November 7, 200718 yr Hi. I saw these plans on the a www site.http://www.blacksmithing.org/projects/SN24BenchShear.pdf What would the capacity of them be? It says that they can cut more than tin snips. About all I can figure out is that bulldog snips can do 16 ga with about 6x2 = 12 compound leverage. This shear has 10.66 X leverage, but it uses arm power rather than hand power. Probably no more than 4 X given the cross-section of the muscles involved? Recently, I needed to cut some sheet metal which was thicker than the capacity of the typical compound aviation snips 15 ga vs 18 ga. There is no way that the snips can cut 5/64" sheet. I used an anvil and cold chisel according to some instructions that I saw on an armoring site. Just score the metal, and it will crack. No jagged edges. It worked just great! Just like a weak cold shut on a forging goof-up. But, it would be nice to have a set of shears with better capacity than tin snips.
November 8, 200718 yr probably about 16 gauge before the wood gives out. I made this years ago from straight grader blade, I have a two foot handle for it and if I add another 18 inches or 2 feet of pipe I can cut narrow 3/16 flat, it will cut 1/8 by 2 flat but you have to jump on the handle.
November 8, 200718 yr Take the design and make it as heavy as you need, and like Sam said build it out of steel. Looks like a decent design. welder19
November 8, 200718 yr Francis Whitaker's Blacksmith's Cookbook has a good plan for a hand shear. He said he had built his several decades before and it still worked fine.
November 8, 200718 yr heres one on ebay that is about like that. The page gives information on what it can cut5" Sheet Metal Shear Steel Aluminum Copper Hand Cutter - (eBay item 250184829116 end time Nov-09-07 15:31:35 PST) I bought one last year it does need to be mounted to a solid base ..I need to re mount mine
November 11, 200718 yr Author Hi. Thanks for the replies. I did a few scaling calculations, and agree that 16 ga. is all this thing can cut. The problem is the long end (6") that protrudes past the pivot. This is just too weak. In order to cut thicker stock, it either has to be shorter, or bigger, or made of steel. I think that this is a Popular Mechanics type of article, and I have found these articles to be somewhat spotty in full disclosure. Somebody once told me that you have to be an engineer or scientist to make some of them work, since they require extensive modification. Similar to Harbor Freight "kits".
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