Is CG-5 mount a Vixen GP?
Sydney Corp.
Great Polaris (Vixen) sold by Orion. But the Celestron generally sells
for about $ 250 less ($450 vs. $699). Does anyone know the difference
between these two? How does Celestron's dual-axis drives compare to the
Orion? Thanks.
Phillip Hosey
Sydney Corp. wrote in message <36EB0AE5...@albany.net>...
I had this mount, for about a week. From many I have heard that it is an
exact copy of the Vixen, but there were a few minor differences, mostly in
the type of lubricant that was used on it. I had no problems with the mount
other than it was a little stiff due to the type of grease that was used on
it. I did have a problem with the dual axis drive that came with mine. I
had considerable difficulty in getting it to stay together - the gears that
attatched to the motor and the axes on the mount were held in place by small
set screws that were difficult to tighten to the required tightness to hold
them on, so I wound up super-gluing them on. My drive did not track very
well and there was alot of backlash when changing directions. My mount also
came with the wrong RA setting circle installed. (It was for Southern
hemisphere.) The CG-5 mount I had came with the Celestron G8. I finally
got tired of messing with it and sent it back and got the Celestar Deluxe
instead. All I can say is that there was definitly a BIG difference in the
drive system, the Celestar Deluxe is SO much better. I don't know how
Orion's drives are compared the the ones that came with the CG-5, but I
can't imagine anything being much worse. If I were going to use a CG-5
mount, I would try to get a better set of drives than the ones Celestron had
made for the CG-5. Celestron tech support told me that any drive system
made for the Vixen GP would work with the CG-5.
Phillip Hosey
LaGrange, GA
hel...@nospam.charter.net
(remove 'nospam' to reply)
Auburn Astronomical Society
http://www.mindspring.com/~rwhigham/
Thomas A Davis
Orion dual axis drives are produced by Vixen as well. The are much
more robust than the Celestron drives which are not of the same
quality as the Vixen motor drives. The Vixen motors should work
on the CG5 mount without a problem, and I would recommend them
strongly over the Celestron drives.
Thanks, Tom Davis
Greg Thomas
don't know if this is the case with all of these mounts but although they
may be the same as a Vixen GP, I would put them in the catagory of a
simi-finished kit. (Some have reported here that the allen wrenches that
came with the mount were undersized. Mine were oversized. In point of
fact, although it came with wrenches, a screwdriver, etc., I found no use
for most of the supplied tools and used my own.
I read on this ng a statement by someone that his drives sounded happy.
Mine did not and were very selective of when they would choose to work. I
had cleaned up the burrs, loose plastic, etc. associated with the motor
drive gears. I also had filed a flat for the set screws on the motor
shafts. With the right file, you can make these flats looked like they were
machined by precision equipment. The mount seemed smooth enough when hand
operated. However, when I took it apart, I found numerous metal fillings in
the hard to get to places. Some of them were embeded in the plastic washers
used to reduce friction. The grease, contrary to what I've read here,
seemed adaquate and if I could have found some, I would have considered
using it. In the end, I selected a synthetic grease used for disk brake
metal to metal surfaces.
There were numerous internal surfaces in the mount that I smoothed down with
an Arkansas stone and crocus cloth. The part that took me perhaps 16 hours
to solve was the discovery that I was originally correct in my association
of which parts I took out of what pieces and wrong in thinking otherwise.
I kept trying and measuring and finding I just couldn't get it to fit right
even though everything would work. It turned out that the greared sleeve
for the declination axis was about 3/16 inch too short for it's bearing
surface. I could not believe that such an error could have been made on
what appears to be a well thought out mount. Since I had no other simple
choices I smoothed out the unmachined surfaces, packed it full of grease and
put it back together. The missing bearing surface support is at the far end
of the sleeve and away from the higher pressure surface associated
immeadiatly with the gear.
I might also mention that although many parts look similar, they are not.
The sleeves are different sizes, screws are different lengths, etc. Also,
keep track of the small plastic disks under the axis locks. I lost one and
had to machine a new one out of brass stock.
Now that its finished, I can turn the gear shaft with my thumb and index
finger without using the knob. Really very very smooth. My motors are
happy and the tracking is steady and reliable. As I have read reported here
and there, it takes about 10 to 12 seconds to take up all the backlash in
the gears if changing directions. I have gone from thinking this mount and
motors were pieces of junk to being very happy with how they are working
now. My guess is that the Vixen GP mount and motor is a completely finished
and tuned setup. Having to do the final work to make the CG-5 work to its
potential probably accounts for the substancial difference in price. I am
speculating though because I have only used one CG-5 mount and seen only
pictures of the GP.
Greg Thomas
Glendora, CA
PI3P1415
Hillier, Bob (EXCHANGE:QUAL:7S01)
the GP-5 mount. I have recently ordered a clock drive motors for my GP-5
and I am expecting I will be cleaning up my mount's internals.
Regarding the grease that you selected to use.... could you give me a
bit
more detail/description about what it is? How does it work in cold
weather?
I live in Canada and attempt to do my observing after 10PM if its not
too
cold. I managed to endure -29 (-20F) for about an hour and a half one
evening
and found my mount very stiff to use. There is no way a clock drive
would have
worked that night. (Excellent seeing but way too cold!
Future, winter expiditions will occur only when the temperature is above
-15 (+5F). Do you have any knowledge of how well your selected grease
would
perform at this temperature?
Is there another type of grease that would perform well at this
temperature
(and at higher temperatures)?
Any assistance/advivce is appreciated.
Bob
"A hundred years from now it will not matter what my
bank account was, the sort of house I lived in, or the
kind of car I drove... But the world may be different
because I was important in the life of a child."
Harry Pulley
> Regarding the grease that you selected to use.... could you give me a
> bit
> more detail/description about what it is? How does it work in cold
> weather?
I am not the original poster but I thought I'd reply. I live in Canada
too and found the grease in my Vixen GP mount to be terrible at low
temperatures. I actually broke a gear in my drive's stepdown box!
Before having a machinist friend fix the gear, I went to Canadian Tire
and bought a whole grease gun sized tube (couldn't find anything
smaller) of lithium snowmobile grease for $4.95. I removed the old
grease with varsol and put the new grease on, carefully lapping through
the gears while removing backlash but not introducing binding spots
afterward. I did this to both the mount's gears, worms and sleeves, and
the gears in the stepdown box. I can now observe at -25C with no ill
effects on the mount or drive at all. Colder than that and I'm too cold
to be out for long. It is also much easier to balance the mount now, as
it moves freely enough to know when it is out of whack.
Lithium grease also performs well at fairly high temperatures, certainly
fine up to any nighttime temperatures found on earth.
--
<:-{} Harry C. Pulley, IV
\ member RASC Hamilton/KW centres, ALPO, IOTA, TPS
mailto:hpu...@home.com http://members.home.com/hpulley
Guelph, Ontario, Canada, 43.51N, 80.28W
Greg Thomas
here is some additional info I've written through email:
<Greg Thomas wrote>
I used Sta-Lube Brake Caliper Synthetic Grease. I also looked at a
Valvoline synthetic grease. The Valvoline was in a tube for a grease gun
and had a temperature rating from 550 to -40 as I recall. I
chose the Sta-Lube because it was in a smaller tube with a replaceable cap
and appeared to be blacker. Both greases noted that they contained
molybdenum disulfide which is black. I had just read an article in
The American Rifleman (yes, I'm an NRA member) about some test they had done
for moly coated bullets. It was quite impressive for its ability to stick
to the rifle bore and prevent contamination build up. It also appears that
the maintenance department at work uses moly for hi voltage electrical
disconnect switches. I talked to one of the field people who was very
impressed with moly's ability to provide molecular level friction
lubrication.
I've used synthetic motor oils and fluids for perhaps 20 years. They are
noted for their ability to maintain lubrication in cold climates, sticking
to metal parts when normal oils will run off, and for their ability to
maintain suspension properties under heat for ridiculously long times. It
is not uncommon for me to go 20 to 25,000 miles between oil changes and
still get 170 to 250,000 mile engine life.
As a final few words, I've seen several responses from people in cold
climates who recommend snowmobile grease. I suspect that the best
snowmobile greases are synthetic. If you get any synthetic grease I think
you will do fine. However, my CG-5 mount needed more than grease.
Smoothing out burrs and rough millings, careful adjustment of the worm
gears, and general attention to detail is just as important as the grease.
As an after thought, I might ought to describe the spanner tool I made to
remove the threaded rings holding the RA and dec. shafts in. They looked
something like this: [_]. Through the flanged ends, I drilled
a hole and then used the same hole for the drill bit to function as my pin.
For the other side I used the next sized drill bit. You'll need two of
these or a similar tool to loosen and finally tighten these rings. Watch
out for the allen set screws before you try loosening them.
Somebody wrote:
> Many thanks for the comments Greg.
>
> This is possibly a silly question (and probably hard to answer) but...
>
> I'm not experienced in reassembling mechanical equipment and am
> uncertain how much grease to apply. My previous experience is with
> small equipment where I needed a surface coat of lubricant as opposed
> to a liberal "slathering". For example... I would think rifle bullets
would
> have a surface coat only but the rifle bolt (???) may likely have more.
> (Maybe this is a bad example.... I have little experience with rifles. :(
> )
>
> How much grease do I apply? Should I slather it on and wipe away
> any that spills over or oozes out? ...or do I use a thin surface coat?
> ...or is the answer dependent on different parts of the mount?
>
> Thanks for the comment on making the special ratchet for removing
> the RA and Dec. retaining ring. I checked and these rings have ratchet
> holes already embedded.
>
<Greg Thomas wrote>
I packed the worm and the ring gear (i.e. slather it on). I first put it on
and then spread it and pressed it into recesses with my finger tip. Its a
messy job! I used kleenex and a paper towel to wipe my hands off
periodically but kept the paper away from the gears. Usually no more than 1
paper towel and 3 Kleenexes per 2 hour session. I also set a large heavy
paper under my work area (i.e. kitchen table). After the worm and the ring
were put together and adjusted, I lapped them (run the gear round and round
until you've gone all the way around). If you're careful when you slather
you get a smaller amount of grease squeezed out. The important thing, in my
mind, is to get as much grease in there that stays in there. That is why I
carefully press it in with my finger before I put the gears together.
Other greased surfaces are any type of metal to metal contact. In
particular, I made sure that each side of the plastic washers had grease on
them before I put them on the shafts. Any inside bearing surfaces were also
checked that I had a coat of grease on them. The idea here is to have an
thin even coat of grease on these surfaces after they are lapped. For
example, I generally put small dabs of grease evenly spaced round the
plastic washer and then observed that it was evenly distributed after it was
rotated in position. This is where the honing with a stone and/or crocus
cloth on metal surfaces, along with the synthetic grease pays off.
A little story might help regarding grease. The first time I packed wheel
bearings I was surprised at the process because it seemed so dirty. It
wasn't - but it was greasy. In fact it should be very clean - but greasy.
You have a can of grease and you scoop up a handful in one hand. Then you
take the wheel
bearing and slide it into the grease squeezing the grease between your hand
and the bearing. You are pressing the grease into every nook and cranny
between the ball or roller bearings and the bearing race. I was amazed at
how much grease disappeared in that bearing. By the time I was done I found
I needed
several scoops of grease before it wouldn't take any more. To the
uninitiated, it might appear that the grease is just slathered on. If you
slathered rather pressed, you'd use a fraction of the grease and get less
benefit from the grease.
The silver colored ring gears have the gear on one end only. This is the
only place I greased. (I could have greased the bearing surfaces on the
interior of the ring but I greased the shaft that fit inside instead.)
Inadvertently I got grease on parts of the ring gear I did not intend to
grease. Especially where the RA & Dec. lock rides. This I wiped off with a
Kleenex being careful not to get too close to the gears. I was concerned
about not getting tiny pieces of paper mixed in with the grease. Excess
grease after the gears were lapped was removed by finger.
Regarding the holes you referred to as a ratchet. It is not. Picture a
squat cylindrical ring with threads on the inside of the ring. (Just like a
round nut with no wrench flats.) Then drill a hole on the sides of the ring,
but not all the way through, and 180 degrees apart. This is what you have to
unscrew (after you loosen the allen head set screws hidden in the face of
the ring).
One last word. I used diesel oil (i.e. the fuel they burn in the big
trucks) to clean everything up before I started the reassembly process. It
has some minor lubricating and corrosion resistant properties by itself.
Hope this helps. Maybe I should put all this together in a post to the saa
ng.
Greg Thomas
Glendora, CA
Hillier, Bob (EXCHANGE:QUAL:7S01)
In defense of my mechanical ignorance, I got into hi-tech
to keep my hands clean. Now I find myself a hobby (which would
seem to be a clean hands hobby) where I'm getting full of grease!
I'll tell you now... my wife just loves this!
Bob :)