 180FL weighs in at 36.5lbs. I first put
the rings on the mount without the scope in the rings with the rings
open. I then carefully place the OTA in the rings, and close the
rings one handed one at a time with the other hand on the OTA, just in
case. Works well for me.

This OTA is the limit of what I would want to comfortably lift alone,
but it is not hard to do. My 160EDF at 28lbs was, by comparison,
easier to manage. The difference is that with the 180FL I have to be
thinking about nothing but putting the OTA on the mount, while the
160EDF didn't require ones "full" attention to do the same.


Philip
Joe Zeglinski
 

Hi,

Just got my "modified" DOVELM2 saddle back from a local machine shop, and
the original design oversight, is now very nicely resolved.

I had the original "4-hole bolt pattern" for the AP900 duplicated (mirror
imaged) on the opposite side of saddle centre. Now the OTA can be safely
clipped in place, with the "lock down knobs" along the top of the saddle.

As I had reported previously, the problem begins with how your OTA sits in
it's foam padded field case. It seems that most cases - from the manufacturer,
or a supplier like JMI - usually have the eyepiece draw tube on your "right
hand side", as you face the open case. When you lift it up, it is already
oriented to clip into the saddle correctly.

However, a brief search has shown that this is NOT always true - there are
field cases where the eyepiece end is on "your left hand side", as you lift.
This makes it impossible to drop the OTA into the DOVELM2 groove directly,
with the knobs at the top, V-groove on the bottom - because of the DIRECTION
of offset in the bolt pattern.

You are faced with one of the following options:

(1) Put the OTA down on the ground (snow, dirt, etc.), walk around it to
reverse hand directions, before picking it up again.

(2) Or, flip it over end-over-end, in the case. You will do the same as you
dismount the OTA, slippery with dew, at the end of the session, when packing
it back into the case.

(3) Or, continue to use the unmodified saddle, and be forced to tighten the
knobs, "upward", against the weight of the OTA, since in that orientation, it
will always drop into the notches in the knob pins "along the bottom". That is
also a rocky, initial 2-point contact.

I have a Questar-7 OTA, which sits in it's foam lined case, as I
described, eyepiece end "at the left hand" - and this situation was
unsatisfactory. It is not only unwieldy, but you also LOSE a couple of inches
of plate adjustment range, because the saddle ends up shifted below DEC axle
centre if you use the "unmodified" DOVELM2. There is also nearly 2 inches of
saddle, overhang weight at the eyepiece end, in this situation, which you
don't want since you will already be bottom end heavy with cameras etc. Thus
OTA centering is affected in two ways.

Now, with the duplicated bolted pattern, the DOVELM2 can be used correctly
for ALL OTA field case designs - left or right handed.

Some may say that this is a picky point, but I disagree. I think there
should be as standard, TWO bolt patterns - one shift left and the other
shifted right of the DOVELM2 centre line.
I suppose this might also apply to other saddles.

Roland, I recommend you consider this on future production runs of the
DOVELM2, and perhaps offer the mod on present stock, depending on which
orientation (eyepiece on left or right hand side) the user's field case comes
in. When you designed the offset approach, you could not have possibly
realized the potential conflicts with OTA case designs, out there.
The "offset bolt pattern" was a good idea - just wasn't fully implemented.

Joe

----- Original Message -----
From: "Joseph Zeglinski" <J.Zeglinski@rogers.com>
To: <ap-gto@yahoogroups.com>
Sent: Saturday, April 14, 2007 12:00 AM
Subject: [ap-gto] Re: Safely installing a heavy OTA onto an AP900


Hi Mal,

Thanks for the info,

I went through the AP accessory list, and came across Roland's
justification, as you describe. The DOVEM2 is a nice design because as you
say - simply set the dovetail horizontal and flip the matching plate into
it's bottom edge, lock the knobs. However, I think there is also a "design
flaw" in the manufacture.

O.K. - please forgive this bravado, from a total newbie, however, I have
just attached the DOVEM2 dovetail and noticed what seems a bit of a
problem - not a deal breaker, but certainly an inconvenience.

I attached the DOVEM2 with the "offset hole pattern", such that it sits
higher up on the face of the DEC end face, so that the approx. one inch of
excess moment will be "towards the front of the MAK/SCT OTA (which is mirror
end heavy). If I were to flip the DOVEM2 around 180 degrees, the off centre
hole patter, would be towards the back of an SCT,, making the mirror end
moment even worse, and thus decreasing the adjustment range of the mating
plate, before it slips out of the bottom end, lock knob. I know, it could be
moved to a centre hole, but that would make the DOVEM2 effectively half
length, and the OTA "rocky".

I hope I am being clear, so far. Surely, those with SCT's must be aware
of this situation.
Please bear with me.

The bad news, if the DOVEM2 is bolted in, high up, as I started to
describe, and you then set it horizontal in preparation to receive your SCT
and plate, the lock knobs are now along the bottom edge. Also, the bottom
V-groove where you will drop the plate into for first contact is actually a
shallow, milled down channel (not a full notch, like the other side). So
basically, the SCT's mating plate edge is initially resting on just two
points - the two brass locking pins. As you then tip the horizontal SCT up,
to be fully inside the DOVEM2 channels, you must now screw the two locking
knobs "upward" against the entire weight of the SCT.
Note: I am intentionally not talking about a "refractor", here. This is an
awkward way of installing a mirror end heavy SCT or a MAK like a Questar-7,
correct?

The only other way to make this still viable, is to rotate the DOVEM2
"counter clockwise" instead, so that the knobs will be along the top, and
you will dip the SCT plate into the other, FULL V-groove, which now is
along the bottom edge. This is almost perfect, since after you tip the SCT
into the DOVEM2 surface, the lock knobs are loose, and can easily be screwed
downward, into a full lock, while the SCT's dovetail plate fully occupies
the full V-groove.

Perfect ... right?

Not quite. The problem in making this compromise - rotating the high
bolted DOVEM2 counter clockwise, is that you first have to remove your very
heavy SCT (C9) or a MAK (like my Q7), from the transport case, and flip it
around "hand over hand" (end to end), so it is facing now LEFT.

Problem is - my Q7 sits in it's case "facing right", and I suspect that
all telescopes, are placed in their travel cases with the objective or
corrector lens facing to the RIGHT. The alternative, to avoid hand over hand
flipping of a heavy scope, is to bend over from behind and over, the case
lid, and lift it out that way, backwards - back killer!

The solution:
Roland should have drilled a third "4-hole pattern", in the opposite
direction, relative to DOVEM2 centre. That way, everything I have
meticulously described above, will work correctly, with the lock knobs at
the top, and the SCT lifted from it's case, facing to the right, as you
install it, and the DOVEM2 dovetail will no longer be back end heavy, giving
you more room to shift the SCT balance in the saddle. We can't sacrifice any
loss of adjustment position for SCT's, because there will also be heavy
eyepieces, and possibly cameras, making things even worse for loss of
adjustment range.

Looks like I am going to need a machine shop to drill 4 more holes in the
standard DOVEM2, for use with SCT's and MAK's.

I think that Roland may have chosen the "current direction" for the
offset hole pattern, is because he was thinking of AP "refractors", which
are lens end, forward heavy, and the DOVEM2 being eyepiece end heavy,
provided more latitude for adjusting a refractor's balance point.

As I said - I may be WAY OFF on this, since I haven't had my AP900 fully
configured, but at this point, the DOVEM2 seems not to be particularly made
very well for it. Certainly, it makes mounting an SCT inconvenient.

Fortunately, this can be easily remedied on future DOVEM2 production, by
simply drilling one more 4-hole mount pattern, on the opposite side of
centre.

Perhaps, you or someone else in the group can explain if I am totally
mistaken. Your experience with the DOVEM2 will be much better than mine.
Certainly, after an evening of playing with the DOVEM2, to see how it will
seat itself on the end of the DEC axis, and how I would lift up my heavy MAK
OTA, I can see no easy procedure.

Please comment, and save me a trip to a machine shop. I hope I have
explained myself fairly clearly, above. Sorry for such a long post.

Thanks,
Joe

----- Original Message -----
From: "Mal Speer" <mal@malcoprecision.com>
To: <ap-gto@yahoogroups.com>
Sent: Friday, April 13, 2007 10:02 PM
Subject: [ap-gto] Re: Safely installing a heavy OTA onto an AP900


AP and Cassidy both make newer upgraded saddles with a much better
locking system using two large knobs. The reason for only a dovetail
on one side is that that is a tip in saddle. You don't have to slide
a heavy scope in from the end, just tip the scope into the dovetail
drop it down and lock it in.
Mal





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