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Lightbridge 12 new base project

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#1 Gastrol

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Posted 12 November 2012 - 01:39 PM

Hello.... Here are some build photos of the new base I'm currently working on for my Lightbridge 12.
I'm using 1" hardwood plywood throughout.
I added leveling feet to make leveling easier when using setting circles where a level base is critical for its accuracy. This sure beats getting down on my hands and knees to use shims to level the base.
The ground board is only 18" in diameter, plus a couple of inches for the ears for the leveling feet. This is much smaller than the stock ground board diameter of over 22". Actually, the new azimuth bearing contact diameter will be larger than stock.
The altitude bearings are 24" in diameter, roughly 1.7x the OTA diameter. Hopefully, I won't be needing counterweights when switching from light to heavy eye pieces. I also moved the scope's horizontal center point of gravity slightly higher up the OTA for better balance.
The base will be painted white to match the scope.
I'll be posting more photos as I near completion.

Thanks for looking.


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#2 Project Galileo

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Posted 12 November 2012 - 01:50 PM

Slick!

#3 Gastrol

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Posted 14 November 2012 - 11:54 AM

Here's a size comparison between my old modified/downsized stock base and my new base.
Although I trimmed bits and pieces from the stock base to make it quite a bit smaller and lighter the new plywood base is by far much lighter and more compact.
A cutout will be made at the front of the base for the azimuth setting circle.

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#4 starman345

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Posted 14 November 2012 - 01:17 PM

You would think the manufacturers of these big dobs would go with something this elegant, light, but yet simple, of course with your setup they wouldn't have anyplace to put their LIGHTBRIDGE logo. I love those leveling feet, talk about the ultimate in convenience :bow:

#5 Gastrol

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Posted 14 November 2012 - 01:39 PM

Thanks guys!

I think, in general, the problem with manufacturers using pressboard is that bases need to be kept overly large in order for them to be strong and long lasting. Anything compact and or skeletal can be made as rigid out of pressboard but might not last that long with prolonged use.

#6 ThreeD

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Posted 14 November 2012 - 02:30 PM

Wow, that looks nice!

Not sure how well it is going to balance... I built a new base for my LB16 and can now use it without any counterweights (from naked BGO to 31T5 with Paracorr) but the center of radius of my trunnions seems to be several inches higher than yours. Then again, yours is a 12 and mine is 16. It does look great though...

EDIT: I went back an read how you said the center is a few inches up -- that should work. I think I moved mine up 2" or 2.5". (I weighed everything, calculated the moment arms to determine where the trunnions needed to be, and it all worked out great.)


#7 Gastrol

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Posted 14 November 2012 - 02:42 PM

Not sure how well it is going to balance... I built a new base for my LB16 and can now use it without any counterweights (from naked BGO to 31T5 with Paracorr) but the center of radius of my trunnions seems to be several inches higher than yours.


Thanks! Actually, my trunnions are less than a half circle (less than 180°) so that puts the center of diameter and pivot point about an inch higher than the middle of where the old alloy trunnions used to be. I'm pretty certain it will balance well, at least better than before with the stock alloy trunnions. :)

#8 jgraham

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Posted 14 November 2012 - 04:06 PM

Very nice! That'll look really sharp when it's finished.

#9 Gastrol

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Posted 14 November 2012 - 04:47 PM

Thanks for the additional comments!

I originally wanted to move the pivot point just a tad over 2" above the factory pivot point but at the same time wanted the base to be as low profile as I can get. I compromised and decided to go only an inch higher instead. This most likely means having to use the FarPoint counterweights which I don't mind as I already have a set of them, besides, they look elegant.

#10 Gastrol

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Posted 15 November 2012 - 11:58 AM

I made a cut out at the front of the base for the azimuth setting circle. I also started applying thin coats of white primer to the base. The base will end up with gloss white paint to match the rest of the scope.

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#11 Scanning4Comets

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Posted 17 November 2012 - 03:37 PM

Ohhhhhh....

Amazing craftsmanship !

This will be an interesting thread!

Cheers,

#12 Gastrol

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Posted 29 November 2012 - 12:03 PM

Slow progress but the base is done except for a few minor details.
The next step is finish mounting up the humongous alt bearings to the Lightbridge LTA.

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#13 rguasto

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Posted 29 November 2012 - 12:23 PM

WOW!

#14 Project Galileo

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Posted 29 November 2012 - 01:26 PM

That looks great. The black setting circles ring is wonderful too. Well done!

#15 Pinbout

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Posted 29 November 2012 - 04:17 PM

yes the black does look really sweet with the white base.

#16 Gastrol

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Posted 29 November 2012 - 04:22 PM

Thanks guys, and thanks to Pinbout for that setting circle pdf. That white on black really stands out.

#17 Gastrol

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Posted 02 December 2012 - 12:09 PM

With no counterweights I have no balance issues going from no EP to the heaviest EP until I bring the scope to about 30° altitude. Looks like I will be re-installing the set of Far Point counterweights at the rear cell.

I'm also having second thoughts about the black color of the altitude bearings looking too obtrusive due to their large size. Perhaps they should be white as well so they can blend in with the OTA.

Another mod I will be making is to add a circular strip of aluminum around near the bottom of the trusses, riveting each truss pole to the strip, thus enabling the upper tube assembly and the trusses to be installed and removed as a single, large component, similar to a split-tube dob. Portability is not important for me.

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#18 Old Rookie

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Posted 02 December 2012 - 12:31 PM

That is a very nice looking telescope. I'll bet the movement is quite a bit smoother than stock.

#19 pdfermat

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Posted 02 December 2012 - 12:57 PM

That is truly a thing of beauty!

#20 Project Galileo

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Posted 02 December 2012 - 04:34 PM

I really like how it all gives the feeling that the telescope is floating. Really well done.

#21 rguasto

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Posted 02 December 2012 - 05:00 PM

Leave them black!

#22 Aperturefever

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Posted 02 December 2012 - 05:32 PM

Mate,
That's a first-class job. Well done. :waytogo: I reckon leave them black - white might get scuffed up too easily.

#23 Scott in NC

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Posted 02 December 2012 - 05:37 PM

Very nice work! :bow:

#24 Astrojensen

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Posted 02 December 2012 - 05:44 PM

Extremely nice! I am thinking about converting my own 12" LB, but was thinking more along something Obsession-lookalike. Your design is refreshingly original and very well thought out.


Clear skies!
Thomas, Denmark

#25 starman345

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Posted 02 December 2012 - 05:52 PM

Personally I like the black altitude bearings, it gives it just enough contrast overall with all the white.






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