planetman83

On 09/09/2022 at 04:06, Michele Scotti said:

It's time to attach the upper cage - luckily it's light enough that can be easily handled by one single person

How much will the whole upper cage weight?

On 23/12/2021 at 19:24, astrosathya said:

What an excellent thread I must say. I recently completed an 8.5" f/8 Mirror and since I plan to use it for outreach (needs to be portable), I do not want to make a full tube DOB for it but a truss design. I have used The Dobsonian Telescope Book and found that with a 9" tall mirror box and a single ring secondary cage (0.75kg total weight including secondary mirror, focuser etc) and 70 inch long trusses of 3/4th inch OD, I get the torque in the front aseembly as 5.4kgm and the bottom section a mere 1kgm. Will this play a role in the balancing of the scope? How big would the bearings need to be? I hope I am not hijacking this thread, just thought my question would fit in with the very experienced folks here.

TIA.

I don't know. You have to balance the OTA to see where the balance point is.

Hello again I made some touches to the telescope.

I made new bearings in order to balance perfectly without any counterweights. U made them 1 piece this time but the drawback is that the scope can point from 15 degrees and not lower. I made them like this in order to fit in my car.

I also painted the rocker and the mirror box black.

Guys, the goto works well with you? I also tried it tonight. Every time i was going to a target, I was syncing. But every time i went to saturn, it went way up and to the left. I manually went then to saturn, I was syncing, i then went somewhere else near, then again to Saturn and it went way up and to the left again. 5 degrees away or something like that.

the base was leveled and the clutches were tight. The problem is that it hasn't a finder, so if you want to go to something invisible to the unaided eye and it doesn't go there, then you cannot find it. Skysafari also cannot sync to an object if it thinks you are far from it.

2 hours ago, happy-kat said:

It might be too thick but what about trying insulator tape instead of ptfe

I couldn't turn the focuser all the way with even the PTFE. I will try again.

Has anyone tried video astronomy with tiis thing?

29 minutes ago, Astro_Dad said:

Yes as mentioned a couple times this is normal - your video shows the same movement as mine does. It doesn’t affect GOTO and as noted you can refine the alignment if a target is slightly off centre - no need to worry. 
You might want to consider making a light shroud and applying some PTFE tape - well known mods for this ‘scope. 

Yes but when I changed to lighter eyepieces, it moved and then the goto was not accurate etc. Anyway, if you say they alla are like this, I cankot do anything about it.

I am aware of the 2 hacks. I have already tried the PTFE tape but it didn't stay in place, it teared apart.

And I will definitely make the shroud.

Yesterday I managed to split the double double, saw some other objects also.

PS: the focuser is the weakest part of this telescope.

Here you can see the backlash. Is it normal? Because it creates problem to goto. I am thinking it has to be front heavy balanced in order not to move when i change eyepieces etc.

Has anyone updated the firmware of the mount? Is there any update?

Also, the backlash in altitude is very big. Is it normal? The alt clutch is tightened and i can move up and down the tube for, I don't know, maybe 1-2 degrees?

Guys, when I turn the mount on, where is the telescope supposed to he looking before I start the star alignment? The north star? And if i cannot see the north star?

I cannot find Skywatcher SynScanLink option. You are talking in SkySafari options in telescope setup, right? I also tried port 11882 but it doesn't work. Where can I find the exact steps I have to make? The skywatcher manual is totally useless.

Do I have to make any firmware update or something?

PS: It worked! I changed the IP address to 192.168.4.2. 

Theae are the settings vut it doesn't connect. Is it something wrong here?

I just received it! I haven't connected it yet to power but I can feel that there is some backlash in alt movement moving it by hand. Is it normal?

Ps: I just connected the telescope with synscan, it moves. But I cannot connect to sky safari 6 pro. What settings do I use?

So, if you release the clutch and move the telescope by hand, is it working exactly like Omegon's push+ with skySafari Pro?

Can I ask: does the goto, tracking system connect with sky safari? Or just with synscan? The synscan works fine?

Thank you very much. Something I think it might be a problem is that it is not convenient neither to be stand, either sitted when observing. How is convenient for you?

Are these car battery starters suitable as powerbanks 12v?

Hello guys, I am ready to buy this telescope. Do we have any new ideas about this? Any problems so far? Are you satisfied with it? 

I just read that it has also something about Freedom-find technology that you can push the telescope with your hand and the telescope doesn't lose the coordinates so you can track immediately? Somethig like push-to? Is this true? Have you use this?

Guys, I deal with a very frustrating problem these days with Sky Safari Pro. I use it in my phone and in my tablet. The stars appear right on the phone but on the tablet some stars are missing. Not the faint ones but SOME of them. I have bought the gaia extension database. The settings are the same on both of them.

Try to add a piece of teflon at the center and tighten the central bolt really tight.

3 hours ago, Swoop1 said:

A bit late to be asking this Planetman but, did you overcome the star nut issue? I ask because the thought of star nuts in carbon fiber tubing makes certain parts of me twitch uncomfortably!

In the cycle industry, star nuts are used in steel and aluminium steerer tubes whilst expanding wedges/ plugs are used in carbon fiber. Like these (sorry for the Amazon link). Star nuts can cause carbon fiber to crack/ split because they are quite harsh on the internal surfaces.

I added (glued) 0.7mm thickness aluminum foil inside the carbon tubes with epoxy and then I added the star nuts.

Hello again guys,

in order to solve the bearing gap problem, I just have concluded to the solution you can see in the photos. It is a pvc abs strip with 2mm thickness. It is very flexible and also seems very durable. I also added a 3rd group of roller bearings to alt that is adjustable.  As long as I turn the screw to the right, the rollers are getting closer to the bearings so the motion gets softer. On azimuth, I also added a 3rd group of rollers and tightened the center bolt so the motion there is quite soft and smooth.

I have not put anything yet, I am in the process of trying different materials. I ordered t-molding yesterday in order to try this material. I added a 3rd set of rollers on alt and now the motion is softer. I will soft the az also. The motion and bearing thing is the last thing I want to improve (I hope). I haven't finish with this matter yet.

I had another night after the new holder and it seems now ok. No astigmatism seen. I also sewed a light shroud. I still need to fix the 2 piece bearing problem because the rollers bump there.

After 3 times I tried the telescope, I think I can see astigmatism and I think it is because of how I glued the secondary on the holder. So, I made a new holder design that I will attach it to the aluminum triangle, I 3D printed it and I will try it again tonight. I hope this time the stars will be better.

I took some better photos with my DSLR and I would like to introduce the upper cage assembly in this post.

Total height is 25cm. The inner diameter is 636mm, the outside diameter is 716mm. There are 7 carbon fiber tubes that connect the rings. The spider vanes are made of 1mm thick stainless steel with 4.5cm width. There is 1.5mm aircraft plywood to fill the space and connect the rings also. There is laser crafted the number 24 next to the focuser.

The final total weight is 5.8kg mirror included.

9 hours ago, Michele Scotti said:

Fount it! I tried on a old-ish Android I have and it works.

https://play.google.com/store/apps/details?id=de.bremen.btm.movalyzer&hl=it&gl=US

Sorry to pester but if you could do that it's would be of great help

I can see here your post but I cannot find the youtube video in order to understand exactly how it works. If I understand right, we can see how rigid and well built is our construction in terms of vibrations? I am very interested in doing it. Please help me doing this experiment.