Wednesday, August 29, 2012

Lightbridge Mods Part 2

A productive weekend with the scope rebuild.

I started out by putting the foam on the truss tubes, I may still go with heatshrink eventually, but the foam was cheap and it works for now.

I started by laying everything out and making sure that my foam tubes were cut to the correct sizes.
Since I glued the seam with the Pilobond, they were solid tubes and the seam is pretty hard to see.

It took a little effort to slide the foam onto the tubes, I initially tried to slide them on from the bottom but the sharp square end made that difficult and ended up damaging one of the foam tubes.  You can find it if you look for it but but its not too bad.

I ended up having to take the truss tube assemblies apart to slide the foam on from the rounded side of the trusses.

Ultimately I am satisfied with the truss tubes for now, but since they are one of the easiest things to mod on this scope and the foam is only attached via friction I can change it any time.

The next thing was to put the truss rings together and test the fit of all the parts.

I think it looks pretty good already and it's nice to see how things go together.

Looking at this picture I think I may end up hitting the truss tubes with some flat black enamel.  If I have some left after I am done with the bottom tube I will probably hit the ends at least.

I was debating refinishing the upper tube right now as well but I don't know if I am going to keep the spider and secondary and I only want to tear into that once.

I was holding off until I got a new focuser (moonlite droooooooool) but then a George, a member of a Lightbridge telescope group I joined told me about an upgrade that will turn the stock focuser into a dual speed focuser.  Its pretty affordable but they are out of stock at the moment.

With the truss poles and rings assembled, it was time to turn my attention to the bottom tube.
I ran through several ideas like having the 1/28" steel tube replaced with a 1/16" 5046 Aluminum tube.  I tried sourcing a prefab product that fit the bill but after a few hours on the internet and a couple dozen phone calls, I started calling local metal shops.  I got a few ballpark quotes but all of them were $200+

I considered making my own tube out of fiberglass, but since one of the main reasons for replacing the tube would be to lighten the scope, a home made fiberglass tube probably wouldn't help.

I also looked into carbon fiber tubes.  There is a company Public Missiles which manufactures drop in replacements for some telescopes (all SCTs) and at one point offered a 14" ID tube.  Again prices were easily north of $200 and I wanted to try and keep the costs for ALL the mods I want to make under 200.  After you add replacing the colimation knobs, and the dual speed upgrade, that only leaves about $100 bucks for the tube.
This little handle, makes a HUGE difference

That's when I decided that I was going to paint it.

I knew I was going to repaint it, but wasn't sure what color to go with.  I know how to get a nice paintjob with rattlecans but still wanted to run some tests on the color I settled on.

 I had a piece of scrap galvanized steel that I used for some testing. First I started with black automotive primer, since this was a test I intended to see what impact multiple coats of primer does or doesn't have on the finished product.

Here is the piece after two coats on the end, one coat in the middle and no coats on the end.

There is a little orange peel and the galvanized coating texture coming through despite pre-sanding the metal and then wetsanding each coat of primer with 1500 grit.

And now.....

Its a metal flake with holographic or dichroic flakes so you get different colors in different lighting conditions.

You are supposed to apply it to a black undercoat, being the skeptic I am, part of my test was to see what it did to bare metal.

As you can see, it has little to no effect on the bare metal.  In the sunlight I could see a slight bluish sheen but it was hard to discern from the regular blue highlights I was getting from the reflection of the sky in the wet paint.

While I let that dry I started working on the bottom tube.

First I removed the altitude bearings,

then I got to work with my Harbor Freight fender and body kit.  I used it to fix my mailbox the other day as well.....

The tube had some dings and dents where what I think was the mirror banged around since most of the dents were actually on the INSIDE of the tube resulting in little bulges and ridges on the outside of the tube.

Since the key to a good paintjob is patience, I decided to call it a day.

More updates to follow.

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