little giantLittle Giant sells springs, toggle links, etc for the 25,50,100# hammers. Instead of trying to calculate which truck spring to buy, just get a complete toggle link from them. Use the same crank offset as the LG. Or use the LG crank. I like the later LG upside-down Pitman arm. Buying the above from LG is probably less expensive than making it all. And it would be correct the first time. No need to re-invent the whole thing. Most of the early tire hammers used big structural tube as the frame, in place of the big sand-cast iron frames of the early 1900s power hammers. Instead of structural tube or I-beam, use an A-frame like the Japanese power hammers. An A-frame hammer with a separate anvil can be deconstructed and moved more easily than a monolithic design. An a-frame can be made stiffer than a structural tube or beam, which will tend to develop oscillations and rocking with a small base and high center of gravity. The recommended anvil weight ratio (from IronKiss) is 16:1. A 6x36" bar of 1018 should weigh around 289#, but I've seen different on the scales! 7x36 would be closer to 400#, the ideal weight. For a 50# hammer, a 11" base.. Metals weight calc for dimensions. http://www.machined-castings.com/calc.html
Meh. Bow spring or coil.