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2:38 pm
January 18, 2011
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I've often watched smiths turn their work on the anvil and the power hammer (sometimes at mind boggling speed) 90 deg each time they strike the bar they're forging. I rarely do this prefering to work down one side and then the other.....What if any is the advantage of this?
"Be who you are and say what you feel, because those who mind don't matter, and those who matter don't mind."
— Dr. Seuss
4:13 pm
NWBA Member
September 29, 2011
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The same thought crossed my mind yesterday as I was drawing an octagonal taper. There is simply no way I could form anything close to even, straight facets if I flipped the stock back and forth. Paying attention to the strength of the strike and the squareness is enough to try to handle.
6:35 pm
May 11, 2010
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Bruce Macmillan;17167 wrote: I've often watched smiths turn their work on the anvil and the power hammer (sometimes at mind boggling speed) 90 deg each time they strike the bar they're forging. I rarely do this prefering to work down one side and then the other.....What if any is the advantage of this?
the same guys hold their Glock sideways when they shoot...
12:41 am
September 24, 2010
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I do this when drawing points on a taper die because it balances the spread of the material between hits and allows a faster cycle; the heat also seems to be better retained due to energy transfer from the power hammer. When drawing down in a straight profile (like 1" round to 3/4" square) I practice what you described, i.e. several hits in one plane followed by the flip.
The only trouble with flipping between hits is when you mess up and over rotate, which seems to be a worse problem due to the pace.
6:37 am
March 22, 2010
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Your kidding right? Turning the work 90 deg between blows is fundamental forging 101 and it is exponentially more efficient than forging down one side and then the other. Bruce I'm shocked to hear you say that. If your not rotating your work between blows your expending many, many times more effort than is necessary, we are not talking a little bit but like 4 - 8 times as many blows. I cant explain the physics of it but Im sure someone could but basically rather than mushing the material about your squirting it in the direction you want.
Whatever you are, be a good one.
Abraham Lincoln
3:14 pm
NWBA Member
March 22, 2011
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Larry L;17198 wrote: I cant explain the physics of it but Im sure someone could but basically rather than mushing the material about your squirting it in the direction you want.
Here's what Brian Brazeal says on the subject:
"What happens when you strike it between a hammer and anvil at a forgeable heat? It will form a pill shape. You would not want to strike it again on the same side and form a thinner and longer pill shape if you are trying to draw it out. If you turn it 90 degrees after each hit it will maintain a smaller surface area contact with both hammer and anvil and come back to a more square shape. If it is struck properly, it will actually bulge the previous sides and therefore keep the surface area contact down to a minimum every time you turn it. It will put energy into the material with each strike instead of wicking heat away with the larger surface area contact with hammer and anvil."
as always
peace and love
billyO
3:21 pm
NWBA Member
September 29, 2011
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It seems completely counterintuitive to me that the boogie could draw material better than working a length of one side then a length of the other, but it wouldn't be the first time I found out that reality turned out to be the opposite of what I thought it was. I wonder if anyone has actually recorded data to test the idea. Maybe it's part of the reason my work goes so slowly.
3:36 pm
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March 30, 2010
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OK, here's another way to look at it.
The objective in drawing out a rod or bar is to *stretch* it lengthwise. That makes it thinner because its volume stays constant.
Normally it's said that drawing out requires hammering with or or a cylindrical surface, which will push material away preferentially in a direction perpendicular to the cylinder's axis. So, we use the horn, the rounded edge of the anvil, the rounded edge of a hammer. or a straight, cross or diagonal peen.
However, if the metal itself has a cylindrical shape (e.g. it's a round rod) and you hit it with a flat hammer against the flat face of the anvil, it will initially spread in the direction perpendicular to its own axis because it doesn't support itself well in that direction. Hit it once and it flattens outward. But then it's not cylindrical anymore. In fact, in flattening it forms a bulge out on both sides. If you rotate it 90 degrees and hit it, you're effectively hitting a new cylindrical surface (the bulge) whose axis is perpendicular to the rod's axis. It's not well supported in a direction along the rod's axis, so it gets pushed mostly in that direction.
As the others have said, this is the most efficient use of energy: only move the metal in the direction you want it to move-- along the length of the bar or rod.
Ken Albert;17205 wrote: It seems completely counterintuitive to me that the boogie could draw material better than working a length of one side then a length of the other, but it wouldn't be the first time I found out that reality turned out to be the opposite of what I thought it was. I wonder if anyone has actually recorded data to test the idea. Maybe it's part of the reason my work goes so slowly.
10:41 pm
January 18, 2011
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Larry L;17198 wrote: Your kidding right? Turning the work 90 deg between blows is fundamental forging 101 and it is exponentially more efficient than forging down one side and then the other. Bruce I'm shocked to hear you say that. If your not rotating your work between blows your expending many, many times more effort than is necessary, we are not talking a little bit but like 4 - 8 times as many blows. I cant explain the physics of it but Im sure someone could but basically rather than mushing the material about your squirting it in the direction you want.
Let's just say I never thought about it very much....:skip: ''Rarely'' was a bit heavy, It's more like when If feel inclined to. Tapers and points pretty much always at the anvil not as much in the PH where there's usually surplus power. Forging bars from round to flat in the PH never. My friend David Norrie shown tapering 4'' rd in his 5B never does in this situation and I doubt if he could There's still a whole lot more I don't know about blacksmithing even after 30 years or so than I do know and that comes with experience (oxymoron)hehe.
I think the physics are simple; the flatter something gets the cooler bigger surface area is way harder to move whereas the ''pill'' shape turned on end is going to be hotter/narrower and move allot easier when struck. Somebody at IFI kinda nailed it when he pointed out you could never heat a rod red hot on the anvil wailing on it without the boogie. Overlapping blows on one side and then the other work for me, but not so much when it comes taper and do the finishing blows.........WTF, I'm an old dog.....;)
"Be who you are and say what you feel, because those who mind don't matter, and those who matter don't mind."
— Dr. Seuss
1:49 am
June 24, 2010
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I've always figured that flipping the piece 90 degrees on each blow makes it easy for your eye to compare the width of the adjacent sides. That's probably more important when you're sneaking up on final size than when you still have a long way to go.
Somewhat along the same lines, if you place several blows next to each other to flatten a longer section, and then flip it to square up the same length, the piece will be cooler after you flip it. If you don't adjust the strength of your blows, it will end up rectangular. And even if you do adjust them, there's no way to calibrate how much you need without flipping the piece to compare the sides.
5:04 am
NWBA Member
November 8, 2010
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If you see it done properly it is pretty amazing how fast you can taper something out. From my limited experience it seems you can keep up comfortably with about 200 hits per minute. I watched Pat Maher here in Seattle do it probably better than anyone and I believe he learned it at Grant's shop. It looks like watching a good foosball player in action, all wrist...
My little kuhn is 220 per minute and I can run with it for a minute before I skip a beat and make a mess. Most times I am too lazy and run down one side then the other
They only remember you when you SCREW UP~!!!
5:19 pm
August 5, 2010
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NWBA Member
June 17, 2010
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Bruce Macmillan;17167 wrote: I've often watched smiths turn their work on the anvil and the power hammer (sometimes at mind boggling speed) 90 deg each time they strike the bar they're forging. I rarely do this prefering to work down one side and then the other.....What if any is the advantage of this?
When forging tool steels, turning is critical to coax the grain alignment into place and prevent potential cracks. This is frequently done by turning the steel 60 degrees between blows so it forms a hexagonal shape. The hexagonal shape has the advantage of having reduced corner angles, where a crack is most likely to start.
Sometimes with mild steel, if I am greatly changing the dimension of the stock, I will work it at ninety degrees halfway, forge to octogon, then continue forging with ninety degree blows to the final dimension.
This extra step doesn't seem to take more time. I can concentrate on moving the mass first and the octogonal shape allows for better correction of the alignment of the surface planes. This also seems to prevent small cracks that can sometimes form when doing tight bends.
7:31 pm
January 18, 2011
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''You can boogie all the iron some of the time, and
some of the iron all the time, but you cannot boogie all the iron all
the time''......BM...... [Image Can Not Be Found] .
"Be who you are and say what you feel, because those who mind don't matter, and those who matter don't mind."
— Dr. Seuss
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