The last post was really just a teaser with brief definitions and photos. Now let’s look a little further and try to get a handle on some of the tools and terms associated with raising.
(we will expand on these as we go along)
Raising: forming metal over (or on) a stake (of some sort) using a hammer to compress and stretch the metal.
Stake: a solid object (can be various material) with varying curvatures.
Course: one complete pass of hammering while raising.
Synclastic: forging metal along two curves at right angles to one another and moving in the same direction. (bowl)
Anticlastic: forging metal along two curves which are moving in opposite directions. (pringle)
Annealing: heating metal to increase its flexibility (annealing article here)
I thought a little sketch might help clarify the curvatures for us. These sketches are reproductions of ones found in the book Form Emphasis. (I considered taking a photo of the page and then decided that went too far into copyright issues…so my crude sketches will have to do.)
anticlastic and synclastic sketch
Alternate imagery is sometimes helpful.
A saddle is anticlast as it curves in two opposing directions.
One curve goes ‘down’
One curve goes ‘up’
think of the long line as a curvature that follows the horses body, it would wrap around the horses ‘trunk’. The other, shorter, line creates a space for the riders bottom.
As an abstract – it can hold something from the top and from the bottom
Alternately, a synclast shape, in its basic form, only holds from one direction.
all of the curves move in the same direction.
or if the bowl were flipped, all curves would move ‘down’
Don’t be fooled by imposters!
The following image is neither synclast or anticlast.
only one curve!
Why? Because there is only one curve.
To become anticlast, the two points on the straight line/plane would need to move down.
To become synclast, the two points on the straight line/plane would need to move up.
The Tools I Use
These are fairly simple stakes. The metal ones having only one curvature on each end. Typical sinusoidal stakes have a series of curves on one stake.
Surprisingly, there is a lot of variation in forming that can be done on these.
Stakes 1 and 2 are metal and would be used with a nylon or delrin hammer.
Stakes 3 and 4 are delrin and would be used with a metal hammer.
Never use a metal hammer on a metal stake as it would mar and pinch the metal too much.
A delrin hammer is not used on a delrin stake as both materials are going to ‘give’ a little and therefore the force of the hammer blow is going to be diffused too much. You will waste a lot of energy hammering for very little movement of metal.
Here I have two metal ‘raising’ hammers and one hammer that is made of delrin.
Technically, the metal hammers are sold as ‘bordering’ hammers. I have two because they have different sized heads.
Hammers used for raising typically have profiles longer than they are wide.
The other tool is a vise. I use a regular vise bolted to my workbench although alternatives could be a GRS system that has a holding mechanism or some stake sets may come with their own holder.
One problem that can occur with a regular vise is slippage of the stake in the vise while hammering.
I combat that problem by making a hammock for my stakes. Basically it is a hanger made of brass sheet that overlaps the top of the vise jaws.
Here is how I make mine:
Estimate how much you need to hang over the top of the vise jaw. Place that much of the sheet of brass down into the vise. Bend and mallet down.
Remove sheet from vise and place stake at the bend. Mark the depth of your stake.
Bend that second line, bringing the first fold UP. Now you have a little ledge for your stake to sit on.
Bend again at the end of the stake, bringing the bottom ledge up the other side of the stake.
Next, mark a line at the top of the stake, while it is on the ledge.
You will fold DOWN, away from the stake at this line.
Now you have a little hammock for your stake. This will help give the stake something to rest on and keep it from moving down while you hammer!
I normally place this entire packet back into the vise, tighten the vise up, and mallet down the top edges. This confirms all the folds so they stay put.
You can also conform the top of the flaps to the top of your vise jaws.
When you take the ‘hammock’ out of the vise, trim and sand so you don’t inadvertently cut yourself!
Next time we’ll move on to the actual forming process!