Tsigmon Posted December 12, 2008 Share Posted December 12, 2008 I'm new to this forum and have searched the past threads and have not found the answer to my question. I need to forge some rings from 3/8" round stock that will be 3" in diameter. I had the formula at one time but can't remember where I wrote it down. It was not the basic pi(d) . It figured the diameter of the stock used also. If anyone is interested I'm making the drag rings and links that cover the seeds on an Oliver Superior horse drawn grain drill. Quote Link to comment Share on other sites More sharing options...
rlarkin Posted December 12, 2008 Share Posted December 12, 2008 If your 3" diameter is the inside of the ring, add the stock size to the diameter. 3" + 3/8" = 3 3/8" If the 3" is the outside measurement, substract the stock size. 3" - 3/8" = 2 5/8" Formula still applies. Quote Link to comment Share on other sites More sharing options...
Gayle Brooks Posted December 12, 2008 Share Posted December 12, 2008 ohhhh ya I get ya. rlarkin has got it Quote Link to comment Share on other sites More sharing options...
TASMITH Posted December 12, 2008 Share Posted December 12, 2008 Quick and dirty formula I use to calculate length of stock for a ring is ...3 times diameter of ring + 3 times diameter of stock +1/4 inch when working with smaller dia. stock such as 3/8th's. Therefore for a 3" inside dia. using 3/8" stock: 3x3 + 3 x 3/8 + 1/4 = 10 5/8" stock req'd. Quote Link to comment Share on other sites More sharing options...
Grant Posted December 12, 2008 Share Posted December 12, 2008 The Blacksmith's Craft solution is similar to above, stated: "To determine the allowance for bending, add the thickness of the metal to the inside diameter of the finished ring, and multiply this figure by 3 1/7 (Pi). To determine the allowance for welding, take the final figure arrived at above, and add twice the thickness of the metal." -grant Quote Link to comment Share on other sites More sharing options...
Jack Evers Posted December 12, 2008 Share Posted December 12, 2008 The key is that the centerline of the stock remains unchanged in length. If you want a ring of 3/8 stock with a 3" ID, the centerline of the stock will form a 3-3/8" circle. Length = Pi times 3.375 equals 10.6 inches with a bit of variance for the way you forge the weld. Basically as Grant said above. Quote Link to comment Share on other sites More sharing options...
Tsigmon Posted December 13, 2008 Author Share Posted December 13, 2008 Thank you all. This hepls alot Quote Link to comment Share on other sites More sharing options...
Tsigmon Posted December 13, 2008 Author Share Posted December 13, 2008 Thank you all. This helps alot. Quote Link to comment Share on other sites More sharing options...
Ice Czar Posted December 13, 2008 Share Posted December 13, 2008 errr.... is this for estimating stock needed or precutting? we used to make quite a bit of chain and rings not the forge welded ship anchor variety but serious enough to hold up 9 ft dia chandeliers a lot of it pre-twisted square stock or octagonal for decoration then heated and wrapped as a coil around either a pipe or circleoval jig to form a large coil, pounded tight to maintain dimensional similarity it was then generally cut square right on the jig an economical approach for both stock and time of course with that approach there is an unknown amount of stock on the first coil and last coil that will be scrap point is that there was definitely a +/- attribute that having seen video of Fred Dibnah forge welding ship chain I'd think would also apply unless your individually handcrafting each ring and comparing it to a standard. A simple jig make a huge difference in time invested Quote Link to comment Share on other sites More sharing options...
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