Fe-Wood Posted October 11, 2011 Share Posted October 11, 2011 I am working out the details for a piece and have a question on cracking. When I cut the smaller thin section away and forged it out, all was fine. I then closed up the "Y" and began to forge the shape on the bottom of the "Y", where it goes into what I call the Gumby Foot (left side of first picture). While I was drawing that part out, the crack began to appear. Do you guys have any tricks for stopping this kind of thing? I'm using "off the shelf" mild steel and I didn't quench that area. I believe it has to do with the vibration caused from hammering... Suggestions? Thanks! Quote Link to comment Share on other sites More sharing options...
Thomas Dean Posted October 11, 2011 Share Posted October 11, 2011 Looks like a cool element! Yes, the craking can come from the vibration of forging the lower portion. Try doing your heavy forging first then step up and do the split and forging of the little "finger". What is this? I do like the way it looks. Quote Link to comment Share on other sites More sharing options...
Fosterob Posted October 11, 2011 Share Posted October 11, 2011 Are you hammering on Gumby's foot after you have finished the small tendril? Maybe keep the tendril tucked up against the body for support and one of the last things you do is bend it out. Rob Quote Link to comment Share on other sites More sharing options...
Timothy Miller Posted October 11, 2011 Share Posted October 11, 2011 My guess was there was a very small crack or defect in the stock. It was worked too cold at some point in the forging process and it opened up more AKA (too much fussing). Fill it with weld blend it in and move on with your life. Then vow not to work it too cold next time. If you were using better quality material 1018 or such it probably would not happened. Hot rolled steel is basically remelted scrap with variable working qualities we use it because its cheep not because it is the best. Quote Link to comment Share on other sites More sharing options...
HWooldridge Posted October 11, 2011 Share Posted October 11, 2011 It looks like the section just above the crack was thinned by one or more miss-hits. In addition, cracks propagate from stress risers which typically start as notches, however minute. This one may have originated in your chisel cut and developed during the forging operation then finally became apparent when the element was pulled out. If you want to save the piece and are careful, it might forge weld shut, especially if you use an O/A torch to control the heat (or you can "dot" it with a MIG and grind it). Quote Link to comment Share on other sites More sharing options...
Ten Hammers Posted October 11, 2011 Share Posted October 11, 2011 I'll second what Hollis says about the torch (and perhaps some E70s6 standard rod). I rescue some of my own this way. I also have added rod (wire) with the mig and blended THAT with the torch, heating well past the issue ( inch or more both ways). Quote Link to comment Share on other sites More sharing options...
Fe-Wood Posted October 11, 2011 Author Share Posted October 11, 2011 Thanks for all the ideas and suggestions. I am using this piece as the template and learning piece. When I forge the "real" ones I'm hoping I don't run into the same problem. I did close up the "tendril" (but not all the way at the root, the tip was touching the main part) thinking it would help with vibration. I was working with medium to high red heat. I watched the crack form as I was drawing out the "foot" section. I don't think it was caused by the chiseling in the beginning, but it could have been. I did file out the flashing from cut area before forging with the hopes of eliminating this problem. I don't really want to do the tendril last because it will make blending the sizes harder. I am thinking maybe wrapping it with baling wire to help stabilize it.... I'm going to try again in the morning. Quote Link to comment Share on other sites More sharing options...
Timothy Miller Posted October 11, 2011 Share Posted October 11, 2011 I have also noticed that hot rolled steel will sometimes form a bunch of very small cracks in the skin of the steel from time to time. While heating and reheating it sort of looks like very dry skin. I never figured out what causes this. I always thought it was something wrong with the steel. Quote Link to comment Share on other sites More sharing options...
David Einhorn Posted October 11, 2011 Share Posted October 11, 2011 You could also try drilling a small hole where your cut is going to terminate. That way the end of the cut is round instead of being a sharp V that could become the start of a crack. If that doesn't work, then I would try a different batch of steel. Quote Link to comment Share on other sites More sharing options...
double_edge2 Posted October 11, 2011 Share Posted October 11, 2011 Thin and cold, when moving or bending, don't really mix, unless you want cracking. To my untrained eye that is, better to heat again than try to get the "just a little bit more...." Usually, with forging faults, they get bigger as you go on. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted October 11, 2011 Share Posted October 11, 2011 I agree with rounding out the end of the cut---I often use a chainsaw file to do this. Also using a better grade steel a *real* 1018 will work a lot softer than A-36 and pure iron better than the 1018! Quote Link to comment Share on other sites More sharing options...
evfreek Posted October 11, 2011 Share Posted October 11, 2011 Hi Fewood. I had the exact same problem with almost the exact same element that you showed above. The problem is that the little finger has enough mass so that its inertia causes flexing at the root when the main trunk is impacted. There are a bunch of ways to solve this problem. The way I solved it was changing the order of operations and doing any forging after the tendril was developed at a very high heat. Also, it helped to interpose a lossy material at the places where vibrations can cause problem, like a wet sock or piece of rotten wood. The problem is not really vibrations, it is the inertia of the secondary piece. Imagine standing on one of those whirly platforms that are often found in playgrounds. Someone starts it impulsively. You are liable to slip. Now, imagine holding a big heavy box over your head, and the person does the same thing. Give it a try. See??? Quote Link to comment Share on other sites More sharing options...
Fe-Wood Posted October 11, 2011 Author Share Posted October 11, 2011 I like the drilled hole idea... I have never worked 1018 that I know of. Love working wrought. I may try fullering it into a small radius after cutting too... I just bought a Fly Press so I'm going to wait until I get that before I make more..... Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted October 11, 2011 Share Posted October 11, 2011 The h-frame in CA one? Quote Link to comment Share on other sites More sharing options...
David Einhorn Posted October 11, 2011 Share Posted October 11, 2011 ... ..... I may try fullering it into a small radius after cutting too... For a book about fullering a cut, I highly recommend the book: The Skills of a Blacksmith: v.1: Mastering the Fundamentals of Blacksmithing [Hardcover] Author: Mark Aspery Hardcover: 300 pages Publisher: Mark Aspery (March 24, 2007) ISBN-10: 0981548008 ISBN-13: 978-0981548005 Product Dimensions: 11 x 8.8 x 1 inches He shows making and using a nifty tool for fullering the cut. Quote Link to comment Share on other sites More sharing options...
Steve McCarthy Posted October 12, 2011 Share Posted October 12, 2011 I have made some tree branches out of 1/2"X1". I split like you did then had to work the two parts to round. The same thing happened to my first one. Dressing the end of the split with a small fuller before working the remaining arms stopped the problem. Quote Link to comment Share on other sites More sharing options...
Fe-Wood Posted October 12, 2011 Author Share Posted October 12, 2011 No Thomas its from out east, its a "C" frame. Mark's books are excellent! I don't have any but I have worked some of the projects with friends. Steve, Fullering seams the ticket. I am going to try the drilled hole too because it will help with layout... I think Quote Link to comment Share on other sites More sharing options...
clinton Posted October 12, 2011 Share Posted October 12, 2011 Fuller or file so there is no sharp edge. and you have to control movement. Flopping back and forth at black heat is no good. You sure did not waste any time finding a flypress- what did you get? I have been looking but with no work now it is just looking. Quote Link to comment Share on other sites More sharing options...
Frank Turley Posted October 16, 2011 Share Posted October 16, 2011 There is something called the blue brittle range of temperature from about 300 to 700ºF. It is said that it doesn't affect our everyday A36 and 1018 so much, but I wonder. I have experienced breaking at one end of a bar while I'm hammering on the other end. The end that broke was warm, possibly in the blue brittle range. The Vanishing Point. A fellow smith pointed out the natural, growthy looking joint of a branch to a stem in blacksmithing, and he called it the vanishing point. It is the interior of the joint where the two pieces beome one line, a shut, and then the line narrows and disappears. To me this is an aesthetically nice appearance in blacksmithing which can be gained from forge welding or hot splitting. If you punch or drill a hole at the base of the hot split, you will lose some material. I haven't tried to make a hole and then close it up again to attempt to get the 'vanishing point.' I think you'd have to start with oversized material. I've punched a hole when splitting the tines of a barbeque fork, and I made a loss allowance. Quote Link to comment Share on other sites More sharing options...
bigfootnampa Posted October 17, 2011 Share Posted October 17, 2011 Something that Mark Aspery teaches is to use a chisel with a rounded edge on the side where the Y will be so that you have a slight radius there instead of a sharp split. That way the tendency to act as a crack starter is mostly countered. I have seemingly had good results with this system. Quote Link to comment Share on other sites More sharing options...
Fe-Wood Posted October 17, 2011 Author Share Posted October 17, 2011 Frank and Bigfoot- Good points both- If I were going to drill a hole, it would be in the 3/32" range because I like the "vanishing point" you speak of. I'm waiting for my press to arrive before I continue with this project. I believe I will soften one edge of the butchers that are coming with the press. I may end up making steeper angled "slitters" to do this too so they act more like a chisel. Quote Link to comment Share on other sites More sharing options...
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