A Homemade Jig For Forming Solar Collector Fins (or radiant floor heat spreaders)


This is a plan for a simple "Honda Powered" homemade jig to bend alum sheet into U channels that can be used as the collector fins for solar water collectors, or as heat spreaders for radiant floors.


The jig is in two pieces.  The alum fin sheet is placed over the left half of the jig.  The right half of the jig is placed over the alum sheet, and I drive over the whole thing with my car.  The alum sheet gets pressed into the groove in the left part of the jig by the steel rod on the right part.  I use a guide that is not show to keep them lined up with each other as I drive over them.  It makes a very nice "U" channel that fits the CPVC or PEX tubing well (would also probably fit copper tube well).


There are a couple more links to simple bending tools from RedRok at the bottom of this page.




Picture showing the jigs nested together.


The end product.  This is a cut through the finished fin and tube.


Made as follows:

Form alum sheet fins with jig as described above

Put a light bead of silicone along the bottom of U channel

Lay the tubing on the backing plywood (or any light material you can staple into)

Put a bead of silicone along each side of the tube where it meets the plywood

Place the U fin over the tube, and while compressing it against the tube with your fingers, staple every few inches.


The gap between the tube and fin is very small, and is filled with silicone, as can be seen in the picture.



Other Methods:


Here are links to two simple jigs at www.RedRok.com


A Wrapping Jig.

Or a Beading Jig.


Here is an idea from Nick Pine for using a fin that has been bent by the first of the two jigs above:

                                               .  .  .  .
                   aluminum flashing   rivet . .  1/2"  . .   
                .........................|... .  copper  . .  
                .........................|... .   pipe   . . 
                                       rivet . .        . . 
                                               .  .  .  .
                                  --- .           .  .
                                   |  . <--foil-faced foamboard
                                      .    on the back side?
...then open it up like this:         .  
                                      .           .  .
                                      .        .  .  .  .
     Home Depot sells dark-           .rivet . .        . .   
     brown-painted aluminum       ~5" ...|... .  copper  . .  
     roof flashing for $46.50         ...|... .   pipe   . . 
     for a 50'x2'x0.027" roll.        .rivet . .        . . 
                                      .        .  .  .  .
                                      .           .  .
     [View in Courier font.]          .  
                                   |  .    This solar collector might be
                                      .    60% efficient heating 120 F
                                  --- .    water inside an 80 F sunspace.