Endo Posted November 8, 2014 Share Posted November 8, 2014 hi everyone, I have a problem that seems there should be a simple remedy to. I am going to attemp to forge a tomahawk head and when I have forged flat an end of bar before I end up with a hollow in the end I am drawing flat. So what prep do I need to do to prevent this. Thanks in advance Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted November 8, 2014 Share Posted November 8, 2014 Sounds like what is called "fish mouth" its a cold shunt. grind it off. To prevent it forge a very blunt taper on the end, say 45 deg (meets at a 90) or so, then push the taper back tord the eye, enstead or drowing tord the edge, this shiuld fix your problem. Just another case of smithing being counter intuitive Quote Link to comment Share on other sites More sharing options...
Endo Posted November 8, 2014 Author Share Posted November 8, 2014 Charles, I was thinking it was something like that. I remember watching a video that explained how to prevent that but when I needed the knowledge couldn't find said video. Thanks for the quick reply Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted November 8, 2014 Share Posted November 8, 2014 No problem, been there myself. Quote Link to comment Share on other sites More sharing options...
Stefflus Posted November 8, 2014 Share Posted November 8, 2014 Isn't this a ultimately a consequense of too light blows? I realize one would have to get a power hammer to escape dealing with the problem, but I just wanted to point out the underlying cause. -If I understood the problem correctly. Quote Link to comment Share on other sites More sharing options...
Damion78 Posted November 8, 2014 Share Posted November 8, 2014 My understanding is that it could be caused by either not hitting hard enough thus only moving the outer layer or not heating enough so that the center is not being moved? Quote Link to comment Share on other sites More sharing options...
John B Posted November 8, 2014 Share Posted November 8, 2014 It is a natural phenomenon that occurs when forging, the top surface under the hammer moves more than the surface in contact with the anvil's face. Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted November 8, 2014 Share Posted November 8, 2014 All true, but he wanted to know how to start off to solve the problem. Even a 14# slede wont solve the problem if you dont point the end first. I did have to read the original pos several times to understand the problem and what he was asking for. Basicly when you start out you knock the corners of the leding edge back in to the parent stock, if you dont the leading face will fold and the leading corners will close together. Any one good with sketch up or somthing that can illistrate this? I can sketch it on paper but geting it to somthing electronic so I can post it is beuond me. Quote Link to comment Share on other sites More sharing options...
jacobd Posted November 8, 2014 Share Posted November 8, 2014 Almost beating the edges back into the material before drawing out seemed to help me. I drew it out after rounding it off and then redefined the edges on the end. Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted November 8, 2014 Share Posted November 8, 2014 Same thing when pointing a bar before drawing out a punch or chisel. When you start playingwith larger sections you can see it happaning because it takes multiple heats to draw it out, and it takes more than a quick pass with a grinder to fix. I guess ill have to try and draw a picture and let Glenn tydy up the mess, lol Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted November 8, 2014 Share Posted November 8, 2014 Ok, so this is the problem, 1, starting stock 2, first blow 3, second blow 4, forth blow Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted November 8, 2014 Share Posted November 8, 2014 This is the cure 1, starting stock 2, first blow 3, second blow 4, forth blow 5, sixth blow 6, eighth blow Quote Link to comment Share on other sites More sharing options...
arkie Posted November 9, 2014 Share Posted November 9, 2014 Endo, you didn't mention the thickness of your bar, but another cause of a "fishmouth" is uneven heat. On thicker stock, if you rapidly heat the stock then forge it, the outside will be somewhat hotter than the middle, hence the hammer will move the hotter outside metal further resulting in the lip protruding over the cooler,harder inside. Remedy...soak the metal for a longer time to insure even heat distribution throughout the metal before hammering. If thinner, then the remedy Charles suggested would work. Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted November 9, 2014 Share Posted November 9, 2014 Actually your thick stock will fish mouth at a good heat if you have a square edge and try to forge a taper with out pointing it first. That is if you don't correct your error. Thin stock gives you less of a chance to catch your mistake and correct it. Quote Link to comment Share on other sites More sharing options...
Endo Posted November 9, 2014 Author Share Posted November 9, 2014 Arkie, It might be due to uneven heat as the stock is somewhere around 1.375" thick round. It's been a few weeks so I don't remember the exact measurement but it is over an inch. On that the technique that Charles has illustrated for me is the info I was looking for as I have experienced this on smaller stock also. Again thanks. Quote Link to comment Share on other sites More sharing options...
Damion78 Posted November 9, 2014 Share Posted November 9, 2014 Great illustration Charles that makes things very clear. Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted November 9, 2014 Share Posted November 9, 2014 Your welome. Like anything you hear or read, make our own judgement and in the case of smithing try it if it apears safe. All to often arm chair experts regurgitate what they have heard, or the well meaning misunderstand the question. Quote Link to comment Share on other sites More sharing options...
arkie Posted November 10, 2014 Share Posted November 10, 2014 Arkie, It might be due to uneven heat as the stock is somewhere around 1.375" thick round. It's been a few weeks so I don't remember the exact measurement but it is over an inch. On that the technique that Charles has illustrated for me is the info I was looking for as I have experienced this on smaller stock also. Again thanks. My first experience with a fishmouth was when I was making a hammer punch from a ball pien hammer head. Not ever having worked with thick metal before, I just rammed it into a hot fire, ran the blower up to heat it up fast so I didn't have to spend a long time with the heating process (such as a soaking heat), and when it got to orange-yellow, I started hammering away. After a few heats and the tapering process proceeded along, the fishmouth developed so much that you could stick a marble in the hole. Well, that fishmouth got cut off with an angle grinder and cutoff wheel after it cooled! I started the forging again from there and subsequent heats were allowed to soak and the temp was brought up to forging heat more slowly than before and the punch was nicely drawn out to about 6-7 inches long with NO fishmouth! :) Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted November 10, 2014 Share Posted November 10, 2014 Yes, Arkie that certainly aggravates the situation, as dose to lite a hammer or indecisive blows. But after making that mistake you are keen to correct it and with large stock you can correct the problem as it happens. But even with proper heat and square corners the stock will try to fish mouth if you try to taper toward the tip instead of driving the edges back and starting your taper at the tip then drawin it out. It's simply in the way the hot steel moves under the hammer. Your problem was in not starting the taper off right, made worse by uneven heat and from your description inefficient technique. After grinding out your oops, you were on guard and either changed you technique, ground a radius on the end or corrected as you forged. But if you make stone carving tools you want the struck end to fish mouth, lol Quote Link to comment Share on other sites More sharing options...
arkie Posted November 10, 2014 Share Posted November 10, 2014 Charles, after I "corrected" and cut off the fishmouth, I indeed did taper off the square corners first and then worked the punch thinning process. I also used a 4# then later a 3# hammer, hitting hard to work the metal while it was all hot and never hammered cooler than red-orange. That way the soaking for the next hammering round was less time. Going too cool to extend hammering time is NOT the way to do it. Gotta keep that steel hot all the way through. :) Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted November 11, 2014 Share Posted November 11, 2014 Yes sir, that fallowes my experiance, tho 3# is my go to hammer, 4# when i cant find a striker Quote Link to comment Share on other sites More sharing options...
arkie Posted November 11, 2014 Share Posted November 11, 2014 Charles, I hear you on the 4-pounders. My hammering rhythm with a 4# is: "bang, bang, bang, bang..bang...bang.....bang.........bang.............bang....................bang" (you get the picture) :wacko: Quote Link to comment Share on other sites More sharing options...
Charles R. Stevens Posted November 11, 2014 Share Posted November 11, 2014 Try a 14# one handed Quote Link to comment Share on other sites More sharing options...
rockstar.esq Posted November 26, 2014 Share Posted November 26, 2014 A 14# hammer one handed sounds like something Buggs Bunney would do! Quote Link to comment Share on other sites More sharing options...
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