16" Grab 'n Go Dobsonian?

[tomato]

Dare I say it, image capture can sometimes get a bit routine for hour after hour on the same object, so myself and @Tomatobro decided to get a scope for some visual astronomy for the nights when the imaging rig behaves itself. Living in a Bortle 4/5 area and with convenient access to Bortle 3 location I wanted a decent aperture, but also mindful that it would need to be moved and setup by one person.

As you might expect, the aperture argument won out when a used 16" SW Goto Dob came up. When loading it (disassembled)  into the car after purchase I was thinking that it might be a bit on the large size for casual use, it was clearly going to need some sort of mobile base if it wasn't going to become a white (and black) elephant. So @Tomatobro came up with a low profile 4 wheel frame that the scope can sit on permanently, enabling it to be trundled out of the garage, round the side of the house and onto the back lawn by one person. And it works! From garage to lawn takes around 2 minutes of careful manoeuvring, it only just goes through the side gate and I have to watch out for a plastic drain pipe on the corner of the house. The collimation doesn't survive the journey, but I expected that, one minute with a Hotech SCA collimator puts that right.

The scope is a goto model which wasn't  working when purchased, and to date it we haven't managed to fix it despite some fantastic  assistance from @malc-c who supplied lots of knowledge and  some replacement PICs. So for now we are using it in manual mode, @Tomatobro has made and installed an azimuth protractor for the base, complete with illuminated reticle, and an inclinometer with magnetic base takes care of altitude angle measurement.  

So is it grab 'n go? Well not really, but it can be grabbed and it certainly goes on the 4 wheel trolley. I'm sure if I had gone with a 10" model I would have always been thinking what would this look like through a 16", so I have avoided that regret.

At this rate I might even post in the observing section...😉

n

 

[malc-c]

Wow, that's amazing.  I love the dolly design and the convenience it provides.

It's a shame the goto function couldn't be resolved.  We tried... I'll drop you a further PM later....

Fantastic light bucket you have there...and I'm sure it will bring you lots of enjoyment  

[Tomatobro]

We tried Malc-c we really tried to get the go to working. I do a lot of work with PIC's but in the end we went for our tried and tested Alt/Az system.

I have made a controller that operates the motors via a radio handset, Its nearly finished but will have up/down left/right fast and slow speeds and a start/stop circular search.

Thanks again for all yo did re the chips and advice.

[lenscap]

11 minutes ago, Tomatobro said:

We tried Malc-c we really tried to get the go to working. I do a lot of work with PIC's but in the end we went for our tried and tested Alt/Az system.

Have you considered building an OnStep Goto controller?

Since you have the motors in place it would be straightforward & inexpensive.

https://onstep.groups.io/g/main/wiki/3860

[malc-c]

17 minutes ago, Tomatobro said:

We tried Malc-c we really tried to get the go to working. I do a lot of work with PIC's but in the end we went for our tried and tested Alt/Az system.

I have made a controller that operates the motors via a radio handset, Its nearly finished but will have up/down left/right fast and slow speeds and a start/stop circular search.

Thanks again for all yo did re the chips and advice.

If it works then that's all that matters.  I have sent  a PM to @tomato - should you want the synscan unit looked at... You probably know more about PICs than I do, but unless the board is completely fried, there should be a way to get it back up and running...

[Tomatobro]

1 hour ago, lenscap said:

Have you considered building an OnStep Goto controller?

Thanks for the tip. I just had a quick look but I think this is only for equatorial mounts.

The Alt Az system we employ is very effective and only requires one known object in the eyepiece for calibration. Will have a proper read of the websitel tonight

[lenscap]

11 minutes ago, Tomatobro said:

Thanks for the tip. I just had a quick look but I think this is only for equatorial mounts.

No, Onstep software can be configured for any type of mount that can be driven by steppers including Alt/Az.

Examples of Dobsonian conversions here.

https://onstep.groups.io/g/main/wiki/4414

 

[fwm891]

Great project. I've been thinking along the same lines and I'm in the process of building a 16" f5 dob for visual use while imaging. I've ordered a mirror set from John Nichol and just taken delivery of some aluminium ready to start making the mirror support structure.

Enjoy, and let us know how things fare.

Francis

[Tomatobro]

1 hour ago, lenscap said:

driven by steppers including Alt/Az.

Thanks will read up later. The motors on the SW are DC with encoders.

[Marvin Jenkins]

Absolutely brilliant. A grab and go 16 inch! I have a smile a mile wide. I wish you nothing but clear skies, or even one hour breaks in the cloud.

Marv

[tomato]

Thanks Marv,

I watched a review of the SW 16” Dob on YouTube, the reviewer cautioned anyone living in a first floor flat against buying one. Now making that one Grab ‘n Go would be a real challenge…

Edited June 24, 2021 by tomato
Typo correction

[Tomatobro]

hear are some pics of the controller

[malc-c]

That's really cool.  Do I spy a microcontroller in there ? - I presume you just change some variables to match the gearing of the scope it will be used with and let it send the sidereal pulses to the steppers....?

Care to PM me some details ?