ThomasPowers Posted September 9, 2020 Share Posted September 9, 2020 Biggest mistake folks new to the craft make is heating the tire too hot and having it char the wood. Definitely a black heat, a pine sliver should slide easily on the hot metal---which is more like 500 to 600 degF IIRC. I'm going to stay out of the "not uniform heating" discussion as there are too many variables in it for me to worry about. Quote Link to comment Share on other sites More sharing options...
anvil Posted September 9, 2020 Share Posted September 9, 2020 makes sense. I had not considered all edges and centerline expanding equally. By the way, your hole/whole explanation is priceless! 11 minutes ago, ThomasPowers said: "not uniform heating" Lol, 2-1\2 years of aerospace engineering just before the Wright bro's flew, creeps out of the long dark. Quote Link to comment Share on other sites More sharing options...
Chris Williams Posted September 9, 2020 Share Posted September 9, 2020 The astute reader may now be wondering, "What about a hole in the center of a large plate?" If you heat the plate evenly, then the hole expands in proportion to the plate. Circumference = pi * diameter = pi * radius * 2. The length of the side of a square around said circle = radius * 2. They expand and contract in proportion, provided there is no external constraint such as uneven heating. I leave any attempt at determining specific conditions suitable for shrinking a hole with the addition of localized heat as an exercise for the motivated reader. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted September 9, 2020 Share Posted September 9, 2020 Not to mention non-uniform heating make the plate bow; which of course can be used as a method of dealing with a previous deformation. Shrinking sheet metal with a torch and wet rag....just doesn't work the same with polymer body panels---they don't even work well with lead wiping! Quote Link to comment Share on other sites More sharing options...
anvil Posted September 9, 2020 Share Posted September 9, 2020 I can add complexity to that. Perhaps it only bows if the top is hotter than the bottom. If I put a 10' length of half x one in the fire, and heat up 6", no bow,warp, or twist. But if I heat the top half of 1'x1'x1/2", it bows. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted September 9, 2020 Share Posted September 9, 2020 Sorry; I've never considered 1/2x1" to be plate. Quote Link to comment Share on other sites More sharing options...
arkie Posted September 9, 2020 Share Posted September 9, 2020 1 hour ago, Chris Williams said: Simply put, there is far more length dimension than width or thickness dimension for the wagon tire. The thickness and width also expand, but nowhere close to as much as the length. That is the simplest and most accurate description I have run across. Quote Link to comment Share on other sites More sharing options...
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