|Hi Dan -|
Here's a couple of shots that hopefully show how I installed the tube and how I use a loop of fine mono to hold the fly at the end of the tube.
One thing: I used a piece of 1/16" white plastic tube because at the time that's all I had. A heavy fly can cause it to bend slightly. Jay sent me a piece of 1/16" brass tube that I think might work better because it will stay straight and won't be bent downward by the weight of a heavy fly. A metal tube would also work better if you plan to use pieces of matt board for different background colors. The weight of the matt board can also cause the plastic tube to bend slightly. Just something to consider if you're building your own.
I cut my piece of plastic tube about 5 - 6 inches long, using the straightest section I had. Some of the plastic tubing has a slight bend to it.
Next, through the rear wall of my box, I made a hole ever so slightly smaller than the outside diameter of the tube. The tighter the fit the better. Insert the tube through this hole so approximately 1/2 inch to 1 inch extends out the back of the box. This provides enough tube for the glue to adhere to and also helps to keep the tube straight.
I cut some pieces of packing foam and arranged them inside the box so they would support the tube while the glue dries. It is critical to get the tube as level and as straight as possible. If the tube is not level or bends it won't be hidden behind the fly and you have to position your camera as best you can to try to hide the tube. If the tube is straight and level, it makes it much easier to position your camera straight on to the fly.
Using 5 minute epoxy, I glued the tube in place. I only put glue around the tube that extends outside the rear of the box. If you put glue inside, it might be visible behind your fly. This isn't a problem if you plan to always use a back plate of some kind. But regardless, I recommend not building up a big fillet of glue inside the box. I built up a big enough fillet on the outside of the box to hold the tube straight and level. If you just barely glue the tube to the cardboard, there isn't sufficient leverage to keep the tube from tilting downward. Hence the big fillet of glue.
Now to secure the fly, I made a long loop of 6X or maybe even 7X mono. The loop is about twice as long as my tube. I inserted the loop through the tube, from the rear. Then I found a needle that was nearly the same inside diameter as my tube. By inserting the needle, I can secure the mono loop tight enough to hold the fly in place for the photo shoot. When I want to change flies, I simply pull out the needle, open the loop inside the box, carefully remove the fly, and insert another fly. Then pull the loop tight from the back and re-insert the needle. Actually, my needle is about 4 inches long so I never completely remove it. I just pull it out enough so I can open or close the mono loop.
Hope that helps. If not, keep asking questions. I'm learning still as I use this thing.
[click here to display pictures]