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Lightbridge II

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#1 Aperturefever

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Posted 06 April 2012 - 07:16 PM

Once – a very long time ago when I was in the second grade – my teacher rang my parents, greatly concerned. One of the kids had told her of my plans to blast off for the moon the following day in a spaceship I had cobbled together in my dad’s garage. My teacher was concerned that I was either dellusional, or was going to take half the neighbourhood with me if I used my dad’s huge tin of Shell A Racing Fuel as propellant for said spaceship, or a combination of both. Needless to say, blast-off was aborted and my old man disassembled my spaceship that was taking up all his shed - and was almost crushed in the process, as one end was nailed to the wall. I know, I know ... but it was a minor design flaw that I was going to take care of. Happily, my dad healed up just fine and has kept me in the will.
What has that got to do with the Lightbridge II?
It struck me as I modded up my year-or-two old Lightbridge how much amateur telescope making (ok, modding in my case) rekindled the little kid dying to get to the stars. In a way, you’re 10 again, building a spaceship – the difference is you really take flight ... and there’s no apparent danger to the immediate neighbourhood.
Oh - and I didn’t nail this one to the wall of the shed!

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#2 Aperturefever

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Posted 06 April 2012 - 07:17 PM

I wasn’t interested in taking out the optics and building something entirely new. Frankly, I think the Lightbridge is a good-looking telescope. What I set out to do was create a new Lightbridge that may have come about if price was not a governing factor to manufacturer and consumer. I think Meade should be congratulated for putting a decent-sized dobsonian out there at a budget price. There was plenty of reading material on the web to ensure that I completely understood what I was getting.
Did I need to do all this to my Lightbridge? No. It worked fine. I remember one fine winter night shooting down globular after globular. Paired with good eyepieces and Paracorr II I’m happy as can be. But ... after bolting on a Farpoint counterweight system, then adding an extra counterweight, then watching the Paracorr/21 Ethos-laden nose sag to the horizontal, I decided it was time to act. And a wise call it was, too, as the east coast of Oz has just endured one of the coldest, wettest, cloudiest summers I can remember.
I am well pleased with the result. It is an easier telescope to set up and use. I might add that I am no trailblazer here, and have copied and drawn on the knowledge of others. The side bearing thing is about the only thing I haven’t seen done to a Lightbridge in this way.

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#3 Aperturefever

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Posted 06 April 2012 - 07:18 PM

It all began with the altitude bearings, which decided everything else mechanical about the re-design. Bigger means better, smoother tracking, as well as a smaller rocker box and better balance. That old particle board monstrosity had to go. So I got a piece of cardboard and made a template. I settled on a size that matched the diameter of the tube. As it is not a box shape, anything bigger would have started to get unwieldy. I also like the matching symmetry. I added cut-outs to lighten the load, and matched them to the circle cut-outs within the existing side bearings ... I insist it’s symmetry, not obsessive compulsiveness!
I briefly considered making the new bearing out of metal, but I’m no good at metalwork. Wood is another matter. So I checked in with my dad, a woodworker in the antique trade. Sometimes, when he can’t rescue an antique, he rescues the wood. He fished out a piece – old shelving – from under the house that he declared ‘‘pretty solid’’. It looked like grey gum (Janka scale rating of 14), ate a bandsaw, a jigsaw, two brand new blades and had scorch marks from the cuts by the time I had fashioned what I wanted.
Bonding my new wooden bearings to the existing metal ones was a crucial step in the process. I used Devcon FasMetal 10 HVAC 19770 - made in Massachusetts. It’s real strong. How strong? They glued Australia to the bottom of the planet with this gear, and it’s still there. OK, I made that bit up, but it’s serious stuff all the same: aluminium-filled two-part epoxy that I had to go to a specialist outlet for. I simply wasn’t prepared to risk anything cheaper that mightn’t work. I had a working time of 45 minutes or so and setting time of two hours, which suited me just fine. I roughed up the metal bearing surface, said a prayer, wondered briefly if it is possible to order replacement Lightbridge bearings, then took the leap of faith.

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#4 Aperturefever

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Posted 06 April 2012 - 07:20 PM

Having sorted that out, I disassembled the old rocker box (the lazy susan bearing had a kink in it - no idea how that happened) and traced out the side onto a piece of cardboard. I then used the side bearing template as an overlay and dreamed up the new design.
I used marine ply for the rocker box and ground board. I glued and screwed it, puttied it up, and sanded and primed it several thousand times. Although I changed the colour I decided to drive myself nuts adding black trim to preserve the original theme. I got online and made up a Lightbridge II sticker, hoping fervently Meade’s solicitors would see it as just a bit of fun, and it was mailed to me within a few days. Then I sealed it all up with a coat of polyuerethane. There might be a couple of minor blemishes here and there ... but it’s a telescope. It’ll be dark, right?

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#5 Aperturefever

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Posted 06 April 2012 - 07:21 PM

Red? Why? Well way back in the olden days – as the impending visit of Halley’s Comet loomed – I drooled over a bright red Tasco three-inch reflector as a teenager. I used to stare fascinated at the box it was assembled from in the shop; thinking that those amazing images of Jupiter and co simply must have been snapshots right out of the eyepiece ... right?! Anyway, I was scarred for life - by the red colour scheme that is, not the false advertising. That little three-incher now sits by the french doors in my study.
Initially I envisaged all white with black trim, and just trying to make it look like it came out of the factory. But while designing my decal online, and trying to get the fonts to match, I found one I liked better. Which got me thinking the Lightbridge II could be a bit different while keeping the essential spirit of the original. Thanks to my Tasco experience, as a youngster I was always designing gigantic red scopes. Lots of people remake their bases and go for the wood look, but I wanted everything to tie in (there goes that obssessive compulsive thing again). It also took the pressure off my woodworking cause I knew I could bog up my mistakes and cover them with paint! Hooray! And anyway ... the red will help preserve my night vision!

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#6 bherv

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Posted 06 April 2012 - 07:43 PM

Very nice work. I like the color.
Barry

#7 Gastrol

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Posted 06 April 2012 - 07:51 PM

Very nice! I especially like the bearing mod. Well thought out.

#8 tezster

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Posted 06 April 2012 - 08:18 PM

Very eye-catching :)

#9 pdfermat

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Posted 06 April 2012 - 09:39 PM

Elegant.

#10 mak17

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Posted 06 April 2012 - 09:54 PM

Impressive.

#11 cchapkido

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Posted 07 April 2012 - 05:55 AM

How strong? They glued Australia to the bottom of the planet with this gear, and it’s still there.


Nice work and entertaining read, thanks.

#12 Scanning4Comets

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Posted 07 April 2012 - 07:10 AM

Very nice indeed ! :bow:

Love the RED

Cheers,

#13 Aperturefever

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Posted 07 April 2012 - 08:14 AM

Thanks for the positive input everyone. I had a blast doing it. Obviously the earlier photos show the scope as I was making sure I got the design elements right - hence the paper towel instead of teflon! :grin: The later shot also doesn't show the couple of internal metal brackets and bumps that keep this thing sitting in the right spot ...

#14 Aperturefever

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Posted 07 April 2012 - 08:17 AM

It’s always the little jobs that trip you up. And so it was I lobbed over to my mate Paul’s place. Paul has a welder; a friend in need is a friend indeed, as they say. ‘‘Just weld this nut onto this metal plate and drill a few holes,’’ says I. ‘‘Should only take us (as if I was going to be any help) 20 minutes.’’ Old mate whips out a plate of stainless steel instead when I mention the ability to avoid rust. And so we welded on the nut ... after which we discovered how tricky it is to keep a small plate of stainless from warping. So we banged it with a big mallet thing (I’m no metal worker) and yelled at it. For some time. ‘‘Oh dear,’’ we chorused as it came out of the vice for the umpteenth time. ‘‘Look how difficult stainless is to work with.’’ OK ... we didn’t say that exactly. But this is a family website. And after an extended session we came up with a nice pivot assembly ... that is more or less straight!
The real fun part of amateur telescope making, or modding, is the unexpected discovery. I dropped into a nearby industrial estate to chase some laminate at a showroom. Knowing there was no chance of ebony star I asked for something with a suitable surface pattern. The woman in the showroom looked at me blankly, then explained how virtually everything was smooth these days because of manufacturing costs.
She then pointed out a nondescript cabinet maker down the road and advised me to try my luck there. After going through the same rigmarole I was sent to the "back roller door" where there "might be a few offcuts". A workman sent me to a bunch of pigeon holes to try my luck. I pulled out a few bits of laminate that had a suitable surface, was just about to call it quits when I decided to stick my hand in amongst a bunch of real dusty stuff. My fingers ran across something interesting so I pulled it out: it had a familiar look to it. I turned it over and saw the familiar Wilson art stamp .... And old school ebony star code! I couldn't believe my luck! A huge bit, too. "Mate, 20 bucks will do ya," says the workman. It's funny how happy a dusty piece of laminate can make you.

#15 Aperturefever

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Posted 07 April 2012 - 08:30 AM

So everything has gone together well. Preliminary testing says it's smooth as silk, and less temperamental with balance. I have a Farpoint counterweight set with two two-pound add-ons, and it balances out a Paracorr II, Ethos 21, 50mm finder and Telrad smooth as silk, even when it’s pointing low. I added handles on the side of the rocker box and it's down to 30 pounds from the 54 of the original. After I took the pics I added big washers to the secondary spider anchor points so I can tighten it right up without dimpling the tube, and turned the focuser 45 degrees to make it easier to use. I have installed a Noiseblocker Multiframe fan to replace the stock fan. This thing is so powerful it will suck low-lying cloud cover out the atmosphere, so I have a variable speed control which I am in the process of mounting in a little enclosure which will bolt to the inside of the rocker box. This will work in with a di mauro baffle which I have yet to complete.
I will flock it eventually, but I regard this as being at the lower end of the scale of bang for buck. I will also do the standard upgrade of the mirror cell covered in other parts of this forum so well, and whack in some aftermarket knobs - I like the look of Farpoint best. But frankly, the optics are good, it collimates fine and it's just not a priority.
I’ve hassled the life out of Alex – Maroubraboy of sketching fame here at Cloudy Nights – with a million questions over the past couple of months, which he has patiently answered and put up with my warped sense of humour. I’ll be sure to pass the karma on to the next bloke who needs a hand.
I’ve also picked the brains of ThreeD, Starman1, careysub, sixela, cavefrog and George Goltzin over the past number of months – so thanks your help fellas. I think we created a monster!

#16 oldmapman

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Posted 07 April 2012 - 08:31 AM

Very Nice...

#17 cheapersleeper

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Posted 07 April 2012 - 08:39 AM

Every time I look at a stock Lightbridge I think "Nice looking scope but those bearings are too small1!" Wonderful to see your solution. Interestingly, I suggested that solution to someone on this site, but they declined to do it. I think they will look at your scope and smack themselves in the forehead.

Regards,
Brad

#18 Old Rookie

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Posted 07 April 2012 - 09:06 AM

Excellent job and good choice on the red. Those bearings have to be an improvement over the stock bearing.

#19 Jb32828

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Posted 07 April 2012 - 10:27 AM

Wow, I hope Meade looks at this thread to see what their flagship dob could really be. Very impressive.

#20 ThreeD

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Posted 07 April 2012 - 10:47 AM

Very nice!

I've been slowly building a new base/bearings for mine as well. It's just a very slow process due to the lack of spare time to work on it. (I just need to finish sanding it so I can stain, varnish, and assemble.)

Mine will be a bit larger due to my desire to completely eliminate the use a counterweights with a SV60 finder and telrad mounted while using a Paracorr and TermiNagler. I'll end up adding weight up top when the EP drops back to a lone ortho but I hope to avoid trips to the back of the scope. I'm also removing the aluminum bearings and replacing them with wooden ones rather than adding wood around the aluminum. By adjusting where the lower tube mounts to the bearings I can fine tune the balance.

Oh, and mine won't be color matching my OTA. Hopefully I'll be posting pics within a few weeks but it's tough due to being at basketball tournaments every weekend. (It's about time to head out to the court as I type!)

Again, nice job. It looks fantastic.

#21 Gastrol

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Posted 07 April 2012 - 10:48 AM

Just curious, would offsetting the stock bearings rearward and deeper a few mm's within the new oversized bearings improve balance as scope is pointed at lower angles? This in effect moves the altitude pivot point on the scope just a tad forward, eliminating the use of counterweights for the most part.

I was thinking of moving the stock bearings a bit higher on my Lightbridge, but that would also require a slightly taller rocker box.

#22 sevenhelmet

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Posted 07 April 2012 - 02:17 PM

I'm not sure you can move the stock bearings on a Lightbridge. Mine seem to be an integral part of the lower OTA.

I've thought about adding radius to my altitude bearings like the OP did though. I like the Lightbridge II.

#23 Ed D

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Posted 07 April 2012 - 06:42 PM

Wow, that is really nice, and I like the red!

Ed D

#24 ThreeD

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Posted 08 April 2012 - 02:01 PM

Just curious, would offsetting the stock bearings rearward and deeper a few mm's within the new oversized bearings improve balance as scope is pointed at lower angles? This in effect moves the altitude pivot point on the scope just a tad forward, eliminating the use of counterweights for the most part.,

I was thinking of moving the stock bearings a bit higher on my Lightbridge, but that would also require a slightly taller rocker box.

Absolutely. That's what I'm doing with my base rebuild. When experimenting with bearings prior to starting the actual base, I was able to place them such that the whole OTA with a SV60 finder, telrad, Paracorr, and 31mm Nagler balanced perfectly (when the bearings were resting on my saw horses). I could adjust the altitude to any angle and let go and the scope would not move at all -- with no counter weights!

I was also careful to make sure that the COG of the entire assembly was along a line that is parallel to the tube axis and passed through the center of the original bearing. Doing so made it so I only need to adjust the bearing up/down along the tube to tune it for the desired EP weight thus simplifying any minor tuning I might do.

#25 Aperturefever

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Posted 09 April 2012 - 06:16 AM

Thanks again for the positive feedback. You sometimes question yourself in the dark of cloudy nights within the depths of your shed!
Brad, great minds think alike :grin: but I can understand someone's reluctance to mess with the bearings. It's a little bit all or nothing, really.
Scott, I'm looking forward to seeing what you come up with. Of course the ultimate solution would require no additional weight. I'd already splurged on the Farpoint counterweights and didn't want to look at puckered old holes in the tube so I went this way. I don't mind the few extra pounds. And I know what you mean about time being of the essence. The thing I liked about this project was the fact that I could still use the scope until the last week, when I joined the new bearing to the old. Because of that I just took my time over the summer, which was unbelievably cloudy, wet and cool on the east coast of Australia.
Oh well ... blame it on the Cloudy Nights!






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