Sunday, June 28, 2020

Corvette Quality Telescope Tube

Readers familiar with this blog will remember about one year ago I posted an article about helping some friends with their projects here at Beltsville Shell West.  One of the projects was to build a prototype of a telescope tube out of carbon fiber materials for my friend Tom Bartol.

That project led to the creation of a full-scale telescope tube that Tom and I, with a few of Tom's friends, developed.  Here is the story.

Dr. Bartol is a neuroscientist at the Salk Institute here in San Diego.  We met while commuting to work about 7 years ago.  Tom is also a skilled machinist and an amateur astronomer.  Everything about Tom is interesting.

In 1999 Tom started designing and building a computer-controlled robotic telescope.  For all these years he has been machining his own parts to his own design and specifications.  He would give me constant updates on his progress complete with photos of the finely machined parts.  After so many years he finally finished the masterpiece and it was featured in the September 2019 edition of "Sky & Telescope" magazine.

The instrument was perfect in many ways, and so precise that Tom can mount his camera to it and the robotics and computer adjust for the all the movements on the Earth and in the universe for clear photos of planets, stars and other heavenly objects.  But there was one part that Tom felt could be improved -- the actual tube that holds the mirror and lens.  In the Version 1.0 of "BlueShift" (that's the name of his telescope) the tube was made of cardboard.

Tom and I have worked on a few projects together and he has been very helpful in machining parts for my Go karts.  In return, I made a commitment to try to help him build a carbon fiber tube for BlueShift.  This would be Version 2.0.

The prototype we built last year was super strong and Tom was now ready to go for the final project.

Tom did all the prep work by wrapping an 11 3/4" cardboard tube with duct tape (as a release agent), capping the ends with plywood, and creating a spit out of saw horses and a central shaft.  We then rolled out a long spool of carbon fiber across Tom's garage floor and down the driveway. This arrangement would allow us to carefully roll the material onto the tube while wetting out each successive layer/turn with epoxy.

We needed extra hands to mix the epoxy a cup at a time, pour the epoxy onto the carbon fiber, work the epoxy into the fabric with paint brushes, smooth out the material getting rid of any bubbles, and align the fabric for a perfect part.  We were joined by Bryan Paquette and Kevin Winchell.

The guys did an excellent job, being quick and precise.  Once the determined number of layers were securely rolled onto the mold, we wrapped the entire tube with Peel Ply (to give the outer surface a satin finish - explained below), and used a heat gun to "kickoff" the chemical reaction.

We left the assembly to dry overnight, and the next day Tom had the honor of removing the peel ply to expose the smooth, satin, strong tube.

At this stage the tube "could" have been perfectly suitable for BlueShift.  But Tom, ever the perfectionist, wanted more.  He had researched a very nice composite material that was a mixture of carbon fiber with a blue Kevlar weave.  The satin finish of the base tube was a perfect bonding surface for the finish coat. We used the same procedure as the day before and finished off the tube with several more coats of clear epoxy.

Tom completed the project by cutting the ends of the tube square . . . . . 

. . . . . soaking the tube with a garden hose (the cardboard disintegrated) and easily peeling away the duct tape from the inside of the tube.

He then drilled holes and made all the other adjustments necessary to mount the tube on BlueShift.

The finished product was so beautiful that Tom, once again, appeared "Sky & Telescope", this time the April 2020 edition.

The best part?  The name of the article is "A telescope made with a paint brush"!

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