I have read the many benefits forging has before rolling metal. I have experienced the benefits and found forging necessary before rolling small gold ingots to prevent them from cracking. I am wondering what exactly I should do to fully reap the benefits of forging. Must I forge to a certain reduction, say increase the length of a wire ingot by 1/3 or reduce sheet thickness by 1/2? Can I get away with less than this? I suppose I’ll need to pour wider, heavier ingots if I do need to forge to such a large reduction…
So from what I understand, grip the ingot ingot in vice grips, place on a steel bench block (unfortunately I don’t have an anvil) forge with cross peen until around had its original diameter or one third longer then flatten hammer marks with flat side of hammer, anneal then roll?
For regular forgers, how do you do it? Don i have the right idea? Can I get away with less forging than this?
I just did an experiment Actually I just forgot to forge so I made the stock twice out of the same metal. I made a 35 g rod ingot and rolled it to 2X2 square first without and then with forging. My forging is fairly rigorous, but I don’t use any specific indices of completeness. In the case of a rod ingot, I forge it square and then cross peen all sides. The not forged ingot rolled great for several passes and then it began to feather and crack. The forged ingot rolled fine out to 2X2 square. The step that I do that you don’t describe is that I first remove any mold flashing and other surface irregularities by sanding the entire ingot using my lapidary expansion wheel and 220 grit belt. Otherwise, when you forge and later roll, these little irregularities get rolled into the surface and reappear later. Anneal after forging and often when rolling and you should be good to go. My melts usually are proceeded by removing solder joints in the scrap and anything that looks suspect and magnetic. I heat the ingot in my kiln at 600F for 5 minutes, carbon coat the inside of the ingot with a gas only flame, assemble, melt and pour. I always add a little new metal to the scrap, a little borax and stir with a carbon rod. This all becomes kind of a ceremony. Good luck…Rob
also, re forging sterling silver ingots of approx 4mm thickness, with my 20oz fretz sledge hammer, or my 2lb (32oz) blacksmithing sledge hammer, i have kinda figured out that it is best to “listen” to the metal, and be mindful of how it “feels”…
i have tried to follow the 30-50% reduction rule but it isnt always that cut and dried…i have experienced fatigue in the metal before it had hit that reduction amount, and could feel the difference right before i went “too far”…if that makes sense…
the crosspeen will move metal faster, in one direction…at a time…
the rounded face will move the metal slower in all directions…
I find that I follow the same general patterns as most of us when it comes to forging ingots and rolling sheet. While we use a lot of science in what we do it is science learned of centuries of experience and shared among us. When I forge an ingot I know what and why I am doing it but I have no way other than the finished product to know if I was a success at it. And since I am consistently more often than not successful I am assuming I do it right.
Like my brother when I am forging an ingot I beat it up pretty good with a cross peen hammer. I don’t know how hard or often I hit it but I follow the same pattern every time. And I would bet the number of strikes are pretty much the same on all four side. Rob mentions that it is a ceremony and it really is. Probably the most important thing we do with our work is the consistency of procedure we follow. And it may be the thing we think about least. We probably light a torch the same way every time we light it. (Our Dad would tap a file once on the bench every time before he would use it) Over time we develop processes that work for us and without thinking about it too much we continue to follow those same steps every time. I will bet that I anneal a piece of metal the same amount of times every time I roll some sheet from an ingot down to .20 gauge.
With the exception of the kiln I follow the same ritual as my brother when I am casting some scrap into an ingot. One thing I do that may not be common is I will wash with Dawn and scrub with a brass brush the sheet every time I anneal it. I will dry it well before I roll it further.
Also it is critical that you tap the plate with your bat three times only, check the label, and rest it on your shoulder BEFORE you take a practice swing.