26 replies to this topic

[Noger]

So a few weeks ago i finally decided to get a telescope after wanting one for a couple decades. I got what i thought would be a good start with a celestron astromaster114eq. After a couple uses and post purchase research it went back and i replaced it with the orion skyline 6in dob. Got it all built and setup, scope aligned and took it out to gander at jupiter last night. Firstly, yay man so cool to see the moons and barely perceptible cloud bands. Then the frustration started setting in when i attempted to change from the 25mm eyepeice to the 9mm. The azimuth movement on this thing is horrid, i mean seriously what the heck. It takes honest force to get the thing to spin so much so that even with the 25mm lens im constantly over shooting trying to adjust for planetary movement. The force also knocks the altitude out because thats much much lighter and causes a rebounding effect where i get jupiter lined up and let go and it shifts back a little.

 

I took it all apart and made sure i assembled things correctly and re-read instructions a few times and its correct but it its not smooth movement at all and takes what i feel is too much force to spin. The adjustments on the celestron with the slow motion controls was so much better but i thought dobs were more ideal? I also got a dob because i thought they were supposed to be more stable but when i attempt to focus things shake even worse than the celestron on the eq mount. 

 

Did i do something wrong? or did i get a badly manufactured one? Or is it supposed to be like this? I had high hopes and excitement to finally get into this hobby but theres no way im going to enjoy anything if i cant move it precise enough to even spend a few minutes tracking anything.

 

Thanks for any help or advice, right now im just considering returning this and getting another EQ model so i can more easily track things. The problem is those barely come in 6in or higher and i want the best posisble views i can get in my budget.

[Ionthesky]

Welcome to CN, and to the astronomy hobby, Noger.   

 

Each type of scope and mount has a learning curve attached to it.  I have an old 6" Dob, and I experienced similar frustration at first.  One thing about a 6", compared with say, an 8" or larger, is that the mirror isn't very heavy, compared with the rest of the long tube, so it tilts downward very easily, particularly with heavy eyepieces and at low elevations.

 

The easiest way to compensate for the imbalance is to attach weighted magnets at the bottom of the tube near the mirror.  As far as the azimuth motion goes, try placing your hands at the top of the tube and as far down as you can reach, preferably below the elevation pivot point.  I found that the az motion does loosen up over time.

 

Oh, and make sure that the pivot bolt in the base isn't too tight.  It basically just needs to be tight enough to hold the rocker base to the ground board without a lot of slop.  The weight of the scope will keep things plenty stable. Some dobs come with a knob bolted to the tube, right at the top of the tube, to help with steering.  If your scope doesn't have one, you can easily add a simple drawer pull to do the job.

 

I hope this is helpful.  A 6" Dob is a great starter scope,

 

Regards,

Dave 

Edited by Ionthesky, 28 January 2023 - 08:03 AM.

[Echolight]

With the low weight of a the supplied 9mm eyepiece, I don’t think balance from weight of the eyepiece should present a problem.

 

Possibly you have the center bolt too tight? The scope should spin easily with a fairly light touch.

 

Focusing should also be done as gently as possible.

Edited by Echolight, 28 January 2023 - 08:45 AM.

[Noger]

With the low weight of a the supplied 9mm eyepiece, I don’t think balance from weight of the eyepiece should present a problem.

 

Possibly you have the center bolt too tight? The scope should spin easily with a fairly light touch.

 

Focusing should also be done as gently as possible.

Yeah it does not spin easily at all. I have the base tensioner bolt basically out and just threaded in enough to keep a pivot point, any looser and i might as well not have it in and it still is so hard to move. Im getting teflon wear marks on the top plate as well, but maybe if i tighten it alot so teflon wears off on the upper mount it will start to spin easier. Or use some fine sandpaper to smoth out the bottom of the upper plate. I really shouldnt have to do this though and its going to make returning if theres an issue impossible.

 

If i touch the tube at all trying to use it to help spin it easily throws the altitude out. I wish this model had knobs instead of springs but i thnk im going to try and use the keyrings to grasp some spring coils to help tighten. I'd prefer is my issues were reversed and i had trouble with tube tilt. Even trying to adjust the scope alignment causes the tube to move.

 

As far as balance, i need more tension on the tub but its the mirror side that drifts down even with an eyepeice. However at the high angles im using it at it seems to be fine and only an issue if im more horizontal. I like the magnet idea though so i might try balancing it a little too. Maybe use hot glue to keep the magnets in place better.

Edited by Noger, 28 January 2023 - 09:08 AM.

[gstrumol]

This is just my opinion, so take it with a pound of salt.

 

A Dob is certainly the best 'bang for the buck' you can find, and it is great for doing some DSO hunting. But as a high power planetary scope it has issues, some of which you already discovered. Regardless of the scope design, as magnification increases the FOV shrinks in the EP and the object moves out of the FOV faster. This necessitates being able to constantly adjust the position of the scope to keep it centered (assuming you don't have a motorized system).

 

With a mount that has slow motion controls (like you had with an Eq mount) this is an easy task that doesn't induce any noticeable vibration on the image. But with a Dob you are forced to manually move the entire OTA all the time. For a DSO not a big problem as you are most likely using a low magnification. But if you want to see detail on Jupiter (or even worse, Mars) you need high power. And this will always be a challenge.

 

Gary

[Echolight]

I have used an 8 inch dob in the past. But only briefly. Hopefully some dob experts will chime in with some better advice than I can give. 
 

All I got is this Ed Ting XT6 video.

https://m.youtube.co...h?v=QK7Y7gE6r3k

[Noger]

so what are all of you using if youre using larger scopes, go to ones? I wanted a larger scope but dont have a huge budget so dobsonians seem to be my only option.

[Echolight]

so what are all of you using if youre using larger scopes, go to ones? I wanted a larger scope but dont have a huge budget so dobsonians seem to be my only option.

A dobsonian is surely the best bang for your buck as far as inch of aperture per dollar. There is basically no other 6 inch or larger scope that you can buy for the same money. They are hugely popular on this forum, but I don’t use one.

 

My scope choices are fairly unconventional, anti-establishment 

I use achromatic refractors (which are loathed by many).
And modified with reducers and 2 inch diagonal SCT’s (which are equally frowned upon).

 

I have but don’t use GoTo mounts. They are great for the tracking feature. But more tedious to use than I want to deal with.
I appreciate the ease of setup and ease of use that manual alt/az mounts provide. 

And I don’t have slow motion controls on any of my mounts.

I use this 6 inch achromat on a very special, very tall alt/az mount that I bought used for a very fair price. Up to 375x on the Moon with no slow motion controls. A delicate touch both on the single speed focuser as well as guiding is helpful.. or essential.

These can sometimes be found on the used market for a reasonable price.

They are a couple of handfuls and then some to set up. But in this configuration, not really any more trouble than an 8 inch dob. And for me personally, easier to look through. Others will oppose and argue against this point if view.

 

But mostly, I use a little 4 inch f5 achromat, the Startravel 102, on a big photo tripod. And a modded (expensive) C5 on the same mount.

 

A used C6 is an option that you may find affordable with some patience to find a good deal. SCT’s can be finicky, and fragile. This one has a crack in the corrector, that somehow doesn’t seem to affect the view

I have it (again, modded $$$ with a reducer and very special 2 inch diagonal) on a very old and bought used super duty video mount (modded for counterbalance)

About as portable and versatile as you can get in a 6 inch scope.

Again, no slow motion controls. Yet I use it up to 295x on occasion.

Attached Thumbnails

• 

Edited by Echolight, 28 January 2023 - 10:19 AM.

[hcf]

Search for threads on Dob "stiction" problems and how to reduce it.

 

An example:

 

https://www.cloudyni...tion-orion-xt8/

 

I have a GSO 8" Dob which comes with a different kind pf Azimuth bearing (lazy susan type) and does not have any such problems.

Edited by hcf, 28 January 2023 - 04:45 PM.

[Philip Jodry]

If your mount sits on a slippery sheet of plastic, it should have plastic washers under metal washers, too. A bolt too tight can make things difficult, but maybe a bolt too loose. Any anti friction plastic under the the yoke could be wiped and sprayed with lemon wax.

[Philip Jodry]

If your mount sits on a slippery sheet of plastic, it should have plastic washers under metal washers, too. A bolt too tight can make things difficult, but maybe a bolt too loose. Any anti friction plastic under the the yoke could be wiped and sprayed with lemon wax.

[Barlowbill]

Your best bet right now is finding someone to help figure out what is wrong.  Is there an Astronomy group where you live?  There may be a Cloudy Night member close to you who would be willing to help.  But you are going to have to tell us where you live.  There are old threads in Reflector section which will probably discuss your issues and advise how to work it out.  Lots of folks here who are eager to help.

[Noger]

Found a comment in another same issue thread suggesting ivory soap. Got some on and while its not easier to spin its not sticking at all and is letting me make precise movements. If i had only read about dob stiction ahead of time i could have dealt with it.

Thanks all for the help i think im on my way to stargazing!!!

[JamesDuffey]

The traditional fix for sticking in the azimuth bearing is applying soap to the board that rides on the teflon. Regular bar soap works. This tip from Jon Isaacs.  You can also upgrade the upper bearing surface with a ring of laminate < https://www.astrogoo.../specials.shtml > or FRP from your local big box store. - Duffey

[sevenofnine]

Welcome to C/N! 

 

We are here to help you and we will get this sorted out together. So, take a deep breath and start over. I have the Orion XT8+ and I can tell you that little set up errors in assembly can cause the problems you are describing.

 

Check these things again. 1) The base plate bolt with lock nut should be so loose it rattles...zero tension! That bolt just holds the two plates together. While you have it apart, put some regular bar soap on the pads and where they contact the board. This will free up the Az. motion so that it spins freely with slight stiction. You don't want it to spin like a top either. That creates another problem. 2) This scope has the spring tension system so it's much easier than the tension knobs. Just put a little bar soap on the trunnions and it should smooth thing up. Sometimes a heavy magnet wrapped in duct tape helps the balancing act. You just slide it up and down the belly of the scope to get the Az. motion smooth. Harbor Freight or Amazon are sources.  

 

 

Bottom line: The assembly diagram is your friend   Each bolt, screw, bushing and washer has it's function. Careful attention to the details will reward you with a smooth operating telescope. Best of luck to you! Let us know how it goes 

Edited by sevenofnine, 28 January 2023 - 05:21 PM.

[Noger]

Thanks sevenofnine, 1 is good and 2 i have springs not the knobs so less control of tension but the soap seems to have worked and im excited to try again if only the clouds would go away.

[Tony Flanders]

I wish I could see the scope. The degree of roughness in azimuth that you're describing sounds pretty dire, much worse than your average budget-priced Dob should be. Possibly due to a manufacturing defect.

It's tricky to get the altitude bearing right, because you always have to compromise between being loose enough to move smoothly and tight enough to keep the scope from slipping when you change eyepieces. It ought to be easy to get the azimuth bearing right.

[Noger]

I wish I could see the scope. The degree of roughness in azimuth that you're describing sounds pretty dire, much worse than your average budget-priced Dob should be. Possibly due to a manufacturing defect.

It's tricky to get the altitude bearing right, because you always have to compromise between being loose enough to move smoothly and tight enough to keep the scope from slipping when you change eyepieces. It ought to be easy to get the azimuth bearing right.

I think ill probably try one of those rings jamesduffy suggested as a perm solution since this is really my best option for affordability right now. Ill gladly sacrifice some DIY mount fixes for the better optics and quality the skyline has. The mount could use some weight reduction too and i think it's weight is really the main cause of the problems. Maybe they are using cheaper denser materials these days.

 

right now without the eyepeice its weighted to the rear but im already eyeballing a right angle finder and am wondering how thats going to throw the balance out. Thanks to the suggestion of magnets though ive got a plan to deal with that because theres really no way for me to tighten the altitude tension.

[clearwaterdave]

I am sorry to report that I bought a 10" Orion dob and experienced the very same issue.,the azimuth was like a truck without power steering.,I tried everything I could come up with and finally I bought a lazy Susan type thing which is much better but the thing is still like driving a tank compared to my Zhumell 8" dob. Not sure what to say or do because so many are happy with their Orion dobs.,Good luck with your choices.,

[Noger]

I am sorry to report that I bought a 10" Orion dob and experienced the very same issue.,the azimuth was like a truck without power steering.,I tried everything I could come up with and finally I bought a lazy Susan type thing which is much better but the thing is still like driving a tank compared to my Zhumell 8" dob. Not sure what to say or do because so many are happy with their Orion dobs.,Good luck with your choices.,

Thats too bad, ill play with it and use it best i can but then it gives me a good excuse for a future upgrade. Im curious to know that when in my research orion, zhumell, apetura, etc are basically all rebrands that your zhumell is better than the orion?

[clearwaterdave]

Thats too bad, ill play with it and use it best i can but then it gives me a good excuse for a future upgrade. Im curious to know that when in my research orion, zhumell, apetura, etc are basically all rebrands that your zhumell is better than the orion?

The Zhumell is a much different setup than the Orion.,Zhumell and Apetura are the same.,They have a bearing plate for azimuth and tension knobs for the Alt.,Much better in my opinion.,

[Neanderthal]

I bet if you take a few photos of the un-assembled base so that we can see the mechanics, you'll get some great suggestions to help/improve it.

[WillR]

I see the soap fix has already been suggested and applied? It worked wonders for my stiff azimuth bearings. I made a paste from Ivory soap and water, applied to the bearings and let dry as per Jon Isaacs.

 

Alt bearings are another issue. The nice thing about tension knobs as opposed to springs, is you can tighten temporarily to change eyepieces. You could rig up some sort of a tension knob on yours. I have found that all Dobs need some tweaking of one kind or another.

 

All scope and mount designs have their pros and cons. A dob or alt/az mount requires you to track in two directions. A EQ mount only requires you to track in one, but with a Newtonian on a EQ, you get all sorts of uncomfortable eyepiece positions and it requires a lot of counterweight.

[vtornado]

I have had a dozen commerial dobs go through my hands and nothing was as bad as you describe.

As others say a picture would really help.  If you have trouble with uploads decrease the resolution of your camera.

With no information, here are some ideas.

 

Does the center bolt have a sleeve (bushing)?  It should.

Are the teflon pads over the ground board feet?  If not the ground board can sag.

Are either the ground board or azimuth board warped?

The teflon pads are typically stapled to the ground board.  Are the staples recessed?  Sometimes they are not

   pounded completely in.

Is there any sticky stuff on the underside of the azimuth board (like spilled adhesive)

Is the laminate of the underside of the ground board smooth?

Edited by vtornado, 30 January 2023 - 10:09 AM.

[rhetfield]

Yeah it does not spin easily at all. I have the base tensioner bolt basically out and just threaded in enough to keep a pivot point, any looser and i might as well not have it in and it still is so hard to move. Im getting teflon wear marks on the top plate as well, but maybe if i tighten it alot so teflon wears off on the upper mount it will start to spin easier. Or use some fine sandpaper to smoth out the bottom of the upper plate. I really shouldnt have to do this though and its going to make returning if theres an issue impossible.

If i touch the tube at all trying to use it to help spin it easily throws the altitude out. I wish this model had knobs instead of springs but i thnk im going to try and use the keyrings to grasp some spring coils to help tighten. I'd prefer is my issues were reversed and i had trouble with tube tilt. Even trying to adjust the scope alignment causes the tube to move.

As far as balance, i need more tension on the tub but its the mirror side that drifts down even with an eyepeice. However at the high angles im using it at it seems to be fine and only an issue if im more horizontal. I like the magnet idea though so i might try balancing it a little too. Maybe use hot glue to keep the magnets in place better.

adding soap to the bottom of the top base should help with azimuth motion. However, if the tension bolt is loose, it should still move easy. Sounds like something is still binding. Mine has a bushing that would cause issues if it was tight. For me, it was the opposite problem - too loose.