This fin clamp is modeled after Tom's vice-grip clamp for those of us who don't own a welder.
Its purpose is to clamp the fin tightly to the copper tube and to get a little more wrap of the fin onto the copper tube near the bottom.
Once the fin is clamped in place, you then staple or screw the fin to the backing board, and it will stay in tight contact with the tube.
If you are wondering what in the world this is all about, go here...
When you press down on the handle, the wood cam pushed the upper end of the two vertical pieces apart, which pushes the lower end of these pieces together, and pushes the two pieces of angle iron into the fin right near the bottom of the tube. As you can see from the picture below, it does make for a tight fit, and it pushes the aluminum fin a ways further in at the bottom of the pipe.
I don't think its necessary to build this gadget, but it probably does improve performance a bit. The most important thing is that whatever method you use, that you pull the alum down very tight over the tube so that it contact the copper tube over as much area as possible.
Not matter how tight you get the fin to fit on the tube, there will be some very thin air gaps, and (in my view) this is a good reason to still use the silicone between the two, since silicone 10X more conductive than air. All explained here...
I also still like the idea of running the 2nd strip of 3 or 4 inch wide flat aluminum under the tube. I believe that this both increases contact area between fin and tube, but also provide more heat conduction path through the fin where the heat flow is highest (ie near the tube).
Update on Tom's Absorber Plates
Tom has decided to make absorber plates from his press available as a regular product from his UP Truck Center business.
He offers plates to fit 1/2 inch and 5/8 inch copper or PEX pipe. Fin length can be customized from 24 to 34 inches. He offers a "standard" fit as well as a 90% wrap fit. The modified vice-grip that make it easier to clamp the fins tight to the tubes are also available.
The prices are very reasonable, and I can attest to the fact that the plate fit is very good. I think this is a very good option for anyone who does not want to bother with making fins.
All the details on ordering and using the fins on ordering fins from Tom...
Gary December 8, 2009