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Hi Leo:
For question number 1, most mount manufacturers
give weight ratings in terms of the instrument load they can manage and you can
assume that the required counterbalance weights will also be handled OK. For
example, if the mount is rated at 22 lbs load, you can put 22 pounds of scope,
camera, etc on it, plus whatever counterbalance weights are needed, making a
total of well over 22 lbs.
For number 2 (meshing of the gears), it's a
bit hard to picture this without a diagram, but yes, if the GP-DX is like
most drives, the two gears should mesh as fully as possible to get maximum
surface contact between the teeth without causing binding. Depending on the
diameter of the large gear and the size of the teeth, you may have only a couple
of teeth on the two gears in contact or 6 or 8 teeth in contact. I assume it is
a worm gear arrangement? So you would want the shaft of the worm (the small,
spiral cut, faster-moving gear) to be in the same plane as the large gear and
precisely at right angles to the shaft of the large gear. Take all of this with
a grain of salt --- not having one of these mounts, I don't want to lead you
astray and it's possible that the designers of the GP-DX had some additional
tricks up their sleeves that I don't know about. The one thing that is very much
affected by the degree of contact between the worm and the large gear is the
backlash. Lots of tight contact reduces backlash but also increases binding, so
you have to compromise.
There is one statement in your note that sounds
strange and maybe I misunderstood: 'sliding
the wheel on to the RA "Decl. slow-motion control shaft" ' The
declination axis and controls should be completely independent of the RA axis
and controls. So you shouldn't be sliding any RA wheels onto any Decl
shafts.
Good luck!
Bert
----- Original Message -----
Sent: Monday, August 05, 2002 5:51
PM
Subject: Re: [APML] Setting up GP-DX
mount
At 15:40 05/08/02 -0700, you wrote:
The lighter the mount, the more important is good
balance. I assume the
GP-DX
is
relatively light weight.
Bert,It weighs ~36 lbs. and will hold
~22 lbs(10Kg),so i guess i will be investing in a counterweight. I also have a
roll of quite beefy lead "tape" which i think could make a good substitute,if
i can find a way to secure it to the "weight shaft".
Probably a dumb
question ...but does the max weight rating of a mount also include the
contribution of weight from a counterweight?
If your current setup permits the two screws to meet in
the middle,
you're
missing
the fixed, tripod-mounted peg or block, which should be
sticking up
between the two
screws.
Hope this helps....
Yes,thanks!! This explains why i have not
been able to understand the mechanism... It looks like part of the mount has
not been included... I can see from the diagrams/pics in the instruction
manual that there is another part at the base of the mount which i do not have
- everything is labeled in the diagram,with the name of the part EXEPT the
part at the base:) There is also no check-list of the parts which should be
included in the package so i can't see if the part is meant to be there or
not. I will ring Orion Optics and see if they can help!
I think i
should be ok now if i can get the missing part! Thanks again for the help
Bert,
Leo
PS. One further question if i may...
I attached
the drives earlier,but on the RA motor could not get the two gear weals to sit
exactly flush with each other...i was reluctant to apply any more force than i
had to for fear of breaking/bending something when i was sliding the weal on
to the RA "Decl. slow-motion control shaft" and the teeth on the drive shaft
already had about 3/4 of their surface area in contact with each other
...would this result in more tracking error? Should the teeth be meshing
"perfectly" together?
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