85 replies to this topic

[ragaltron]

Thanks for the great review, Chris!

 

Question about replacing the focuser: are you still using the stock focuser mounting base, or is that a different one? The focuser mounting base that came with my UL16 is half-height (only the bottom two focuser screws attach to it). Yours looks to be full-height.

 

I'm considering swapping out the focuser but want to make sure I do it right.

[Chris Westland]

Thanks for the great review, Chris!

 

Question about replacing the focuser: are you still using the stock focuser mounting base, or is that a different one? The focuser mounting base that came with my UL16 is half-height (only the bottom two focuser screws attach to it). Yours looks to be full-height.

 

I'm considering swapping out the focuser but want to make sure I do it right.

I'm not actually sure what focuser Tong is using now on the Dobs.  The one I got was a bit rough, which is why I wanted to replace it.   Mine is full height; that said, I had a machine shop do all of the holes and centering.   I would think that you could have a machine shop just make you a proper bracket for the focuser.   With a Dob in particular, I think having a nice focuser is a real plus -- either MoonLite or SI FeatherTouch (I think these are most people's choice).  

 

Just a comment on my Hubble CDK 10.  I have two backs and focusers -- one visual and one for AP (because of the different focuses).  Both focusers from HO are substantially better quality than the one I received with the Dob and I don't feel a need to replace them.  They both appear to have the rachet similar to the sort that I think the FeatherTouch focusers use, which makes for more stability when loaded with a filterwheel, camera, autofocus, etc. for AP.    The MoonLite focusers are friction Crayfords and super-smooth; but I'm not sure whether they would be as stable under load.

[Mike Q]

What a very well done review.  I am now actually giving Hubble Optics a look now.  I am eyeballing the 16 inch F5 and adding the DSC.  I am not wholly sold on a rocker box design as it leaves the mirror so exposed and it seems to me that dew on the primary would be a real issue, and here in Ohio dew is a real thing.  

[cRule5]

Mike, I have a UL14 HO Dob and was concerned not so much about dew but about dust and sand in some desert areas. So I bought on Amazon some thin, black plastic PVC sheets which I cut to size and taped inside the box that holds the mirror. You simply cut the sheets to size by deeply scoring them and carefully bending them. Then tape them inside the box with black duct tape or gaffer’s tape. This also keeps out any stray ambient light!

[Waynosworld]

I bought a used Hubble Optics UL20 F/3.7 back in April 2022, I have done a lot of modifications over the last month, some to make it easier for me to use, others to make it easier to collimate and hold collimation, I am not done yet but getting closer.

 

Here is my thread about this telescope/dob.

 

https://www.cloudyni...ptics-ul20-f37/

 

Here are a few of the modifications I made.

 

I replaced the collimation springs as the ones in it were not working properly, I was having issues even getting it collimated, I replaced the springs in it, I tried a few different ones in the stock configuration and gave up and started over with large springs that work great, details are in the thread.

 

 

I deleted the sling arrangement as my collimation was drastically changing with altitude, I tried a couple different ways and am not done with this, a double wiffle tree arrangement was stressing the top plate, so at this time I am only supporting the bottom plate, the view thru the eyepiece is much better, but I need to come up with something better, I am not done with this yet.

 

 

And I also put it on wheels so I could move it around on my property without dismantling it, I just use the UTA as a handle, tilt it onto the wheels and roll it where I need to using only one bracket on the back to lock it and the base, obviously more is involved as it has to be set up to do this, but it is the easiest telescope I have to use on my property now, everything I did to make this happen is in the thread.

 

 

I made a traditional UTA as dew and light is an issue where I live(observe from my Bortle 7+ backyard), I am also using this dob manually right now and it is easy to use, I have put a lot of thought into each modification and am happy with most of them now(except for the wiffle tree arrangement), as I mentioned, this is the easiest telescope I have to use now and I have several, the term easier involves all aspects, this is easier to use than my 10" GSO and that one is easy to use.

 

 

 

[resonance]

Thanks for a very detailed review and to all comments.  

[jacktbear69]

I received my UL 14 this week, seems there a couple of updates. HO includes a sheet of black pvc, cut to size for a mirror cover, the azimuth bearing assembly is now black powder coated, the alt bearing side supports are included, and the azimuth bearing brake is included also.

Packaging was great. No sharp edges on any fabricated part. Welds were ground smooth.

So far the only issue was an incorrect spider hub.

[spaceoddity]

I'd be interested in a 18 or 20 if I could find a used one at the right price. Some concerns I have are the edge support on these sandwich mirrors. It seems like it would be impossible to put a sling or whiffle tree at the COG. I wonder if you could use JB weld or something along the bottom edge to make some solid contact points inbetween the 2 mirror discs. Maybe that would distort the mirror and make things worse? Seems to me they would have designed it that way if possible. Another thing I wonder is if it is possible to add encoders for push-to DSC's. The other mechanical issues seem like they wouldn't be too difficult to modify. 

 

I bought a used Hubble Optics UL20 F/3.7 back in April 2022, I have done a lot of modifications over the last month, some to make it easier for me to use, others to make it easier to collimate and hold collimation, I am not done yet but getting closer.

 

Here is my thread about this telescope/dob.

 

https://www.cloudyni...ptics-ul20-f37/

 

Here are a few of the modifications I made.

 

I replaced the collimation springs as the ones in it were not working properly, I was having issues even getting it collimated, I replaced the springs in it, I tried a few different ones in the stock configuration and gave up and started over with large springs that work great, details are in the thread.

 

DSC00217.JPG

 

I deleted the sling arrangement as my collimation was drastically changing with altitude, I tried a couple different ways and am not done with this, a double wiffle tree arrangement was stressing the top plate, so at this time I am only supporting the bottom plate, the view thru the eyepiece is much better, but I need to come up with something better, I am not done with this yet.

 

DSC00234.JPG

 

And I also put it on wheels so I could move it around on my property without dismantling it, I just use the UTA as a handle, tilt it onto the wheels and roll it where I need to using only one bracket on the back to lock it and the base, obviously more is involved as it has to be set up to do this, but it is the easiest telescope I have to use on my property now, everything I did to make this happen is in the thread.

 

DSC00134.JPG

 

I made a traditional UTA as dew and light is an issue where I live(observe from my Bortle 7+ backyard), I am also using this dob manually right now and it is easy to use, I have put a lot of thought into each modification and am happy with most of them now(except for the wiffle tree arrangement), as I mentioned, this is the easiest telescope I have to use now and I have several, the term easier involves all aspects, this is easier to use than my 10" GSO and that one is easy to use.

Maybe try some nylon roller bearing wheels for the contact points on your whiffle tree instead of the square pads. If you could adjust the height on them, that would be even better. There's no way to calculate the COG of a sandwich mirror that I'm aware of, as it would probably be in the open space between the mirror discs but if you had adjustable roller bearings you could use trial and error to get the best results. I'm guessing the upper end of the bottom mirror disc might work.

[gandoe]

Chris, 

 

Thank you for the great review, and the ongoing dialogue of Q&A! I just acquired a lightly used UL16 f4.5, and have been reading the reviews and comments to find the best upgrades and adaptations. You had put a metal cover on the "lazy susan" azimuth bearing ring; did you have a cover on both the top and bottom, or just the top? And what material did you use? The photo of the metal cover looked....unstressed, as if a ring as cut from a sheet and the edges simple folded down. I assume it's attached to the rocker box, and the metal cover slides over the interior portion of the lazy susan as the rocker box, and outer ring of the lazy susan, rotate?

 

TIA

Ed

[Waynosworld]

I'd be interested in a 18 or 20 if I could find a used one at the right price. Some concerns I have are the edge support on these sandwich mirrors. It seems like it would be impossible to put a sling or whiffle tree at the COG. I wonder if you could use JB weld or something along the bottom edge to make some solid contact points inbetween the 2 mirror discs. Maybe that would distort the mirror and make things worse? Seems to me they would have designed it that way if possible. Another thing I wonder is if it is possible to add encoders for push-to DSC's. The other mechanical issues seem like they wouldn't be too difficult to modify. 

 

Maybe try some nylon roller bearing wheels for the contact points on your whiffle tree instead of the square pads. If you could adjust the height on them, that would be even better. There's no way to calculate the COG of a sandwich mirror that I'm aware of, as it would probably be in the open space between the mirror discs but if you had adjustable roller bearings you could use trial and error to get the best results. I'm guessing the upper end of the bottom mirror disc might work.

I have done a lot to this 20" F/3.7 since my post in May of 2022, I used a double roller wiffle tree style like in this photo below of my 16" F/4.42 dob once I figured out my collimation changing issue on the 20"(mirror cell frame issue, flexing), it had a sling that I thought was the issue, they had glued Velcro on each mirror plate and connected Velcro to the sling also, that seemed to work, but I like the wiffle tree as the primary mirror is always in the same spot using it while the sling the mirror can shift sideways.

 

 

I do not know much about electronics, this telescope came with them but I am not a computer guy, I removed them from the telescope, it is much easier for me to use.

 

I think the AZ bearing is by big issue now, the little bearings rust inside the aluminum bearing rings(dew?), my dob is stored in a shed when not in use, oil attracts dirt so I did not use oil, a member is asking about a cover for that bearing that interests me in a thread, but dirt/dust can still get in the bearing from the bottom especially where oil/grease is involved, there is no way to cover/enclose the whole bearing that I know of yet, my bearing is removed right now, it is the third time I removed it because of resistance to turning, it just binds sometimes, I am waiting for replies to that CN members question as I do not have an answer at this time.

[JorgeM]

Hello, I have a question:

 

with what glue do the multiple blocks stick?