The interior was already primed by Joe but I decided to take it one shade darker and fuller using Krylon® 4290 Camouflage Paint with Fusion Technology.
Masked the exterior with some tape and newspaper as I wanted the outside unpainted to keep thermal equilibrium better to ambient
Deep inside the tube
A sample of the tube's interior with flocking material against the primer. The flocking material also went against the tube's interior opposite the focuser drawtube
Big thanks to Joe Nastasi at Parallax Instruments, Inc. for the custom tube.
Let's bring these together Joe!
Joe helped turn my sonotube mockup into reality.
Joe making his magic!
I will always have some fond memories of working with such a fine professional in his workshop, thanks Joe!
Excitedly I got 1st light on January 30th, 2011!
I didn't realize how high the focuser and eyepiece would be so I had to whip out the ladder especially for the wife who got to share my 1st views of. Rigel, M42, M1 and M45!
On the ladder
Pausing to take it all in!
Going back to finish off the construction blog. On January 24, 2011, I finally got everything assembled and nearly ready for 1st light. I wanted to try and focus on a star before mounting it with the bungie cords. Strange as it sounds, Polaris is quite visible through the skylights in my family room if you stand in the dining room entrance. If you know your astronomy, Polaris doesn't rotate much as it is <1° from the celestial pole. I knew I can see it but could the telescope see it through the dirty skylight and glass at 1600mm focal length? YES IT COULD! Is it first light, techically, yes?! But I wanted better, see the next post...
A view of completed setup
Poiting out the skylight
FOCUS ACHIEVED!!! This was a big sigh of relief that all the designs and plans panned out!
Now let's put this bad boy on the mount and wait for clear skies!
Big thanks to Anthony Wesley (http://www.acquerra.com.au/astro/) for not only his design but also for his endless, undying help and assistance. He put up with many a question from me on trying to wrap my brain around this. For those less inclined with Newtonian design, we'll start with the tube and retaining ring. The 3x collimation bolts in a threaded into the holes in the ring.
Next is the mirror cell. This holds the mirror in place and allows the collimation bolts to adjust the primaries axial position in the tube. The addition of the cooling unit should not interfere with this operation and in my tests and observations, it does not in this design.
Next we need to find space near the mirror and cell to place the internal fans. The 1st video shows this quite well and provides a unique, 'inside the tube' view.
Click to view full screen for higher-res!
Manufacturer: Playstation Premodds (httpnull/www.premodds.com/)
290-439 watts, 29 amp switching, 10-15 volt DC power
3 x Thermoelectric coolers (TEC aka Peltiers):
Manufacturer: TE Technology, Inc. 1590 Keane Dr., Traverse City, MI
Power: 80 watt(s)
Dimensions: 40mm x 40mm x 3.4mm
Cold plate, conducts peltier's cold side to tube's interior:
6061-T6 ALUMINUM SHEET / PLATE
.080" x 14” square. My buddy Emerson help triangle the edges from a square to octagon. Then we sanded them down to a mostly round shape. The work turned out great, which is good because its hard to get a round metal of that size!
3 x FAN-EC9225M12CA
EverCool 92mm 12V 3-Pin DC Fan
1 x FDC08025S1M
Here's the mirror cell without fans:
3 on each side of the triangle and one on the center
HOT-SIDE Heat sinks:
3 x Rosewill RCX-Z90-CP 92mm
3000 ±10% RPM
The challenge with these heat sinks is they are set for a specific computer CPU height. It was too high above the top of the plexiglass so I took some scrap aluminum and poured on the thermal paste.
note the screws and also the height of the heatsink over the plexiglass. There's a stack of 2x 0.08" scrap aluminum and thermal paste to make the heatsink have contact to the peltier.
Plexiglass insulator, goes in between the cold plate and the heat sinks (aka hot side)
Name brand Lexan, which is a thermoplastic, from a local art & frame shop
1/8” thick and 17” diameter
store cut into a circle
it's very easy to work with, both drilling and straight lines with a dremel
>3/8” holes for each collimation bolt to pass through (plexiglass cut only)
~1/4” x4 holes for each heat sink (plexiglass and cold aluminum plate both,
these are bolted on with 1/4” bolts, nuts and washers. This is the only
thing holding the plexiglass and cold plate together at this time.
The hardest cuts to make were the ones that pass the Peltiers through from the heat sink (hot side)
to the cold plate. I drilled 1/4” holes just inside the corners and connected them to make a
nice rounded square that neatly fit the Peltiers just inside.
2x small holes for the female banana pegs that connect up the inside fans.
All the holes are NOT insulated and most use metal bolts.
Power Supply Unit (PSU) to main distribution on edge of plexiglass uses ~8ft 10AWG
with male banana plugs on both ends. This is the scope end:
Main distribution to exterior heat sinks and Peltiers is 18AWG (I think?)
There are 3 x +/- pairs, one for each Peltier / Heat sink combo each 'device' lead
is soldered to the extending 18AWG wires.
Each of the 3 pairs is in parallel and connects to a nice receiving hole that tensions
them in place to the female banana plug on the outside.
The inside fans are hidden and inaccessible unless the cooling unit is removed.
The photo above shows the small metal bolts that stick out of the female binding posts.
These house bare leads to the fans, but they are held on by nuts and washers and not
easily disconnected. This meant I need a way to quickly remove them. I was able to find
a male and female PC power connected that you may see in the videos below!
and oh, lots and lots of Thermal Paste! null
How the mirror connects to the cell
Mirror attached to cell:
Cell resting in tube. Basically with the tube at an angle downwards, the weight of the cell and mirror are enough to hold them in place despite the 'upward' force of the springs.
Here you can see how the collimation bolts and knobs play with the cooling 'cap' if you would
Fully operating! The noise you hear is actually almost all the 2x 90mm fans that keep the PSU cooler. They're badly jury rigged and my not be necessary, but the power supply is near max capacity with all the 7 fans and 3 Peltiers running.
This tube was 12ft long and I got the folks at Form Tech Concrete Forms, Inc. in Raleigh to cut it in two before I took it home. Perhaps I can sell the other half to a local person?
I did some trial work on one of the 6ft (~72in) sections. Only needing ~50-60in, I used the over hang to test drill and cut some. Here you can see the focuser base drilled into a test spot:
The aluminum sheet is used to make a straight cut for the ends and line up on a proper radial axis.
Read to install the custom adapter ring with collimation screws:
I estimated the depth based on the screw and mirror height, but might shave 1/2 - 1" off the end in the final design. Note the end was recut from the factory cuts to make a smoother edge from the abuse it took in shipping. I used that strip as reinforcing on the outside screws that hold the ring in place.
I pre-drilled the holes in the center of the ring and finding them and lining them up on the tube side required some probing with a long, skinny wire, like this yard flag. I was assured of hitting the center of the ring and not grazing the edge or coming too close to a fragile part instead of the spot I predrilled.
Ohh, there it is...
Screws in place:
I removed the 'test' end of the tube at 58" (I think? I'll have to remeasure) and used it as reinforcing inside the tube.
Measuring front end cut with the aluminum sheet to keep the cut square!
Tight and lined up on the edges, that means a straight line all the way around right?
Now that looks like a telescope!!
Making a ~3" hole for the focuser was a bit rough, as was the final cut...
A view all the way down
Well done Mike! Meet Akule!
Lots of 100% silicone adhesive per Carl Zambuto's recommendation!
Now the cell has bolts securing it to the ring that will secure to the tube walls
The wing nuts get replaced with knurled knobs later
The spring is below the nut and above the cell
I had a strange predicament with the mirror cell inside a tube. I followed some of the ideas that Anthony Wesley had used on his collimation setup and he deserves much credit for the base design. I needed major help in making the adapter ring for the temporary, test sonotube. Emerson Sox lended his hand and we came up with a bang up, awesome idea!
Cutting a large piece of plywood, 3/4" thick
Shaving it down to the right size
Drilling out the mirror cell mointing holes:
Snug fit, but it works!
Not the final design, we swapped the copper pipe 'spacers' for self-locking nuts to gap the springs proper. I think I will swap out the springs for stronger and longer ones for more travel to collimate:
A Job well done! Cheers Emerson!
Just a quick link to the gallery for now. Basically I measured the center of the mirror and holder and stuck on some 100% silicone adhesive.
Post questions in the comments!
A good workspace
back of mirror
measure both axis to find the center of mirror and align to center of holder for axial alignment of the tube to mirrors
some whiteboard math
draw and measure the calulcations and leave airgap using some toothpick spacers (removed later)