Knightviper
Use zinc primer after you drill the hole before you put the rivets in

is that the stuff you put in the acorn nut when joining aluminum to copper wires?

Finally figured a way to show the rivet holes:

 

I think it will work like a champ.  I got special rivets that are designed to join sheet metal to plastic.  They rip apart and flower.  The flowering will be going on inside each hole.  I think 24 may be a bit excessive, but you guys know how I do...

 
Oh, the Marine Grade HDPE sheet just arrived.  I am kind of speechless.  It's almost as stiff as aluminum to begin with.  To think it only has to hold 2.5 lbs per corner.   Its currently cutting on my machine and it cuts like butter.  I honestly can't tell the difference between this stuff and Delrin.  Probably have some pics up in the next few hours. 

Sawzall or a jig saw with metal blades. Trick to the sawzall with metal is go slow. If you go fast the blades get dull fast.
A high speed grinder with cutoff wheels. Or even the grinder wheel itself.
Take it to a shop and let them use a plasma cutter and cut it for you.
Buy a plasma cutter and cut it your self.

 
Shower pole slides right through like a charm:

(high res: https://i.imgur.com/R4Bjno7.jpg)
 
Super excited for the build now!

Yes, sawzall and jigsaw cut when the blade retracts back.
The edge will have to be sanded or filed down to make it smooth.
A cutoff wheel on a drill or grinder will be fairly smooth edge .
Masonite would help keep the metal rigid and will make a guide to keep the cut on the line.

Looks very good Nateman, of course... On cutting it sounds like you have a couple good ideas, but what about a Dremel?? I love mine for many different things. Coming along quite nicely!! 

nateman_doo
 
 Will probably get a sheet of the 26 gauge steel and experiment cutting next.
 

Why not carbon fiber ?  $21.00  www dot ebay.com/itm/Carbon-Fiber-Cloth-Fabric-2x2-Twill-50-3k-6oz-203-43gsm-Commercial-Grade/131688779234?hash=item1ea9434de2:g:My4AAOSwEzxYZsdm.. It is lighter and stronger than steel, given the same dimensions.  Since you are doing an open truss design the amount you need is minimal.  Looking at the pics, it looks like one 36" x 50" sheet cut in half for one layer would do both of the tubes.  14" mirror correct so the tubes are approximately 15" or so in diameter ?  I would buy two though for two layers, which is what I did for mine. You can even use the steel you already bought as the form for the fiber.

 

Was just figuring out how my new mount works when I took a few pictures.  Visual only, no stacking of photography programs involved:
 
The beehive:

Was still figuring out the polar alignment.
 
The Pleiades:

Damn, cut off one of the stars.
(high res: https://i.imgur.com/r5OgD90.jpg)
 
Was aiming for the horsehead nebula, and got this instead:

(high res:https://i.imgur.com/SmYSDgW.jpg)
 
And my best photo of the night of the Orion Nebula:

(high res: https://i.imgur.com/Rxdp00x.jpg)
 
Again, nothing is perfect,  I am still figuring out things.  It was VERY difficult because the screw that holds down the finder scope sheared off, so I had to align a scope with no finder scope.  For those of you who have ever tried such a feat... with its in the single digits knows how trying it can be.
 
Will be outdoors more later in the week, but will keep updates on the new scopes production as parts arrive.   Feel free to subscribe and chime in if you have any suggestions to offer.  Ordered these rivets to try out instead of those "flowering" ones: 
 
 

Nice Orion pic!

Can you use screws or something like a #8 nut and bolt? Maybe easier in the long run.
Maybe use some blue locktight on the threads to keep them in place.

Cutting the last rings:


 
Setting them up to check alignment:

 
and a look at the clamps:

 
Sad news, my poles are probably 2" too short.  I have 2 options.  Buy astoundingly more expensive poles, or pay more for some hella thick plastic to make 8 new clamps that are 1.5" thick instead of what you see as 0.5" thick.
 
I can get 0.05 walled thick steel for $24 each, or "rigid aluminum tubing 0.065 wall thickness for $23.00, or reproduce 8 clamps 1.5" thick for over $100
 
The steel tubing matches best with what I have now, and the scope will still weigh in at 32 lbs, or the aluminum which will be the same size but lighter.  Going from $7.00 shower poles to almost $100 dollars doesn't sit well with me.  
 
I am open to suggestions.  

They were random (and the only) shower poles in this length that I found at Lowes.
 
https://www.lowes.com/pd/Project-Source-60-in-Chrome-Single-Straight-Zinc-Fixed-Shower-Rod/50014244
 
based the entire build around it.

How about emt conduit  homedepot dot com/b/Electrical-Electrical-Boxes-Conduit-Fittings-Conduit/N-5yc1vZbohl
comes in different sizes but it is I.D. so check the specs for O.D.

Hi Nateman,
 
I love astronomy to bad it has been to cold lately to work on my astrophotography but here is my best pic of Andromeda, Jupiter, the Moon and Orion's nebula. I have a lot to learn and I need a better camera suited to make these pics better. These were taken with a cannon T5.