Re: Does G11G keep polar alignment when adding/removing heavy scope
Thanks all. ?Good advice.
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Re: Nextstar 8se & a G8 - need help with dovetail
The simple answer here is to replace the saddle on the mount with the dual D /V saddle.?
You can move your C8 back and forth as it has a V style rail.? Any other scope will have one or the other.?
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The slightly narrower plate that came with the G8 and its original saddle are relics of the past.
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Re: Does G11G keep polar alignment when adding/removing heavy scope
On Tue, Nov 19, 2024 at 10:33 AM, <sctom1@...> wrote:
If I very accurately PA the G11G on a pier and then set my scope on it for the next session will the PA stay accurate for doing this many times? Avoiding PA most of the time is the main point.
This is the last question on which route to go. A permanent pier with a removable scope and a very small outhouse type of rolloff building (or even lift off) or the much bigger affair where I just turn the power on after rolling off the roof.
Many thanks
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How long your mount holds PA really depends on how much you jar it with any one action. Just putting a scope on may or may not nudge it of place. I think for larger heavy scopes this would be more common than small lightweight gear. You can see in your guiding whether PA is off. All your Dec corrections going in one direction up or down is a PA issue. Also check how well your target stays centered over the course of a few hours. If it is constantly drifting toward one side of the sensor that is PA. Other incidents like walking into the scope in the dark, or hitting your head on it (happens to most of us at some time) can knock out PA. My G11 on a pier in my shed can stay aligned for months if I never take the scope off. Then one night I'll see drifting and I know something has finally worked loose. So, the answer is how fastidious do you wish to be. Do a PA every time and be sure, or just watch for drift issues to get so bad you need to take action.
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Regards,
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John
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Losmandy G11G2 on pier; refurbed Losmandy G11 with OnStep controller; SkyShed design roll-off observatory; ZWO ASI2600MM-P; ZWO ASI071MC; Sky-Watcher Esprit 100 ED with field flattener; Celestron C925 Edge HD with 0.7XFR, William Optics Zenithstar 61 APO; PHD2, NINA, Sequence Generator Pro and PixInsight user
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Re: East-Heavy Guiding With G11T?
My previous long time strategy had been to use 3x 1lb threaded weights that thread into each other like a stack of pancakes and then threaded to end of CW shaft in place of toe-saver bolt. ?I found these at “ScopeStuff.com”
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I balanced the mount with 2 weights attached. Then, depending on which side of meridian was imaging on, i would operate with either 1 or 3 weights in place by removing or replacing the outer two
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I stopped using this technique after setting up automated meridian flips. I now have spring loaded worm so hopefully will not be needed as much. ?To be seen when all of my stuff comes out of storage next year.
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Edward
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Re: Does G11G keep polar alignment when adding/removing heavy scope
I can verify that the PA is unchanging over months of taking the scope on and off of my gm811g. In fact I store both the scope along with the mount inside, and am able to reposition everything very precisely every night. The key is to make a durable base for the tripod to be placed using pipe and pipe flanges. I've been doing this for years and it works great with about 3 minutes of setup time per night. Details here:
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Re: East-Heavy Guiding With G11T?
This is fantastic. I'll be printing this tonight. Thank you!!!
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Regards,?
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George
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Re: East-Heavy Guiding With G11T?
Hey George,
Happy to share: here is the .3mf file from my Bambu P1S, but I also am attaching the STL exported from Fusion 360.
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I printed it out of PLA at 100% fill, but I'm sure you could go with a lower fill setting if you wanted. I used a 35mm M5 hex bolt and nut but I believe a standard10-32 bolt would work as well.
Additionally, you can add a layer of felt to the inside if you want to protect the DEC axis a little more.
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Let me know if you have any questions, ?and hope it helps!
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Ryan
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Re: Does G11G keep polar alignment when adding/removing heavy scope
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How well your scope stays well polar aligned depends on the quality of your mounting hardware and how much you bang on the mount while loading the saddle. For visual this is not a big deal but for imaging you won't know how well you are PA'd without checking and if you have to do this every time you use the scope why not just stay setup all the time??
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My advice is to just bite the bullet and build the ROR and leave the scope in the saddle year round. Be sure to have a low watt heater in there to keep moisture at bay. It helps to cover the scope tune and put a low Watt heating element like a Golden Rod below the cover to push moisture.?
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I'm sure others will have an opinion on this.?
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Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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Re: East-Heavy Guiding With G11T?
Thank you both Paul and Ryan.?
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Thinking this through, the easiest thing for me to do would be to just slide the counterweight down on the east of the meridian and slide it up on the west. To make the process fast, I can measure where these positions should be on the counterweight bar. I have the mount in an observatory in my backyard and have never purposefully gone to sleep while imaging. I sit on the couch, watch television, and monitor subs as they come in. I actually love doing this. Adding about 4 minutes to the process of walking out to the observatory to adjust a counterweight after a meridian flip will not be the end of the world.?
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Of course, a longer-term solution that does not depend on my being able to stay awake at night watching streaming shows would be a counterweight acting specifically on one side of the RA like Ryan has done. This could also work for the G11T and I have an extra 3.5 lbs counterweight from ADM that would work well here.?
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Ryan, do you happen to have the stl for that sleeve you printed to hold the counterweight??
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Regards,?
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George
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Does G11G keep polar alignment when adding/removing heavy scope
Forgive me if this is posted somewhere, but I did a search and I couldn’t find exactly this.
I am at a fork in the road on building my observatory. Either a very small outhouse type covering just my G11G on a pier or a bigger observatory where I can put my scope on the G11G that on the heavy duty tripod. The first is super cheap. The second is super convenient.
If I go the first route, I will take my scope off after every imaging session and then put it on to start the next one. I only get two image sessions at most a week for a couple hours a night, and as usual for most of us, there are long sessions of weather, full moon, etc. where I cannot image for weeks at a time. ?The scope will be kept fully assembled and wired up in a warm room about 10’ from the pier when not used.
My scope is a Stellarvue SVX 140 and loaded up it pushes 35 pounds.
If I very accurately PA the G11G on a pier and then set my scope on it for the next session will the PA stay accurate for doing this many times? Avoiding PA most of the time is the main point.
This is the last question on which route to go. A permanent pier with a removable scope and a very small outhouse type of rolloff building (or even lift off) or the much bigger affair where I just turn the power on after rolling off the roof.
Many thanks
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Re: Nextstar 8se & a G8 - need help with dovetail
Pretty sure the first use of the 1.75" wide bar by Vixen was for the C8-SP. The female saddle was mounted on the rear cell of the C8 using its two rear weight system mounting?holes. The dovetail bar was bolted to? the Super Polaris's saddle. The?bar had a strip of steel to protect the bar from the clamping screw. When the bar was copied by others the clamping guard was omitted resulting in a?narrower bar. This arrangement replaced two rings on the C8 that bolted to the SP's saddle.
The problem with this design was that the female saddle was fastened by two #8-32 screws and the entire load of the OTA was cantilevered. The screws loosened under the load and the weight was borne by the thin aluminum of the OTA. Most of these C8s will have dimples where the tube rested. This also caused the OTA to be out of collimation with the mount's RA axis. The problem was resolved by moving the female saddle to the mount when the Great Pacific was designed. A new dovetail bar was designed that mounted at both ends of the tube. It had side flanges similar to the orange bars but was a bit heavier.
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Re: East-Heavy Guiding With G11T?
On Mon, Nov 18, 2024 at 10:42 PM, George Stallings wrote:
I just received an axis upgrade for the G11T. Travel, poor weather, and stuff still coming in for my imaging setup will prevent me from putting everything through its paces. For G11T (with Titan RA axis) users out there, do you guide east heavy with this mount? I realize experiences may differ, but I'm wondering whether or not some or most users see guiding improvement this way specifically in RA.?
Hi George,
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A little East-heavy balance is needed with most non-spring-loaded worm/gear mounts (including G11T). This is because the worm and the gear can't be meshed too tightly in such a system, as that results in binding and motor stalls.
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Since there must be some distance left between the worm and the gear, the gear has room to float just a tiny bit between the worm teeth (this is also the cause of backlash). With a perfectly balanced RA axis, the gear can shift from engaging one side of the worm groove to the other. Slight wind, slight cable drag, etc. can all cause a sudden jump in the gear position. In the image below, the gear tooth can jump from engaging the left side of the worm groove to the right with no resistance.
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A slight East-heavy balance in RA pushes the gear into one side of the worm groove that drives the gear forward, while tracking. This imbalance produces the resistance needed to stop the gear from free-floating that can cause random jumps during tracking and guiding.
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Regards,
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? ?-Paul
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Re: East-Heavy Guiding With G11T?
Hey George,
I'm not a G11T user but I do use East-Heavy with my G11G and I have noticed an improvement in general. I had an ADM balancing weight with a vixen clamp and I 3D printed a sleeve that clamps around my DEC Axis around the polar-scope area. The East side has a vixen shaped part that the clamp can attach to. I've noticed that a near perfect balance in RA and DEC results in a little less RA chatter during guiding and my guiding seems to have gotten a little more consistent with my 10" newt.  Sorry I'm not answering your direct question, as I don't have a G11T, but just wanted to offer one solution. Hope you don't mind. I can only imagine the G11T would also benefit from this without the spring loaded worm. Another option that was recommended by Michael Herman included a loop of rope around the RA EXT knob on the west side that wraps over the top of the RA EXT and down the left side of the mount. At the bottom of that rope is a hanging weight that puts a constant pressure on the East side of the RA axis. I'll see if I can drum up a photo.
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East-Heavy Guiding With G11T?
I just received an axis upgrade for the G11T. Travel, poor weather, and stuff still coming in for my imaging setup will prevent me from putting everything through its paces. For G11T (with Titan RA axis) users out there, do you guide east heavy with this mount? I realize experiences may differ, but I'm wondering whether or not some or most users see guiding improvement this way specifically in RA.?
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Regards,?
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George
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Re: Nextstar 8se & a G8 - need help with dovetail
On Mon, Nov 18, 2024 at 07:40 AM, WayBack wrote:
On Mon, Nov 18, 2024 at 09:54 AM, George Cushing wrote:
Celestron bar
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The discussion prompted me to examine the terminology, as I had not previously equated the two items.? The curved extrusions are tube-rails that connect to OTA tubes, creating a box-like structure. This structure utilizes the tube's rigidity to form a truss-like unit with a dovetail.? Losmandy's dovetail plates are versatile, featuring holes for bolting various items, thus the plate alone must provide rigidity. Tube-rails serve a more singular purpose, requiring attachment to the tube—here, with prestressed connecting bolts—to ensure rigidity.
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These two choices present their own sets of pros and cons. For me, portability, weight, inertia, and simplicity are important, and I prefer stock option. I'm comfortable with the lighter weight and relying on the OTA for rigidity since I don't need to support heavy accessories with my C11HD usage.
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Doug
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The only redeeming factors about the stock Celestron dovetails are that they are already on the OTA and they are a cool Halloween color.?
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I don't know where you got your ideas or if you have ever used and setup a Losmandy or ADM SCT dovetail on a larger SCT but you are wrong about the Losmandy SCT dovetails.? The Losmandy and ADM dovetails are more rigid than the relatively flat Celestron extrusions even if you include the OTA in your cross section dimension.? The reasons that Losmandy and ADM use the radius block design is to add depth to the box shape to take full advantage of the existing OTA structure and to introduce the loads into the tube and cells more evenly reducing stress on the OTA across multiple fasteners and area. I think you know that the larger the box cross section the stiffer it can be.?
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I have seen too many cracked and failed CGE dovetails to recommend that people use them even just for visual use.? ??
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Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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Re: Nextstar 8se & a G8 - need help with dovetail
On Sun, Nov 17, 2024 at 12:07 PM, Allan Der wrote:
I am new to this stuff. I got an ADM Losmandy dovetail for my 10" deforked Meade for use on my EQ6R Pro. I find getting on my mount a little harder than the Vixen dovetail. The section it clamps onto is shallow compared to the Vixen and it takes me a while to line up with my heavy telescope. The vixens are narrower and deeper and they seem very solid. If I could go back, I think Vixen or another brand of Losmandy next time, something that has more to grab onto.
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Allan Der
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HI Allan,
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You should use the best part for the job to stay happy in the long run.? The Vixen dovetails were developed back when Vixen sold lightweight tiny refractors and these days they are just too small which is why most SCTs larger than 8" and many higher quality refractors usually come with the larger Losmandy D dovetail.??
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Maybe this will help you, do you know the trick where you open up the saddle enough to just drop the dovetail into the saddle sideways without having to slide the dovetail down the full length of the dovetail?? You should test your saddles first to see if there are enough extra threads to allow opening the saddle jaws without the coming apart.??I do this with all of my newer dual D/V Losmandy saddles as well as older dual D/V ADM saddles.?
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Years ago I also installed longer threaded bits to my older Orion Sirius and Atlas saddles to allow this same trick.? But many better, newer mounts have dual D/V saddles with tapered or beveled entry to the saddle to make it easier to load the larger dovetails.? If not the side-loading trick is one to try but be aware that not all saddles designs can accommodate this without adding longer threaded parts to them.? If you do modify your saddle be sure to use only stainless steel threaded bits to avoid rust which will happen.? ? ? ??
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HTH
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Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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Re: Nextstar 8se & a G8 - need help with dovetail
On Mon, Nov 18, 2024 at 09:54 AM, George Cushing wrote:
Celestron bar
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The discussion prompted me to examine the terminology, as I had not previously equated the two items.? The curved extrusions are tube-rails that connect to OTA tubes, creating a box-like structure. This structure utilizes the tube's rigidity to form a truss-like unit with a dovetail.? Losmandy's dovetail plates are versatile, featuring holes for bolting various items, thus the plate alone must provide rigidity. Tube-rails serve a more singular purpose, requiring attachment to the tube—here, with prestressed connecting bolts—to ensure rigidity.
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These two choices present their own sets of pros and cons. For me, portability, weight, inertia, and simplicity are important, and I prefer stock option. I'm comfortable with the lighter weight and relying on the OTA for rigidity since I don't need to support heavy accessories with my C11HD usage.
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Doug
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Re: Nextstar 8se & a G8 - need help with dovetail
I find the Celestron bar to be fine for the C8, while the Losmandy and ADM are heavy and clumsy. I was a bit surprised that they offered one for the C14.
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Re: Nextstar 8se & a G8 - need help with dovetail
I am new to this stuff. I got an ADM Losmandy dovetail for my 10" deforked Meade for use on my EQ6R Pro. I find getting on my mount a little harder than the Vixen dovetail. The section it clamps onto is shallow compared to the Vixen and it takes me a while to line up with my heavy telescope. The vixens are narrower and deeper and they seem very solid. If I could go back, I think Vixen or another brand of Losmandy next time, something that has more to grab onto.
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Allan Der
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Re: Nextstar 8se & a G8 - need help with dovetail
On Sat, Nov 16, 2024 at 07:25 AM, George Cushing wrote:
Celestron sells a 3" wide bar it calls the for the C8, 9.25, 11 and 14. The C8 bar is quite a bit lighter and certainly?stiff enough. About $50.
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The stock Celestron CGE dovetails are cheap crap.? They are inexpensive under engineered extrusions that tend to crack where the dovetail top meets the part that is clamped by the saddle. I have seen several others as well as my own, purchased used, C14 and C11 factory CGE dovetails crack or were cracked when I bought them.? I had no idea you had to look for this issue before it happened to me, TWICE!?
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The problem is the clamped part has no mechanical support against the compression forces of the saddle clamp.? This causes the flange to act as a spring and because in general aluminum is not a good spring material that joint flexs, fatigues, cracks and then the crack migrates up and down the extrusion.? If you don't see it in time and replace the dovetail the SCT will end up on the ground.?
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Buy once cry once.? You can buy a Losmandy or ADM dovetail and use it on your SCT and when you sell the SCT continue to use the basic dovetail plate with your next scope sans the radius blocks which are popular as used items.??
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Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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Edward Plumer
Jamie Amendolagine
Ryan Noonan
Chip Louie
Paul Kanevsky
