This whole project started with a very basic piece of firewood and drilling holes in it. The holes are approximately 1 1/4" in diameter and 1" deep. The hole size is not critical. This just happened to work well when I upgraded to my caulking tube filler. One squeeze of the caulking gun and one hole is filled. Dumb luck.
Step 1: Filling the Feeder
Filling these with suet or lard was a messy job. One day I'm surfing Wikipedia and learned that margarine was invented as a turkey food. Picked up some margarine on sale and started using it in lieu of suet or lard.
Opinions vary, but it doesn't seem natural to me to be feeding birds who are vegetarian by nature animal fat. I haven't seen any birds drop dead from eating the margarine and they sure do like it, preferring it over suet or other animal fats. It was still kind of messy pressing the sticks of margarine into the holes.
I'm looking at a standard caulking gun tube one day and thought it was about the same diameter as a stick of margarine is square. Turns out its pretty darn close. I used compressed air to blow out the plug from an empty water based caulking tube and thoroughly washed the tube and plug. And started filling the tube with sticks of margarine. The rectangular sticks are a close fit, but shave the corners of the stick. Not a big deal to just put them back in the tube, but the goal was to keep mess to a minimum.
Step 2: Rounding Out the Margarine
This isn't really necessary, but in an effort to achieve my goal of minimal mess, I put this "margarine squeezer" together. A short (about 8" long" piece of 1 1/4" conduit, split lengthwise, then flattened or reshaped a bit to squeeze the margarine stick to about 1 1/2" in diameter. A hinge across one side and a couple handles for some leverage completes the squeezer. The caulking tube measures roughly 1 5/8" inside diameter.
Taking the margarine out of the freezer (where we store the margarine bought on sale) and then running each stick through the squeezing process while the margarine is still in it's wrapper. Takes a matter of seconds. Easier if done while still frozen. Easier to unwrap while still frozen and actually easier to unwrap after squeezing. Mine isn't pretty, but works well. At this point I can see no place to improve on it.
Step 3: This Shows the Plugs Blown Out of the Tube and the Margarine Being Loaded
The tubes are completely reusable. After squirting the margarine in the suet feeder's holes and emptying the tube, I blow the plugs back out using compressed air. I'm sure a stick would work, but since I have the air handy... Be sure to point the plug end of the tube in a safe direction. I put a piece of paper towel in my left hand and while the tube is setting on my hand squirt air down the nozzle end. The plug will come shooting out with a noise and velocity to rival a low grade spud gun. Take it easy with the air volume and pressure.
The sticks just slide into the tube, two sticks per tube and its pretty well filled. I keep the filled tubes in a cool place, but the one I am using at the time is kept at room temperature. As the temperature drops towards freezing the margarine (which contains a fair percentage of water) becomes too hard to easily squirt out with the caulking gun.
Step 4: I Had Problems With the Original Plugs Leaking a Bit
As they were used, the plugs/followers seemed to start leaking a bit, losing their seal and allowing margarine go past. I tried a couple things, but the best fix (and its been working perfectly for 3 years now) is casting plug material and using sections of it to replace the originals.
I sacrificed a caulking tube to make these. I had some urethane rubber resin left over from a previous project that was still usable. I plugged the nozzle end of the tube, mixed the resin and filled the tube which was held upright by the nozzle. After the rubber cured, I split the tube, removed the rubber "rod" that had formed and cut it into sections about an inch long. The company I originally purchased the resin from is gone, but it is very similar to Smooth-On's Econ® 80 Urethane Rubber. I've ordered from Smooth-On in the past and their tech support is great as are the products I've ordered. Lots of fun stuff there.
This attracts an amazing number of birds. The ones that really surprised me are the woodpeckers. They show up in surprising numbers during the winter and love the margarine. Chickadees are also very fond of it. Being diligent about keeping these filled is important both to the birds and to having them hang around on a daily basis.