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_dslr_mirrorlesss_winners.thumb.jpg.9deb4a8db27e7485a7bb99d98667c94e.jpg

JED-E3

Splitting my 12" dob.

Recommended Posts

I've decided to split my 12" Revelation/GSO Dobsonian scope. I find it a bit cumbersome to move around, and hopefully if my measurements are correct, I should be able to fit it in the boot of a smallish car with the lower section mounted on the base when finished.

I cut down the base a while ago so it's square with a smaller footprint than standard, but I've not done anything to the tube as yet, so while it's in bits I'm going to flock it, wrap the top section in matt black vinyl, fit an extra finder shoe and move the center bearing up the tube a bit. 

I'll update this thread with my progress, so far it looks like this:

post-26021-0-12510300-1397315824_thumb.j

James.

Share this post


Link to post
Share on other sites

I have a 17" Newt and a 8.8" refractor with split tubes, not for transportation purposes but for not being able to source long enough full tubes.  :smiley:

  • Like 1

Share this post


Link to post
Share on other sites

I'll be interested in your ideas for joining the two together. often though about this for my 16" f4.

Share this post


Link to post
Share on other sites

To join my tubes, as the two were  too long initially, I cut a 4" length off one of them and then cut a portion out of the resulting ring. This was then carefully fettled until it was a tight fit inside the original tube. I then attached 2" of the ring inside one of the tubes, fitted the other tube to the projecting remaining 2" of the ring and secured both tubes with csk screws. Has worked perfectly well so far.  :smiley:

  • Like 1

Share this post


Link to post
Share on other sites

You could hold the two halves together with something like this. If you are using Peters method above.

Website%20BF-1000.jpg

Edited by 8kids

Share this post


Link to post
Share on other sites

Toggle catch, but I'm sure they have other names. You see them on the front of trunks and chests.

Share this post


Link to post
Share on other sites

Yep, I've used three toggle clamps or over center latches as they're also known.

Peters method sounds nice and simple, my method was slightly less so. I made some hoops from aluminium to stiffen the joint they are rolled from 1/8" thick material but the one edge is 1/4" thick if that makes sense, it's like an angle section with one very short leg.

There is no overlap as such between the top and bottom section but the joint is quite tight and I added some overlapping bits to help align and center the tube.

post-26021-0-00740700-1397422158_thumb.j

I'll add some more pictures tomorrow when I reassemble it all.

  • Like 4

Share this post


Link to post
Share on other sites

Looks a real neat job :)

Is there enough room to move the bearing up the tube to get balance, or will you have to add weight to the mirror end to compensate for the weight of the joint?

Share this post


Link to post
Share on other sites

Hi James,

I note in your signature that you have binoviewers. I use mine with my 12" flextube with the trusses not quite extended fully (actually about 10cm from the limiting position) to compensate for the BV back focus requirement. Did you think of getting your BVs to work with your 12" rigid tube scope?

Ed

Share this post


Link to post
Share on other sites

Looks a real neat job :)

Is there enough room to move the bearing up the tube to get balance, or will you have to add weight to the mirror end to compensate for the weight of the joint?

The weight of the joint is so close to the alt bearing that I don't think it will affect the balance too much but I have moved it up the tube by about 25mm, I probably could have gone more like 50mm but that wouldn't have left much clearance on the base.

Hopefully I'll have enough adjustment without using counterweights but the flocking is going to affect the balance too..

Share this post


Link to post
Share on other sites

Hi James,

I note in your signature that you have binoviewers. I use mine with my 12" flextube with the trusses not quite extended fully (actually about 10cm from the limiting position) to compensate for the BV back focus requirement. Did you think of getting your BVs to work with your 12" rigid tube scope?

Ed

I had thought about having a removable section that I could take out to allow the use of the binoviewers but in the end I decided against it. My 8" skyliner dob has a low profile focuser and almost reaches focus with the binoviewer (without barlow) so i'm going to move the mirror up the tube and use that exclusively with the binos mostly for planetary viewing, and use the 12" for the faint stuff.

James.

Share this post


Link to post
Share on other sites

What a really good solution!! Now you get the best of both worlds. :cool:

When I came to measuring up the back seat of my motor for a solid tube 300P I found it was never going to fit. Being a fan of solid tubes over flexi I decided to stick with a 200P but this would have been the ideal solution for me. I bet cutting the OTA got the heart a pumping a bit though didn't it ? :D

  • Like 1

Share this post


Link to post
Share on other sites

Jed,

Can you please take a photograph of the tubes taken apart? I would have thought some sort of rebate/inner sleeve around the circumference of the tube where it is split would take the strain off the clasps when the telescope tube is tilted.

Share this post


Link to post
Share on other sites

Jed,

Can you please take a photograph of the tubes taken apart? I would have thought some sort of rebate/inner sleeve around the circumference of the tube where it is split would take the strain off the clasps when the telescope tube is tilted.

The tube is held under tension from the latches and cannot slide sideways because of the little luggs shown in the following picture.

post-26021-0-06268400-1397507081_thumb.j

Share this post


Link to post
Share on other sites

It's basically finished now, I've collimated it and just need to fine tune the balance.

post-26021-0-18731400-1397507256_thumb.j

It's ok with the Telrad and a lightweight eyepiece, I need to adjust it with both finders and a midweight eyepiece.

post-26021-0-60917600-1397507477_thumb.j

It goes together and comes apart very easily, I think having adjustable latches is a must, there's a fine line between too tight and too loose.

post-26021-0-71523900-1397507655.jpg

I'll try and fit it in my car tomorrow, it is possible to lift the base with the lower tube fitted but it's heavy, probably 30kgs, I might fit heavy duty handles to the sides, I also plan on making a solid cover for the lower tube, so I'll add more photos when done.

James.

  • Like 3

Share this post


Link to post
Share on other sites

Great job james, I must admit at first I wondered how this was going to end .....but im glad to say this is a really professional looking finish.

well done !

Share this post


Link to post
Share on other sites

lovely job james, very brave, i thought i was brave adding a stiffner tube around my focuser but that is extreme, brilliant job mate

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.