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The Evolution of a Lightbridge 16.

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#1 Project Galileo

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Posted 11 November 2011 - 01:40 PM

In June of this year I had the opportunity drive from Denver, Colorado to St. George, Utah. The trek was to buy a wonderful Lightbridge 16 from another astronomer. He had purchased it new from a store in Las Vegas. However, his aperture fever brought him an Obsession 20 shortly after he bought the Lightbridge. So the 16 was left in the garage covered, unused, and alone. I was a lucky man because I got to buy this nearly brand new telescope.

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His additions included an Astrozap light shroud, a Telrad, a set of 3 x 1 lb. Far Point counter weights, 2 x 2 lbs. clip on JMI weights, upgraded Far Point collimation knobs and springs, a JMI deluxe transporter storage kit, and a JMI wheely bar cart. All together his additions brought the complete package to over $2500. I got it all for almost half of that. It was a no-brainer and I got in my Kia soul to go pick it up. Yes, it does fit with the back seat folded down.

On a side note he also had a digital setting circles push-to computer system mounted on it he was selling too. I had him remove it feeling it was unnecessary for my needs.

So that is how it started. I have enjoyed the scope through the summer and fall and really have been stunned by it's essentially out of the box performance. Aperture really does rule. I have forsaken all my other telescopes this summer leaving them sit and wait while I enjoy the Lightbridge. The improvement in views and function of this telescope from my previous Dobsonians is profound. I have enjoyed an Orion XT8 classic and an XT10i. Both were fun to use, modify, and improve. However, out of the box, this 16 smokes them.

It is time to modify and improve this one however. I knew all along that this time would come. With all of my scopes and mounts I have loved overhauling, supercharging, modifying, and pimping them out. This one will be equally fun bringing its own set of challenges.

That is what this thread is about. The evolution of a Lightbridge.

#2 Project Galileo

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Posted 11 November 2011 - 02:01 PM

My need to start the upgrades came from using the LB. After adding a visual Paracorr to the mix I found that I could no longer balance the telescope with it and some of my larger eyepieces. The amount of weight the previous owner had and the telescope came with, 7 pounds, just wasn't enough anymore. I also had a desire to add a larger finder, flock, and maybe add a light shield. All of these additions would add more nose weight so I looked for solutions.

Reading about barbells, tow hitches, magnets, lead shot, roofing lead, bungee cords, and even water filled jugs left me with plenty of options. However, the elegant Far Point one pounders I already had that the previous owner popped for had me craving an elegant solution to more weight. The two pound doughnut weights by Far Point that fit over the ones I had were my first choice even though they are crazy pricey. The ability to quickly take them on and off with the twist a of screw made for an adjustable solution I decided was just right for me.

I went with the cheapest vendor, ordered a couple, and waited. When they arrived I was disappointed. They were discolored with gold and purple swirling and one even had a huge area of corrosion or grinding that just wasn't going to fit my OCD ways. I know, they are just weights, it will be dark, they are on the bottom of the scope unseen etc. However, for the money I was spending I had hoped they would be silver and new looking to match the other weights I had.

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I notified the vendor who immediately sent a return shipping label to replace them. They also told me they would open the replacements before sending to ensure they would be silver. They felt it must have been a bad batch from the maker. I sent them back and waited.

I got a call a few days later letting me know that all the other weights they had in stock were also discolored and they felt this was how they were meant to be and had been heat treated. I decided to get a refund on them and go a different route.

That got me thinking and catalyzed me to action. It was time to modify, powder coat, flock, and implement my hopes and dreams for this light bucket.

#3 Project Galileo

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Posted 11 November 2011 - 02:24 PM

The first thing I did was start taking the lower assembly apart. I began making piles of parts to go to powder coating and piles waiting the rebuilding. In no time it was apart and I was looking at the primary and its cell. I first noticed that all three mirror retaining clips had not been overtightened. I was pleased. Having read about factory techs over tightening these causing astigmatism had me worried. You could see light underneath all three.

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I also saw the typical 6 black silicone smears around the outside of the mirror holding it to the edge of the mirror cell. That was going to have to go! I got a thin sharp knife and began cutting through the blobs one at a time. I felt like I was cutting a cake out of a pan that wasn't greased. After freeing up the edges I lifted up on the edge of the mirror and pulled it free.

Looking at the bottom I saw that all three floating supports had stuck to the bottom of the mirror. I expected to find this. In manufacturing they use double sided tape to glue one of the three supports on each trio leaving the other two unstuck. Not very "floating". They pried off easily. I put the mirror away for now and focused on cleaning up the double sided stickers, cell supports, and black silicone.

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The double sided stickers peeled off with some effort but by the time I got done with the 18 tabs I had a system down and it was easier. The silicone was tenacious and I ended up using a razor blade scraper to shave as much as I could off of the cell. I left the mirror alone for now. It also had huge gobs of black silicone and stickers on the back.

It took as long as a half hour show on tv to get the cell cleaned up.

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#4 Starman1

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Posted 11 November 2011 - 02:50 PM

You could simply have had the counterweights powder-coated and they would have been fine. They aren't made of stainless steel, so they would never be the finish of the main weights.

On the 16":
--the rocker box is too light and flimsy. It needs triangular gussets on the side to prevent some of the shimmies.
--the curved indentation in the rocker box where the altitude trunnions ride is too large so the scope rolls back and forth as it goes up and down. thicker felt solves this.
--the primary mirror springs are a little weak. changing to stronger springs makes collimation much easier and more stable when the scope is used. This was solved in yours.
--the primary mirror is glued to the cell and pinched at the edge. there are simple fixes to this. There is a thread here on CN right now that talks about creating bottom supports for the loose mirror and how to preserve the orientation of the backing triangles.
--the poles move in the clamps that hold them, and the screws that hold the end rings on the tube segments move in their holes. this is easy to fix with star washers under the screws and knurling the ends of the poles.
--the spider cannot be sufficiently tightened to provide collimation stability without dimpling the upper tube section. fender washers will solve this and allow a higher tension on the spider.
--the lazy-susan bearing in the bottom moves too easily and tends to move in jerks when it is tightened down. ultimately, teflon on formica is better.
--the secondary is glued to the secondary stalk. that's ok, but because the secondary's edge is exposed, it reflects low-angle light. the sides of the secondary need to be blackened.
--the poles need to be blackened by painting, shrink-wrap vinyl tubing over them, or pipe insulation. In the newly arriving versions, they are now black. Ditto on the rings on the end of the tube sections.
--the scope is top heavy so needs counterweights on the bottom. Many different solutions, here.
--the secondary collimation screws are difficult and need to be replaced with, say, Bob's Knobs or similar.
--the base won't fit through most doors--it needs to be tipped over and rolled through the door. It could be trimmed in size, or, even better, rebuilt in the traditional manner using plywood.

Some of the modifications are already started or done on this scope. I just wanted to add some suggestions on where to go next.

#5 Fireball

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Posted 11 November 2011 - 03:54 PM

On top of the ones Don listed you can
- flock the UTA and LTA
- add a light dew cap (more counter weights will be needed)
- modify the alt brake (I increased the contact area)
- reverse the fan and close the back of the tube
- add a bigger battery (e.g. motorcycle battery)
- mount a handling knob
- get some dust caps (e.g. shower caps or the ones from Scopestuff)
- Telrad w riser and dew cap, RACI finder, catseyes center marks ...
Take a closer look at Sky Captain's and Calibos' LBs - many more mods ... :)

#6 Project Galileo

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Posted 11 November 2011 - 03:55 PM

Thanks for your inputs Don. You bring up interesting points about the finish of the weights I had ordered. When looking at the two pound donuts online they look to have the same silver finish and are made of the same steel as the one pounders. Even seeing them on others' scopes online and in person they looked like and I believed them to be made of the same stainless steel used for the one pounders. However, like you pointed out, they are made of different metal and will never have the same finish as the stainless.

I could powder coat the new weights too and considered doing just that. However, once you see how I am adding the extra weight I need you will see why I opted to just return the donuts and go a different route.

I guess I am posting this information so others can learn about my experiences and make their own choices about the direction to go with their own telescopes. I am aware of the shortcomings, perceived short comings, and urban mythos of the Lightbridge. I have seen or read a thousand posts and threads about how different people have solved or not solved these issues. Stay tuned. This is going to be good.

#7 Slartibartfast

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Posted 11 November 2011 - 04:02 PM

Stay tuned. This is going to be good.


I'm following this one! :gotpopcorn:

#8 Project Galileo

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Posted 11 November 2011 - 04:02 PM

Hi Fireball. Thanks. Again, I know there are many things that can be done. This post isn't about what can be done but more what I am doing, how I did it, and why I made the choices in the modifications of my LB16 and perhaps why I didn't do some modifications that others have done. Sometimes I will be cloning other fixes, other times I plan on doing it differently, and in other cases I am not doing anything. Stay tuned!

In all of this I hope everyone can see my love of this hobby, my love of tinkering, and my love of sharing. When I was a newer astronomer, and even now, I love reading threads about other people getting new scopes, improving them, and using them. I vicariously get to experience so many different telescopes and equipment this way. I hope sharing my LB16 will inspire other LB owners to do their own thing and entertain those who have never played with one.

#9 Project Galileo

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Posted 11 November 2011 - 04:51 PM

Now that I had the mirror free of the restrictive silicone on the sides, had freed up the sticky double sided tape on the back, and the mirror cell was cleaned up it was time to improve it. First was to fashion new pads for the mirror to "float" on.

I wanted to have the mirror glide as freely as possible as is best. Cork is used by many but I felt that it may be to "grabby" on the back. Felt sliders have also been used with moderate success. Heck, doing nothing at all and letting the mirror rest directly on the cell is an option some well respected astronomers I hold in high esteem have done. I opted for a UHMW answer.

When I was improving my CGEM there was an issue of stiction between the mount and the tripod. When adjusting the alt/az screws the roughish surface coatings made it almost impossible to make fine adjustments. I found a product called Slick Strips that others here have used to free up the stickiness. I placed it on the tripod and it allowed the mount above to glide nicely. I had some left over and decided it was just the thing.

Slick Stips is basically UHMW (Ultra-high-molecular-weight polyethylene) with a pressure sensitive adhesive tape backing. There is a lot of information about Slick Strips and UHMW online but here is a highlight of this space age stuff.

Slick Strips reduce friction on all surfaces. Wherever you need to increase sliding action on metal, wood, concrete, tile, glass, stone or other surfaces - you're going to love what Slick Strips do for you.

Brilliant! The idea is that you either put the "Slick Strip" on the ITEM or the SURFACE to create slickness. If you put the Slick Strip on BOTH, you get extreme slickness.

Mounting is done via a pressure sensitive adhesive, velcro strips, or mechanical fasteners. It is available from business card thickness to 8" thick. Widths are from 1/2" to 24" in the thin guage, and up to 48"+ on thicker.

The natural color is white, and colors are available, as well as printing on the surface. Additives can be for UV, oil filled, anti-stat for electronics, conductive for electrical apps, ceramic filling, etc etc.

You can machine it, saw it, and even die-cut thinner pieces.

It's also great as a protector, bumper, industrial cutting surface, wear protector, chute liner..... and is similar to the material on a ski or snowboard bottom (known as P-tex).

People have lined the inside of cement mixers, lined gravel chutes in mining operations, put wear strips under moving chains, bumpers on the corners of storage facilities, and even created a dock bumper for aircraft carriers at North Island Naval Air Station in San Diego (this was 6" thick, 24" high, and well, as long as a carrier).

Slick Strip property information and advantages offered:


-The highest abrasion resistance of any thermoplastic polymer
-Outstanding impact strength even at very low temperatures
-An excellent sliding material due to the low coefficient of friction
-Self-lubricating (non-caking and sticking)
-Sound dampening properties
-Good chemical and stress cracking resistance
-Easily machined
-FDA and USDA approved
-15 times more resistant to abrasion than carbon steel.

Slick Strip has a long list of properties that make it ideal for applications in a wide range of fields. It combines the greatest impact strength of any thermoplastic, with a low coefficient of friction and tremendous abrasion resistance. It is extremely stable in temperatures ranging from 220o F, down to cryogenic lows. It is an excellent electric insulator, and is easily machined, punched, sawed, and drilled.

The low coefficient of friction, tremendous abrasion resistance, and non-absorbing nature of Slick Strip makes for an outstanding running surface for snowboards and skis. Its impact resistance and machinability allow for Slick Strip to be used as tip fill and sidewalls, and the bondability and light weight makes for a great top sheet. Similar requirements are creating new opportunities for Slick Strip in the wakeboard and kite board industries.

Slick Strips can be supplied with an adhesive on one side for use as a buzz, squeak and rattle tape (BSR) in the automotive industry. These tapes are also used in the furniture, appliance and material handling industries. Slick Strip tapes and films can be die cut into washers, gaskets and various other wear parts for use in machinery components, and countless other anti-friction / anti-wear applications. Its coefficient of friction is significantly lower than that of nylon and acetal, and is comparable to that of polytetrafluoroethylene (Teflon), but UHMW has better abrasion resistance than PTFE.

So...I used it again.


I got to say "space age". Pretty cool.

#10 Project Galileo

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Posted 11 November 2011 - 04:59 PM

First I cleaned off each spot the Slick Strip pads were going to be placed with an alcohol swab. I cut the Slick Stips into, well, strips. In the second picture I peeled back the adhesive backing protective paper so you can see what it looks like. The UHMW is only 0.10" thick, about as thick as a credit card.

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I used a punch we had around the house to cut circle pads. The product had no deformation from the punching and made perfect little flat pads. I peeled the back off and stuck each on the mirror supports. This is very sticky stuff and I think it will not go anywhere. Be careful placing it. Once it is in place and pressed down it is hard to take off and move. I am well pleased.

I have enough left over to cut into 3/4" strips...

wait...

...I am getting ahead of myself.

#11 Dakota1

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Posted 11 November 2011 - 05:17 PM

This whole thread should be sent to Meade if it would do any good to help maybe improve the product.

#12 GeneT

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Posted 11 November 2011 - 06:34 PM

You got a great deal price wise. One small input: I found PVC pipe filled with BB's to be a good solution to add weight to achieve balance. The pipe can be cut to variety sizes, and filled with various amounts of BB's. I achieved balance for my 12.5 inch Portaball by using wrap around ankle weights. They come in 1.5 pound sections. You can cut them to any size/weight you want. They nicely lay flat where ever placed.

#13 Project Galileo

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Posted 11 November 2011 - 06:44 PM

Great ideas Gene! I love how inventive and creative people are at solving their telescopic challenges.

#14 Starman1

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Posted 11 November 2011 - 07:07 PM

The altitude balance problem is solved by:
--a chain attached to the bottom of the mirror box--as the scope goes lower, more chain is lifted off the ground. This, of course, only works with one weight of eyepiece and is a little too "Hamlet"
--a spring joining the rocker box and the back of the altitude trunnion. As the scope goes lower, the spring is stretched, providing lift.
--counterweights (too many different types to mention, but I like the sliding ones because they have variable effects for different weight eyepieces and different altitudes of pointing.
--matching eyepiece weights using heavy adapters or even clip-on weights for the UTA.

My own scope uses 5 lbs on the bottom of the mirror box for the 21 Ethos when pointed below 15 degrees, but has zero counterweight when the same eyepiece is pointed at 75 degrees, and I use a 2 lb counterweight on the UTA when the 8 Ethos is pointed above 75 degrees.

That is an annoying, but necessary, part of using a dob. I understand that using an altitude trunnion diameter 1.5X or more the diameter of the mirror educes this sensitivity, but then you are talking a completely custom-made scope. Adding drag to the altitude action is not a solution.

#15 Project Galileo

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Posted 12 November 2011 - 03:43 AM

Its cloudy.

I spent the night researching fans again. I was thinking about upgrading to a more powerful and more quiet/vibration free fan. I don't think the stock one is a bad one nor do I think it is underpowered for the task. At the eyepiece I have never noticed vibration one from the stock, unmarked, indistinguishable, generic, boring, mundane, regular, ho-hum fan. Even at higher magnifications it didn't vibrate.

Its just that I got to reading about them in the ATM section, linked to another website or two and another forum or two, read this and that, and found out there is some amazing technology being used in the quietest and most advanced fans.

I fell in love with what is one of the consensus "best" fans. The descriptions, science, data sheets, technology, and reviews all had me impressed and mesmerized. Heck, the darn thing even looked cool. So I went shopping out of curiosity. Then I found out how inexpensive that cool space age technology is. I did spend most of today tinkering on some special things for the rear of the scope and it would look so good and match so well. Of course function over form, right? However, this fun little powerful and quiet fan did function amazingly. My internal gadget geek was well pleased.

I pulled the trigger on it. I am lighter $27 and it will be here in a few days.

Stop by next week and see which one I fell in love with and why. How is that for a cliff hanger?


I got to say "space age" again.

#16 Starman1

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Posted 12 November 2011 - 10:31 AM

Anybody who researches each component as thoroughly should read about "belleville springs". They are THE solution to spring issues because:
--you can make them stiffer with the addition of an additional washer, so you can tailor the stiffness to your taste
--they can be quite stiff, yet short--perfect for the LightBridge
--they don't suffer from lateral squirm.
--they don't lose effectiveness over time
--they take up very little lateral space in high-load capacities, unlike coil springs.

#17 careysub

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Posted 12 November 2011 - 11:18 AM

...

I fell in love with what is one of the consensus "best" fans. The descriptions, science, data sheets, technology, and reviews all had me impressed and mesmerized. Heck, the darn thing even looked cool. So I went shopping out of curiosity. Then I found out how inexpensive that cool space age technology is. I did spend most of today tinkering on some special things for the rear of the scope and it would look so good and match so well. Of course function over form, right? However, this fun little powerful and quiet fan did function amazingly. My internal gadget geek was well pleased.

I pulled the trigger on it. I am lighter $27 and it will be here in a few days...


So... what did you buy? We are all in suspense.

I am a bit of a "fan fan" (having evaluated many computer case fans for computers). If using a computer case fan I strongly recommend Scythe fans -- they are high tech (the blades look like jet turbine fans), efficient, silent, vibration free, and extremely reliable (you will never use you scope enough to wear them out).

#18 Project Galileo

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Posted 13 November 2011 - 12:31 PM

So, the weekend had me tinkering again. It has been such a joy working with this telescope. The mirror cell needed to be finished! So, here is what I did.

Edge support is a big deal. Most of what I learned I have learned from Cloudy Nights discussions and how-to threads. Many of them all end up linking to the Dobsonian Mirror Edge Support Calculator at Edge Calculator. What a neat and helpful tool. There is also a great discussion on edge support methods and some pics I found very helpful on this page.

As I understand things I need to have the least amount of friction against the mirror's back and edge so it can float and adjust thermally. I also need to support the side of the mirror at the center of gravity and at just the right places to impart the smallest amount of surface deformation possible. Mirror cells should generate surface errors low enough to not be detectable by the eye if possible. RMS Surface Errors that do occur should measure at a value of 5 nm or below. This corresponds to a virtually perfect edge support. A 5 nm RMS astigmatism is indistinguishable from perfection to our eyes. Check out the pictures on the link above.

The way this LB16's mirror was glued and sticky tape stuck in the cell I can only imagine how much crazy deformation was happening. The calculator shows that gluing this mirror into an 18 point cell generates an RMS surface error of 14.2 nm. That much astigmatism can be seen by an average viewer. The severe factory gluing of the LB can only be causing worse too. Not acceptable.

However, to just put it back in and let it rest against the cork on the metal edge supports is a no-no too. The Obsession web site says of metal edge support, "Rigid edge supports deform the glass causing astigmatic images. (especially with 1.60 inch ulta-thin mirrors). As the scope is rotated downwards the glass is deformed more and more from the metal supports. These deleterious effects have been proven with interferometric analysis."

The best edge support is the sling method and playing with the calculator shows how much. Another very acceptable edge support I have seen done would be two ball bearing roller supports at the center of gravity (COG) of the mirror placed at 45 degrees from vertical and 90 degrees to each other. After plugging in the numbers to the edge calculator it shows 90 degree edge support with bearings gives 1.2 nm reduction of Strehl Ratio. The sling gives 0.5 btw. Once again the calculator shows how effective the 90 degree edge support method is. It is well within the 5 nm limit. So, how can I best or closest achieve the lowest level of edge support in this LB16's cell?

The sling is out with this cell without major mods I don't have the know how to do. I didn't feel like I wanted to go into the more involved modifications necessary to add bearings like I have seen done. However, I may save that mod for another day.

I went with a 90° edge support using nylon screws instead of bearings.

First I measured and marked the side of the mirror's COG as per the calculator.

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Then I placed the mirror in the cell, adjusted all the supports, and centered it. I then marked on the side of the cell where the COG struck the metal edge of the support. This is where I planned to drill and tap a hole for the nylon screw.

This was the first time I had the mirror in the cell since adding the UHMW pads. I have to say I am well pleased. I had to give minimal pressure to adjust the mirror around on the pads from side to side. The mirror glides very nicely on the pads.

#19 Project Galileo

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Posted 13 November 2011 - 12:56 PM

Once I marked the COG on the metal edge I set and drilled a hole in the side so I could tap new threads. A tap and some lubricating oil had me in business soon. Be careful. It is an aluminum cell and is very soft and easy to work with. I opted for a 10/24 screw size so I had many threads in the thinner metal cell side.

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In the close up picture you can see the hole I drilled is 2.5 mm below the COG mark above it. I chose to back up the support to allow for more metal at the lip of the hole and cell. I felt I would be drilling and tapping a hole too close to the edge using the true COG.

The Edge Support Calculator showed that by changing the support position relative to the COG 1/20th of the mirror thickness (2.5 mm in my case) it would change the RMS Surface Error to 3.3 nm. Still within the 5 nm goal and undetectable with the eye. I opted to move the screw in trade for more strength.

The new 10/24 nylon screws fit perfectly. I will round and smooth the tips of the screws to lower their friction on the mirror's edge too. Finally, I will use left over UHMW tape pads stuck to the side of the mirror where it contacts the nylon screws to lower friction even more.

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Ta da! Mirror cell improved and done for now!

#20 Starman1

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Posted 13 November 2011 - 01:10 PM

If you install altitude stops on your altitude trunnions to prevent the scope from ever going below, say, an altitude of 5 degrees, you can dispense with the mirror clips entirely and reduce whatever diffraction they cause.

Because the mirror will not tip forward out of the cell if the scope cannot go to horizontal or below.

I've seen these stops installed as small blocks or even screws that are attached to the altitude trunnions so they hit the rocker box at the appropriate moment to prevent the scope from diving into the dirt.

Should the need ever arise to look below that 5 degree altitude (unlikely), you can simply tip the base slightly from horizontal by putting a spacer under one of the base's feet.

#21 Project Galileo

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Posted 13 November 2011 - 01:22 PM

Interesting solution Don. I find that tall trees limit me from moving my telescope low enough to tip my mirror. In fact that is kind of why I didn't stress about bearings vs. nylon screws for side supports at 45 and 45. My mirror rarely takes much of a side load. Most of my viewing is well above 45 degrees. I also leave a thin paper sized gap between my clips and mirror. The clips just don't come into play or cause astigmatisms for me.

#22 Project Galileo

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Posted 13 November 2011 - 07:57 PM

It was another day of playing in the shop and creating. Today's focus was boundary layers, mirror cooling, and fan configurations.

I have decided to have a pulling fan configuration with a Mauro da Lio baffle. The reasons are well explained here and experimented on here.

I was persuaded to use this technique not only by reading and seeing the laminar flow studies but also by watching some YouTube fan smoke test videos. If you haven't peeked at them do so. In the videos an astronomer experiments with smoke and fans and different set ups. Powerful and compelling. Seeing is believing. It is all smoke and mirrors, right?

Sealing off the rear of the tube was first on the agenda. Having seen a million ways to do this I pondered my own ideas. At first I thought about making the rear tube seal out of 1/4" plywood. There is a recess on the back of the LB16 that would be perfect for this. However, I couldn't find a piece of 1/4" plywood anywhere that wasn't warped enough to make it unusable. I also figured over time warping may make the part I fashioned unusable. I pondered plastic, plexiglass, and Lexan and even started to look for a supplier. Then it hit me. Make it out of metal!

Lightbridge's are notorious for being nose heavy. The bearings are misplaced and undersized sadly. Using even modest eyepieces can tip the scales sending the nose to the ground. Adding Paracorrs, big eyepieces, large finders, or any accessories quickly can create massive imbalance. Meade offers a friction break to help with this problem. I hate it, don't use it, and am of the school that if the scope was properly balanced friction breaks are unneeded. Astronomers easily fix this nose heavy tendency by adding rear weight.

In my set up I always have three pounds of Far Point weights and four pounds of JMI weights attached, seven pounds total, no matter what I am doing. I have often found myself holding up the UTA a bit to adjust for imbalance. I just don't have enough extra weight in the rear for my balancing needs. Adding more accessories is out of the question without doing something and the new Paracorr put me over the limit permanently. That was the genesis of ordering those add-on weights I mentioned earlier in the thread.

Today I wasn't planning on addressing balance issues, I was going to make a rear tube seal. However, 1/8" steel is 5.01 lbs/sq ft. If I made the rear seal 1.5' across it would be approximately 8 pounds. Cut out the center for a fan, punch and drill some holes for mounting and collimation knobs and the rear seal would weigh around 7.5-8 lbs. I would solve two problems with one solution.

I had a piece of scrap laying around that would work perfectly. It was measured, then cut, and the edges got a little grinding to smooth them out.

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#23 Project Galileo

Project Galileo

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Posted 13 November 2011 - 08:07 PM

The new part fits just inside the recessed back of the cast rear piece. Now I needed to drill some holes. My buddy Shane just got a cool punch, cutter, huge machine thing in his shop. I called him up, told him my needs, and was on the way to his garage in minutes. I have no idea what this is called but it has ridiculous power and looks cool.

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The two parts were lined up, clamped together, and the center of each of the holes was marked. Shane put in the proper die to his punch machine, lined up the marks, and punched the cleanest, most precise holes possible. Wow, was this machine fun. The result is a great looking part coming to life.

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#24 Project Galileo

Project Galileo

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Posted 13 November 2011 - 08:09 PM

A quick dry fitting shows how the rear of the scope will look and how the new part fits. It weighs 7.5 lbs. Perfection!

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#25 Project Galileo

Project Galileo

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  • Joined: 14 Nov 2007
  • Loc: Jefferson County, Colorado

Posted 13 November 2011 - 08:30 PM

I laid the new part down and started doing dot-to-dot lines with the punched holes creating a cool geometric pattern. I was looking for aesthetic positions to drill holes. After standing back and trying a few ideas out I decided upon two of the points that looked promising. I marked the spots and used a nail to set some places to drill.

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Out to the drill press I went and two holes were made.

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Once I had the holes done I was able to fit some electronic parts to the rear. I added a 2.1 mm DC power jack socket for the fan wiring and a tiny dim LED to come on when the fan is powered on. I figured with the super quiet fan I ordered it would be hard to tell if it was on. A small indicator light would be nice. So...

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...it works like a charm even if it is only test fitted for now. The LED is very dim and will not come into play with scattered light problems. I even like the symmetry of the placement. Now it is time to add this rear tube seal to the pile of parts going to the powder coater.

Very auspicious. I am pleased.

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