Dragon Astro 12" Dob

[Dragon_Astro]

In the past I've looked into building my own Dobsonian, but the cost of the mirrors alone made me think it was cheaper just to buy one.

The other day though I noticed on AstroBoot a complete set of mirrors from a 12" Dob, a SW 300P I believe.

Brand new mirrors, complete with cell and spider etc, so after some umming and aah-ing I bought them.

The plan is to make a truss Dob, which can be broken down to reduce storage space needed.

Ultra light "skeleton/frame" look, probably aluminium?

Ill update this thread wth pics etc as often as possible.......here goes folks! 

[Peter Drew]

Worthwhile project. Good luck!  

[Dragon_Astro]

Thanks Peter

The first hurdle will be explaining to the wife when the mirrors arrive....now that will need luck lol

[DougM43]

Have often thought of building my own telescope but not done so for the very same reason,, cheaper to just buy one,

I’ll be following this thread with interest.

[Stub Mandrel]

9 hours ago, Dragon_Astro said:

Brand new mirrors, complete with cell and spider etc, so after some umming and aah-ing I bought them.

A man after my own heart!

(Apologies if you're not a man...)

[Dragon_Astro]

1 hour ago, Stub Mandrel said:

A man after my own heart!

(Apologies if you're not a man...)

Haha yeh I'm a man  50% chance of getting that wrong lol

yeah was a big decision, but if I didn't do this project now I never will.

[Dragon_Astro]

James @ AstroBoot (very nice chap) gave me a quick call this morning, all being well I should have the mirrors sometime this coming week  

[Alan White]

I look forward to your build posts, something I would love to do myself but as a wood butcher rather than carpenter, feel may be beyond my skill set.

 

[Dragon_Astro]

To be honest I'm not much of a carpenter either, haven't done any woodwork since school (I'm 36 now).

my meccano skills are better, so will be more metal than anything lol

[furrysocks2]

Have you got a design in mind already?

I've got a 12" f/5 revelation dob and unless I sell it, hoping to re-mount the mirrors as a lighter-weight collapsible dob. I think I've settled on a design where the struts are attached directly to the altitude bearings. I like the relative simplicity and wider base for the struts which should (I guess) increase stability of the top end.

[mapstar]

Nice project and plenty of builds on here to look through.

I'm planning a 14" in the near future and will follow with interest.

Good luck with your build. 

[Dragon_Astro]

2 hours ago, furrysocks2 said:

Have you got a design in mind already?

I've got a 12" f/5 revelation dob and unless I sell it, hoping to re-mount the mirrors as a lighter-weight collapsible dob. I think I've settled on a design where the struts are attached directly to the altitude bearings. I like the relative simplicity and wider base for the struts which should (I guess) increase stability of the top end.

I think it will be quite similar to the truss dob in your photo, but maybe not so open at the bottom? I would like the altitude bearings "box" become part of the storage box when it's broken down....if that makes sense.

[mapstar]

Here's mine in the boot of the car 

[Timebandit]

4 hours ago, furrysocks2 said:

Have you got a design in mind already?

I've got a 12" f/5 revelation dob and unless I sell it, hoping to re-mount the mirrors as a lighter-weight collapsible dob. I think I've settled on a design where the struts are attached directly to the altitude bearings. I like the relative simplicity and wider base for the struts which should (I guess) increase stability of the top end.

 

Nice  Truss design?

Have you future proofed the scope?

I am sure you could get a lot bigger primary mirror in the lower cradle section.

Maybe time to start a 18" grind ?

 

 

 

1 hour ago, mapstar said:

Here's mine in the boot of the car 

 

 

That's a better fit than I had thought it maybe. For a big 22" scope then it shows you can get it in a sensible size vehicle . No need for a Chelsea then? ?

 

 

 

[mapstar]

1 hour ago, Timebandit said:

That's a better fit than I had thought it maybe. For a big 22" scope then it shows you can get it in a sensible size vehicle .

Only small for a 22" probably smaller than most 20" scopes, also get a weeks worth of camping gear in with the seats down and still see out the rear window.

 

[furrysocks2]

1 hour ago, Timebandit said:

Nice  Truss design?

Have you future proofed the scope?

I am sure you could get a lot bigger primary mirror in the lower cradle section.

Maybe time to start a 18" grind ?

That's not my scope, unfortunately.

http://members.ziggo.nl/jhm.vangastel/Astronomy/30cmscope/5_30cm.htm

[Dragon_Astro]

The mirrors arrived this morning by UPS, very well packed up as you can imagine.

I don't think I'll need to buy anymore bubble wrap for the rest of this year lol.

Until you have them in front of you, you don't really appreciate how big (and heavy) this big mirrors actually are.

Now I've got the mirrors I can start planning/making, literally from the bottom up with the box to hold the cell first.

[mapstar]

3 hours ago, Dragon_Astro said:

The mirrors arrived this morning by UPS, very well packed up as you can imagine.

I don't think I'll need to buy anymore bubble wrap for the rest of this year lol.

Until you have them in front of you, you don't really appreciate how big (and heavy) this big mirrors actually are.

Now I've got the mirrors I can start planning/making, literally from the bottom up with the box to hold the cell first.

Full steam ahead with the build 

[Dragon_Astro]

Making a start on the project has been a bit slow, as I'm working full time hours at the moment.

Ive been cutting the ply wood for the mirror box when I've had chance, the odd spare hour or so before work.

Its not looking too pretty at the moment 

[Mr Flibble]

Good luck with the build.

Plenty of pics please

[Dragon_Astro]

Progress is ticking along here, all be it slowly.

Lower rocker box is nearly finished, just lazy Susan type bearings to sort.

Next step will be to order in the aluminium truss tubes, going for an 8 truss.....1" dia tube should be ok?

 

 

[Beulah]

I used around 10swg (3.25mm thickness), just under an inch diameter (roughtly 22cm) tubes and they are pretty sturdy. If you are planning to connect the 8 truss tubes as one unit, make sure you don't overtighten the fixings as there needs to be some flexibility and movement when you construct the telescope. Once connected to the primary box and secondary cage (those fixings should be hand tight), the truss tubes are sturdy, trust me!.

The great thing is that parts can be replaced as you have made them and mods are never ending! I'm using metal wing nuts and have promised myself to replace with ergonomic plastic ones as soon as funds allow.

Pics, please!

[Stub Mandrel]

3D printed knobs can work well with stock nuts/bolts, although i'd recommend getting black high tensile ones if you can.

[mapstar]

10 hours ago, Beulah said:

I used around 10swg (3.25mm thickness), just under an inch diameter (roughtly 22cm) tubes and they are pretty sturdy. If you are planning to connect the 8 truss tubes as one unit, make sure you don't overtighten the fixings as there needs to be some flexibility and movement when you construct the telescope. Once connected to the primary box and secondary cage (those fixings should be hand tight), the truss tubes are sturdy, trust me!.

The great thing is that parts can be replaced as you have made them and mods are never ending! I'm using metal wing nuts and have promised myself to replace with ergonomic plastic ones as soon as funds allow.

Pics, please!

Mine are 22mm dia and 1.6mm wall thickness.

They are all linked together but once fitted to the rocker I use a T bar allen key to tighten them up.

The uppers are fixed with bike skewers so there's no rattle or movement on any of them. 

[estwing]

good luck with this....