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Is 40 lbs. too much for an Atlas EQ-G?

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#1 Yedgy

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Posted 13 July 2009 - 06:20 PM

Assuming a carefully balanced SBS setup with a relatively short moment arm (FSQ106EDX and a guidescope), is 40 pounds (total of 2 scopes, rings, plates, cameras, etc.) too much for an Atlas? :help: In case it matters, the Atlas will be mounted on a transportable pier, not on the usual tripod.

Thanks!
Tony

#2 gillmj24

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Posted 13 July 2009 - 08:53 PM

If you want sub arc second photographic resolution my gut tells me no but it might work OK for visual. Though if you are using a FSQ strictly for visual..... :smirk:

I was a little uneasy putting a single Meade 10" R tube on the Atlas and I think its weight is quoted at 32 pounds (though I had two losmandy dovetails, and of course a diag and an eyepiece making it closer to 40)

#3 jrcrilly

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Posted 13 July 2009 - 08:59 PM

If you want sub arc second photographic resolution my gut tells me no but it might work OK for visual.


It'll require very small pixels to get down to an arcsecond with an FSQ. Even my ST-10 (with 6.8 micron pixels) operates at nearly 3 arcseconds/pixel.

#4 gillmj24

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Posted 13 July 2009 - 09:26 PM

I was trying to make a point :)

#5 jrcrilly

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Posted 13 July 2009 - 09:35 PM

I was trying to make a point :)


Hi, Joe! ;)

I didn't mean to appear argumentative, or to interrupt. I suppose my comment didn't add anything, as I agree that even on a pier and at short focal lengths an EQ-6 should be derated for imaging load. Still, 530mm is pretty forgiving. I've shot unguided with the FSQ and a better mount but with a mediocre polar alignment with acceptable results.

#6 gillmj24

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Posted 13 July 2009 - 09:38 PM

That's very true. An FSQ will be more forgiving than a Meade 10" f/10!

#7 Yedgy

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Posted 13 July 2009 - 11:48 PM

Thanks, guys. Yep, I'm planning to use the FSQ exclusively for widefield imaging. I don't know the exact weight of all the components yet, so I deliberately overestimated the total weight to be 40 lbs. It might well be closer to 35 or even 32. Does anyone happen to know how much a large Tak Juraplate weighs?

And a follow-up question, I suppose: would using large counterweights far up the shaft (closer to the center of balance) lend more stability than smaller weights near the end of the shaft?

Tony

#8 Luigi

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Posted 14 July 2009 - 06:52 AM

You're upgrading the saddle and dovetail, right?

#9 Brodie

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Posted 14 July 2009 - 08:49 AM

It is rated for 40lbs and, in my optinion, that is a conservative number. I need 44 lbs of counter weights to balance my newt and other goodies. no problems here. Of course ive done mostly visual with this setup.

#10 Eddgie

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Posted 14 July 2009 - 10:09 AM

You know, there was a posting in the Mounts forum where a guy beat up the LXD 55 or something because of a stripped screw.

What does that have to do with you? Well another guy responding to his post beat up his EQ6 because he thought that it had "Cheap Castings."

Now I responded and said that it COULD be that the DESIGN had a limitation or perhaps that there was a slight flaw in the casting an the COMBINATION of these factors could have caused his problem.

Here is what I said in that forum and I think it bears repeating.

When you put 40 lbs of counterweight way out on the end of the CW bar, you are creating a long lever that has a folcrum point at the Altitude axis. The torque is then transferred down the lug at the base of the altitude assy and transferred to a SINGLE point, which is the altitude adjusting screw. So, now you have greatly amplified the 40 lbs of weight and concentrated all of the force on the single small altitude adjustment screw. All of this force gets concentrated at the WEAKEST point in the rear wall casting (the place where they drilled a freaking HOLE which is ALWAYS the weakeest point in a casting and is typically re-enforced by the designer when point loads are placed on it).

At SOME point, you MIGHT see this. Maybe his casting was just sub par. Or maybe the designer didn't intend the mount to be used at this kind of weight. What the vendor says and what the designer say are often two different things, and since no one even has a remote clue as to who the designer is, we really don't KNOW the true load capacity of the Atlas.

I wrote a reveiw 3 or 4 year ago and in it I SERIOUSLY questioned vendors asserting that the Atlas was a true "Heavy Duty" mount. At the time, people were saying that it was a competitor to the C11 and CGE. I didn't think so. At the time, I did not recognize this particular weakness, but I also didn't think the mount had the same carrying capacity as the CGE or G11.

I still don't think so.

As they say, you can't turn a sow's ear into a silk purse, and turning an Atlas into a heavy duty mount with bigger saddles and such might not really be that advisable either.

Just an opinion. Lot so people do it though, so maybe his was just a bad casting.

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#11 michiel

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Posted 14 July 2009 - 10:10 AM

yes!

#12 Eddgie

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Posted 14 July 2009 - 10:12 AM

Picture was from the other poster that was complaingin about the cheap castings on the EQ6. I thought that it was instructive to show my concern for trying to overload this mount. Hope he doesn't object.

#13 rmollise

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Posted 14 July 2009 - 12:10 PM

Picture was from the other poster that was complaingin about the cheap castings on the EQ6. I thought that it was instructive to show my concern for trying to overload this mount. Hope he doesn't object.


Well...the thing is:

While I wouldn't suggest a C14 for the mount (how you gonna balance it?) it is capable of handling 40 pounds. What happened to this dude's mount? I don't know and neither do you. Does this happen all the time? No. Frequently? No. More than once? I don't know but this is the only one I've heard of. ;)

#14 NewAstronomer

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Posted 14 July 2009 - 01:13 PM

Picture was from the other poster that was complaingin about the cheap castings on the EQ6. I thought that it was instructive to show my concern for trying to overload this mount. Hope he doesn't object.


Well...the thing is:

While I wouldn't suggest a C14 for the mount (how you gonna balance it?) it is capable of handling 40 pounds. What happened to this dude's mount? I don't know and neither do you. Does this happen all the time? No. Frequently? No. More than once? I don't know but this is the only one I've heard of. ;)


A few thoughts.

1) The mount in the picture (I realize it isn't the poster's) has massive damage to the top of the legs. Was it used as a battering ram or dropped a few times? That might have further weakened the casting. It sure looks like the damage to the tops of the tripod isn't "normal wear and tear".

2) That being said, I 100% agree that the Atlas isn't a heavy duty mount. I've only owned it for 1 week, have a C11 on it, and that the maximum (28lbs without attachments) I would put on this mount. I recommend solar system imaging with that setup, or very short exposure DSO imaging, but thats it. I have no degree in engineering, just some imaging backround and use of an EQ2, SVP and now Atlas as my "bed of knowledge".

My Atlas GoTo's are spot on after level, polar align (no drift) and 3 star alignment. Amazingly accurate at 2800mm focal length. Highly recommended for the sub $2000 mount range.

40 lb OTA + attachments? I wouldn't do that, wouldn't even try it. With 33lbs of CW (supplied and needed for C11) I think its at 100% max right there.

#15 Eddgie

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Posted 14 July 2009 - 02:05 PM

Not my mount. Just my belief. But after working around military jets for 8 years and seeing castings being removed from service because of cracking around pass-thorugh holes, I would say that this design was not something I would overload on a regular basis. If I look at the Atlas and can put my finger the one point that limits its capacity, I would say that picture is spot on.

Of course the OP thought it was a "Cheap Casting" and I was somewhat disagreeing. I thought it was more a design issue Me?.. I would have NEVER bored a hole in a concave casting and put a huge load on it! The casting should have been made so the curve was INWARD towards the load so the natural arch shape would have RE-ENFORCED the laod capacity. This design transferres the pressure throught the casting to the outer perimeter of the hole... The picture shows EXACTLY the kind of failure one would expect to see from this kind of design. An inward facting curve would be a COMPRESSION load, and castings are VERY strong under compression loading. An outward curve as was used by the designer places the casting under TENSION, and holes in castings that are under tension are prone to failure.

Or maybe the person that submitted the picture was right and it is simply a case of using cheap castings.

And maybe in the end it was plain and simple bad luck. Like the bumber sticker says... Stuff happens.

#16 rmollise

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Posted 14 July 2009 - 04:29 PM

2) That being said, I 100% agree that the Atlas isn't a heavy duty mount.


I won't deny that...and IMHO, the CGE and G11 are not "heavy duty mounts" (whatever that is) _either_. Both are barely sufficient for the C14 in my judgment. To get to heavy duty you need to step up to the Titan league at least. Course many folks do not need and cannot afford to do that. The Atlas is a high quality mount perfect for many users. ;)

#17 rmollise

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Posted 14 July 2009 - 04:43 PM

Or maybe the person that submitted the picture was right and it is simply a case of using cheap castings.

And maybe in the end it was plain and simple bad luck. Like the bumber sticker says... Stuff happens.


If this were some kind of inherent limitation we would have plenty more cases similar to this one. A lot of folks _are_ loading this mount heavily. We are not seeing these cases, so my diagnosis is "manufacturing defect in this example" or "abuse by end user." ;)

#18 jason_milani

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Posted 14 July 2009 - 10:01 PM

2) That being said, I 100% agree that the Atlas isn't a heavy duty mount.


I won't deny that...and IMHO, the CGE and G11 are not "heavy duty mounts" (whatever that is) _either_. Both are barely sufficient for the C14 in my judgment. To get to heavy duty you need to step up to the Titan league at least. Course many folks do not need and cannot afford to do that. The Atlas is a high quality mount perfect for many users. ;)


I like my Atlas. Nevertheless, i picked up my third CGE recently and for good reason. It CAN handle a C14 fairly easily for visual and piggybacking a small refractor isn't out of the question either. The Atlas just isn't in the same class as the CGE when it comes to load capacity. I had 70 lbs. on a CGE (on a pier) and it was fine visually. i did have a problem with goto accuracy but i found out later after i sold the Meade 14" that was on it that a loose saddle bolt was to blame.

The Atlas is a nice mid sized, quiet, fairly accurate mount.

But....there is a reason the CGE cost twice as much.

And there is also a reason why an AP1200GTO is 3 times the price of a CGE ;).

#19 Trebor777

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Posted 14 July 2009 - 10:56 PM

That picture was of my old (my first one) Atlas.

There could have been a hairline fracture in the casting or it could have been because of torque over time. I was always careful with the mount. I had a SN10 on there w/ a80ED piggy-backed.

I liked the Atlas so much, I purchased another one (that I'm selling now because I have a CGE)

By the way, Orion sent me another mounting base and I replaced it and then sold the mount after I regreased it. I've rebuilt 3 different Atlas in the past 8 months. They're amazing mounts that CAN take more then 40lbs if properly balanced.

My casting, might have been a bad one, or a hairline fracture, or it might have been my own fault, over time with too much torque on the back bolt there. But I was always careful and when I adjusted the altitude bolts I always made sure there was some room for adjusting.

Also, the altitude modification to the Atlas makes adjusting the altitude bolts easier. (see pic).

The 3 set screws that are behind the Atlas plastic cover are "usually" too tight - hence the altitude bolts being a pain to adjust, especially if you have gear/CW mounted.

The Atlas is a great mount, my first one was the "excpetion to the rule", IMO.

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#20 Trebor777

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Posted 14 July 2009 - 10:58 PM

Picture was from the other poster that was complaingin about the cheap castings on the EQ6. I thought that it was instructive to show my concern for trying to overload this mount. Hope he doesn't object.


No, I don't object. But it wasn't overloading, IMO that broke the casting like that. I think the main reason might have been the 3 locking screws behind the plactic cap - that out of the 3 I've come across have all been way too tight.

#21 Trebor777

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Posted 14 July 2009 - 11:05 PM

1) The mount in the picture (I realize it isn't the poster's) has massive damage to the top of the legs. Was it used as a battering ram or dropped a few times? That might have further weakened the casting. It sure looks like the damage to the tops of the tripod isn't "normal wear and tear".


Lol. "Massive damage"??? The tripod had chipped paint...lol. My fist Atlas, I used to keep the tripod in the trunk of my car - hence, chipped paint. But Massive damage"??? Not even close.

And the tripod & mount head were never connected during transport. The mount head was actually in a case I made.

Again, the tripod had paint chips from being in the trunk of my car. Easily fixed with black touch up paint. You can ask the guy who bought the Atlas from me, there was no "massive damage" to it. I replaced the cracked casting & relubed the bearings and uswed touch up paint on the tripod and he gave me 10 $100 dollar bills. ;)

#22 Trebor777

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Posted 14 July 2009 - 11:10 PM

If this were some kind of inherent limitation we would have plenty more cases similar to this one. A lot of folks _are_ loading this mount heavily. We are not seeing these cases, so my diagnosis is "manufacturing defect in this example" or "abuse by end user." ;)


I completely agree, but I didn't abuse the mount. "maybe" some over torquing, but I was always careful.

Again, after rebuilding 3 of these mounts (post crack in base) I think it's the set screws behind the plastic cover that makes it hard(er) for many to adjust the altitude bolts.

#23 Yedgy

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Posted 14 July 2009 - 11:53 PM

Again, after rebuilding 3 of these mounts (post crack in base) I think it's the set screws behind the plastic cover that makes it hard(er) for many to adjust the altitude bolts.

IME what makes the elevation so hard to set (especially under load) is that the hardened stainless steel elevation bolts push against a cast aluminum surface (I think it's called a "dog" or a "boss" or something like that) and eventually grind a hole into the softer metal, making it nearly impossible to turn the bolt (especially the rear one) unless all weight is lifted off it first. Synta could fix this by lining the push surface with a harder metal.

#24 rmollise

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Posted 15 July 2009 - 07:17 AM

I like my Atlas. Nevertheless, i picked up my third CGE recently and for good reason. It CAN handle a C14 fairly easily for visual and piggybacking a small refractor isn't out of the question either.


Well, I like the CGE, but IMHO, again, it is barely sufficient for the C14 visually. Put that sail-like dewshield on the scope and you had better hope for calm weather. ;)

Which doesn't mean it (the CGE or G11) doesn't have its pluses. Including for use with the C14. It's far less expensive (by about half) than the next class up, and is quite portable. In fact, if/when I decide to get back in the C14 bidness, that would probably be my choice. I would never feel like imaging at those focal lengths, and with a set of vibration suppression pads under the tripod legs, I can put up with the mount's C14 faux pas for visual. :lol:

I would _expect_ a CGE or a G11 to be at least somewhat of a step up from an Atlas, since either costs over twice as much. That said, the Atlas is a very useable mount, including for imaging if you keep the payload somewhat reasonable. The mount certainly has one good thing the G11/CGE do not: EQMOD... ;)

#25 skybsd

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Posted 15 July 2009 - 04:57 PM

Hi Rod,

The mount certainly has one good thing the G11/CGE do not: EQMOD... ;)


I'm confused.., regardless of whether or not its any good, surely you actually meant to say that EQMOD is simply AVAILALBLE FOR for the EQ6, but that EQMOD isn't available for the CGE/G11, yes?

Even so, that's the same as someone telling me that one "good" thing that their ms windbloze server has that my FreeBSD server doesn't, is that they can use MSSQL Server on theirs, but that application isn't native to my server :smirk:

Not really meaningful..,

Regards,

skybsd






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