CounterWeight
Postmaster
Reged: 10/05/08
Loc: Cloudyopolis, OR.
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GEM mount noise...
#3100172 - 05/12/09 10:42 AM
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Hi,
If I wanted a mount in the 55lb weight range (imaging) or above, and noise was a dominant factor in choosing - what would you recommend? I know the obvious answer is a "push-to" but I am curious about the motor-driven (computer assisted or computer capable - including those with hand controllers)
Most of the GEM's I've been around, are very quiet while tracking - so I guess I am asking more about slewing noise. A friend said it may just be the difference in which ones use steppers and which ones use servos? I have been unsing a CGE (when the sky allows that is) and consider it a bit noisey - terrific in almost all ways possible (I think best out there for the $$), and the noise is not a problem. So I'm not asking as a replacement, but for keeping in mind for possible future purchase. I understand rating this is pretty subjective and 'relative' is fine.
Parallax?
Iott?
MCI?
Tak?
Los?
Celestron?
AP?
others?
Thanks 
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Chris Curran
scholastic sledgehammer
Reged: 06/14/05
Loc: Brandon, FL
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Re: GEM mount noise...
[Re: CounterWeight]
#3106145 - 05/15/09 07:21 AM
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I have a Tak EM-200 and an AP 1200 (and a 900 before that). Both are silent when tracking. When slewing they are also very quiet, but not silent. However, they are no where near as loud as all those coffee grinder's you will hear on the field either.
Just curious: Why do you care about slew noise? There are far better reasons for buying a premium mount...
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David Pavlich
Transmographied
Reged: 05/18/05
Loc: Mandeville, LA USA
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Re: GEM mount noise...
[Re: Chris Curran]
#3106908 - 05/15/09 03:13 PM
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The quietest slewing mount I've been around is the Orion Atlas. But it still is quite audible. The noisiest is the CG5-GT. However, that's at maximum slew speed. Slow it down a bit and it's not bad.
However, as Chris points out, there's a lot of good or bad reasons to buy or not to buy a specific mount. For the money, noisey or not, the CG5-GT is a very nice mount. If I were looking into a mount for that price, the CG5 would be high on my list. I wouldn't let the sound a mount makes be a deciding factor, especially considering that the slewing is a tiny fraction of the time spent observing. Even more so if you're imaging.
David
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Joe Cipriano
Entropy Personified
Reged: 09/03/05
Loc: Uh... anyone have a GPS?
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Re: GEM mount noise...
[Re: David Pavlich]
#3106922 - 05/15/09 03:26 PM
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There are also some easy solutions to mitigate noise on certain mounts. With my CGE, I removed the motor covers and placed small rubber o-rings over the screws, isolating the cover from the housing - went a ways towards reducing slew noise.
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David Pavlich
Transmographied
Reged: 05/18/05
Loc: Mandeville, LA USA
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Re: GEM mount noise...
[Re: Joe Cipriano]
#3107286 - 05/15/09 06:58 PM
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Yea, but you were on a first name basis with the innards of that mount. 
David
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Joe Cipriano
Entropy Personified
Reged: 09/03/05
Loc: Uh... anyone have a GPS?
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Re: GEM mount noise...
[Re: David Pavlich]
#3107440 - 05/15/09 08:55 PM
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Quote:
Yea, but you were on a first name basis with the innards of that mount.
David
Yeah - and?!?!?
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peregrineflier
professor emeritus
Reged: 09/14/08
Loc: Lost wages, Nevada (las Vegas...
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Re: GEM mount noise...
[Re: Joe Cipriano]
#3107451 - 05/15/09 09:01 PM
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"The noisiest is the CG5-GT."
I would put my LXD-55 mount up against it any day! Coyotes and dogs howl when I slew!
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CounterWeight
Postmaster
Reged: 10/05/08
Loc: Cloudyopolis, OR.
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Re: GEM mount noise...
[Re: peregrineflier]
#3107477 - 05/15/09 09:28 PM
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David you were pretty cozy with your CGE too I'm great friends with mine ! who for whatever reasons insists on being called 'George'.
No I'm not trying to do a noise bashing thing and as mentioned it is not a criteria for dumping one mount over another. I think the CG5-ASGT is an insane deal 'almost a crazy larry deal' at under $500 new which is what I paid for mine.
Was interested more in if servos noisier than steppers and stuff like that in the more heavy lifting region. Maybe I should have said 100lbs in my original post? Can we say 100 lbs? Last time I bought a mount the CGE was at the low price end of the medium lift, I see some pretty nice ones out there... that seem pretty competitively priced.
Like larger scopes, there aren't a lot of them out there as a proportion, and I don't imagine seeing any near me anytime soon. I don't imagine any are like having duty on the flight deck... but apprecite keeping it jovial.
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David Pavlich
Transmographied
Reged: 05/18/05
Loc: Mandeville, LA USA
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Re: GEM mount noise...
[Re: Joe Cipriano]
#3107592 - 05/15/09 10:54 PM
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Quote:
Quote:
Yea, but you were on a first name basis with the innards of that mount.
David
Yeah - and?!?!?
Word has it that you'd sit around it while eating a big slab of Giordano's deep dish pie. Now, I never paid any creedence to that rumor, but.... 
David
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David Pavlich
Transmographied
Reged: 05/18/05
Loc: Mandeville, LA USA
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Re: GEM mount noise...
[Re: peregrineflier]
#3107596 - 05/15/09 10:55 PM
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Quote:
"The noisiest is the CG5-GT."
I would put my LXD-55 mount up against it any day! Coyotes and dogs howl when I slew!
NOW I know why my ears were ringing the other night. 
David
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David Pavlich
Transmographied
Reged: 05/18/05
Loc: Mandeville, LA USA
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Re: GEM mount noise...
[Re: CounterWeight]
#3107611 - 05/15/09 11:05 PM
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Quote:
David you were pretty cozy with your CGE too I'm great friends with mine ! who for whatever reasons insists on being called 'George'.
No I'm not trying to do a noise bashing thing and as mentioned it is not a criteria for dumping one mount over another. I think the CG5-ASGT is an insane deal 'almost a crazy larry deal' at under $500 new which is what I paid for mine.
Was interested more in if servos noisier than steppers and stuff like that in the more heavy lifting region. Maybe I should have said 100lbs in my original post? Can we say 100 lbs? Last time I bought a mount the CGE was at the low price end of the medium lift, I see some pretty nice ones out there... that seem pretty competitively priced.
Like larger scopes, there aren't a lot of them out there as a proportion, and I don't imagine seeing any near me anytime soon. I don't imagine any are like having duty on the flight deck... but apprecite keeping it jovial.
I got it now. I just misunderstood the reason for the post. It is a good question. I know that the CGE would really tell you in no uncertain terms when it was out of balance, especially the Dec axis. Just whine like it was being beat with a stick!!
Of course, you now have the CGE Pro. I would wait until some of CN's own mount torturers give us some information. And there's the venerable Losmandy Titan. The next step, of course, is a big one up to the Paramount and AP1200 class. Or, perhaps, the smallest of the Chronos mounts, but it's in a different league mechanically speaking.
I guess we need to go to each site and see what kind of motors are used. I know whatever is in AP's mounts works pretty well. My MI250 is Gemini equipped and it works pretty well (I find the sound quite pleasing in a mechanical sort of way) and now the new 250 is rated at 85lbs. This is why I like the mount section so much. A gizmo guy's dream forum!!
David
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Chris Curran
scholastic sledgehammer
Reged: 06/14/05
Loc: Brandon, FL
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Re: GEM mount noise...
[Re: David Pavlich]
#3107719 - 05/16/09 12:16 AM
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CW,
Assuming you're somewhere close to balanced, those steppers/servos never have to "lift" 100lbs.
David,
AP and Tak both use servos.
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CounterWeight
Postmaster
Reged: 10/05/08
Loc: Cloudyopolis, OR.
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Re: GEM mount noise...
[Re: Chris Curran]
#3108294 - 05/16/09 10:34 AM
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Chris,
Absolutely... don't mean to describe them like a winch or launch vehicle , hope folks understand my meaning 'lift' = 'load rating'. (In a technical sense they are working with / against gravity though in the linear and transverse torque moment or arm needed to move any payload on a fulcrum point.) Lift isn't all that terrible a term. It's interesting trying to get numbers for mounts wrt 'payload', I appreciate the difficulty and language AP and others use to try and characterize it. It's very much a YMMV /YMWV 'depending' arena. Lots of ways to try and talk about it.
Load capacity
Load capacity for imaging
Load capacity including counterweights
In my work over the years I've seen and worked with both types of systems and their control loops / systems used in industrial robotics and military applications... Often 'excessive' noise was an indication of loss of efficiency, or exceeding design limits. Like David describes the unbalanced CGE - it can also provide valuable audible feedback. So I don't know if I'd want an absolutely silent mount... if one existed.
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Luigi
Postmaster
Reged: 07/03/07
Loc: MA
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Re: GEM mount noise...
[Re: CounterWeight]
#3108700 - 05/16/09 01:51 PM
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>>>Often 'excessive' noise was an indication of loss of efficiency, or exceeding design limits.<<<
In this case, it's most often inexpensive spur gears running at high speed.
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Chris Curran
scholastic sledgehammer
Reged: 06/14/05
Loc: Brandon, FL
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Re: GEM mount noise...
[Re: Luigi]
#3109687 - 05/17/09 12:19 AM
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hope folks understand my meaning 'lift' = 'load rating'.
Nope. When in Rome...
It's very much a YMMV /YMWV 'depending' arena. Lots of ways to try and talk about it.
Not really. You have visual and imaging capacity. What you need to find out is how the vendor specifies capacity: visual or imaging? If the vendor specifies visual load, cut in in half for the usable imaging load. If the vendor specifies imaging load, double it for visual load.
Counterweights are included in the capacity ratings.
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Luigi
Postmaster
Reged: 07/03/07
Loc: MA
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Re: GEM mount noise...
[Re: Chris Curran]
#3110027 - 05/17/09 08:10 AM
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Without a useful quantitative measure of performance, load rating is pretty meaningless. What one observer/manufacturer might consider adequately solid, another might consider hopelessly wobbly. And as we all know, it's just not weight but moment of inertia and wind loading that matter too. Anyway, regardless of "load rating", a properly balanced rig driven at tracking and guiding rates should load its drive mechanism well below its limit, which is based on being able to withstand reasonable pushing and pulling on the scope when changing accessories and slewing at high speed. I haven't heard of anybody breaking the drives on their mount in regular use. If its way out of balance you might stall the mount. You can try this: With the mount moving, either tracking or slewing, try gently helping it and hindering it to see if it makes difference in the noise.
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Chris Curran
scholastic sledgehammer
Reged: 06/14/05
Loc: Brandon, FL
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Re: GEM mount noise...
[Re: Luigi]
#3110057 - 05/17/09 08:35 AM
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What one observer/manufacturer might consider adequately solid, another might consider hopelessly wobbly.
Perhaps. Every vendor I know of that sells "imaging" mounts understate their capacity. Every vendor I know of that sells "visual" mounts overstates their capacity. I think we already know who are the vendors that overstate capacities... at least most of us do.
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CounterWeight
Postmaster
Reged: 10/05/08
Loc: Cloudyopolis, OR.
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Re: GEM mount noise...
[Re: Chris Curran]
#3110529 - 05/17/09 01:22 PM
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Chris,
I didn't start the thread to dicker about terminology regarding 'lift' or 'rated loads' and etc.
I started it to discuss noise. If you need to school me on physics or terminology, send me a PM (or better we can start another thread about it as I think it is interesting) and lets try and keep my thread on topic please? I explained I think clearly enough - you disagree, fine, let's move on. Thank you.
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Chris Curran
scholastic sledgehammer
Reged: 06/14/05
Loc: Brandon, FL
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Re: GEM mount noise...
[Re: CounterWeight]
#3110596 - 05/17/09 01:54 PM
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Dude - have a Coke and a smile. I'm not debating anything and I'm not trying to school you on anything. Just never mind...
Quote:
Chris,
I didn't start the thread to dicker about terminology regarding 'lift' or 'rated loads' and etc.
I started it to discuss noise. If you need to school me on physics or terminology, send me a PM (or better we can start another thread about it as I think it is interesting) and lets try and keep my thread on topic please? I explained I think clearly enough - you disagree, fine, let's move on. Thank you.
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