Installing Heat-Shrunk Iron Banding on Wooden Trebuchet Axles

[@suzz1776]

So u should make a black powder powered trebuchet. Lol. I have no idea how it would look or work but it should cool and would love to see something like that. Lol.

[@ironcladranchandforge7292]

Not trying to be critical, but that Blacksmith did just about everything wrong, especially on that first set of bands. When measuring the material to make square bands, the measurement must be taken to the center of the steel thickness. This is because as the bends are made, the inner surface will compact (shrink) while the outer surface will stretch. The center stays relatively stable. I would have also "upset" the corners and squared them up better to make full contact with the wood. The bands should have been made so that they just tap on when heated. Besides making them too small, he overheated them to a yellow heat (about 1,800 degrees), burning the heck out of your beautiful wood. If made properly, the steel band shouldn't show any color when heated and hammered in place. I noticed that's what you did on the second set though, which is good. When not in a controlled environment (like an oven), it's obviously hard to tell what temperature the steel is heated up to. Inch per inch linear expansion of carbon steel is 0.00000633". So at 500 degrees you'll be getting a little over 0.003" in expansion on all sides. A good black to dull red heat is anywhere between 500 and 1,000 degrees F. This will give a clue to dimensioning the band. Anyway, cannot wait to see how the new arm and axle performs. Will you be making a video of the Trebuchet in action?

[@MedievalTrebuchet]

Thanks for this additional perspective and information. It was definitely a learning experience for us the first time. It's cool to hear confirmation that you don't need to heat these things red-hot to have it work. The tolerances you are describing for making a good set of bands seem very precise. It would be interesting to learn more about how a blacksmith could have made a good set of bands in the Middle Ages. I bet they knew what made bands work well and likely strived for quality tolerances. But without modern measuring aids it must take a lot of skill and practice. We are shooting the machine with the new axle this weekend! I'll take lots of video

[@ironcladranchandforge7292]

@@MedievalTrebuchet -- Skill and practice to say the least. These Blacksmiths were exceptional !! Typically, Blacksmiths of this period would start their apprenticeship at around 14 years old. The apprenticeship would last about 7 years on average. Take a look at the KZbin channel "Engels Coach Shop". He is the foremost authority on wagon building, and the best as well. He builds all his wagon wheels and uses measuring techniques and tools that have existed for at least 500 years. His hub bands turn out perfect every time. In the book "Decorative Antique Ironwork, A Pictorial Treasury" written by Henry Rene D'Allemagne, pages 362 through 378, you'll see various measuring devices from the 15th to the 18th centuries, including sliding rule measures (calipers). I believe measuring devices such as these existed well before that. By the way, the book mentioned above has absolutely incredible iron work from the 14th century through the 18th century that boggles the mind. Saying all this, I do understand that your primary focus is probably building a Trebuchet of the 11th or 12th century type? While my primary historical blacksmithing focus is 15th through 19th century time period, I believe the general techniques and measuring methods were the same, although the "units" of measure differed drastically from village to village throughout Europe. This was well before country's started to adopt standard units of measure. Looking forward to your upcoming videos. I really like what you're doing here!!

[@mayhemassault]

@@ironcladranchandforge7292 some old smith in Sweden told me long ago that you can tell the temperature of the steel by spitting on it, maybe like if the spit turns brown its some certain number of degrees hot. I cant really remember what he said but something similar. Know anything about that? (im not native english speaker)