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gbwillson

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Reply with quote  #11 
Don-

Fitting the tracks together, especially when the tracks have the wooden reinforcements attached, can be a lot like a jigsaw puzzle. My first thought was to build the frame completely before adding the reinforcements. But that would make attaching the reinforcements a lot more difficult and require a LOT of clamps while trying to keep everything aligned. So I attached the boards and let the glue dry before assembly. I had to get away some of the glue that had oozed out in places. I think the interlocking pieces add a lot to the strength of the overall box.

Below you can see I left a gap for the ΒΌ" plywood back board as well as the sides. So in a sense, I simply inserted tab A into slot B. After a dry fit, I ran some adhesive in the slots before final assembly. After a couple of days drying time, I added rivets for added strength. 

IMG_0615.jpg 

IMG_0620.jpg 

IMG_0614.jpg 

IMG_0623.jpg 


Greg in MN



dbc

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Reply with quote  #12 
Thanks for the pictures Greg.  It looks like you did much the same thing I was trying to do.

I'm going to try it again before I abandon the already made frame and start over; maybe not glue the wood all the way to the end so I can still fit the track frame tab under it.  I may also have to cut off the side tabs on the folded corners, leaving just the center part that slips under the wood  You're right; it's a real jigsaw puzzle.

I am shooting for 1 1/4 inch screen gap, which doesn't leave much depth for a plywood back.  The back will be just the 1 inch polyiso with aluminum flashing 'skin' glued on for weather protection.  I will have to be careful with the air fittings; I plan to fit another (slightly thicker) aluminum sheet on the inside of the polyiso to attach the duct stubs.  This inside plate will be glued and taped to the inner face of the polyiso and also held under the end of the screen frame and the polyiso in the end track.  Hope that's strong enough.
gbwillson

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Reply with quote  #13 
Don-

While I didn't cut off any overlapping tabs, I did trim a few slightly to allow for easier assembly without reducing strength. I WAS planning on not having a plywood back and depending on the polycarbonate. This would have kept things light. But on further thought, since my ZP was built in two sections, and would be moved seasonally, I needed the strength more than the weight savings. 

I got a bit confused on the internal layers you mentioned. Do you have an internal cross-sectional drawing?

Greg in MN
dbc

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Reply with quote  #14 
Greg,

There is a pencil sketch back at the beginning of the thread, which I need to update.  It doesn't show the duct fittings, and I have since decided to use flashing in place of the FRP paneling for the exposed back surface.

Also, I may omit the 1x wood strips at the front, under the track lip; not sure they really serve a purpose.  May just fit polyiso strips into the track after the plywood, all the way up.  I am planning to attach the glazing with angle stock screwed through the frame and into the plywood reinforcing strips.I bought some 8-32 T-nuts that will go into the plywood reinforcing strips from the inside (before getting covered with polyiso.  Idea is to fasten the angle glazing hold-downs with machine screws instead of just screwing into the plywood itself.

You're right - I need to do a new drawing that shows some of these details that are clumsy to describe with words.  I'll do that as soon as I can.

Thanks,
Don C.
gbwillson

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Reply with quote  #15 
My next collector will not have the glazing held in place by screws into the face or side of the collector. I'll likely still use the aluminum angle though. I'm looking for some way to "clip" the angles in place for simple and quick access to the inside of the collector. Heck, even bungie cords would work for a season or two.  Krautman also had a rally good idea whereby the glazing and frame are one piece. I plan to try a one piece frame too. Then again, I'm not sure about trying to move a 4x16 collector twice each year. I could do it now, with difficulty, but years from now?

Your drawing is fine, but the words made it sound like something different. I wanted to use the thin FRP for the back too. I thought it was kinda floppy and heavy for what it was. I needed a bit more structure to hold things together with seasonal moves. You might look at Bert's ZP page were he made his top screen frameless. This might save you some space inside. Krautman used the screen frames, but he had to add littlest out sheet metal corner triangle braces screwed into the frame as well as extra cross bracing to get the screen anything close to tight. Vertically, they were not too bad, but over time in a heated box things might relax and sag a bit. I'd imagine any screen frame over 4' to be hard to get tight. You just can't pull very hard without bowing the sides a great deal. Nice thing about your configuration is the limited vertical height makes any sagging or sloppiness less likely.

Greg in MN
gbwillson

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Reply with quote  #16 
I forgot to ask, how large is the opening between the two sections? I made mine the same size as the gap, but I'm thinking of making it as large as possible to eliminate any chance of a bottleneck between the two sections. I was somewhat limited due to the strength needed for connecting ends. But if I had my collector permanently mounted, like yours will be, I'd consider any and all extra space in the opening between sections. I think the butted section ends could be completely open, with a "splice" holding things together. I think Bert may have done something like that with his ZP. 

Greg in MN
dbc

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Reply with quote  #17 
The opening in the adjoining end pieces is 1 3/4 inch.  That was about as wide as I could make it and still have any strength left.  The remaining 1 1/16 inch between the slot and the back will be covered in any case by the edge of the 1" polyiso back piece.

I like Bert's corners and splices made out of stud sections.  They nest into the track just right, since that's what they are made to do.  I had already made my frame pieces before I saw his, or I might have tried his method.

Greg, on closer inspection it appears you folded the corners slightly different than I did.  I should still be able to get it together with a little persuasion.  My concept was to bend the corners to naturally shed water, but other folds should do just as well, since both sides of the corner are over-lapped.  Going to try this weekend.  I thought about fitting all the corners together without riveting, then clamp it and glue the plywood in.  Then, after the glue sets, rivet two corners, flex the other 2 apart, and slip in the back piece.  Then rivet the final 2 corners.  Don't know if I have enough clamps to keep it all tight and square, but I will check it out.  I'm would still rather glue the wood in first, just stop the bead about 1 1/2 inch short at the non-folded ends.

I thought about clips too.  I like the 2-piece 'cam-action' wire clips holding the airbox down on my ageless Geo Metro.  I also thought about metal banding, like that used on pallet-loads, running all the way around the collector, but that seems a bit crude.  I thought of this in context of the twinwall bulging, which Bert just had to deal with.  His solution seems to work OK.  I may not have as much of a problem with a 2 ft high collector.  I am a bit uncertain about my plan to use t-nuts to anchor the glazing strips; the holes in the angle pieces will have to be drilled right-on, since the nuts will already be fixed in place.

First thing is to get the frame put together, or else start over on a new one if it just won't go.
gbwillson

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Reply with quote  #18 
Don-

I'm glad you made the connecting ends as wide as you did. Ideally, I would eliminate the slot all together and simply butt the two sections together and connect them with a splice of some sort. Being that your ZP will be permanently mounted would make such a connection feasible than a mobile collector like mine as less strength would be needed. I think the corners could be connected in a similar fashion to the screen frames, whereby the ends aren't folded, but meet at the corner, and a separate, corner could be fashioned for reinforcement out of stud track or other suitable material.

At times I think I have far too many clamps, and times like the assembly of my ZP, I barely had enough. With less you can always assemble a corner or two at  time, but what a slow process. 

Bert's solution certainly works, but with an 8' span of twin wall, you need a hold down at least at the manifolds and no more than a 3-4' span. A little bulging is fine, as long as the key hold towns are in place to keep the air from bypassing the screen gap altogether. That's a mistake I made on my current ZP. I didn't think I needed a hold down for the manifold sections, especially the intake section. I used a large piece of weatherstripping and thought everything was fine, but with such a large volume of air being pushed thought the ZP, it bulged the glazing and allowed lots of air to completely bypass the screen gap. Eventually ALL my glazing hold downs failed and I was forced to clamp external braces to get me through the winter. I tried t-nuts on my original test ZP and when mounted in premium poplar, they tore out rather easily. I like your idea of the spring steel clips. Trouble would be finding enough of the right size and shape. But they sure would beat using bungie cords to hold things together(which I did think of using).

Greg in MN




dbc

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Reply with quote  #19 

Made a little more progress on the frames for the 2x16 ZP.  The right-side frame has 3/8 inch plywood glued into the bottom and both ends, and the bottom 2 corners are riveted.  Here are a couple photos.  The bottom is on the right in the picture:

Right frame, 053016.JPG 

End Slot, 053016.JPG   
Corner, 053016.JPG 

The top of the frame is not permanently attached yet, although I did glue the plywood in.  I need to insert the back piece before I rivet the top corners.

This time, I fit the bottom frame corners together according to my original plan with some silicone before I put the plywood strips in.  Clamped the corner and let the silicone set up a while, then glued and clamped the bottom plywood piece.  I glued the plywood with Liquid Nails.  After that set up some, I glued in the plywood side pieces.  Once those were set, I re-checked for square, clamped the frame corners with some spring clamps, and riveted the corners.  The top is just held on with some twine so I can move the frame around.  I discovered you spend a LOT of time waiting for glue to dry with this method.

I had to modify my original plan for the top corners.  I have the tops of the end pieces (these are straight-cut) fitting completely inside the folded ends of the top piece instead of going between the folded tabs.  Kind of hard to explain, but it reduces the difficulty of getting the corner together after after the plywood is glued in.  I needed something I could put together with the back piece already in the frame.  Had to hammer it with a 2x4 to get the ends in tight; fortunately the 25 ga. stud track submitted to the blows without too much protest.

Here is a photo of the left side panel under construction.  Bottom 2 frame corners are glued, and the bottom plywood strip is glued and clamped in with some 2x4's.  No rivets or end plywood yet.

Left frame, clamped, 010116.JPG 

As soon as I get the left frame as far along as the right frame, I need to work on the back pieces.  Plan is to cut the 1 inch polyiso to size and cut matching 'skin' out of aluminum flashing.  The widest I could find was 20 inches, so it will actually be a 6 inch strip at the bottom lapped by the 20 inch piece.  I will probably cut the 6 inch holes for air ducts in the flashing first and use that for a template to cut the hole in the polyiso.  Planning to glue it together before inserting it in the frame.  Never tried this assembly sequence before, but it seems like it should work.  I have a roller to get the flashing stuck down tight.  Not sure yet how to 'clamp' this assembly - probably set a piece of plywood on top with a bunch of concrete blocks (CMU's).

Now if it will just quit raining so much...












gbwillson

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Reply with quote  #20 
Don-

Now imagine how difficult it would be to assemble the entire 2x20 unit at the same time! Two separate sections will be much more manageable. Not to mention you'd be hard pressed to have enough clamps(did you see what I did there?). 

My single stall garage is 20' long. I started to assemble things in the garage, but the floor is uneven, and with the cabinets at the end, there is very little room. Not to mention in the basement workshop are all my tools and the climate is controlled. I might think about partial assembly in the basement workshop, and final assembly either in the garage or outside. But either way, I'd wait until the weather cools and the leaves drop. 

Greg in MN
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