Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_30_second_exp_2_winners.thumb.jpg.b5430b40547c40d344fd4493776ab99f.jpg

astrolunartick

20inch Dobsonian Construction

Recommended Posts

Cheers Pete, I am just curious as I am not too sure whether to reuse the secondary support vanes from the cannibalised 8" scopes I have to make a suitcase dob or to start afresh... I'll keep watching to see how you go then decide ;)

Hi again Soupy

I have made a few suitcase scopes and i used the spider vanes from the scopes i salvaged the optics from. If the vanes are in good condition and made well. you might as well.

Pete

Share this post


Link to post
Share on other sites

Hi again Scopes 

I finally got to spend some time in my workshop. 2 whole evenings. such bliss  :grin:  

So heres some photos of the progression so far.

Firstly cutting up the Birch plywood for the secondary cage and for the Mirror box and mark out and router lots of circles   

post-5432-0-79535400-1431646408_thumb.jppost-5432-0-61464600-1431646678_thumb.jppost-5432-0-15964000-1431646424_thumb.jppost-5432-0-36437700-1431646803_thumb.jp

I decided to use 3mm Bend birch Ply for the secondary cage so i choose to rebate the inside edge of the rings so the ply would have some thing to butt in to.

post-5432-0-50317800-1431647069_thumb.jppost-5432-0-84155200-1431647093_thumb.jp 

Here i drilled location holes for the poles

post-5432-0-34323200-1431647406_thumb.jp

drilling for dowels and Fitting the quick release pole attachments

post-5432-0-15877800-1431647728_thumb.jppost-5432-0-18874700-1431647760_thumb.jppost-5432-0-64907300-1431647533_thumb.jp

partially Assembled 

post-5432-0-99025300-1431647206_thumb.jp

Then i moved on to dovetails for the Mirror box. Ive not done dovetails for about 15 years so i was eager to try some new tricks i had discovered from the internet and my new Japanese Dozuki (Pull Saw) I also made a magnetic dovetail guide. I highly recommend this and the Dozuki. 

post-5432-0-06842800-1431647873_thumb.jppost-5432-0-88286200-1431647898_thumb.jppost-5432-0-73481000-1431647987_thumb.jppost-5432-0-48370100-1431648463_thumb.jp

Finally i began building the side bearings

post-5432-0-93813700-1431648592_thumb.jp

Edited by astrolunartick
  • Like 1

Share this post


Link to post
Share on other sites

Here's one more pic with me in it for scale. The pole length will be shorter by about 8 inches. so the final scope will be a tad shorter. 

post-5432-0-73784100-1431649191_thumb.jp

  • Like 1

Share this post


Link to post
Share on other sites

Great work Pete it's coming along nicely, love the magnetic dovetail guide idea.

  • Like 1

Share this post


Link to post
Share on other sites

Looking really good Pete. Nice to see some dovetails. Man they is sweeeeeet :)

  • Like 1

Share this post


Link to post
Share on other sites

Great progress in just two days Pete and thanks for all the photo's of what is looking like a very nicely constructed scope.

The hand cut dovetailing looks a proper job and always nice to see . I did the same for the upper cage with the aero ply for my scope build rebating 3mm which really add's to the strength. 

I envy the amount of space in that workshop of your's, it's probably the biggest problem I have as when you get 3 sheets of 8x4 in a 20x12 garage it makes it look very small. I also notice the table saw is wood too along with your bandsaw is that another fine effort by yourself.

Will you be bevelling the front lower edge for more clearance as many do on the classic dobs or leaving the box as it is? 

The Dozuki  saw and dove tail jig/guide are usefull tips cheers  :wink:

Damian

  • Like 1

Share this post


Link to post
Share on other sites

Beautiful telescope coming together there! Thanks for all those pictures, it looks like you have a lot of experience judging from the workmanship. I am envious of your workshop and all those neat tools.

  • Like 1

Share this post


Link to post
Share on other sites

Great progress in just two days Pete and thanks for all the photo's of what is looking like a very nicely constructed scope.

The hand cut dovetailing looks a proper job and always nice to see . I did the same for the upper cage with the aero ply for my scope build rebating 3mm which really add's to the strength. 

I envy the amount of space in that workshop of your's, it's probably the biggest problem I have as when you get 3 sheets of 8x4 in a 20x12 garage it makes it look very small. I also notice the table saw is wood too along with your bandsaw is that another fine effort by yourself.

Will you be bevelling the front lower edge for more clearance as many do on the classic dobs or leaving the box as it is? 

The Dozuki  saw and dove tail jig/guide are usefull tips cheers  :wink:

Damian

Hi Damian 

I will indeed bevel the front lower edge. need to get the scope as low as possible. Check out David Barron on Youtube 

Lovely guy and full of useful wood working tips

Pete

  • Like 1

Share this post


Link to post
Share on other sites

Great instructional video Pete he makes it look so easy!

Fan housing looks great too, with lovely dove tails on your corners as well :)

  • Like 1

Share this post


Link to post
Share on other sites

I got the Tailgate sprayed up and the fan mounted on springs to some aluminium bar screwed to the back of the tailgate. All is assembled and ready to go. 

post-5432-0-25659600-1432245206_thumb.jppost-5432-0-07172900-1432245226_thumb.jp

  • Like 1

Share this post


Link to post
Share on other sites

Hello David. 

I used Ash hardwood for the blocks but any hardwood with tight straight grain like Ash, Beech, Birch, Maple, Mahogany should do. Your question in regards to the way the secondary spider is mounted in the secondary cage, pushed me to work on just that today. so heres some images. I used 10mm m6  round threaded sleeve nuts which i cut a slot in with a hack saw and drilled a 2mm hole  for a 2mm sellock roll pin that holds the round threaded sleeve to the spider vane.  All parts i purchased from Ebay. I will be spraying most of this matt black.

hope that helps

Pete 

attachicon.gif20150506_203624.jpg

attachicon.gif20150506_203703.jpg

attachicon.gif20150506_203633.jpg

Hi,

Not done any of this sort of thing, just following the thread. You mentioned mahogany. I have used this wood for various things in the past. It tends to go very brittle and can split easilly. Ash on the other hand is really tough and very strong as is Oak.

Derek

Share this post


Link to post
Share on other sites

Hi,

Not done any of this sort of thing, just following the thread. You mentioned mahogany. I have used this wood for various things in the past. It tends to go very brittle and can split easilly. Ash on the other hand is really tough and very strong as is Oak.

Derek

Hello Derek.  

Ive used Mahogany for years. Ive made Musical instruments, windows, doors, stairs and many other Projects using it and never had a problem with it going brittle. My luck maybe. who knows. I will look in to this thanks mate . ;-)

Peter

Share this post


Link to post
Share on other sites

Hi Peter,

It may be the wood that I was given. I got a load of mahogany benches from Newcastle University several years ago when the chemistry and physics teaching labs were shut down. They were very old. Several of them when cut bowed and when items were made tended to (split is not the correct word) but were easily chipped. They were not as strong as I was expecting. I have used loads of Ash and it is much stronger, as is the Oak I've used. We also have Mahogany furniture that was broken when my late father feel on it. I was very surprised. It could have just been my bad luck!

Regards,

Derek

Share this post


Link to post
Share on other sites

Hello again. Here is another update. I managed to get 3 evenings and all day Saturday this week to work on the scope. As i always do when a project gets to the hardcore part of building, I forget to Take photos along the way. So The Rocker box is missing details but i will get some more photos of that next week.  

After one evening cutting up the side bearings. I chose to put the brace for the truss cut out on the outside of the bearing. So that i wouldn't have to mess around with the shroud. 

post-5432-0-91233100-1432500315_thumb.jppost-5432-0-19259100-1432500519_thumb.jppost-5432-0-94292000-1432500540_thumb.jp

I also got some Handles made for the mirror box as I came to realise how Heavy this is going to be. I had some Ash and some 32mm Aluminium pole left so I constructed them using those.

post-5432-0-31806800-1432500625_thumb.jppost-5432-0-94735400-1432500646_thumb.jp

I made the central part of the Spider from Ash turned on my Lathe. Drilled a 8mm hole through the centre and cut 4 rebates out for the spider vanes to fix too.

post-5432-0-02073600-1432500758_thumb.jppost-5432-0-16574300-1432500792_thumb.jp

Got the Focuser fix ;-) 

post-5432-0-23767200-1432501026_thumb.jp

I spent Saturday building the rocker box had a very fumey evening with the smell of contact adhesive in the workshop after glueing the formica to the underside and to the side bearings.

post-5432-0-67111200-1432501166_thumb.jp  

post-5432-0-05890800-1432501368_thumb.jppost-5432-0-57153600-1432501350_thumb.jppost-5432-0-07434300-1432501392_thumb.jppost-5432-0-95526200-1432501413_thumb.jp

Edited by astrolunartick
  • Like 4

Share this post


Link to post
Share on other sites

Fantastic work Pete and a truly nice construction. Nice photos too thanks for sharing them.

That central boss for the spider looks like the one I made for my last scope build

Works really well.

Where did you get the formica from as I prefer the black to the green I have. How do you intend to finish it? Varnish or painted? Or possibly stain?

Damian

post-28847-0-92279200-1432503054_thumb.j

  • Like 2

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.