Creating the Lightbridge II

[aperturefever (Sean)]

This is the story of how you can get carried away with modifications to a dobsonian ... or perhaps I mean warning! It all began with a 16" Lightbridge I bought few years back from Bintel. While I was quite happy with the performance, balance was a bit of an issue, even with a Farpoint counterweight system. I purchased the scope always intending to make a lighter, smaller rocker box. After some time under the stars, I decided bigger side bearings while I was at it would not only help balance, but also make for smoother motions. After a bit of design work, I came up with this - a marine plywood base, and bearings made out of some antique shelving out of a store. Whatever that wood was, it was hard as the hobs of hell - which was what I wanted. Oh ... putty was the other main component of this build

[aperturefever (Sean)]

Sandpaper and putty are marvellous inventions: so is bright red paint. My amateur woodworking and a billion hours of impatient sanding are happily cloaked in a nod to my youthful days of astronomy and a bright red Tasco three-incher that I chased Halley's Comet with. The larger bearings meant I could drop the height of the rocker box, which I squared off as opposed to the original gigantic round base. I added some cutouts to lighten the load a bit more. The bearing size actually matches the diameter of the tube. It's all about symmetry. I added the black striping not only to drive myself nuts with masking tape, but to follow the general styling of the original design.

[aperturefever (Sean)]

It took a leap of faith to attach the new bearings to the existing ones; I was, after all, attacking a perfectly good telescope - and from this point on there was no going back. A splashed out 40 bucks on an aluminium-filled two-part epoxy to 'glue' the wooden bearings to the metal ones (more like weld). Thankfully it all came together fine - dry fitting is imperative to peace of mind. The Davcon epoxy set like a rock and some months down the track, I have no reason to believe there will ever be a problem with this mod. Holding my breath, I did a dummy fit to make sure I hadn't somehow got any measurements wrong. I was massively relieved to find out all was good.

[aperturefever (Sean)]

I just love it when a plan comes together. I drove to an industrial estate at Cardiff on the search for some laminate that might do the job. After a couple of failures I ended up at a workshop and was directed to a dusty corner and a whole bunch of offcuts. Among it all I found a sheet of Wilsonart Ebony Star, the old original stuff. Mine for 20 bucks. There is a God.

[aperturefever (Sean)]

I am happy with the results. Smoother motions, better balance, far easier to set up. I will add a small brace on the underside of the scope between the bearings just to address some very minor flexing, which appears unavoidable due to the size of the bearings. A Noiseblocker fan, which is adjustable, and Di Mauro baffle, along with tweaks to the mirror cell should polish things off. Oh, and some flockboard in the tube. Oh ... and a 80mm finder .... and ...
Many thanks to Alex - Mental4astro - for patiently suffering through a million and one questions during this rebuild ... I think we created a monster Alex!

[DJ N]

Wow........ what an absolutely A1 job.

Congratulations. I imagine the base would now weigh significantly less.


Cheers

Daniel

[ZeroID (Brent)]

Awesome !! Love the red and black paint job. Don'tcha just luv DIY ??
Well done, it looks really good. ...

[mozzie (Peter)]

what a fantastic job.... you must be happy with that rocker box...they are quiet large and heavy...alex is very knowledgable in regards to atm and his many ideas...also a tops bloke...hope to see it at iisac 2013 next year for a close up look....

[DavidU (Dave)]

Oh yes ! verrry tidy job.

[aperturefever (Sean)]

Thanks for all the kind comments guys
You're right, Brent, DYI is awfully good fun - lucky it was such a cloudy and wet summer cause it took me that long. The red of the tube is actually Avery vinyl wrap - goes on with a heat gun and a little soapy water. It protects the finish underneath and comes off with heat if I ever decided for a change of colour - but red will do me just fine!
Daniel the official stats put the old base at 54 pounds or about 24.5kgs. The new version is about 30 pounds or 13.6kgs, so I almost halved it. Perhaps I can use the old base as a lazy susan on our dinner table!
Peter ... I'll start lobbying for a leave pass for IISAAC 2013 ... if you take a close look it won't even wreck your night vision: it is red, after all