Rindert

Yup, It's a little like jacking up a car so you can crawl under and work on it. You need to be sure of what you are doing, but it is done millions of times a day around the world, successfully. That being said, no the seal between the can and the doesn't have to be so tight, just close enough so the jar won't fall off. Here's a little more info. The one on the right is where this project started. It’s really good for camping, hiking, backpacking. I was using my experience making tlud camp stoves. I just made it with my jack knife. I was amazed at how well it worked, though later ones work even better. The one on the left is just a longer burning version (~36 hrs) of the first one I showed you. Lots of different jars will work, as long you can find a can that fits closely.

I've found a way to make a really good emergency candle in an old jar using an old food can as a chimney. The flame is very steady. It does not produce smoke or soot. It makes very little odor. The wind will not blow it out if you take it out doors. I made a hook out of a nail so I can hang it from a hook in the ceiling. You have to use one of those new type cans that you don't need an opener for. Make 30 wide slits at the top of the chimney 1.4x.08 inches. Make 6 narrow sits .65 inches up from the bottom .7x.03 inches. Bend the flange inside the can, that was left behind when the lid was removed, so that it mimics the cam features that are part of the jar lid. This will allow you to attach the chimney securely to the jar. Save the jar lid. You can remove the chimney and put the jar lid on when you want to put the candle out.