OK, so on to working the segments. As I said, my goal is to complete a can koozie using segmented rings. The best way I found was the 'wedgie sled' concept created by Jerry Bennett. It is basically a 3 part sled. I thought I could get away with just the adjustable arms and quickly figured out why the parts are there. It is really a simple concept. You adjust the 2 bars on the sled according to how many segments you want per ring. You can do math (360 degree circle divided by 18 segments per circle = 20 degree angle. Divide by 2 since each wedge has 2 sides making it a 20 degree total angle or 10 degrees from center on each side) or you can have a predetermined wedge to drop between the two adjustable bars (hence the wedgie sled name).
Each segment has 4 critical dimensions. We set the side angles in the first step. In this step we determine the outside diameter of the ring. The inside diameter was established earlier in prepping the wood. In this case I purchased 2 strips of dimensioned wood from Woodcraft (1/4" x 3/4" x 16" purpleheart and yellowheart). So in this case the 3/4" width will make a ring 3/4" wide. I wanted to set my outer diameter at 3.5". Now I will be totally honest here, I didn't do this math. I could have, and I did earlier when I made the original koozie. But why? I found an app, put in some numbers and it spit out a length of .619". You cannot see it in the photos, but there is a way to calibrate the stop, then using digital calipers I can set the exact length of each segment.
The third part of the jig is a simple 45 degree strip with magnets on the bottom to keep the cut of segments from riding the blade and getting flung across the shop. Didn't think it was necessary until one smacked my safety goggles (safety first kids).
You can see the segments below. It goes pretty quick. I made 36 segments in less than 5 minutes. Basically trim the square edge off the end, then move the wood to the stop and cut. Switch to the opposite bar, move to the stop, and cut. The way the sled is designed it eliminates any error in the angles by moving between bars vice trying to make multiple cuts on the same bar where errors are compounded. Each 16 inch strip of wood made 24 segments which is more than enough for two rings, seen below.
Some of you who are good at math probably see the error already. "Uh, Joe? If your outside diameter is 3 1/2", and each segment is 3/4" (x2 is 1 1/2") then that hole in the center is only 2" across. You making Red Bull Koozies?"...And you would be right. In my hurry to show off how the sled works I skipped a step. I should have ripped the 2 strips down to 1/2" wide before running them thru the sled. I went back and ripped some oak down to 1/2" x 1/2" and made the segments again. So now I simply glue and zip tie in a circle to dry. They fit around the can well. I will need to trim the center to round which will give me a little room around the can. I plan to use a cheap thin foam koozie to insulate the inside and that will make this a snug fit.
So for now it is simply cut and glue, cut and glue. If my math is good I should be able to get more than 6 koozies from a single 2"x6"x24" block of oak (2 BF). Assuming around $7 per BF for oak, it looks like I am in for $2.50 in wood per koozie plus glue and time. My initial temptation is to price these at around $10 except that there is likely a ton of man hours in this. $15 might be better, but not sure if that is pricing myself out of the market.
So I am already seeing a few issues that I will have to overcome. First, I was able to dimension down the large block of oak into 24"x1/2"x1 1/2" Strips. Using the band saw I ripped these into 1/2 inch strips, but they were not ripped in a straight line at all. So now I have a 24 inch x 1/2 inch x a wavy 1/2 inch strip. Not a big deal except the top of the rings once formed is not flat. Since the rings eventually have to be glued together, and need to be parallel to each other I have to figure a way to flatten the rings out. The strength of these segments comes from each ring supporting the other. The individual rings are end grain glued together and provide some structure but not a ton of strength. The strength comes from the edge to edge gluing between rings. So I guess I will sand the rings with my Ryobi combo belt and disc sander.
Thanks for reading, as always comments, questions, and recommendations are welcome.